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Tropical Storm Jimena Forecast Discussion Number 11
2021-08-05 16:37:31| National Hurricane Center (East Pacific)
Issued at 500 AM HST Thu Aug 05 2021 000 WTPZ44 KNHC 051437 TCDEP4 Tropical Storm Jimena Discussion Number 11 NWS National Hurricane Center Miami FL EP092021 500 AM HST Thu Aug 05 2021 Conventional satellite imagery indicates that Jimena's cloud pattern has changed little during the past several hours, although most recently, enhanced infrared images show some warming of the cloud tops just west of the center. Timely AMSR-2 and GMI passive microwave color composite images revealed a well-developed banding feature wrapping around the surface center from the north and west portions of the cyclone. The initial intensity is held at 35 kt and is in agreement with the Dvorak satellite intensity estimates from TAFB and SAB. The large-scale models and the statistical-dynamical SHIPS intensity guidance (GFS/ECMWF) show that the previously noted period of conducive atmospheric and oceanic conditions should be ending soon. By the 36-hour period, sub-25C sea-surface temperatures and a gradually stabilizing/drier surrounding air mass should cause Jimena to weaken. Guidance also shows increasing west-northwesterly shear beyond 48 hours. Accordingly, the NHC forecast calls for Jimena to weaken to a depression by mid-period, and degenerate into a remnant low in 60 hours. Based on the aforementioned microwave images, the initial motion is estimated to be northwestward, or 315/6 kt. A subtropical ridge anchored to the northeast of the cyclone is forecast to steer Jimena toward the northwest through the 48 period. Afterward, a turn toward the west-northwest is expected as the vertically shallow system is influenced more by the easterly tradewinds. The official forecast is basically an update of the previous one and lies near the multi-model consensus (TVCN) aid. FORECAST POSITIONS AND MAX WINDS INIT 05/1500Z 16.1N 137.2W 35 KT 40 MPH 12H 06/0000Z 16.5N 137.7W 35 KT 40 MPH 24H 06/1200Z 17.5N 138.9W 35 KT 40 MPH 36H 07/0000Z 18.5N 140.2W 30 KT 35 MPH 48H 07/1200Z 19.5N 141.5W 30 KT 35 MPH 60H 08/0000Z 20.3N 142.9W 25 KT 30 MPH...POST-TROP/REMNT LOW 72H 08/1200Z 20.9N 144.3W 20 KT 25 MPH...POST-TROP/REMNT LOW 96H 09/1200Z...DISSIPATED $$ Forecaster Roberts
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