# Presentation: 509314

## EFFECT OF TAMDAR ON RUC SHORT-TERM FORECASTS OF AVIATION-IMPACT FIELDSFOR CEILING, VISIBILITY, REFLECTIVITY AND PRECIPITATION 

-  Ed Szoke*, Stan Benjamin,  Randy Collander*, Brian Jamison*, Bill Moninger, Tom Schlatter**, Barry Schwartz
- and Tracy Smith*
- NOAA/Earth Systems Research Laboratory
-  Global Systems Division
- *Joint collaboration with the Cooperative Institute for Research in the Atmosphere, Colorado State University, Fort Collins, CO
- **Cooperative Institute for Research in Environmental Sciences (CIRES), Boulder, Colorado

## Overview

-  TAMDAR soundings have been shown to be useful for forecasting
- Talks at the last SLS Conference and previous Annual Meetings
- WFO Green Bay helps maintain the official NOAA TAMDAR web page at http://www.crh.noaa.gov/tamdar/
-  In this talk we focus on the impact of TAMDAR on short-term NWP:
- Evaluation of RUC precipitation and visibility/ceiling short-term forecasts for runs with and without TAMDAR
- No reflectivity comparisons yet; these are coming....
- Mostly a subjective evaluation, but objective scoring for 2007 cases
-  Procedure:
- RUC is run at 20-km horizontal grid resolution
- Identical runs made hourly to 6 h, and out to 24 h every 3 h
- Here we will concentrate on shorter term (usually first 6 h to 12 h) forecasts initialized when TAMDAR data is most plentiful
- 1800 UTC and 0000 UTC initialization times generally used

## Typical TAMDAR coverage (shown here 1000 UTC/14 Jan – 0400 UTC/15 Jan 08)

- Flights into a number
- of smaller airports
- in addition to the
- 3 main hubs
- And at lower
- altitudes (generally
- to 20 kft or so)

- Typical TAMDAR coverage (shown here 1000 UTC/14 Jan – 0400 UTC/15 Jan 08)

## Verification areas.

- Objective scoring is
- done on both areas,
- for this study we will
- show some scores
- for the inner (blue) box .

## Case 1: 4 October 2005 – 2100 UTC Surface analyses and reflectivity

- Still one of the most
- dramatic cases...4-5 Oct
- 2005: heavy precip in
- the Upper Midwest.
- Flooding reported in
- Minnesota to northern
- Wisconsin.

## NPVU estimated precipitation for 6-h ending 0000 UTC 5 October 2005 

- Very sharp
- cut off to the
- precip in WI
- and a huge
- gradient with
- a 2-3” max.

- NPVU estimated precipitation for 6-h ending 0000 UTC 5 October 2005

## RUC forecasts from the 4 October 2005 1800 UTC runs

- Both runs forecast too much precip in southern half of Wisconsin, but the RUC run with
- TAMDAR correctly forecasts more precip (small spots of >1.00”) across the northern
- half of the state.

-    6-h total precipitation ending 0000 UTC 5 October

## Sounding comparison: RUC 6-h forecasts with (labeled dev2) and without

- (labeled dev1, in black) TAMDAR, compared to the RAOB for Detroit (green)
- at 0000 UTC 5 Oct 05.  Incorrect dry layer in the dev1 forecast.

## Same comparison but for Peoria, Illinois.  The RUC run with TAMDAR 

- Same comparison but for Peoria, Illinois.  The RUC run with TAMDAR
- is closer to the RAOB especially at and below 700 mb.

## Case 1/part 2: 5 October 2005 – 0300 UTC Surface analyses and reflectivity

- Heavy precip continues
- in the same areas

## NPVU estimated precipitation for 6-h ending 0600 UTC 5 October 2005

## RUC forecasts from the 5 October 2005 0000 UTC runs

- For this period the RUC run that used the TAMDAR data is a much better forecast with
- a very sharp cut off to the precipitation in Wisconsin and a better location for the heavy
- precip.

-    6-h total precipitation ending 0600 UTC 5 October

**No TAMDAR**

**With TAMDAR**

## Case 2: 7 December 2007 – 1200 UTC 500 mb obs and analysis

- Area of interest:
-   KY/TN
- Very weak short-
- wave trough

## Case 2: 8 December 2007 0000 UTC 850 mb obs and analysis

- Area of interest:
-   KY/TN
- Overrunning
- situation in place.

