# Presentation: 737126

## Pablo Santos and Guy Rader
WFO Miami, FL

David Sharp and Matthew Volkmer
WFO Melbourne, FL

- WFO Miami, FL
- David Sharp and Matthew Volkmer
- WFO Melbourne, FL

**From the 2007 NOAA Hurricane Conference**

*PS/DS*

***“******HURRICANE CONDITIONS EXPECTED.”***

- Using Tropical CycloneWind Speed Probabilities to ImprovePublic and Marine Text Forecasts

- Module #1

**Notes:**
Hello, once again.  Welcome to another hurricane season!  My name is David Sharp.  I am the Science & Operations Officer at the National Weather Service Forecast Office in Melbourne, FL.  On behalf of my colleagues Pablo Santos and Guy Rader of the Miami Forecast Office, and Matthew Volkmer here at Melbourne, I would like to share with you the latest information on Using Tropical Cyclone Wind Speed Probabilities to Improve Public and Marine Text Forecasts.  Although this training is in direct support of an ongoing experiment, it is designed specifically for preparation regarding the 2008 season.  Again, this experimental effort endeavors to elevate the quality and usefulness of our wind forecasts whenever tropical storms or hurricanes threaten.  To the new WFOs participating this year, we warmly extend a hearty welcome aboard!  And, to our returning participants from previous years, a big thanks for your continued hard work and commitment.  We’re certainly poised for a potentially exciting hurricane season as it pertains to our project.  

## Two Training Modules

- Module #1: *Concepts for Using Tropical Cyclone*
*                      **Wind Speed Probabilities to Generate*
*                      **Expressions of Uncertainty*
- Module #2: *Applying Expressions of Uncertainty*
*                      **to the ZFP and CWF during*
*                      **Tropical Cyclone Wind Situations*

**In Support of an Experimental Project for 2008**

**Notes:**
There are two training modules associated with supporting this experiment.  They are designed to be viewed by WFO forecasters at participating coastal offices within the Eastern and Southern Regions.  The modules are intended to help prepare forecasters and local management for collectively taking the important step of embracing probabilistic information, and addressing the specific applications of benefit as it relates to the stated project.  Module #1 is entitled “Concepts for Using Tropical Cyclone Wind Speed Probabilities to Generate Expressions of Uncertainty.”  Module #2 is labeled “Applying Expressions of Uncertainty to the ZFP and CWF during Tropical Cyclone Wind Situations.”  Thus, Module # 1 is {click} is more about concepts and head knowledge, while Module #2 {click} is more about the hands-on nuts and bolts.         

## Training Module (1 of 2)

- Module #1: Concepts
- Motivation
- Overview and Background
- Probability Concepts
- Situational Thresholds
- gridded inputs
- Expressions of Uncertainty
- unique expressions
- text formatters
- Future Plans

**Notes:**
So, let’s begin!  The module that you are now viewing is the first of the two modules.  Much like last year, the subsequent series of slides in this lesson will present to the viewer a discussion on the motivating factors for the Expressions of Uncertainty experiment, while also giving a brief overview and some supporting background.  This module will offer a quick review of concepts and terms associated with the newly available tropical wind speed probabilities.  Then, specific gridded inputs will be identified for the dynamic generation of unique expressions of uncertainty by text formatters according to the forecast situation and period.  These formatters include the GFE-version for the Zone Forecast Product (or ZFP) and the Coastal Waters Forecast (or CWF).  However, the logic is also being tested for use within the formatters located at the respective National Weather Service web servers which support the Point-n-Click forecasts that are commonly used when customers desire point-specific weather information.  And finally, as with any experimental project, there are associated goals which, of course, lead to future plans.  We’ll take a brief moment at the end of this module to do a little road mapping.               

## Objectives

- To better understand the shortcomings of deterministic-only wind speed forecasts during high impact weather events.
- To gain a greater appreciation for the value of probabilistic wind speed information and how incremental probabilities can be used to improve certain text products.
- To become familiar with the nine identified expressions of uncertainty and the unique situations that invoke them.

**Notes:**
Importantly, as you view this module you are asked to consider the following three objectives.  By the end of our session here, it is hoped that you will have {click} a better understanding of the shortcomings of deterministic-only wind speed forecasts, especially for high impact weather events such as landfalling tropical cyclones.  A second objective {click} is that you gain a greater appreciation for the value of probabilistic wind speed information.  Recall that probability information can be offered to decision-makers and users in a variety of forms, but each form is designed to answer specific questions or to accommodate particular forecast or warning dilemmas.  In this module, we’ll examine the use of the incremental form of the wind speed probabilities.  The third objective {click} is to become familiar with the nine identified expressions of uncertainty used when tropical cyclones threaten within the 5-day forecast, and the unique situations that invoke them via the text formatters.   

## Wind Speed Probabilities

- Interval Probabilities &
- Cumulative Probabilities

**Cumulative – 64 knot**

- PWS

**Notes:**
OK...Tropical Cyclone Wind Speed Probabilities.  By now, many coastal WFOs should be getting used to seeing...and using...some of the wind speed probabilities that are now officially available.  For example, the Probabilistic Wind Speed text product (or PWS) as issued by the National Hurricane Center is now widely available to users and is displayable on AWIPS.  It contains both the interval-form and cumulative-form of the probabilities out to 120 hours for pre-defined locations.  Here we have an example from Tropical Storm Ernesto (2006) showing the probabilities associated with 34-knot winds for several select sites in Florida and Georgia.  Of notable relevance {click} for forecasters is the fact that the cumulative probabilities can also be displayed graphically on D2D such as the example here from Hurricane Frances (2004).  More so, they can be fed into GFE for various tool applications such as the TC WindThreat tool.     

## Probability Definitions 

** ****Cumulative** – The probability of sustained winds reaching or exceeding the specified wind speed threshold between the 00 hour forecast and a specified forecast hour.
-  Available in D2D and within the PWSAT# text product.
** ****Individual (Interval)** – The probability of sustained winds reaching or exceeding the specified wind speed threshold beginning during an individual 12 hour forecast period ending at the specified forecast hour (e.g., period of onset).
-  Not available in D2D, but within the PWSAT# text product.

