|
Show Selection: |
| #904917 (Received by flhurricane at: 4:41 AM 28.Sep.2017) TCDAT5 Tropical Storm Maria Discussion Number 49 NWS National Hurricane Center Miami FL AL152017 500 AM EDT Thu Sep 28 2017 Maria`s satellite presentation has not changed much during the past six hours, with 15-20 kt of northwesterly shear continuing to displace much of the deep convection to the east of the center. Despite the discrepancy between aircraft observations and Dvorak estimates noted yesterday, a pair of ASCAT passes from a few hours ago showed maximum winds in the 50-55 kt range. Even with the assumption that the resolution of the ASCAT data may not have revealed the highest winds, an analysis suggests that Maria has weakened back to a 60-kt tropical storm. Little change in intensity is anticipated during the next two days while Maria moves over sea surface temperatures of 26-27 degrees Celsius, and while vertical shear decreases during the next 24 hours. After 48 hours, a marked jump in shear and much colder waters should induce more weakening, and model guidance indicates that Maria should complete extratropical transition by day 3. The extratropical low should then be absorbed by a larger system over the northeastern Atlantic by day 4. This scenario is in agreement with guidance provided by the NOAA Ocean Prediction Center. Maria is becoming embedded in the mid-latitude westerlies and is now moving toward the east-northeast, or 060/7 kt. The cyclone is expected to turn eastward very soon, but then turn back toward the east-northeast in 36 hours as a positively tilted trough moves off the New England and Atlantic Canada coasts. The speed differences among the track models are not as significant as they were yesterday, although the updated NHC track forecast was nudged southward for much of the forecast period to follow an overall modest shift in the guidance envelope. FORECAST POSITIONS AND MAX WINDS INIT 28/0900Z 36.8N 71.0W 60 KT 70 MPH 12H 28/1800Z 36.8N 68.8W 55 KT 65 MPH 24H 29/0600Z 37.0N 64.9W 55 KT 65 MPH 36H 29/1800Z 38.0N 59.7W 55 KT 65 MPH 48H 30/0600Z 40.0N 53.1W 55 KT 65 MPH 72H 01/0600Z 46.4N 35.5W 45 KT 50 MPH...POST-TROP/EXTRATROP 96H 02/0600Z...DISSIPATED $$ Forecaster Berg |
