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Hurricane Beryl Forecast Discussion Number 7
2018-07-07 04:40:41| National Hurricane Center (Atlantic)
Issued at 1100 PM AST Fri Jul 06 2018 000 WTNT42 KNHC 070240 TCDAT2 Hurricane Beryl Discussion Number 7 NWS National Hurricane Center Miami FL AL022018 1100 PM AST Fri Jul 06 2018 While Beryl continues to produce a cluster of convection near the center, the system appears a little less organized than earlier. In addition, there are no recent microwave overpasses showing an eye under the overcast. The various satellite intensity estimates are unchanged since the previous advisory, so the initial intensity is held at 70 kt. However, it is possible that this is a bit generous given the observed decay of the cloud pattern. The hurricane continues moving westward or 280/12. The track guidance insists that a turn toward the west-northwest and an increase in forward speed should occur in the next 12-24 h as Beryl continues to be steered by the strong subtropical ridge to the north. The new NHC forecast again follows this scenario, but it lies on the south side of the guidance envelope due to current trends and the overall northeast bias that the track guidance has shown so far. The new NHC track has the center near the Lesser Antilles in about 48 h, over the north central Caribbean Sea in about 72 h, and near eastern Cuba in about 96 h - if the system actually survives that long. Beryl is expected to remain in a light vertical wind shear environment for 36 h or so, then encounter steadily increasing westerly shear as it moves into the Caribbean Sea. The intensity guidance forecasts less strengthening during the time of favorable conditions than previously, and based on this first part of the intensity forecast is lowered slightly from that of the previous advisory. Steady to rapid weakening should occur over the eastern Caribbean due to stronger shear, and the current forecast has Beryl weakening to a tropical wave after 96 h. An alternative scenario, supported by the large-scale models, is that Beryl weakens to a tropical wave near the 72-h point. The technical issue with the NHC wind speed probabilities text products at land locations has been resolved. The wind speed probability values provided in the text product, the graphics on the the NHC website at hurricanes.gov, and the publicly disseminated grid files will all correctly reflect the reduced probabilities over land. Key Messages: 1. Beryl is forecast to be a hurricane when it moves through the Lesser Antilles Sunday night or Monday, and the chance of some islands receiving direct impacts from wind and rainfall are increasing. Hurricane and tropical storm watches are in effect for some of the countries in the Lesser Antilles, and additional watches could be required for other islands early Saturday. 2. Due to its very small size, there is greater-than-usual uncertainty in the analysis of Beryl's current intensity, and confidence in the official intensity forecast is also lower than normal. Rapid changes in intensity, both up and down, that are difficult to predict are possible during the next couple of days. FORECAST POSITIONS AND MAX WINDS INIT 07/0300Z 10.9N 48.9W 70 KT 80 MPH 12H 07/1200Z 11.3N 50.6W 75 KT 85 MPH 24H 08/0000Z 12.3N 53.5W 75 KT 85 MPH 36H 08/1200Z 13.3N 56.8W 75 KT 85 MPH 48H 09/0000Z 14.4N 60.6W 70 KT 80 MPH 72H 10/0000Z 16.5N 68.5W 50 KT 60 MPH 96H 11/0000Z 19.5N 76.5W 35 KT 40 MPH 120H 12/0000Z...DISSIPATED $$ Forecaster Beven
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