je.st
news
Tropical Storm RACHEL Forecast Discussion Number 3
2014-09-25 04:42:01| National Hurricane Center (East Pacific)
Issued at 800 PM PDT WED SEP 24 2014 000 WTPZ43 KNHC 250241 TCDEP3 TROPICAL STORM RACHEL DISCUSSION NUMBER 3 NWS NATIONAL HURRICANE CENTER MIAMI FL EP182014 800 PM PDT WED SEP 24 2014 Vigorous deep convection has expanded in association with the tropical cyclone this evening, primarily in the southwestern semicircle. The asymmetric distribution of thunderstorms around the system is due to about 25 kt of northeasterly vertical shear being caused by a strong upper-level anticyclone to its north. The current intensity is based upon 35 kt estimates from both the Satellite Analysis Branch and the Advanced Dvorak Technique, though the Tropical Analysis and Forecast Branch suggests a slightly stronger system. Thus the cyclone is now named Tropical Storm Rachel. The system may gradually intensify during the next two to three days as the shear diminishes some. However, Rachel should also encounter cooler sea surface temperatures and drier low-level air as it moves toward the west-northwest. The system is expected to peak in intensity as a moderate tropical storm around day 2 or 3, followed by a gradual weakening. The NHC official intensity forecast is based upon the tightly clustered IVCN multi-model ensemble and is about the same as the previous advisory. The earlier ASCAT scatterometer pass suggested a radius of maximum wind of around 40 nm, which helped to define the tropical-storm- force wind radii now that the cyclone has strengthened. The global and regional hurricane models suggest that Rachel will remain rather small in size. A blend of these models with the climatology- persistence technique is the basis for the NHC wind radii predictions. A 2333Z SSMIS microwave image assisted in locating the center of Rachel, as the low-level swirl has remain tucked just under the convective overcast. Rachel is moving toward the west at about 10 kt. The tropical storm should turn toward the west-northwest during the next two days as it moves around the periphery of the mid-level subtropical ridge. In about three days, a strong short wave trough will be passing north of Rachel over California. The new 18Z GFS and the hurricane models run from it respond by turning Rachel northeastward toward Baja California, while the older 12Z ECMWF and UK Met Office global models continue moving a weaker Rachel west-northwestward. The NHC official track splits the difference and is slightly eastward from that of the previous advisory, but not as far eastward as the TVCE multi-model ensemble. FORECAST POSITIONS AND MAX WINDS INIT 25/0300Z 15.3N 107.4W 35 KT 40 MPH 12H 25/1200Z 15.8N 108.8W 35 KT 40 MPH 24H 26/0000Z 16.9N 110.7W 40 KT 45 MPH 36H 26/1200Z 17.9N 112.5W 40 KT 45 MPH 48H 27/0000Z 18.6N 113.9W 45 KT 50 MPH 72H 28/0000Z 19.7N 115.5W 45 KT 50 MPH 96H 29/0000Z 20.5N 116.0W 40 KT 45 MPH 120H 30/0000Z 21.5N 116.0W 30 KT 35 MPH $$ Forecaster Landsea
Tags: number
discussion
storm
tropical
Category:Transportation and Logistics
Latest from this category |
All news |
||||||||||||||||||
|
|||||||||||||||||||