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Tropical Storm Lorena Forecast Discussion Number 2
2019-09-17 22:41:47| National Hurricane Center (East Pacific)
Issued at 400 PM CDT Tue Sep 17 2019 000 WTPZ45 KNHC 172041 TCDEP5 Tropical Storm Lorena Discussion Number 2 NWS National Hurricane Center Miami FL EP152019 400 PM CDT Tue Sep 17 2019 A pair of ASCAT passes sampled the circulation of Lorena earlier this afternoon and showed multiple 40-45 kt wind vectors. Based on that data, the initial wind speed has been increased to 45 kt for this advisory. Lorena's cloud structure has improved somewhat during the afternoon, though Dvorak-based wind estimates are still notably lower than the ASCAT winds. The track models have come into much better agreement, and there has been a large shift eastward in the track guidance. However, since the NHC track forecast was previously on the east side of the guidance envelope, only a slight eastward shift was made to the official forecast. Lorena is still expected to move generally northwestward for the next day or two, and should move over or very near the southwestern coast of Mexico by late Wednesday or early Thursday. If the circulation survives its interaction with land, it should continue to head northwestward, perhaps toward the Baja California peninsula. That said, this portion of the forecast is highly conditional, and Lorena may end up just dissipating over the high terrain of Mexico. The NHC track forecast is now very close to TVCN and HCCA, especially through 72 h, and confidence in the track forecast has increased. The tropical storm has strengthened, and conditions appear favorable for additional slow strengthening. Once the circulation approaches the coast of Mexico, its intensity will become closely tied to its track. If Lorena moves inland, it will likely weaken quickly and could dissipate entirely shortly thereafter. If it stays offshore, it could maintain its strength and even intensify further as it moves away from the coast of Mexico later this week, as shown by the HWRF, DSHP, and LGEM models. The NHC intensity forecast is consistent with the track forecast, and therefore shows Lorena weakening due to land interaction after 48 h, but is below the intensity consensus since a number of those models keep the cyclone farther from the coast. Key Messages: 1. Lorena is forecast to cause heavy rain over portions of the Mexican states of Guerrero, Michoacan, Colima, and Jalisco during the next few days. This rainfall may produce life-threatening flash flooding and mudslides. 2. Tropical storm conditions are expected along a portion of the southwestern coast of Mexico by late Wednesday. FORECAST POSITIONS AND MAX WINDS INIT 17/2100Z 14.6N 101.3W 45 KT 50 MPH 12H 18/0600Z 15.7N 102.3W 50 KT 60 MPH 24H 18/1800Z 17.3N 103.3W 55 KT 65 MPH 36H 19/0600Z 18.5N 104.1W 55 KT 65 MPH 48H 19/1800Z 19.2N 104.8W 55 KT 65 MPH...NEAR THE COAST 72H 20/1800Z 20.5N 106.5W 40 KT 45 MPH 96H 21/1800Z 22.0N 109.5W 35 KT 40 MPH 120H 22/1800Z 23.5N 112.0W 35 KT 40 MPH $$ Forecaster Zelinsky
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