je.st
news
Tropical Storm HERNAN Forecast Discussion Number 10
2014-07-28 16:38:02| National Hurricane Center (East Pacific)
Issued at 800 AM PDT MON JUL 28 2014 000 WTPZ43 KNHC 281437 TCDEP3 TROPICAL STORM HERNAN DISCUSSION NUMBER 10 NWS NATIONAL HURRICANE CENTER MIAMI FL EP082014 800 AM PDT MON JUL 28 2014 Persistent 15-20 kt of westerly shear is certainly deteriorating the cyclone's organization this morning. Conventional satellite imagery shows a rather shapeless cloud pattern with warming cloud tops. A fortuitous 0934 UTC AMSU-A microwave pass indicated an eastward vertical tilt with the low-level center located near the western edge of the deep convection. A compromise of satellite intensity estimates from TAFB and SAB along with a 0933 UTC UW-CIMSS SATCON (which includes ADT, and AMSU intensity estimates) of 54 kt supports an initial intensity of 55 kt for this advisory. The large-scale models and the statistical/dynamical intensity guidance all show a moderate shear environment through the forecast period. Furthermore, an increasingly stable air mass and decreasing sea surface temperatures should ultimately weaken Hernan into a shallow post-tropical cyclone in 48 hours. Hernan continues to move northwestward, with an initial motion estimate of 295/14 kt. Global model guidance indicates that a mid-level ridge to the northeast of the cyclone should steer Hernan in this general motion through the 36 hour period. Afterward, a turn toward the west and a reduction in forward speed is forecast as the remnant low moves within the lower tropospheric flow of the subtropical ridge. The NHC forecast is again adjusted slightly to the left of the previous track beyond 36 hours, and lies between the consensus model and the ECMWF. FORECAST POSITIONS AND MAX WINDS INIT 28/1500Z 20.5N 115.9W 55 KT 65 MPH 12H 29/0000Z 21.6N 117.8W 50 KT 60 MPH 24H 29/1200Z 22.9N 120.3W 40 KT 45 MPH 36H 30/0000Z 23.8N 122.2W 30 KT 35 MPH 48H 30/1200Z 24.0N 123.4W 25 KT 30 MPH...POST-TROP/REMNT LOW 72H 31/1200Z 24.0N 125.0W 20 KT 25 MPH...POST-TROP/REMNT LOW 96H 01/1200Z 24.0N 127.5W 20 KT 25 MPH...POST-TROP/REMNT LOW 120H 02/1200Z...DISSIPATED $$ Forecaster Roberts
Tags: number
discussion
storm
tropical
Category:Transportation and Logistics