- (A Quick Review)

**Notes:**
As a quick review:  Cumulative probabilities answer the question: “What is the probability that sustained winds in a given location will reach or exceed either 34-, 50-, or 64-knots over the course of the next 120 hours?”  This question may be posed for the 00-12hr period, 00-24hr period, 00-36-hr, 00-48hr, and out to the 120hr period if desired.  Contrastingly, interval probabilities (or sometime called individual probabilities) answer the question: “What is the most likely forecast period that the particular wind speed threshold will be reached or exceeded?”  Or, in other words, “What is the expected period of onset?”  Again, WFO forecasters should be becoming familiar, if not comfortable, with these probabilities.  

## Suggested Training

- (additional background information)

**For more information, also see:**
** ****Knaff and DeMaria (2005)**
** ****Gross et al. (2004)**

**Notes:**
But we’re not here to discuss these particular probability sets today.  So, for further information, viewers are directed to an excellent training module on the subject as prepared by representatives at the Hurricane Center and should be available through the Learning Management System.  If interested in some of the more intricate details {click} you may read the Joint Hurricane Testbed Project Report by Knaff and DeMaria (2005), or perhaps the extended abstract by Gross et al., as presented at the AMS Hurricane Conference (2004).  Also, a quick literature search through the AMS will reveal several more recent extended abstracts written on these wind speed probabilities, to include the generation methodology, operational use, and particular validation studies.        

## Probability Definitions 

** ****Cumulative** – The probability of sustained winds reaching or exceeding the specified wind speed threshold between the 00 hour forecast and a specified forecast hour.
-  Available in D2D and within the PWSAT# text product.
** ****Individual (Interval)** – The probability of sustained winds reaching or exceeding the specified wind speed threshold beginning during an individual 12 hour forecast period ending at the specified forecast hour (e.g., period of onset).
-  Not available in D2D, but within the PWSAT# text product.
** ****Incremental** –The probability of sustained winds reaching or exceeding the specified threshold during the 12 hour forecast period ending at the specified forecast hour.
-  Now available in D2D (across the SBN), but not within the PWSAT#.
** ****These are the probabilities referenced throughout this presentation.**

- (A Quick Review)

**Notes:**
Now, there is a third form of the probabilities that has not been so widely advertised. This is the incremental form of the probabilities {click}.  This is the probability set employed by the Expressions of Uncertainty project and therefore referenced throughout the remainder of this training.  These probabilities are currently not explicitly released to the public, nor included in the PWS text product.   However, they are now available for transmission over the AWIPS/SBN starting this season, and therefore available for WFO use.              

## Incremental Probabilities

** ****Incremental** –The probability of sustained winds reaching or exceeding the specified threshold during the 12 hour forecast period ending at the specified forecast hour.
-  Now available in D2D (across the SBN), but not within the PWSAT#.

- What do they look like?

**Notes:**
So, what do the incremental probabilities look like, and of what value are they?  The incremental probabilities express {click} the probability that sustained winds will reach or exceed 34-, 50-, or 64-knots during successive 12-hour forecast periods ending at the specified forecast hour.  That is, the 00-12hr period, the 12-24hr period, the 24-36hr period, and so on out to 120 hours if desired.  Let’s examine these a little closer.   

## 34 Knot (36 Hours)

**TC Wind Speed Probabilities on AWIPS-D2D**
**(Incremental-form for 34-, 50-, and 64-knots)**

**34 knot / 36 hour**

**= EXAMPLE =**

**Hurricane Charley 2004**

**Notes:**
Here is an example of the incremental probabilities...as displayed on D2D... for the 34-knot wind speed threshold for the 24-36hr forecast period as Hurricane Charley was forecast to move across Western Cuba, across the Lower Keys, and toward the Western Florida Peninsula.  Recall that Charley did make landfall as a major hurricane at Punta Gorda back in August 2004.  In application, we can see the elevated probabilities over the stated areas are to at least experience tropical storm force winds during this period.  This is from the 06Z advisory on the 12th.  

## 34 Knot (48 Hours)

**Hurricane Charley 2004**

**34 knot / 48 hour**

**= EXAMPLE =**

**TC Wind Speed Probabilities on AWIPS-D2D**
**(Incremental-form for 34-, 50-, and 64-knots)**

**Notes:**
Here is an example extracted from the same probability set (that is, the same advisory) for the 34-knot threshold for the 36-48hr period.  The image shows high probabilities for at least tropical storm force winds to then overspread Central Florida during this period. 

## 34 Knot (60 Hours)

**Hurricane Charley 2004**

**34 knot / 60 hour**

**= EXAMPLE =**

**TC Wind Speed Probabilities on AWIPS-D2D**
**(Incremental-form for 34-, 50-, and 64-knots)**

**Notes:**
And one more for the 48-60 hr period to give you a sense of behavior for successive forecast increments. Note that an additional benefit of the incremental probabilities is that they help mitigate the “skinny black line” syndrome with respect to the center track forecast; and as we’ve seen is especially true when the images are looped in sequence.  This is because the probabilities are distributed about the official forecast track, and account for inherent uncertainties when forecasting that track, as well as the intensity and size of the tropical cyclone. 

## 64 Knot (36 Hours)

**Hurricane Charley 2004**

**64 knot / 36 hour**

**= EXAMPLE =**

**TC Wind Speed Probabilities on AWIPS-D2D**
**(Incremental-form for 34-, 50-, and 64-knots)**

**Notes:**
Well, that’s great information, but Charley was a hurricane.  So, let’s look at the incremental probabilities for 64-knots and see what can be gleaned.  Here is the D2D depiction for the 24-36hr forecast period, but I believe that this is taken from the next advisory cycle.  This is the 12Z advisory on the 12th.  Elevated probabilities for hurricane force  winds are zero-ing in on WFO Tampa’s area of responsibility.  

## 64 Knot (48 Hours)

**Hurricane Charley 2004**

**64 knot / 48 hour**

**= EXAMPLE =**

**TC Wind Speed Probabilities on AWIPS-D2D**
**(Incremental-form for 34-, 50-, and 64-knots)**

**Notes:**
For the 36-48hr forecast period, post landfall.  Notice that the probabilities are getting much smaller.  This occurs for two reasons: Reason1 – the cyclone is forecast to suffer from inland wind decay after landfall, and Reason 2 – the incremental probability for select wind speed thresholds naturally decreases with time.    

