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Hurricane HILARY Forecast Discussion Number 26
2017-07-27 22:36:45| National Hurricane Center (East Pacific)
Issued at 200 PM PDT Thu Jul 27 2017 000 WTPZ44 KNHC 272036 TCDEP4 Hurricane Hilary Discussion Number 26 NWS National Hurricane Center Miami FL EP092017 200 PM PDT Thu Jul 27 2017 Since the last advisory, the structure of Hilary has changed quite a bit. The primary feature is now a long band, extending almost 3/4 of the way around the circulation. Cloud tops have warmed during this time and a pronounced dry slot is visible over the eastern half of the circulation. Subjective and objective Dvorak intensity estimates have decreased, so the intensity has been decreased accordingly, to 65 kt. The intensity guidance remains divided, with the HWRF and COAMPS-TC models insisting on reintensification, and SHIPS and LGEM showing steady state or weakening. Simulated IR imagery from the HWRF forecast shows the development of a nearly clear eye in only 12 hours. Given the current structure of the cyclone, this seems unlikely. Therefore, the new official intensity forecast favors the statistical guidance and is a little above a blend of SHIPS and LGEM through 36 h. After that time, decreasing SSTs along the forecast track should result in steady weakening, ultimately causing the cyclone to become a remnant low. Since it is the stronger system, Hilary is still expected to dominate the interaction with Irwin, and is now forecast to absorb Irwin in about 96 h, as depicted by the ECMWF. 1-minute visible imagery from GOES-16 was very helpful in determining the initial position of of Hilary at 1800 UTC, and the low-level circulation has at times been visible through the higher cirrus cover. The initial motion is a somewhat more certain 290/8 kt. The extent to which Irwin will affect the track of Hilary still varies between the global models, with the GFS showing a stronger Hilary moving farther north, and the UKMET and ECMWF showing a weaker Hilary pulled farther south. The official track forecast still lies between these solutions, but favors the southern solution since the intensity forecast calls for gradual weakening throughout the forecast period. FORECAST POSITIONS AND MAX WINDS INIT 27/2100Z 17.9N 116.6W 65 KT 75 MPH 12H 28/0600Z 18.3N 117.9W 65 KT 75 MPH 24H 28/1800Z 19.1N 119.5W 65 KT 75 MPH 36H 29/0600Z 19.8N 121.3W 60 KT 70 MPH 48H 29/1800Z 20.5N 123.5W 60 KT 70 MPH 72H 30/1800Z 21.4N 128.0W 45 KT 50 MPH 96H 31/1800Z 22.5N 131.7W 35 KT 40 MPH 120H 01/1800Z 23.7N 134.8W 25 KT 30 MPH...POST-TROP/REMNT LOW $$ Forecaster Zelinsky
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