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| #1019695 (Received by flhurricane at: 10:45 PM 02.Oct.2020) TCDAT5 Tropical Storm Gamma Discussion Number 3 NWS National Hurricane Center Miami FL AL252020 1000 PM CDT Fri Oct 02 2020 A few hours ago, the Air Force Hurricane Hunters found maximum winds of around 35 kt in the northeastern quadrant of the cyclone, which was the reason why it was upgraded to Tropical Storm Gamma. Since then, there have been no stronger winds reported so the initial intensity remains 35 kt. The minimum pressure estimated by the aircraft is quite low at 998 mb, so it seems likely that the winds will increase soon. The storm also has better banding features compared to hours ago and deep convection has also been persisting near the center. Fixes from the aircraft indicate that Gamma has jogged to the left recently, but smoothing through the short-term jog suggests an initial motion of 310/8 kt. The tropical storm is expected to remain on the western periphery of a subtropical high during the next couple of days, and that should cause the storm to move slowly northwestward during that time period. This track should take Gamma across the northern Yucatan Peninsula and perhaps over the extreme south-central Gulf of Mexico this weekend. By early next week, a mid-level ridge is expected to build to the north of the storm while another low pressure area is forecast to develop to the east of Gamma. This change in the steering pattern is expected to cause the storm to make a sharp left turn toward the Bay of Campeche, but continue to move at a fairly slow forward speed. The models have shifted well to the south from 48-120 hours this cycle, and the NHC track forecast has been adjusted in that direction. Despite the shift, most of the reliable models are south of the new official track forecast, and future southward adjustments could be necessary. Environmental conditions appear generally favorable for additional strengthening until the cyclone reaches the Yucatan Peninsula on Saturday, and the NHC intensity forecast shows a slightly higher landfall intensity there. Once the system moves over the Yucatan Peninsula and the extreme southern Gulf of Mexico, the combination of land interaction, an increase in shear, and drier air should limit the amount of strengthening into next week. At this point, no model shows Gamma becoming a hurricane, and the NHC intensity forecast shows little change in strength for much of the forecast period. The biggest threat from this large and slow-moving storm is the the potential for heavy rainfall and flooding, particularly near and over mountainous terrain. KEY MESSAGES: 1. Gamma is expected to produce heavy rainfall that could result in life-threatening flash flooding over portions of the Yucatan Peninsula, far western Cuba and well away from the center in the Mexican states of Campeche, Tabasco, and northern Chiapas. 2. Gamma is forecast to bring tropical storm conditions to portions of the Yucatan Peninsula on Saturday, where a Tropical Storm Warning is in effect. FORECAST POSITIONS AND MAX WINDS INIT 03/0300Z 19.1N 86.1W 35 KT 40 MPH 12H 03/1200Z 19.8N 86.9W 45 KT 50 MPH 24H 04/0000Z 20.8N 87.6W 45 KT 50 MPH...INLAND 36H 04/1200Z 21.6N 88.0W 40 KT 45 MPH...INLAND 48H 05/0000Z 22.0N 88.3W 40 KT 45 MPH 60H 05/1200Z 21.9N 88.9W 40 KT 45 MPH 72H 06/0000Z 21.7N 90.0W 45 KT 50 MPH 96H 07/0000Z 21.0N 91.8W 45 KT 50 MPH 120H 08/0000Z 20.3N 92.8W 45 KT 50 MPH $$ Forecaster Cangialosi |