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Tropical Storm Jimena Forecast Discussion Number 15
2021-08-06 16:37:48| National Hurricane Center (East Pacific)
Issued at 500 AM HST Fri Aug 06 2021 000 WTPZ44 KNHC 061437 TCDEP4 Tropical Storm Jimena Discussion Number 15 NWS National Hurricane Center Miami FL EP092021 500 AM HST Fri Aug 06 2021 A convective mass continues to persist over the center of Jimena, although coldest cloud tops have warmed over the past few hours. A fortuitous 1105 UTC AMSR-2 pass shows the center a bit west of the earlier estimates, which places it beneath the coldest remaining cloud tops. The intensity is held at 35 kt based on a blend of Final-T and CI numbers from TAFB, SAB and ADT. This intensity is also supported by overnight ASCAT data and a more recent ship observation. Jimena is currently moving over SSTs near 24C. Going forward, westerly shear will increase along the cyclone's path during the next 12-24 hr. These factors should cause the tropical cyclone to weaken, and Jimena is expected to degenerate into a remnant low by Saturday morning. The NHC intensity forecast is in good agreement with the SHIPS and HCCA guidance. The initial motion estimate is 300/8 kt. As Jimena weakens, the increasingly shallow system is expected to be steered by the low-level trade-wind flow, which should cause it to gradually turn toward the west in about 48 hours. The ECMWF is a little faster and lies on the southwest side of the guidance envelope, while the GFS is slower and northeast of the consensus. The NHC forecast was adjusted to the southwest of the previous forecast during the first 12-24 hours based on the farther west initial position. Thereafter, the track is close to the previous forecast, and in best agreement with the HCCA and TVCN consensus models. FORECAST POSITIONS AND MAX WINDS INIT 06/1500Z 17.5N 139.3W 35 KT 40 MPH 12H 07/0000Z 18.0N 140.4W 30 KT 35 MPH 24H 07/1200Z 18.7N 141.8W 25 KT 30 MPH...POST-TROP/REMNT LOW 36H 08/0000Z 19.2N 143.3W 25 KT 30 MPH...POST-TROP/REMNT LOW 48H 08/1200Z 19.5N 144.9W 20 KT 25 MPH...POST-TROP/REMNT LOW 60H 09/0000Z 19.6N 146.7W 20 KT 25 MPH...POST-TROP/REMNT LOW 72H 09/1200Z...DISSIPATED $$ Forecaster Hagen/Brown
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