000 WTPZ42 KNHC 230838 TCDEP2 Hurricane Gilma Discussion Number 20 NWS National Hurricane Center Miami FL EP072024 1100 PM HST Thu Aug 22 2024 The satellite presentation of Gilma has not changed much since the previous advisory. The ragged eye of the hurricane is still surrounded by deep convection, with the coldest cloud tops located over the western and southern portions of the inner core. Based on consensus T-5.5/102 kt Dvorak current intensity estimates from TAFB and SAB, and similar estimates from the various UW-CIMSS objective techniques, the initial intensity is held at 105 kt. The center of the hurricane has jogged westward during the past few hours, but the longer-term motion is still west-northwestward at about 5 kt. A deep-layer trough near the west coast of the United States is expected to lift out over the next couple of days, which will allow a high pressure ridge to build westward over the eastern North Pacific. As a result, Gilma should gradually move faster toward the west-northwest and west during the next several days. The track guidance remains tightly clustered, and the NHC forecast is essentially an update of the previous one with no notable changes. As previously discussed, the slow forward speed of Gilma is likely resulting in some upwelling of cooler waters underneath the hurricane. Although the vertical wind shear is forecast to remain relatively weak during the next couple of days, the track of Gilma will bring the hurricane over even cooler waters and into a drier mid-level environment by this weekend. These factors suggest at least gradual weakening should continue in the near term, followed by more significant weakening beyond 72 h as the cyclone encounters stronger shear and the upper air pattern becomes more convergent. Some slight downward adjustments were made to the NHC prediction later in the period. Gilma is forecast to become a post-tropical cyclone by 120 h, but the lack of organized convection in GFS and ECMWF model-simulated satellite imagery indicates this transition could occur as early as day 4. FORECAST POSITIONS AND MAX WINDS INIT 23/0900Z 17.4N 126.1W 105 KT 120 MPH 12H 23/1800Z 17.6N 127.2W 100 KT 115 MPH 24H 24/0600Z 18.0N 128.8W 95 KT 110 MPH 36H 24/1800Z 18.4N 130.5W 90 KT 105 MPH 48H 25/0600Z 18.7N 132.2W 80 KT 90 MPH 60H 25/1800Z 19.0N 134.1W 70 KT 80 MPH 72H 26/0600Z 19.3N 136.1W 65 KT 75 MPH 96H 27/0600Z 19.9N 140.8W 50 KT 60 MPH 120H 28/0600Z 20.5N 146.0W 35 KT 40 MPH...POST-TROPICAL $$ Forecaster Reinhart
Hurricane Gilma Forecast Discussion
23
Aug