je.st
news
Tropical Storm Alvin Forecast Discussion Number 7
2019-06-27 10:47:31| National Hurricane Center (East Pacific)
Issued at 300 AM MDT Thu Jun 27 2019 000 WTPZ41 KNHC 270847 TCDEP1 Tropical Storm Alvin Discussion Number 7 NWS National Hurricane Center Miami FL EP012019 300 AM MDT Thu Jun 27 2019 Alvin's satellite presentation is much improved since this time yesterday, consisting of a small but distinct CDO with extremely cold overshooting cloud tops of about -90C near the well-defined center. Outflow is fairly symmetrical due to the low vertical wind shear conditions affecting the compact cyclone. A 0435Z ASCAT-A pass revealed that tropical-storm-force winds only extended 15-20 nmi away from the center in the northern semicircle along with one peak wind vector of 46 kt located in the northwestern quadrant near the overshooting cloud tops. Given Alvin's small size and likely undersampling by the scatterometer instrument, the intensity is raised to 50 kt, which is consistent with ADT and SATCON estimates. The initial position and motion vector of 300/11 kt are based on ASCAT-A/-C scatterometer wind data and passive microwave fixes. Although the new track has been shifted north of the previous advisory track, there otherwise are no significant changes to the previous forecast track reasoning. Alvin is expected to move steadily west-northwestward around the southwestern periphery of a deep-layer subtropical ridge that extends westward from northwestern Mexico. The latest track guidance has again shifted northward and the new NHC track has likewise been shifted northward, but not quite as far the consensus models out of the respect for the lower latitude ECMWF and FSSE models. Additional strengthening is expected during the next 12 to 24 hours while Alvin remains over SSTs greater than 26 deg C and within a low vertical wind shear regime. By 36 hours, however, the combination of cooling SSTs and a more stable airmass is forecast to induce steady to rapid weakening. Alvin is expected to degenerate into a remnant low by late Saturday, and dissipate by Monday. The NHC intensity forecast is similar to a blend of the consensus models IVCN. HCCA, and FSSE. FORECAST POSITIONS AND MAX WINDS INIT 27/0900Z 15.1N 111.9W 50 KT 60 MPH 12H 27/1800Z 15.9N 113.5W 55 KT 65 MPH 24H 28/0600Z 17.3N 116.0W 55 KT 65 MPH 36H 28/1800Z 18.7N 118.1W 45 KT 50 MPH 48H 29/0600Z 19.6N 119.9W 35 KT 40 MPH 72H 30/0600Z 20.7N 122.7W 20 KT 25 MPH...POST-TROP/REMNT LOW 96H 01/0600Z...DISSIPATED $$ Forecaster Stewart
Tags: number
discussion
storm
tropical
Category:Transportation and Logistics
Latest from this category |
All news |
||||||||||||||||||
|
|||||||||||||||||||