je.st
news
Tropical Storm Marco Forecast Discussion Number 18
2020-08-24 19:56:48| National Hurricane Center (Atlantic)
Issued at 100 PM CDT Mon Aug 24 2020 000 WTNT44 KNHC 241756 TCDAT4 Tropical Storm Marco Special Discussion Number 18 NWS National Hurricane Center Miami FL AL142020 100 PM CDT Mon Aug 24 2020 Marco continues to weaken as the deep convection has been stripped away from the center since this morning. An Air Force Reserve Hurricane Hunter aircraft currently investigating the system has reported peak 925 mb flight level winds of 38 kt. Although there have been a few recent higher SFMR measurements that are due to rain contamination, a recent ASCAT overpass revealed only a small area of 30-35 kt winds. Based on these data the initial intensity is being lowered to 35 kt and a special advisory has been issued to update the short-term intensity forecast and discontinue warnings for the Gulf coast. The showers and thunderstorms generating the tropical storm force winds to the northeast of Marco's center are forecast by most models to gradually dissipate through this evening. Based on how quickly the vortex has been spinning down and the anticipated decrease of convection, it is reasonable to assume that sustained tropical storm force winds will no longer reach the northern Gulf coast. Therefore, all wind and surge warnings for the Gulf coast associated with Marco have been discontinued. Shortly after the cyclone reaches the Gulf Coast later tonight it should degenerate to a remnant low, with this low dissipating inland within a couple of days. The latest intensity forecast was adjusted downward through 12 h, but remains the same as the previous NHC forecast thereafter. Marco has been moving slowly all day, and an initial motion estimate is now 320/5 kt. There is no change to the forecast track reasoning. As the cyclone continues to weaken and degenerates to a remnant low, a turn to the west-northwest is expected as the system becomes steered in the low level flow. The latest forecast track was adjusted slightly northward through 12 h, but remains the same as the previous one until the system dissipates. This special advisory package replaces the 100 PM CDT (1800 UTC) intermediate public advisory. Key Messages: 1. Gusty winds, heavy rainfall, and lingering coastal flooding are expected from Marco along portions of the Gulf Coast through this evening. For information on these hazards see products from your local National Weather Service office. 2. Tropical Storm Laura could bring dangerous storm surge, rainfall, and wind impacts to portions of the U.S. Gulf Coast by the middle of the week, and tropical cyclone wind and surge watches and warnings could be issued for portions of the U.S. Gulf Coast later today. FORECAST POSITIONS AND MAX WINDS INIT 24/1800Z 28.7N 88.6W 35 KT 40 MPH 12H 25/0000Z 29.4N 89.3W 30 KT 35 MPH...INLAND 24H 25/1200Z 30.0N 91.3W 30 KT 35 MPH...POST-TROP/REMNT LOW 36H 26/0000Z 30.5N 93.6W 30 KT 35 MPH...POST-TROP/REMNT LOW 48H 26/1200Z 30.9N 95.9W 25 KT 30 MPH...POST-TROP/REMNT LOW 60H 27/0000Z...DISSIPATED $$ Forecaster Latto
Tags: number
discussion
marco
storm
Category:Transportation and Logistics