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Tropical Storm ISELLE Forecast Discussion Number 3
2014-08-01 10:48:41| National Hurricane Center (East Pacific)
Issued at 200 AM PDT FRI AUG 01 2014 000 WTPZ44 KNHC 010848 TCDEP4 TROPICAL STORM ISELLE DISCUSSION NUMBER 3 NWS NATIONAL HURRICANE CENTER MIAMI FL EP092014 200 AM PDT FRI AUG 01 2014 Iselle is continuing on an intensification trend with very deep convection in a central dense overcast feature. A recent AMSU microwave pass also suggests that the inner core has become better defined, with perhaps a partial eyewall in the eastern semicircle. The initial wind speed is raised to 50 kt based on an ASCAT-B pass from 0507 UTC. Environmental conditions appear conducive for further strengthening over the next couple of days with light-to-moderate northeasterly shear and warm water. Although the SHIPS-RI index has decreased somewhat from the last cycle, rapid intensification remains a possibility, especially given the recent development of inner core features. The NHC forecast is raised from the previous one, on the higher side of the guidance envelope close to the SHIPS and FSSE models. After 48 hours, Iselle should be moving into a more stable environment near cooler SSTs. Thus, a gradual weakening is forecast, near or slightly above the intensity consensus. Iselle continues to move to the west-northwest while it remains to the south of the subtropical ridge. Global models are in excellent agreement on this general track for the next 3 days while the ridge persists. After that time, the track uncertainty greatly increases due to a trough digging into the eastern Pacific, near or east of the forecast longitude of Iselle. With many varying solutions from the global models, it makes sense to stay close to the track consensus, which generally moves Iselle westward at long range. Since this consensus is near the last NHC prediction, the new forecast is basically unchanged from 6 hours ago. FORECAST POSITIONS AND MAX WINDS INIT 01/0900Z 13.5N 124.6W 50 KT 60 MPH 12H 01/1800Z 14.1N 125.9W 60 KT 70 MPH 24H 02/0600Z 14.8N 127.6W 70 KT 80 MPH 36H 02/1800Z 15.3N 129.4W 75 KT 85 MPH 48H 03/0600Z 15.8N 131.3W 75 KT 85 MPH 72H 04/0600Z 16.5N 134.8W 70 KT 80 MPH 96H 05/0600Z 16.8N 137.5W 60 KT 70 MPH 120H 06/0600Z 17.0N 140.5W 50 KT 60 MPH $$ Forecaster Blake
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