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Tropical Storm FRED Forecast Discussion Number 10
2015-09-01 10:49:42| National Hurricane Center (Atlantic)
Issued at 500 AM AST TUE SEP 01 2015 000 WTNT41 KNHC 010849 TCDAT1 TROPICAL STORM FRED DISCUSSION NUMBER 10 NWS NATIONAL HURRICANE CENTER MIAMI FL AL062015 500 AM AST TUE SEP 01 2015 After a brief convective hiatus between about 0000-0200 UTC, deep convection has redeveloped over the center of Fred and also in the northern semicircle. Several passive microwave satellite images indicate that Fred's low-level center is a little south of the previous advisory track, due to southerly vertical wind shear displacing most of the convection to the north of the center. However, that same imagery also indicated that Fred still has a low-level circulation that is quite robust, including a nearly closed 20 n mi diameter eye. The initial intensity of 55 kt is based on a blend of Dvorak satellite intensity estimates of T4.0/65 kt from TAFB and T3.0/45 kt from SAB. The initial motion estimate is 300/10 kt based on microwave fixes. Fred is expected to move between west-northwest and northwest for the next 72 hours as a mid-level ridge to the north of the cyclone gradually builds westward. After that time, a turn toward the north-northwest and north is forecast due to a deep-layer trough currently over eastern Canada that is expected to dig southeastward over the central Atlantic and erode the ridge. The NHC model guidance is in decent agreement on this developing pattern change. However, there are significant differences in the model solutions with the HWRF, GFS, and GFDL models keeping Fred stronger and making the northward turn sooner, whereas the weaker solution models like the UKMET and ECMWF take a weaker and more vertically shallow cyclone farther west before turning it northward. The official forecast track is a little south of the previous advisory track, mainly due to the more southerly initial position, and follows a blend of the weaker UKMET and ECMWF solutions. Fred is expected to gradually weaken throughout the forecast period as the cyclone moves into an environment of increasing southwesterly vertical wind in excess of 20 kt and drier and more stable air, and over SSTs of near 26 deg C. The NHC intensity forecast is a little lower than the previous advisory, as well as the consensus model IVCN. Please note that the track/cone graphic, an automatically generated product, does not have the capability of displaying warnings for the Cape Verde Islands. FORECAST POSITIONS AND MAX WINDS INIT 01/0900Z 18.0N 26.1W 55 KT 65 MPH 12H 01/1800Z 18.8N 27.4W 45 KT 50 MPH 24H 02/0600Z 19.7N 29.2W 40 KT 45 MPH 36H 02/1800Z 20.3N 30.7W 35 KT 40 MPH 48H 03/0600Z 21.0N 32.3W 35 KT 40 MPH 72H 04/0600Z 22.3N 35.5W 30 KT 35 MPH 96H 05/0600Z 23.7N 38.6W 25 KT 30 MPH 120H 06/0600Z 26.0N 40.7W 25 KT 30 MPH...POST-TROP/REMNT LOW $$ Forecaster Stewart
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