## 64 Knot (60 Hours)

**Hurricane Charley 2004**

**64 knot / 60 hour**

**= EXAMPLE =**

**TC Wind Speed Probabilities on AWIPS-D2D**
**(Incremental-form for 34-, 50-, and 64-knots)**

**Notes:**
And lastly, for the 48-60hr forecast period to complete our introduction to incremental probabilities.  Again, the incremental probabilities are provided through 120 hours (or through Day5), and they are available for wind speed thresholds of 34-, 50-, and 64-knots.  Hopefully, this has given you some feeling for the intended use as you can see the incremental probabilities respond nicely for complementing our incremental deterministic wind speed forecasts such as already delivered in the ZFP or CWF, and of course, in our NDFD grids.  It is important to note here, before going on, that the probabilities do not take into account mesoscale contributions whatsoever.  They are purely derived from the latest synoptic forecast provided by the National Hurricane Center.   

## During potential high impact weather events such as tropical cyclones (TC), users not only demand our ‘best forecast’, but also require a corresponding expression of uncertainty for decision-making purposes.
Therefore, we are exploring the use of TC Wind Speed Probabilities to elevate the utility of official text products:
That is, to include situational expressions of uncertainty within the Zone Forecast Product (ZFP) and the Coastal Waters Forecast (CWF).
For WFOs, this effort crosses a major threshold for incorporating probabilistic data (other than PoP) within official National Weather Service forecast products.

- Therefore, we are exploring the use of TC Wind Speed Probabilities to elevate the utility of official text products:
- That is, to include situational expressions of uncertainty within the Zone Forecast Product (**ZFP**) and the Coastal Waters Forecast (**CWF**).
- For WFOs, this effort crosses a major threshold for incorporating probabilistic data (other than PoP) within official National Weather Service forecast products.

**Proposed WFO Use** (Item 42-05 from NOAA Hurricane Conference, 2005)

**Notes:**
Well, how does this relate to the Expressions of Uncertainty project?  Back in 2005, meteorologists at WFOs Miami and Melbourne decided to put the probabilities to the task with the intent of improving wind speed forecast information during tropical cyclones.  The significant leverage for the endeavor is that during tropical cyclones decision-makers not only demand our best forecast (that is, our deterministic forecast), but also require a corresponding expression of uncertainty in order to make responsible decisions.  Tropical cyclones are high impact events that affect many people.  Motivation came on the heels of the record hurricane season of 2004 when Florida was repeatedly pounded by landfalling systems {click}.  Therefore, forecasters began to explore the use of incremental wind speed probabilities to elevate text product utility {click}.  Specifically, to include expressions of uncertainty in the textual ZFP and CWF {click}.  And, to take an early step in helping to knock down major barriers toward incorporating probabilistic data within official NWS products.

## Expressions of Uncertainty

- ZFP

**Katrina (2005)**

**New Orleans**

**Notes:**
Here’s what we mean.  Hurricane Katrina made landfall on a Monday morning, August 29, 2005.  Certainly, Katrina was well-forecast.  But consider a local forecast by a WFO, say New Orleans, back on Saturday.  What level of confidence might be conveyed about the deterministic wind speed forecast?  And could that level of confidence, an expression of uncertainty, {click} be included in the forecast itself?  Take a look at the experimental Zone Forecast for New Orleans and its deterministic wind speeds.  Although a Hurricane Warning is in effect, winds are not expected to approach tropical storm force until Sunday Night, with hurricane force winds then expected for Monday.  Yet, inherent forecast uncertainties involving potential along-track and cross-track errors over a 24-36 hour period make it difficult to declare this with absolute certainty.  This is also true for potential changes which might involve either the expanding or shrinking of respective wind radii.  Now take a look {click} at the introductory line for the Sunday Night period, as well as the Monday and Monday night periods.  For visual ease, they are underlined in red.  Each period begins with an expression of uncertainty regarding the forecast conditions for that period.  For example, on Sunday Night, tropical storm conditions are expected for New Orleans with hurricane conditions possible.  Then on Monday, hurricane conditions are expected.  And finally, although the high winds are forecast to begin subsiding during Monday Night, hurricane conditions are still possible and thus worth mentioning.  Again, this is the experimental version of the ZFP as generated by the GFE formatter during testing.           

## Expressions of Uncertainty

**New Orleans**
**Lake Pontchartrain**

**Katrina (2005)**

- CWF

**Expressions of Uncertainty**

**Notes:**
Similarly, this can be done for the Coastal Waters Forecast.  The expressions of uncertainty are underlined in red and complement the explicit deterministic wind speed for that period.

## Point-n-Click Web Version

**FRANCES (ZFP)**

**Point-n-Click Web Version**

**Notes:**
A particular showcase feature for this season is the Point-n-Click version of the formatters that have been successfully ported over to the web servers.  This was done to facilitate reasonable consistency between the zone and point forecasts.  Here on the left is a zone forecast for Palm Beach County during Hurricane Frances in 2004.  Note the enhanced wording for each period between Friday and Sunday as the event ramps up and then down.  Keep in mind, Frances was very big and very slow.  Correspondingly, on the right hand side of this slide you see the Point-n-Click version for the city of West Palm Beach (which, of course, is in Palm Beach County).  Note the wording indicated by the red arrows.  Although the point forecast won’t always exactly match the zone forecast as with this example, it will typically come pretty close...which is the case for any other forecast situation.  And then there is the tombstone icons for tropical cyclones which run left to right across the top of the page.  Because of the logic associated with the wind speed probabilities, we can reasonably and responsibly invoke these icons as far out as Day 5.  Otherwise, this would not be possible.                     

## A Few Words of...

- CAUTION !!!

- All forecasters at each of the participating WFOs must understand that during any real-time tropical cyclone event...their first and primary commitment is to the protection of life and property of those within their area of responsibility.  The formatters are still experimental.

**Notes:**
Before we move on to project details, we must take a moment to highlight a few very important words of caution.  It is important to ensure that all forecasters at each of the participating WFOs understand that during any real-time tropical cyclone event this season...their first and primary commitment is to the protection of life and property of those within their area of responsibility.  So, if the experimental tropical cyclone formatters, for any reason, do not deliver to the forecaster a coherent forecast message, it will be their responsibility to fix any confused wording before transmission.  That is, it remains the responsibility of the participating WFO to deliver a quality forecast product to the public.  The experimental formatters should deliver superior text in most situations, but remember, we are still in experimental mode with more to learn.  Your local management, as well as your forecasters, must understand this.           

