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Tropical Storm Alvin Forecast Discussion Number 4
2019-06-26 16:53:48| National Hurricane Center (East Pacific)
Issued at 900 AM MDT Wed Jun 26 2019 000 WTPZ41 KNHC 261453 TCDEP1 Tropical Storm Alvin Discussion Number 4 NWS National Hurricane Center Miami FL EP012019 900 AM MDT Wed Jun 26 2019 Visible and passive microwave imagery this morning indicate that the center of the tropical cyclone is located farther south than previously estimated, possibly due to a reformation of the center. The center of the cyclone is now embedded near the deepest inner- core convection, and some overall improvement in the convective pattern is evident. Satellite intensity estimates indicate that the cyclone has reached tropical storm strength, and the initial intensity of 35 kt is based on the latest Dvorak estimate from SAB. Alvin's formation marks the 3rd latest date of the development of the first named storm in the eastern Pacific basin during the satellite era (since 1966). Alvin has turned a little south of due west and the initial motion estimate is 260/12 kt. The new NHC forecast track over the first couple of days has been adjusted southward, in large part due to the more southerly reformation of the center. Despite this, the overall track forecast philosophy has not changed. Alvin is expected to move westward and then west-northwestward with a gradual decrease in forward speed over the next few days along the southwestern periphery of a subtropical ridge. There remains about a 24-36 hour window for some additional strengthening to occur over warm SSTs in a low-shear and sufficiently moist environment. This environment, combined with the improving structure of the storm, supports raising the intensity forecast a little in the near term. The new NHC forecast is in good agreement with the dynamical models and the intensity consensus. After 36 hours, the forecast track takes Alvin over progressively cooler waters and into a drier and higher-shear environment. This should result in steady weakening, with the cyclone likely becoming devoid of deep convection by 72 hours, and dissipating by day 5. FORECAST POSITIONS AND MAX WINDS INIT 26/1500Z 14.7N 109.4W 35 KT 40 MPH 12H 27/0000Z 14.7N 111.4W 45 KT 50 MPH 24H 27/1200Z 15.0N 113.7W 45 KT 50 MPH 36H 28/0000Z 15.7N 115.8W 45 KT 50 MPH 48H 28/1200Z 16.4N 117.7W 40 KT 45 MPH 72H 29/1200Z 17.4N 121.2W 25 KT 30 MPH...POST-TROP/REMNT LOW 96H 30/1200Z 18.0N 124.0W 20 KT 25 MPH...POST-TROP/REMNT LOW 120H 01/1200Z...DISSIPATED $$ Forecaster Latto/Brennan
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