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Tropical Storm Jerry Forecast Discussion Number 6
2019-09-18 22:41:26| National Hurricane Center (Atlantic)
Issued at 500 PM AST Wed Sep 18 2019 000 WTNT45 KNHC 182041 TCDAT5 Tropical Storm Jerry Discussion Number 6 NWS National Hurricane Center Miami FL AL102019 500 PM AST Wed Sep 18 2019 Jerry continues to strengthen this afternoon, as indicated by 1-min GOES-16 satellite imagery, with a large burst of convection close to the center. In addition, microwave data show that the central structure has improved, displaying a tightly wrapped band near the center. The initial wind speed is set to 50 kt, on the conservative side of the intensity estimates. The storm should become a hurricane on Thursday while it is moving over very warm waters with light shear. Dropsondes from the NOAA G-IV aircraft this afternoon show that Jerry is surrounded by some very dry air in the lower to mid-levels, and this is likely the main limiting factor on the cyclone's strengthening rate in the near term. By 48 hours, almost all of the models show an increase in northwesterly shear due to flow from an upper-level ridge, which seems likely to cause some weakening. At long range, Jerry is likely to interact with a mid-latitude trough, which is notoriously difficult to forecast. Only small changes were made to the previous wind speed prediction, and this advisory is close to a blend of the various consensus aids. The initial motion continues to be west-northwestward, or 290/13 kt. There's no substantial change to the track forecast on this package, with a subtropical ridge providing a well-defined steering current. This ridge should move Jerry along at a faster forward speed in about the same direction for the next couple of days, taking the center close to but north of the northern Leeward Islands. Afterward, a northwest to northward turn, influenced by a weakness in the aforementioned ridge left behind by Humberto and a new mid-latitude shortwave, is anticipated. The new forecast is very close to the previous one and a blend of the latest ECMWF ensemble mean and the corrected-consensus HCCA. Key Messages: 1. Jerry is expected to become a hurricane before it moves close to the northern Leeward Islands Friday. Although the core of Jerry is currently expected to pass north of the islands, tropical-storm- force winds and locally heavy rainfall are possible, and tropical storm watches have been issued for a portion of this area. FORECAST POSITIONS AND MAX WINDS INIT 18/2100Z 15.0N 50.5W 50 KT 60 MPH 12H 19/0600Z 15.7N 52.5W 60 KT 70 MPH 24H 19/1800Z 16.7N 55.3W 70 KT 80 MPH 36H 20/0600Z 17.8N 58.3W 70 KT 80 MPH 48H 20/1800Z 19.1N 61.4W 65 KT 75 MPH 72H 21/1800Z 21.5N 66.5W 60 KT 70 MPH 96H 22/1800Z 25.2N 70.0W 60 KT 70 MPH 120H 23/1800Z 28.5N 69.5W 60 KT 70 MPH $$ Forecaster Blake
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