## Rules for Formatters

- The intent is to establish a set of rules for triggering enhanced wording which responsibly conveys wind speed uncertainties within text forecasts according to the temporal period.
- This is accomplished through the Graphical Forecast Editor (GFE) and automated formatters by making appropriate use of the following grids sets:
- Hazard Grids
- Wind Grids
- Tropical Cyclone 34 kt Wind Speed Probability Grids
- Tropical Cyclone 64 kt Wind Speed Probability Grids
- Initial development and testing was done during the 2005-06 seasons by WFOs MFL and MLB.  The experimental effort was then expanded during the 2007 season to include a few more WFOs, with HGX playing a critical role.  The good news is that more WFOs are being included for the 2008 season, with the Point-n-Click functionality also making its debut.

**Notes:**
The initial work and challenge of Expressions of Uncertainty experiment was to see if a set of rules for triggering enhanced wording could be established that would responsibly convey wind speed uncertainties according to the temporal forecast period and according to the situation at hand.  At the forecaster’s disposal {click} are four grid sets on GFE that are used by the ZFP and CWF formatters to identify the situation.  They are the Hazards Grids, the Wind Grids, the Tropical Cyclone 34-knot Wind Probability Grids, and the 64-knot Wind Probability Grids.  Since the experimental formatters are coded to address either tropical storm or hurricane conditions, the 50-knot Wind Probability Grids are not used (for now anyway).  Early on, most development work was performed {click} by MFL and MLB during the 2005 and 2006 seasons.  A much needed expansion for diversity of experience was facilitated for 2007 as a few more WFOs were added to the project.  In fact, WFO HGX played a critical role last year.  This season also stands to be exciting as additional WFOs will be able to go live with enhanced tropical versions of the ZFP and CWF, bringing a broader opportunity for feedback.  This includes the Point-n-Click forecasts on WFO web sites.  The offices participating in the Expressions of Uncertainty project during 2008 are: Boston, Charleston, Wilmington, Jacksonville, Melbourne, Miami, Key West, Tampa Bay, Tallahassee, Mobile, New Orleans, Houston, Brownsville, and San Juan.            

## Grid Set Descriptions

- The Hazard Grids include Hurricane/Tropical Storm Warning/Watch grids as issued:
- For coastal zones by NHC
- For inland zones by WFO
- For marine zones by WFO
- The Wind Grids represent the sustained wind speed forecast as generated by the TCM Wind tool (from the latest NHC forecast), but with WFO value-added contributions for local effects (e.g., elevation, exposure, gap winds, etc.).
- Again, the Tropical Cyclone Wind Probability Grids (as obtained through TPC) are the incremental-form probabilities for 34 knot and 64 knot winds.
- The incremental probabilities for 50 knot winds are not needed for this application.

**Notes:**
A few words of clarification about the gridded inputs should be said here to ensure that everyone is of the same mindset.  Regarding the Hazard Grids {click}, these include all Hurricane or Tropical Storm Watches or Warnings issued for the coastal zones within your forecast area by NHC, or any inland Watches or Warnings issued by the WFO, or any marine Watches or Warnings issued by the WFO.  So, you see that the local WFO does play a big part here.  Regarding the Wind Grids {click}, these represent the grids as generated by the TCM Wind tool based on NHC’s latest forecast out through Day5, but also including any WFO value-added contributions for local effects such as elevation, windward vs. leeward sides of mountains or even islands, marine exposure for large inland lakes, then there is gap winds, etc.  Lastly, {click} the formatters, of course, use the Tropical Cyclone Wind Speed Probabilities for both 34- and 64-knots out to 120 hours.

## A Series of Situational Rules

- Situational Rules According To Forecast Period
-  00-48 hour Rules (~ Warning/Watch periods)
- 00-12 hours (rule subset)
- 13-24 hours (rule subset)
- 25-48 hours (rule subset)
-  49-120 hour Rules (~ Extended periods)
- Deterministic vs. Probabilistic Information
- Deterministic wind speeds (for sustained winds) have the most value during the 00-24 hour period, and have decreasing value with increasing time.
- Probabilistic wind speeds (for sustained winds) have increasing value with increasing time.
- Watches and Warnings have the greatest weight due to applied human expertise.

**Notes:**
Formatter logic has been laid out to handle all of the permutations of combinations of Watches, Warnings, Wind Speeds, and Probabilities.  This is accomplished through a series of situational rules according to the forecast period.  In general, there is a 00-48hr rule set to handle the Watch and Warning periods, and a 49-120hr rule set to handle the extended forecast periods.  The philosophy of the logic is that deterministic wind speeds have the most value during the Day1 forecast, and have decreasing value with increasing time.  In addition, probabilistic wind speeds have increasing value with increasing time.  And, Watches and Warnings carry the greatest weight among the grid inputs since their issuance is largely based on forecaster expertise and the considerable concern for life and property.      

## Text Formatters: Logic Hierarchy 

| Priority | Sensitivity | Grid Sets |
| --- | --- | --- |
| 1.
 | Official Warnings,
Official Watches | Hazard Grids |
| 2.
 | Official Forecast | Wind Grids (Speed) |
| 3.  | Forecast Uncertainty
 | 64-knot Probability Grids,
34-knot Probability Grids |

- Note: Forecast Uncertainty implies appreciation for the inherent errors regarding the forecast track, intensity, and size of the tropical cyclone.

**Message Sensitivity**
**(Fostering One Forecast Message)**

**Notes:**
The table displayed here shows the logic hierarchy for gridded inputs. When developing the actual logic that distinguishes the various tropical cyclone situations, we wanted to make sure that the “One Message” concept was not disrupted between NHC and the WFO, but rather enhanced.  This is true among adjacent WFOs as well.  As you can see, the formatters are most sensitive to the presence of Watches and Warnings.  They then look at the magnitude of the forecast wind speed.  And finally, they consider forecast uncertainty which we haven’t been able to do before; that is, until now.  Importantly, it takes the collective weight of all of these inputs to determine the appropriate expression of uncertainty for any given situation.   

