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Tropical Storm Maria Forecast Discussion Number 57
2017-09-30 10:37:09| National Hurricane Center (Atlantic)
Issued at 500 AM AST Sat Sep 30 2017 000 WTNT45 KNHC 300837 TCDAT5 Tropical Storm Maria Discussion Number 57 NWS National Hurricane Center Miami FL AL152017 500 AM AST Sat Sep 30 2017 Despite now being over sea surface temperatures of around 25 degrees Celsius, Maria is producing a persistent cluster of deep convection that is displaced to the east of the center due to 15 kt of west-northwesterly shear. Satellite imagery shows cold advection occurring within the western part of the cyclone's circulation behind an approaching cold front, heralding the beginning of Maria's extratropical transition. Based on global model guidance, this transition should be complete within 24 hours, and Maria's intensity is unlikely to change much up until that time due to baroclinic forcing. The extratropical low is likely to gradually weaken after 24 hours and become absorbed within a frontal zone by day 3, if not sooner. Maria is accelerating east-northeastward in the flow ahead of a positively tilted trough moving off the northeastern coast of North America, and the initial motion estimate is 070/28 kt. The trough should continue steering Maria even faster toward the east-northeast for the next couple of days. The GFS is significantly faster than the ECMWF, UKMET, and Canadian models since it shows Maria becoming absorbed by the front much sooner. The NHC track forecast remains close to the latter models and is relatively unchanged from the previous forecast. Guidance from the NOAA Ocean Prediction Center was used for the track, intensity, and wind radii forecasts during Maria's post-tropical stages. FORECAST POSITIONS AND MAX WINDS INIT 30/0900Z 39.6N 50.5W 50 KT 60 MPH 12H 30/1800Z 41.3N 45.4W 50 KT 60 MPH 24H 01/0600Z 43.8N 38.3W 50 KT 60 MPH...POST-TROP/EXTRATROP 36H 01/1800Z 46.6N 30.0W 45 KT 50 MPH...POST-TROP/EXTRATROP 48H 02/0600Z 48.9N 20.5W 40 KT 45 MPH...POST-TROP/EXTRATROP 72H 03/0600Z...ABSORBED WITHIN A FRONTAL ZONE $$ Forecaster Berg
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