|
Show Selection: |
| #1068293 (Received by flhurricane at: 10:44 PM 02.Nov.2021) TCDAT1 Tropical Storm Wanda Discussion Number 13 NWS National Hurricane Center Miami FL AL212021 300 AM GMT Wed Nov 03 2021 Bands of convection have continued to wax and wane around the center of Wanda over the past 6-12 hours, with a band currently located over the western portion of the cyclone. A timely 2320 UTC ASCAT-B overpass detected peak winds of around 40 kt and given the known undersampling of that instrument for small tropical cyclones, the 45-kt initial intensity is maintained. That is also supported by a recent SATCON intensity estimate of 42 kt. The ASCAT data did show that the area of tropical-storm-force winds has increased in size over the eastern semicircle and now extends outward up to about 80 n mi in that portion of the storm. Wanda is moving northward or 010/8 kt. The cyclone should continue moving northward ahead of an approaching mid-latitude trough during the next 24-36 hours. After that time however, the trough is expected to weaken and lift northward causing Wanda to slow down and turn eastward. After 48 hours, the track guidance has continued its southward shift when a narrow ridge is forecast to build to the northwest of the system. The NHC track forecast is again shifted southward in the 60 to 96 h time period. By late in the period, Wanda is forecast to accelerate northeastward ahead of yet another mid-latitude trough. There is a bit more confidence in the latest track prediction as the dynamical model guidance has come into a bit better agreement, however additional southwestward or westward adjustments during the middle portion of the forecast period could be required. Little overall change in strength is anticipated over the next several days. As Wanda moves northward during the next day or so, it will be moving over slightly cooler waters which could cause the cyclone to struggle to produce deep convection. After day 2, there are indications of increasing shear, but a nearby baroclinic zone could help the system maintain its intensity. Later in the period, shear and decreasing mid-level relative humidity are likely to cause Wanda to become post-tropical, and by day 5 the guidance indicates Wanda will merge with a frontal boundary and become extratropical. FORECAST POSITIONS AND MAX WINDS INIT 03/0300Z 37.3N 40.3W 45 KT 50 MPH 12H 03/1200Z 38.5N 40.0W 45 KT 50 MPH 24H 04/0000Z 40.1N 39.9W 45 KT 50 MPH 36H 04/1200Z 41.2N 39.8W 45 KT 50 MPH 48H 05/0000Z 41.2N 39.2W 45 KT 50 MPH 60H 05/1200Z 40.2N 38.1W 45 KT 50 MPH 72H 06/0000Z 38.5N 37.7W 45 KT 50 MPH 96H 07/0000Z 38.0N 36.0W 45 KT 50 MPH...POST-TROPICAL 120H 08/0000Z 43.5N 29.5W 40 KT 45 MPH...POST-TROP/EXTRATROP $$ Forecaster Brown |