## (The Nine Expressions of Uncertainty) 

|  HURRICANE CONDITIONS *
 HURRICANE CONDITIONS  EXPECTED
 HURRICANE CONDITIONS  POSSIBLE |
| --- |
|  TROPICAL STORM CONDITIONS  *
 TROPICAL STORM CONDITIONS  * WITH HURRICANE CONDITIONS POSSIBLE
 TROPICAL STORM CONDITIONS EXPECTED
 TROPICAL STORM CONDITIONS EXPECTED WITH HURRICANE CONDITIONS POSSIBLE
 TROPICAL STORM CONDITIONS POSSIBLE
 TROPICAL STORM CONDITIONS POSSIBLE WITH HURRICANE CONDITIONS ALSO POSSIBLE |

**Baseline Phraseology**

**Notes:**
The formatters weigh the inputs and then chose between nine unique phrases to express the uncertainty of anticipated conditions.  Here are the nine expressions.  There are three expressions for hurricane situations that are presented to you in descending order of confidence level {click}.  The phrase “Hurricane Conditions” is an emphatic expression of very high confidence; it’s categorical {click}.  The phrase “Hurricane Conditions Expected” is an expression of high confidence, but is not emphatic or categorical.  Yet, for a given zone grouping the forecaster is expecting hurricane conditions, even when forecast error is factored-in {click}.  And then the phrase “Hurricane Conditions Possible” denotes a lesser degree of confidence, but remains relevant to mention given the threat.  This thinking {click} is continued along for tropical storm conditions too, where we have six more expressions.  There are more situations to deal with here since it is possible to have a coincident threat for hurricane conditions while considering the threat for tropical storm conditions for a given location and forecast period {click}.  I’ll give you a moment to review the nine expressions used as the baseline phraseology before commenting further.  {wait about 20 seconds}           

## (The Nine Expressions of Uncertainty) 

|  HURRICANE CONDITIONS *
 HURRICANE CONDITIONS  EXPECTED
 HURRICANE CONDITIONS  POSSIBLE |
| --- |
|  TROPICAL STORM CONDITIONS  *
 TROPICAL STORM CONDITIONS  * WITH HURRICANE CONDITIONS POSSIBLE
 TROPICAL STORM CONDITIONS EXPECTED
 TROPICAL STORM CONDITIONS EXPECTED WITH HURRICANE CONDITIONS POSSIBLE
 TROPICAL STORM CONDITIONS POSSIBLE
 TROPICAL STORM CONDITIONS POSSIBLE WITH HURRICANE CONDITIONS ALSO POSSIBLE |

-  The  **********  ***phrases are equivalent to imminent or ongoing conditions as
-   reflected in the 00-12 hour period simultaneously by the hazard, wind, and
-   probability grids.
-  The word **EXPECTED** is used in situations mainly during the Warning period, but is
-   also selectively used in the Watch period (e.g., Day 1 & 2, or out to period 4).
-  The word **POSSIBLE** is used during the extended period (e.g., Day 3 - 5), but is also
-   used in specific situations within Watch/Warning period.
-  Also, certain situations require compound phrases (e.g., when there is a Tropical
-   Storm Warning with a Hurricane Watch).

**Baseline Phraseology**

**Notes:**
OK.  To elaborate further, {click} the phrases highlighted by asterisks are only used in the first period of the forecast.  Again, they are only used during the 00-12hr forecast.  To reach this level of high confidence, hurricane or tropical storm conditions must be imminent or ongoing.  Thus, during the first period, whenever the trigger thresholds for the hazard grids, the wind grids, and the probability grids are simultaneously reached...these phrases are invoked by the formatters and placed within the opening text.  Phrases which use the word “Expected” {click} are mainly invoked during the Warning period (or within the first or second periods).  However, there are a few times when you might see such phrases during the Watch period or when the Warning period itself goes beyond 24 hours as it did prior to the landfall of Hurricane Frances (2004).  The hurricane was big and slow, but well-behaved and well-forecast.  Forecasters were able to confidently extend the warning period beyond the typical 24 hours before landfall.  This scenario has been accommodated within the logic of the formatters.  This (click} leaves us to discuss phrases which use the word “Possible”.  Well, the best and easiest way to describe it as being all of the other remaining situations when the possibility of hurricane or tropical storm conditions is worth mentioning due to the potential impact.  The current directives, especially for the marine forecast, already allow the use of the phrase in the extended part of the forecast.  With the incremental probabilities, we now have a coherent and consistent way of including this expression of uncertainty.  Another way in which the phrase is used is toward the flanks of a rather large Watch area during the third or fourth periods, or even is some cases toward the flanks of a large Warning area during the first or second periods.  A final comment {click} before we move on, certain situations require the use of compound phrases to fully express the uncertainty; there are three such expressions as you can see.  Again, these are invoked whenever there is a coincident threat for both tropical storm and hurricane conditions.  On such example would be when a Tropical Storm Warning is posted along with a Hurricane Watch for a particular zone.            

## Triggers

- For a given zone or zone combination, in order to consider a situation as being imminent or ongoing within the first period of the text forecast requires:
-  Tropical Storm (Hurricane) Warnings to be in effect...***AND***...maximum Wind
-    forecast to be greater than or equal to 34 knots (64 knots)...***AND*****...**the 34 knot
-    (64 knot) Probability to be greater than or equal to the PWS34 threshold
-    (PWS64 threshold).

| Phrase | Period | PWS64 | PWS34 |
| --- | --- | --- | --- |
| ‘Imminent’ or ‘Ongoing’ | 00-12 hr | 30% | 70% |

- Note: Initial probability thresholds were empirically-determined; future refinements
- are likely. This is true for each temporal interval of the forecast.

**Triggers**

**Notes:**
By now, many of you might be wondering what the respective probability thresholds are per forecast period and how they specifically factor into the basic formatter’s logic.  The next few slides will address this.  For the first period, the formatters will evaluate whether tropical storm (or hurricane) conditions are either imminent or ongoing.  For this to be so, Warnings must already be in effect and forecast wind speeds must reach or exceed a corresponding 34-knot (or 64-knot) wind speed threshold.  Additionally, the respective probability threshold must also be met in order to invoke such emphatic language of confidence.  The threshold for the 34-knot probability is 70% for the 00-12hr period, while the 64-knot probability is 30%.  One might ask {click} why these values?  Well, these threshold values, and the others that will soon be shared with you, were empirically-derived and based on probability distribution assessments from multiple storms from the 2004 and 2005 seasons as they affected WFOs MFL and MLB.  Future refinements are up for consideration, especially now that other WFOs are becoming involved in the evaluation process.         

