je.st
news
Tropical Storm HERNAN Forecast Discussion Number 5
2014-07-27 10:43:59| National Hurricane Center (East Pacific)
Issued at 200 AM PDT SUN JUL 27 2014 000 WTPZ43 KNHC 270843 TCDEP3 TROPICAL STORM HERNAN DISCUSSION NUMBER 5 NWS NATIONAL HURRICANE CENTER MIAMI FL EP082014 200 AM PDT SUN JUL 27 2014 Conventional satellite imagery and scatterometer wind data indicate that Hernan has continued to strengthen. A small central dense overcast has persisted over the center during the past 6 hours, and 0418 UTC and 0510 UTC ASCAT-A and ASCAT-B overpasses indicated surface winds of 48 kt and 51 kt, respectively, were present just east of center. Assuming that the coarse resolution ASCAT data has under-sampled the rather small and tight inner core wind field, the initial intensity has been increased to 55 kt. This intensity is supported by satellite intensity estimates of 55 kt from TAFB and 56 kt from UW-CIMSS ADT. The initial motion estimate is northwestward or 310/12 kt. Hernan is being steered along the southwestern periphery of a strong subtropical ridge located across the southwestern and southern United States. This persistent steering pattern is expected to keep Hernan moving in a general northwestward direction for the next 2-3 days, followed by a turn toward the west when the cyclone weakens and is steered primarily the by low-level easterly trade wind flow. Although the models have again shifted slightly northward, the new NHC track forecast is just an update of the previous advisory track and lies along the southern edge of the guidance envelope due to the expected quicker weakening than what the more northerly track GFS and GFDL models are forecasting. Hernan has strengthened 20 kt in the past 12 hours, which is a faster-than-normal rate of intensification. The cyclone has about another 12 hours or so of favorable conditions that could allow Hernan to achieve hurricane strength. After that, however, increasing westerly vertical wind shear should induce at least some weakening until around 48 hours, at which time more rapid weakening is expected as the the system moves over sub-25C SSTs. By Days 4 and 5, decreasing sea surface temperatures and even stronger shear should cause Hernan to degenerate into a remnant low pressure system. FORECAST POSITIONS AND MAX WINDS INIT 27/0900Z 16.9N 110.0W 55 KT 65 MPH 12H 27/1800Z 18.1N 111.7W 65 KT 75 MPH 24H 28/0600Z 19.6N 114.1W 60 KT 70 MPH 36H 28/1800Z 21.0N 116.5W 55 KT 65 MPH 48H 29/0600Z 22.1N 118.6W 45 KT 50 MPH 72H 30/0600Z 23.3N 122.3W 30 KT 35 MPH 96H 31/0600Z 23.6N 125.8W 25 KT 30 MPH...POST-TROP/REMNT LOW 120H 01/0600Z 23.6N 128.7W 20 KT 25 MPH...POST-TROP/REMNT LOW $$ Forecaster Stewart
Tags: number
discussion
storm
tropical
Category:Transportation and Logistics
Latest from this category |
All news |
||||||||||||||||||
|
|||||||||||||||||||