## Case 2: 7 December 2007 – 1800 UTC Surface obs and reflectivity

## Case 2: 7 December 2007 – 2100 UTC Surface obs and reflectivity

## Case 2: 8 December 2007 – 0000 UTC Surface obs and reflectivity

## NPVU estimated precipitation for 6-h ending 0000 UTC 8 December 2007  

- NPVU estimated precipitation for 6-h ending 0000 UTC 8 December 2007

## 3-h accumulated precip forecasts from the 1800 UTC 7 Dec 2007 RUC runs:

- Without TAMAR

- With TAMAR

- 3-h valid at 2100 UTC

- 6-h valid at 0000 UTC

## Sounding comparison between RUC 6-h forecast with (labeled dev2) and without 

- Sounding comparison between RUC 6-h forecast with (labeled dev2) and without
- (labeled dev, in black) TAMDAR, compared to the RAOB for Nashville (BNA)
- for 0000 UTC 8 Dec 07.  dev2 is closer to the observed sounding, while dev is too
- dry, similar to the forecast from the RUC run without TAMDAR.

## Did the TAMDAR data lead to a better forecast?  Here is a comparison between the 

- Did the TAMDAR data lead to a better forecast?  Here is a comparison between the
- two 1800 UTC RUC analysis soundings at Memphis (MEM) compared to some
- nearby TAMDAR soundings.

*Note how the *
*analysis from *
*dev2 (RUC with*
*TAMDAR) is *
*more moist than*
*the dev analysis,*
*and compares*
*better to the *
*TAMDAR data. *

## Case 3 - 7-8 January 2008: Unusual January tornado outbreak in the Midwest

- The SPC severe reports show numerous tornadoes, with some into Southeast Wisconsin
-     (pictures courtesy of Milwaukee/Sullivan, WI WFO).

- followed by rain/snow the next day.

## Case 3 - 500 mb analysis and plot for 0000 UTC 8 January 2008 

- This was a strong system with a deep approaching trough at 500 mb.

- Case 3 - 500 mb analysis and plot for 0000 UTC 8 January 2008

## Case 3: 7 January 2008 – 1800 UTC Surface analyses and reflectivity

## Case 3: 7 January 2008 – 2100 UTC Surface analyses and reflectivity

## Case 3: 8 January 2008 – 0000 UTC Surface analyses and reflectivity

## NPVU estimated precipitation for 6-h ending 0000 UTC 8 January 2008 

- NPVU estimated precipitation for 6-h ending 0000 UTC 8 January 2008

##     RUC forecasts from the 8 January 2008 1800 UTC runs

- Mixed verification: The RUC run with TAMDAR verifies better in northern Illinois (blue
- circle), but not as good as the run without TAMDAR in northern Wisconsin (red circle).

-     RUC forecasts from the 8 January 2008 1800 UTC runs
-         6-h total precipitation ending 0000 UTC 9 January

## Case 4: 10 January 2008 – 1800 UTC Surface & 500 mb analyses and reflectivity

- 2 days after the tornadoes....a modest snowstorm hits the Midwest, with more
- severe weather south to the Gulf coast

## Case 4: 10 January 2008 – Watches and warnings/advisories as of 2200 UTC

- Prompting the
- hoisting of Winter
- Weather Advisories
- from Iowa to
- Wisconsin

## Case 4: comparison of 18-h accumulated precip forecasts from the 1800 UTC 10 Jan 08 runs

- In this case we can compare the
- 18-h accumulated precipitation
- forecasts to the NPVU 24-h
- estimate for portions of the Midwest as the precip fell after 1800 UTC 10 Jan.  The RUC run
- with TAMDAR has more precip in Wisconsin, which verifies better.

- RUC without TAMDAR

- RUC with TAMDAR

## Case 4: comparison of 18-h accumulated precip forecasts from the 1800 UTC 10 Jan 08 runs

- Here is the comparison of the
- 18-h accumulated snowfall
- forecasts to the 24-h snow reports.
- A forecast of more snow in Wisconsin is better.