## Triggers

-  Tropical Storm (Hurricane) Warnings to be in effect...***AND***...maximum Wind forecast to be
-   greater than or equal to 34 knots (64 knots)...***OR***...
-  Tropical Storm (Hurricane) Warnings to be in effect...***AND***...maximum Wind forecast to be
-   greater than or equal to 25 knots (50 knots)...***AND***...the 34 knot (64 knot) Probability to be
-   greater than or equal to the PWS34 threshold (PWS64 threshold) according to the forecast
-   period.

| Phrase | Period | PWS64 | PWS34 |
| --- | --- | --- | --- |
| EXPECTED | 00-12 hr | 15% | 50% |
|  | 13-24 hr | 12% | 40% |
|  | 25-36 hr | 10% | 35% |
|  | 37-48 hr | 9% | 30% |

**(Periods 1-4: When conditions are EXPECTED)**

**Triggers**

**Notes:**
Even so, the empirically-derived thresholds have behaved very well during testing.  So, here is the trigger logic for expressions which utilize the word “Expected.”  The table shows the graduation of probability thresholds as the forecast progresses through the first four periods.  For tropical storms, the threshold begins with 50% for the first period, but gradually reduces to 30% by the fourth period.  For hurricane probabilities, it begins with 15% and reduces to 9%.  You may be thinking, “Wow, those aren’t very high probabilities!”  Remember, the probability of a high impact event such as hurricane force winds to take place in a specific location during a specific forecast period can be fairly small, especially the farther out in time you go.  However, just because the probabilities are small doesn’t mean that they aren’t significant.  It is this fact that fuels the debate as to whether incremental probabilities should be released to the public.  Well, sophisticated users of the data can make good use of it.  This includes WFOs, of course.  For less-sophisticated users, the formatters distill the information along with the other inputs into easy to understand words.  This is an example expert interpretation, a growing area of future service for the National Weather Service.          

For a given zone or zone combination {click}, invoking the word “Expected” requires: 

Tropical Storm (or Hurricane) Warnings to be in effect...AND...maximum Wind forecast to be greater than or equal to 34 knots (or 64 knots)...OR... {click}

Tropical Storm (or Hurricane) Warnings to be in effect...AND...maximum Wind forecast to be  greater than or equal to 25 knots (or 50 knots)...AND...the 34 knot (or 64 knot) Probability to be greater than or equal to the PWS34 threshold (or PWS64 threshold) according to the forecast period. 

## Triggers

| Phrase | Period | PWS64 | PWS34 |
| --- | --- | --- | --- |
| POSSIBLE | 00-12 hr | 15% | 50% |
|  | 13-24 hr | 12% | 40% |
|  | 25-36 hr | 10% | 35% |
|  | 37-48 hr | 9% | 30% |
|  | 49-60 hr | 8% | 25% |
|  | 61-72 hr | 7% | 20% |
|  | 73-84 hr | 6% | 17.5% |
|  | 85-96 hr | 5% | 15% |
|  | 97-108 hr | 4% | 12.5% |
|  | 109-120 hr | 3% | 10% |

- According to the situation, the word **POSSIBLE** can be invoked anytime throughout the five-day forecast, and is the qualifier most often used within the enhanced phrasing. Within the 00-48 hour forecast, if imminent/ongoing criteria are not met, or EXPECTED criteria are not met, the word POSSIBLE is used whenever the probability thresholds are exceeded for the given time period. In the extended (e.g., beyond 48 hours), an additional constraint of winds _>_ 20 knots is imposed.

**(Periods 1-10: When conditions are POSSIBLE)**

**Triggers**

**Notes:**
Well, you should be getting the hang of this by now.  As the table here indicates, the word “Possible” may be used within an expression of uncertainty anytime throughout the five-day forecast.  And as mentioned, it is the qualifier that is most often used whenever an expression of uncertainty is invoked.  Within the 00-48 hour forecast, if imminent/ongoing criteria are not met, and “Expected” criteria are not met, the word “Possible” is used whenever the probability threshold is exceeded for that forecast period.  And then, in the extended (e.g., beyond 48 hours), similar logic applies but with an additional constraint imposed for the winds to be at least 20 knots.  This is done to minimize the risk of overusing the enhanced wording during the lengthy season.   

## Triggers

-  From the Hazard Grids Perspective...a Tropical Storm (Hurricane) Warning to be in effect
-   with maximum Wind and/or Probability criteria met, but criteria for imminent/ongoing conditions
-   or EXPECTED conditions not be met...***OR***...
-  Also From the Hazard Grids Perspective...a Tropical Storm (Hurricane) Watch to be in
-   effect with maximum Wind or Probability criteria met...***OR***...
-  From the Wind Grids Perspective...the maximum Wind to be greater than or equal to 25
-   knots when there is also a Watch/Warning in effect...***OR***...
-  Also From the Wind Grids Perspective...the maximum Wind forecast to be greater than or
-   equal to 34 knots (64 knots), but Watches/Warnings not be in effect...***OR***...
-  From the Probability Grids Perspective...the 34 knot (64 knot) Probability to be greater than
-   or equal to the PWS34 threshold (PWS64 threshold) according to the forecast period,
-   regardless of whether there are Watches/Warnings in effect.  In the extended periods, in   addition to the probability threshold criteria, the forecast wind must also be 20 knots or greater.

**Triggers**

**(Periods 1-10: When conditions are POSSIBLE)**

**Notes:**
To go through all of the ways that the word “Possible” might be triggered within an expression of uncertainty would take considerable time and can quickly become confusing.  This slide verbalizes the logic similar to the preceding slides, but as you might guess, there are many more permutations.  All of these permutations have been flowcharted and accounted for within the formatter.  The flowchart is available if interested, and the authors will be glad to share it upon request.  However, for the sake of this presentation it may be best to simply look at it from either the Hazards Grids perspective, or the Wind Grids perspective, or the Probability Grids perspective.  We’ll pause here so that you may take a few moments to read and consider the identified situations if you so desire.  Take as much time as you need.  When you’re finished, click to go to the next slide and continue this presentation. {pause}     

## Hurricane Wilma (2005)

- Hazard Grids Input

**Notes:**
Let’s take a look at a short series of examples now that we have a better understanding of what’s going on.  This case is from Hurricane Wilma in 2005 as it was forecast to affect Southwest Florida.  Inputs for the experimental Coastal Waters Forecast formatter are extracted from information based on the 5 PM advisory on Sunday, October 23rd.  Wilma was moving northeast at 12 knots and was accelerating in forward speed.  Notice here that hurricane warnings are already in effect for much of the south half of the Florida peninsula, which includes the coastal waters of interest.  This is a prime input for the experimental CWF formatter.        

