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Tropical Storm HELENE
ZCZC MIATCDAT3 ALL TTAA00 KNHC DDHHMM Tropical Storm Helene Discussion Number 9 NWS National Hurricane Center Miami FL AL082018 1100 AM AST Sun Sep 09 2018 Helene continues to exhibit a fairly well-organized cloud pattern, but does not yet have a well-defined inner core. The current intensity estimate, 55 kt, is based on a blend of subjective and objective Dvorak estimates and is also close to the latest SATCON value. The tropical cyclone is expected to remain over warm waters with low to moderate vertical wind shear for the next couple of days. Therefore, strengthening is likely through the early part of this week. Later in the period, marginal SSTs and increasing south-southwesterly shear should induce weakening. The official wind speed forecast is on the high side of the numerical intensity guidance. Helene continues to move westward, or about 270/11 kt. The system should move westward to west-northwestward to the south of a mid-level ridge over the eastern Atlantic over the next 48 hours or so. Thereafter, a mid-level trough is expected to create a pronounced weakness in the ridge along 40W-45W longitude. This steering pattern is likely to cause Helene to turn northwestward to north-northwestward during the latter part of the forecast period. The official track forecast is very similar to the previous NHC prediction and lies roughly in the middle of the numerical guidance suite. FORECAST POSITIONS AND MAX WINDS INIT 09/1500Z 13.2N 25.0W 55 KT 65 MPH 12H 10/0000Z 13.7N 27.1W 65 KT 75 MPH 24H 10/1200Z 14.3N 30.0W 75 KT 85 MPH 36H 11/0000Z 14.9N 32.8W 85 KT 100 MPH 48H 11/1200Z 15.7N 35.2W 90 KT 105 MPH 72H 12/1200Z 17.8N 38.6W 80 KT 90 MPH 96H 13/1200Z 21.0N 41.0W 65 KT 75 MPH 120H 14/1200Z 26.0N 43.0W 55 KT 65 MPH $$ Forecaster Pasch NNNN