- RUC without TAMDAR

- RUC with TAMDAR

## Case 5: 21 December 2007 – the Midwest in a pre-Christmas fog. 21z with vis image.

##      RUC 3-h forecasts of visibility from the 21 December 2007 

- White shading is for a forecast of visibility at or below 1 mile
- Some differences are seen – these are outlined in the forecasts; similar differences
- were found in the 6-h forecasts valid at 0000 UTC.
- Verification: The RUC forecast that uses TAMDAR is better along the WI/MN border
- but worse in WI, where more dense fog is a better forecast.

-      RUC 3-h forecasts of visibility from the 21 December 2007
-                    1800 UTC runs valid 2100 UTC 21 December

**Without TAMDAR**

**With TAMDAR**

## Case 5: 21 December 2007 – WI/MN/IA closeup for 2100 UTC.

## One reason for less improvement with the TAMDAR run might have been

- TAMDAR coverage for the period 1500
- to 1800 UTC on 21 December 2007

- because of flights canceled by the fog.

- TAMDAR coverage for the period 1500
- to 1800 UTC on 7 December 2007 when
- conditions were better.

## Case 6: 8 January 2008 – more Midwest fog; 0600 UTC cig and vis plot from AWIPS.

*Visibilities under*
*a mile cover*
*pretty much all *
*of Wisconsin*

##      RUC 6-h forecasts of visibility from the 8 January 2008 

- White shading is for a forecast of visibility below 1 mile
- Main differences are found in eastern Wisconsin
- Verification: The RUC forecast that uses TAMDAR is better in eastern WI where
-    more fog is the better forecast.

-      RUC 6-h forecasts of visibility from the 8 January 2008
-                    0000 UTC runs valid 0600 UTC 8 January

**Without TAMDAR**

**With TAMDAR**

##      RUC 6-h forecasts of ceiling from the 8 January 2008 

- Only small differences between the forecasts, in southern Wisconsin.  Often many cases
-   had just small differences between the RUC forecasts.
- Verification: There is nothing in the observations to support the sliver of higher CIGS
-   found in the forecast without TAMDAR

-      RUC 6-h forecasts of ceiling from the 8 January 2008
-                    0000 UTC runs valid 0600 UTC 8 January

**Without TAMDAR**

**With TAMDAR**

*ceiling height AGL x1000 feet *

## Statistics (CSI) for the period 20 Nov 2007 – 15 Jan 2008 for LIFR conditions 

- Statistics (CSI) for the period 20 Nov 2007 – 15 Jan 2008 for LIFR conditions
-   (vis < 1 mile and/or cig < 500 ft AGL) from the 1800 UTC runs.

- 6-h forecasts from the 1800 RUC runs
- with (“dev2”) and
- without (“dev”)
- TAMDAR.  Difference plot is positive when dev2 is better than dev.
- Yellow vertical line denotes case day shown earlier.
- No real trend for better
- performance with TAMDAR for this period and forecast cycle.

## Statistics (CSI) for the period 20 Nov 2007 – 15 Jan 2008 for LIFR conditions 

- Statistics (CSI) for the period 20 Nov 2007 – 15 Jan 2008 for LIFR conditions
-   (vis < 1 mile and/or cig < 500 ft AGL) from the 0000 UTC runs.

- 6-h forecasts from the 0000 RUC runs
- with (“dev2”) and
- without (“dev”)
- TAMDAR.  Difference plot is positive when dev2 is better than dev.
- Yellow vertical line denotes case day shown earlier.
- Again, no real trend for better performance with TAMDAR for this period and forecast cycle.

## Objective scores for the two RUC forecasts for the small verification area

- EQTS numbers that favor the RUC run that uses
- TAMDAR are highlighted in red.  Most scores are close
- or slightly favor the run with TAMDAR, especially the
- 6-h forecasts from the 1800 UTC runs.

## Summary

-  One of the earliest precipitation forecasts examined (the 4-5 October        2005 case) remains the most impressive one we've seen in terms of          significantly better forecasts by the RUC run that used TAMDAR
- More typically, we see much smaller impacts
- These tend to favor the RUC run that uses TAMDAR, but not always
- And sometimes mixed...forecast better in some spots but not in others
- Objective scoring of the precipitation forecasts that began in 2007 agrees with our overall subjective impression
- But on a case by case basis can see differences in the scores
- Ceiling and visibility forecasts generally behave like what we have seen with precipitation
- Usually mixed verification...sometimes within the same forecast time.