## Algorithm Example

**Algorithm Example**

**WILMA (CWF)**

-    Contoured Wind Speeds
-   0-24 knots     25-33 knots
- 34-49 knots     50-63 knots
-    64+ knots

- Wind Grids Input

- Advisory Time: 20051023_2100 (First through Third Periods)

**Notes:**
Next, we want to consider the deterministic wind forecast for the first period as generated within the GFE using the TCM Wind tool.  For visual ease, here we have depicted the disposition of the wind grids, our next input, through the use of a colorized map that has been shaded according to the critical thinking of the formatter.  Green shows forecast winds well below tropical storm strength between 0-24 knots, while yellow shows forecast winds approaching tropical storm force between 25-33 knots.  The blue shades represent winds that are forecast to be tropical storm force; those attaining the 34-knot threshold but remaining less than 64-knots.  Tropical storm force winds that are approaching hurricane strength, between 50-63 knots, are depicted in dark blue.  Finally, winds forecast to be hurricane force are highlighted in red.  Certainly, the Southwest Florida coastal waters are forecast to reach hurricane intensity soon, with speeds up to 84 knots or more along with higher gusts. 

## Algorithm Example

**WILMA (CWF)**

- Probability Grids Input

- Advisory Time: 20051023_2100 (First through Third Periods)

**Algorithm Example**

**Notes:**
Correspondingly, the incremental probabilities comprise our third input thus accounting for forecast error.  A probability map has also been created for visual ease in our example case.  A big concern during Wilma was the along-track error for the timing of the winds, for both the onset and retreat.  As you can see, first period probabilities range from about 20 percent to around 60 percent for the indicated coastal water zones.  Now we have all of the necessary inputs for creating the expressions of uncertainty.    

## Algorithm Example

**WILMA (CWF)**

- Advisory Time: 20051023_2100 (First through Third Periods)

**Algorithm Example**

**Notes:**
So, in logical progression for the first period, the formatter weighs the input information.  It places significant weight on the hurricane warning that is in effect {click} while also properly headlining the forecast.  It then {click} deals with the weight of the deterministic wind speed magnitude and places the values within the forecast.  Finally, it considers the weight of the probabilities before deciding on the appropriate expression of uncertainty to begin the worded forecast for the first period.  Note, however, unlike the other two inputs the incremental probabilities are not explicitly stated anywhere within the text.  Some feel that they should be included, but for now they only contribute behind the scenes to the final selection of the uncertainty expression {click}.  In our example, the resulting first period forecast begins by expressing the highest of confidence for the worst of conditions...that is, a categorical expression resoundingly calling for “Hurricane Conditions.”   

## Algorithm Example

**WILMA (CWF)**

- Advisory Time: 20051023_2100 (First through Third Periods)

**Algorithm Example**

**Notes:**
And now on to the second period of the forecast.  The second period also contains hurricane force winds in the presence of a hurricane warning.  These two inputs alone are sufficient to invoke the expression “Hurricane Conditions Expected.”  However, the probabilities further support the use of this  expression.   

## Algorithm Example

**WILMA (CWF)**

- Advisory Time: 20051023_2100 (First through Third Periods)

**Algorithm Example**

**Notes:**
For the third period of the forecast, winds are forecast to decrease below tropical storm force to around 20 knots.  There is no expression of uncertainty that has been invoked.  And if you stop and think about it, what is being said is that the confidence is high that the event will be over by Monday Night.  But, let’s verify that by looking at the probabilities. 

## Algorithm Example

**WILMA (CWF)**

- Advisory Time: 20051023_2100 (First through Third Periods)

**Algorithm Example**

**Notes:**
Well, by the looks of the probability map for hurricane force winds, there is literally zero chance of 64-knot winds in the third period.  If the 64-knot probability had been above the 10% threshold it would have said “Hurricane Conditions Possible”  or if the 34-knot probability had been above 35% it would have said “Tropical Storm Conditions Possible.”  But, the probabilities were indeed lower than threshold thus no expression of uncertainty was invoked.   

## Hurricane Charley (2004)

**Notes:**
Here is another example, but this time we’ll look at Hurricane Charley for the Zone Forecast (or ZFP).  The example is taken from the 5 AM advisory.  As we know, Charley made landfall as a Category 4 hurricane near Punta Gorda which will take place near the end of this first period forecast.  At this time, the center track is forecast to cross the coast near Tampa Bay as indicated by the track plotted with the white boxes.  The actual track is plotted with red boxes.  Since Charley was a tight storm, hurricane force winds do not extend great distances from the center.  Using a purely deterministic wind swath only, hurricane conditions will not be explicitly forecast for many places.  However, Hurricane Warnings are in effect from Key West to Appalachee Bay and it is doubtful that this whole area will experience hurricane conditions.  Let’s see if there is something more that can be responsibly said by employing the incremental probabilities and the experimental formatter.      

## A Second Algorithm Example

**CHARLEY (ZFP)**

- * Naples

- Advisory Time: 20040813_0900 (0-12 Hours – First Period)

**A Second Algorithm Example**

**Notes:**
We’ll be generating the zone forecast for coastal Collier County on the lower southwest coast.  This includes the city of Naples.  We know {click} that a Hurricane Warning is in effect.  And, by looking here at the wind speeds for coastal Collier County (indicated by the black arrow), we note that wind speeds are forecast to a maximum approaching 50 knots, or tropical storm strength.  This {click} is translated to winds becoming 40 to 50 mph by the formatter.  

## A Second Algorithm Example

- Advisory Time: 20040813_0900 (0-12 Hours – First Period)

**CHARLEY (ZFP)**

- * Naples

**A Second Algorithm Example**

**Notes:**
Next we need to check the incremental probabilities.  The visual aid map indicates that the probability for tropical storm force winds is very, very high for the 00-12hr period; well in excess of 90%. And given all of the input information {click}, the formatter invokes an expression which confidently announces “Tropical Storm Conditions With Hurricane Conditions Possible.”  As a side note, if the wind forecast was clearly greater than 50 knots (e.g., 60 mph) and the 64-knot probability was at least 15%, then the expression would have been elevated to “Hurricane Conditions Expected.”  But for now, given the inputs, we have a good expression of uncertainty that clearly highlights tropical storm conditions, but also indicates that hurricane conditions are possible today to account for potential forecast error. 

