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Tropical Storm Ernesto Forecast Discussion Number 8
2018-08-17 04:37:48| National Hurricane Center (Atlantic)
Issued at 1100 PM AST Thu Aug 16 2018 866 WTNT45 KNHC 170237 TCDAT5 Tropical Storm Ernesto Discussion Number 8 NWS National Hurricane Center Miami FL AL052018 1100 PM AST Thu Aug 16 2018 Convection associated with Ernesto has increased in both coverage and intensity since the last advisory, with a large convective band wrapping about three-quarters of the way around the system. However, recent scatterometer data suggests that this has not yet resulted in strengthening, with winds of 35-40 kt observed about 80 n mi southeast of the center. Based mainly on the scatterometer data, the initial intensity remains 40 kt. While Ernesto is in a warm moist air mass to the east of a mid-latitude cyclone near Newfoundland, the forecast track quickly takes it over sea surface temperatures that will decrease to near 15C in 24 h. This should lead to the dissipation of the convection and to Ernesto becoming a post-tropical cyclone. In 36-48 h, the post-tropical cyclone should merge with a frontal zone, with the resulting extratropical low dissipating between 48-72 h. Overall, the new intensity forecast is nudged slightly downward from the previous forecast, as the guidance no longer shows significant strengthening. Given the increased convection, though, some short-lived strengthening could occur in the next 12 h. In addition, the current trends have led to the time of Ernesto becoming post-tropical being moved back 12 h. The initial motion is now 055/19. The cyclone should accelerate further while moving northeastward to east-northeastward within the mid-latitude westerlies over the next day or two. The dynamical model guidance remains tightly clustered and, as with the previous advisory, little change was made to the track forecast. On the forecast track, Ernesto or its remnants should approach Ireland and the United Kingdom in about 48 h. FORECAST POSITIONS AND MAX WINDS INIT 17/0300Z 44.1N 38.9W 40 KT 45 MPH 12H 17/1200Z 46.1N 34.8W 40 KT 45 MPH 24H 18/0000Z 48.9N 27.7W 40 KT 45 MPH...POST-TROPICAL 36H 18/1200Z 51.2N 19.5W 40 KT 45 MPH...POST-TROP/EXTRATROP 48H 19/0000Z 53.2N 12.1W 35 KT 40 MPH...POST-TROP/EXTRATROP 72H 20/0000Z...DISSIPATED $$ Forecaster Beven
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