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Tropical Storm Beryl Forecast Discussion Number 2
2018-07-05 22:18:52| National Hurricane Center (Atlantic)
Issued at 500 PM AST Thu Jul 05 2018 000 WTNT42 KNHC 052018 TCDAT2 Tropical Storm Beryl Discussion Number 2 NWS National Hurricane Center Miami FL AL022018 500 PM AST Thu Jul 05 2018 Beryl has been a bit of a surprise today, which is not uncommon for tiny tropical cyclones such as itself. A 1724 UTC SSMI microwave pass and a 1853 UTC SSMI/S pass both revealed that the cyclone had developed a well-defined 5 nmi-wide mid-level eye, and a dimple has been apparent in visible satellite imagery. It's usually difficult to get a good handle on the intensity of these types of cyclones given their small size, but data-T numbers from TAFB and SAB are a consensus T3.0. The initial intensity is therefore raised to 45 kt, but there is a lot of uncertainty in this estimate. If the initial intensity is uncertain, the future intensity is even more of a quandary. Despite being surrounded by abundant dry air, Beryl has apparently been able to isolate itself and possibly moisten the near-storm environment while located in an area of low shear. Since the shear is expected to remain quite low for the next 36 hours or so, and small cyclones like Beryl often have a tendency to strengthen quickly over a short period of time, continued intensification appears likely for the next day or so. The updated NHC intensity forecast most closely follows the statistical- dynamical guidance, which lies at the upper end of the guidance envelope, and brings Beryl to hurricane strength within 36 hours. After that time, increasing westerly shear, partially due to Beryl accelerating toward the west, is expected to cause weakening. In addition, every global model shows the cyclone opening up into a tropical wave in 72-96 hours, which is what the NHC forecast continues to depict. It cannot be stressed enough, however, that this is a low confidence forecast. The one stable part of the forecast is Beryl's future track. The new guidance has not changed much from the previous forecast cycle, and it continues to show Beryl slowing down a bit during the next 24 hours, followed by a west-northwestward acceleration in 48-72 hours due to a strengthening ridge to the north. The updated NHC track forecast is just a bit south of the previous one and is closest to the HCCA and Florida State Superensemble guidance. Even though Beryl is expected to dissipate just east of the Lesser Antilles early next week, the remnant tropical wave will continue moving quickly westward and will likely bring locally heavy rains and gusty winds to portions of the Leeward Islands on Sunday and Monday. Key Messages: 1. Due to its very small size, there is greater-than-usual uncertainty in the analysis of Beryl's current intensity. Confidence in the official intensity forecast is also much lower than normal. Rapid changes in intensity, both up and down, that are difficult to predict are possible during the next couple of days. 2. While Beryl is still expected to dissipate as a tropical cyclone by Monday before reaching the Lesser Antilles, there will likely be some rain and wind impacts on those islands early next week. Residents there should monitor products from their local weather office for more information. FORECAST POSITIONS AND MAX WINDS INIT 05/2100Z 10.3N 42.8W 45 KT 50 MPH 12H 06/0600Z 10.8N 44.5W 55 KT 65 MPH 24H 06/1800Z 11.4N 46.3W 60 KT 70 MPH 36H 07/0600Z 12.1N 48.3W 65 KT 75 MPH 48H 07/1800Z 13.0N 51.0W 60 KT 70 MPH 72H 08/1800Z 14.5N 58.4W 50 KT 60 MPH 96H 09/1800Z...DISSIPATED $$ Forecaster Berg
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