## Hurricane Charley - Update

**Hurricane Charley - Update**

**Notes:**
Let’s now move ahead in time and perform the mid-morning update based the 11 AM advisory.  Charley is still forecast to make landfall in vicinity of Tampa Bay with hurricane warnings remaining in effect.     

## A Second Algorithm Example

- Advisory Time: 20040813_1500 (0-12 Hours – First Period)

**Morning Update**

**CHARLEY (ZFP)**

- * Naples

**A Second Algorithm Example**

**Notes:**
So, we’re looking closely to see if our sustained winds reach 64 knots, or if the sustained winds reach 50 knots while the 64-knot probability threshold of 15% is simultaneously attained.  The visual aid clearly denotes that the deterministic hurricane force winds remain well away from Collier County, but with wind speeds up slightly to 45 to 55 mph (but not 60 mph; that is, not 50 knots).   

## A Second Algorithm Example

**Morning Update**

**CHARLEY (ZFP)**

- * Naples

**A Second Algorithm Example**

- Advisory Time: 20040813_1500 (0-12 Hours – First Period)

**Notes:**
For kicks, let’s check the 64-knot probabilities to see how they are reacting to the situation.  The visual aid shown here depicts a rather steep gradient of probability over the near shore waters to the right of the forecast track.  Although much of Collier County is at or below 15%, areas near the coast are greater.  So, the formatter is very close to invoking “Hurricane Conditions Expected.”  Nonetheless, {click} it sticks with the expression which states “Tropical Storm Conditions With Hurricane Conditions Possible.”  In retrospect, this turned out to be a pretty good forecast as post storm report winds at Naples were near 45 mph with gusts near 55 mph.   

## A Second Algorithm Example

**CHARLEY (ZFP)**

- * Punta Gorda

- Advisory Time: 20040813_1500 (0-12 Hours – First Period)

**A Second Algorithm Example**

**Notes:**
Another interesting aspect of this challenging forecast is the wording which might have been generated for Punta Gorda at the time.  Even though the forecast center track was still zero’d on Tampa Bay at the 11 AM advisory, should folks in Punta Gorda really have been caught off guard with Charley’s last minute jog to the right?  The location of Punta Gorda is shown by the black arrow.  The text ZFP {click} is appropriately headlined with the Hurricane Warning, but sustained deterministic winds {click} are still just below hurricane strength (50 to 70 mph).  Importantly, the probabilities {click} for hurricane force winds are higher just to the right of track and maximize in the Punta Gorda area.  With these high probabilities, and the fact that the winds are forecast in excess of 50 knots (or 60 mph), the expression {click} “Hurricane Conditions Expected” is used.  And this works out well, especially since the wind gusts were indicated to peak to hurricane strength.  We believe that using confident expression such as this in the forecast would have better prepared Punta Gorda for the hurricane conditions they experienced.  And after making a strong point such as this, it seems a good place to begin winding down this training.               

## Conduct experiment during 2008 season
Generate case study examples from other locations and with an increasing variety of storms (real-time or archived)
Validate probability thresholds; perform ROC Diagram study
Evaluate consistency issues between the ZFP/CWF and their web page Point-n-Click counterparts
Evaluate consistency issues advisory to advisory
Compile experiences and share with the Tropical Cyclone Wind Team (present to NOAA Hurricane Conference - 2008) 
Iterative Decision Points (considering user benefits) 
Continue experimentally, implement officially, or discontinue
ZFP and CWF products 
Click Point forecast web pages
Consider other applications (e.g., Point Forecast Matrices, etc.) 

- Conduct experiment during 2008 season
- Generate case study examples from other locations and with an increasing variety of storms (real-time or archived)
- Validate probability thresholds; perform ROC Diagram study
- Evaluate consistency issues between the ZFP/CWF and their web page Point-n-Click counterparts
- Evaluate consistency issues advisory to advisory
- Compile experiences and share with the Tropical Cyclone Wind Team (present to NOAA Hurricane Conference - 2008)
- Iterative Decision Points (considering user benefits)
- Continue experimentally, implement officially, or discontinue
- ZFP and CWF products
- Click Point forecast web pages
- Consider other applications (e.g., Point Forecast Matrices, etc.)

**Current & Future Work**

**Notes:**
Before we finish with this module, we would like to pass along some road mapping information as it relates to where we are and where we are going (that is, particular emphasis for this season, and then a little farther into the future).  This season, the experiment will once again concentrate on generating more case study examples from other locations and with other storm scenarios; this can be done by any participating WFO using archived data, but we definitely want to take advantage of any targets-of-opportunity with real-time events.  These live situations really test the system, but recall that there is some assumed risk.  As this season progresses, we will also need to validate and/or situationally challenge the probability thresholds themselves.  This might be done empirically by certain interested WFOs.  However, a more formal and thorough ROC Diagram study is being planned by MFL and MLB similar to the very recent work done to validate the cumulative wind speed probabilities.  Additionally, another important aspect to this year centers around various consistency issues; consistency between successive formatter runs, as well as consistency between the corresponding Point-n-Click versions.  Finally, the collection of experiences will need to be compiled and shared with the Tropical Cyclone Wind Team to be presented at the NOAA Hurricane Conference (2008) and also sent up-channel. 

Importantly, appreciation must be given to the user experience in all of this.  We want to make sure that our changes actually result in value-added contributions across the board.  So, iterative decision points are in place as we progress into the future.  For example, at the end of this season the Wind Team will need to decide, based on user benefits, whether to continue in experimental mode (with requested modifications), or to move toward official implementation, or to discontinue the project altogether.  These decisions will need to be made separately regarding the ZFP and CWF products, as well as the Click-Point forecast.  Lastly, it would be wise for us to contemplate the horizon and look to other applications (perhaps the tabular products, Point Forecast Matrices, etc.) where including expressions of uncertainty (or even explicit incremental probability information) would be beneficial.   

## Summary

- This completes Module #1
- Please review Module #2
*Applying Expressions of Uncertainty to the ZFP and CWF during Tropical Cyclone Wind Situations*

- Thank You !!!

**Notes:**
This completes Module #1; please review Module #2 if you’re interested in knowing more about the hands-on aspect of this experiment.  It is entitled: Applying Expressions of Uncertainty to the ZFP and CWF during Tropical Cyclone Wind Situations {click}.  Thank you for your patience, as well as your support in this project.