# Presentation: 248679

## Verification of the National Hurricane Center’s Atlantic and 

***Daniel P. Brown and Jamie R. Rhome***
***National Hurricane Center, Miami, FL***

**Verification of the National Hurricane Center’s Atlantic and **
**eastern North Pacific Tropical Weather Outlooks**

**East Pacific TWO Verification Results****                   ****   **

**Tropical Weather Outlooks (TWO)**

**A low, medium or high chance of development was assigned to each weather system described in every TWO from the 2005 and 2006 hurricane seasons.**

**Verification Methodology**

**Atlantic TWO Verification Results**

**D**

**E**

**F**

_**Mission:**_**  The TWO provides users with a general assessment of activity in the tropics, pertaining to tropical cyclone formation by providing to users possible areas where tropical cyclones could develop.**

**Future Possibilities- Graphical Tropical Weather Outlook**

**During the two year study period (2005-06), 801 forecasts were produced for 88 weather systems.**

_**Content:**_**  The TWOs discuss areas of disturbed weather and the potential for tropical cyclone development during the next **_**48 hours**_**.  **

_**Description:**_**  TWOs text based products that are issued 4 times daily for both the Atlantic and East Pacific basins.**

**    ****-Low-  tropical cyclone formation not expected **
**    ****-Medium- some development possible****  **
**    ****-High-  tropical depression (cyclone) could form**

**The forecasts were then verified by best-track data as to the formation of a tropical cyclone within 48 hours. **

|   | Number
Develop | Number
Forecasts | % develop within 48 h |
| --- | --- | --- | --- |
| 2005 | 17 | 397 | 4.3% |
| 2006 | 3 | 356 | 0.8% |
| Total Low | 20 | 753 | 2.7% |

**Low Chance Development**

|   | Number 
Develop | Number
Forecasts | % develop within 48 h |
| --- | --- | --- | --- |
| 2005 | 86 | 301 | 28.6% |
| 2006 | 25 | 243 | 10.6% |
| Total  Med. | 111 | 544 | 20.4% |

|   | Number
Develop | Number
Forecasts | PCT develop within 48 h |
| --- | --- | --- | --- |
| 2005 | 97 | 167 | 58.1% |
| 2006 | 32 | 76 | 42.1% |
| Total High | 129 | 243 | 53.1% |

**Medium Chance Development**

**High Chance Development**

**During the two year study period (2005-06), 1540 forecasts were produced for 147 weather systems.**

**Within **_**48 h**_** of TC formation **_**74%**_** of TWOs indicate some chance (****med.**** or ****high****) of development.**

**Low Chance Development**

|   | Number
Develop | Number
Forecasts | % develop within 48 h |
| --- | --- | --- | --- |
| 2005 | 2 | 74 | 2.7% |
| 2006 | 2 | 114 | 1.8% |
| Total Low | 4 | 188 | 2.2% |

|   | Number 
Develop | Number
Forecasts | % develop within 48 h |
| --- | --- | --- | --- |
| 2005 | 40 | 161 | 24.8% |
| 2006 | 68 | 218 | 31.2% |
| Total  Med. | 108 | 379 | 28.5% |

**Medium Chance Development**

**High Chance Development**

|   | Number
Develop | Number
Forecasts | PCT develop within 48 h |
| --- | --- | --- | --- |
| 2005 | 66 | 116 | 56.9% |
| 2006 | 83 | 119 | 69.7% |
| Total High | 149 | 235 | 63.4% |

**Real-time verification needed to validate the 2005-06 results.**

- 1).  An area of low pressure located about 150 miles east-southeast of Cape Hatteras North Carolina is moving slowly east-southeastward.  Although the associated shower activity is not well-organized at this time...this system has some potential for development over the next day or so.
- 2).  Cloudiness and disorganized showers extend northeastward from the vicinity of the windward passage into the Atlantic for a few hundred miles.  Upper-level winds are forecast to remain unfavorable for development of this system.  However...locally heavy rains can be expected over portions of eastern Cuba and Hispaniola during the next day or so.
- 3).  The tropical wave located about 250 miles east of the leeward islands is moving west-northwestward at 15-20 mph.  Environmental conditions are only marginally conducive for tropical cyclone development.  Locally heavy showers and strong gusty winds in squalls are likely over portions of the Lesser Antilles during the next day or two.

**Example of assigning color-code to text for verification.  **

**Low**

**Verification provides evidence that a three-tiered color coded system could help to convey relative threat of tropical cyclone formation.**

**Large separation of categories indicate that text TWO does convey relative threat of tropical cyclone genesis.**

**User feedback requested.**

**Graphic is likely quicker and easier to interpret, keeps user from seeking additional information.  **

**Future Work**

**Within **_**24 h**_** of TC formation **_**89%**_** of TWOs indicate some chance (****med.**** or ****high****) of development.**

**Within **_**24 h**_** of TC formation **_**59%**_** of TWOs indicate a ****high**** likelihood of development.**

**Within **_**48 h**_** of TC formation **_**83%**_** of TWOs indicate some chance (****med.**** or ****high****) of development.**

**Within **_**24 h**_** of TC formation **_**98%**_** of TWOs indicate some chance (****med.**** or ****high****) of development.**

**Within **_**24 h**_** of TC formation **_**73%**_** of TWOs indicate a ****high**** likelihood of development.**

**East Pacific Probability of Detection (POD)**

**Atlantic Probability of Detection (POD)**