2100Z Tropical Update

TROPICAL STORM IDA FORECAST #4

TROPICAL FORECAST CENTER

3:45 PM EST SATURDAY NOVEMBER 7, 2009

A Hurricane Watch remains in effect for the Yucatan Peninsula from Tulum to Cabo Catoche. A hurricane watch means that hurricane conditions are possible...generally within 36 hours.

A Tropical Storm Warning remains in effect for the Grand Cayman Island...the Yucatan Peninsula from Punta Allen to San Felipe.

A Tropical Storm Warning remains in effect for the Cuban Providence of Pinar del Rio. Tropical storm warning means that tropical storm conditions are expected...generally within 24 hours.

Tropical Storm Watch remains in effect for the Isle of Youth. Tropical storm watch means that tropical storm conditions are possible...generally within 36 hours.

At 4 PM EST (2100Z)...the center of Tropical Storm Ida is located near 18.4 N 84.2 W or 785 miles south of Apalachicola, FL. Maximum sustained winds are near 70 mph...and some strengthening is possible and Ida could again become a hurricane later today. Motion is to the north at 10 mph and this general motion is expected to continue with a gradual turn to the north-northwest later today...then a turn to the northeast on Wednesday. On the forecast track...Ida will likely move between Cuba and the Yucatan tonight and enter into the Gulf of Mexico early Sunday. Minimum central pressure recorded by Recon is 990 mb/29.23 in.

Ida have once again surprised forecasters...despite wind shear in excess of 20 kts...Ida have continued to become better organized. Dvorak Estimates at 1745Z were T3.5...since then Ida have continued to gather some strength...but not quite a hurricane yet so will put the initial intensity at 60 kts. Not much will be needed for Ida to become a hurricane...and my intensity forecast do show Ida becoming a hurricane in about 12 hours or less. I have also increased the peak winds of Ida to 80 kts as she crosses into the Gulf of Mexico. After Ida cross into the Gulf...wind shear is expected to increase to around 50 to as high as 60 kts and this will likely shear Ida apart and weakening will then be forecast through the remainder of the forecast period and in about 4 days after Ida crosses the Florida Peninsula...Ida will become extratropical.

Initial motion 355/9 kts. Ida continues to move northward with the influence of a mid-level high. Ida will begin to move to the north-northwest in time and this is in agreement of most of the short term model runs. Difficulty in the forecast comes around the 72 hour timeframe where an mid-level trough will come into play. The models seem to split on where the track of Ida will go. Some of the models move Ida eastward across the Florida Peninsula and into the Atlantic...other models pull Ida east...then southeast and not affect any land areas during the forecast period. Other models show Ida merging with a front and then moving through the Florida Peninsula. My forecast will more reflect the early scenario and move Ida across the Florida Peninsula in about 3 days and move well north of Bermuda by the end of the forecast period. Therefore because of the uncertainites of the forecast...areas along the Gulf Coast from Alabama to Florida need to monitor the progress of Ida.

Forecast Position and Intensity:

07/21Z 18.4 N 84.2 W 60 kts

08/09Z 20.0 N 85.1 W 75 kts

08/21Z 21.7 N 86.3 W 80 kts

09/09Z 23.7 N 87.5 W 80 kts

09/21Z 26.2 N 88.1 W 80 kts

10/21Z 30.5 N 85.5 W 65 kts...inland

11/21Z 32.5 N 77.5 W 40 kts...extratropical

12/21Z 34.0 N 67.5 W 40 kts...extratropical

JACKSON