1. BFB: 9/29/2015 Tropical Weather
Zach Hiris & Phil Pascarelli

2. Tropical System Characteristics
Warm core systems (center of storm is warmer than the surroundings)
No frontal boundaries
Eye- Closed center of circulation
Eyewall- Strongest winds occur just outside of the eye
Size of storm does not determine strength

3. Tropical vs. Extra-Tropical Storms
Extratropical/Non-Tropical systems are typically larger and size and have larger wind fields (Sandy 2012)
Extratropical/Non-tropical systems are not affected by friction over land
Warm Core vs. Cold Core

4. Warm Core vs. Cold Core Cold Core Warm Core
Air in low is colder than the surrounding environment
Gets stronger with height
Warm Core
Air in low is warmer than the surrounding environment
Gets weaker with height

5. Tropical Weather Development
Occurs between 23.5° N/S
Main areas of Tropical Cyclones
North Atlantic
East Pacific
Central Pacific
West Pacific
Indian Ocean
Caribbean/Gulf of Mexico

6. Timeframe for Tropical Weather
Atlantic Ocean: June 1st to November 30th
East Pacific: May 15th to November 30th
West Pacific: Nearly all year
Just because Hurricane Season runs from June-November doesn’t mean storms can’t form outside those dates!

7. Stages of Development (NHC)
Tropical Wave
Surface trough/low pressure system which usually originates from the ITCZ (Intertropical Convergence Zone)
Tropical Depression
Closed area of low pressure, with winds of < 39 mph
Aren’t given a name, but a # based on the number of storms in the season
Tropical Storm
Tropical system with winds between mph. Given names
Hurricanes
Tropical system with winds >74 mph
Major Hurricanes - winds >111 mph

8. Developing Storms- What to Look For?
Tropical Wave/Trough
High moisture content
High PWATs, Low SAL
Low Shear
Good low-level convergence (ITCZ)
Warm Ocean temperatures (>80°F)

9. What to Look For- Observations
Upper Level Shear (Left) & Upper Level Divergence (Right)- From CIMSS

10. What to Look For- Observations
SST (°C), WindSat, and Model Forecast tracks (TD Ida)

11. What to Look For- Satellite (IR/VIS)

12. WTLF- Satellite (Microwave/Other)

13. What to Look For - Models

14. Advanced- Cyclone Phase Maps
From Florida State- Used by the NHC to determine Tropical vs. Extratropical

15. Cyclone Intensity Forecasts
Dvorak Method- Universal measure of cyclone intensity
Uses satellite analysis to determine a T-value (Intensity score)
Can be used for anything from Tropical Waves to Strong Typhoons
Not always reliable estimator- Aircraft data is almost always more important!

16. Dvorak Example
For Typhoon Dujuan:

17. Famous Hurricanes- Andrew
Last Category 5 Hurricane to make landfall in the U.S.
Rapidly intensified from a weak system to a Cat. 5 storm within 48 hours
Landfall just south of Miami (NHC Headquarters)

18. Famous Hurricanes- Sandy
Famous Hurricane which eventually made landfall in New Jersey
Was considered extratropical at the time of landfall
Significant damage to NJ/NY, etc.
Also produced heavy snowfall in the Appalachains

19. Hurricane Sandy

20. Famous Typhoon- Haiyan
One of the strongest storms in history
895mb Central Pressure, 195mph Sustained 1m Winds
Killed over 6,000 people in the Phillipines and caused over $2 Billion in damage