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Tropical Storm Hector Forecast Discussion Number 4
2018-08-01 16:46:17| National Hurricane Center (East Pacific)
Issued at 800 AM PDT Wed Aug 01 2018 479 WTPZ45 KNHC 011446 TCDEP5 Tropical Storm Hector Discussion Number 4 NWS National Hurricane Center Miami FL EP102018 800 AM PDT Wed Aug 01 2018 Satellite images indicate that Hector is on a strengthening trend, with a large area of convection near and west of the apparent center. The latest microwave data, a 1159Z F-16 pass, also show the beginnings of an inner core in the 91-Ghz channels. The system has some tilt, however, with suggestions from the microwave pass that the low- and mid-level centers are not well aligned. The latest intensity estimates from TAFB/SAB are 45 kt, but I've elected to only raise the wind speed to 40 kt due to uncertainty in the initial position and the microwave tilt. Hector is forecast to remain over warm water, with light-to- moderate shear and somewhat dry mid-level moisture for the next several days. In 12 to 24 hours, northeasterly shear is forecast to increase near Hector, which should slow the intensification rate. Thus the official forecast shows strengthening at less than a climatological rate for the next few days. At long range, some of model guidance suggest the upper-level environment could become very favorable, with the HWRF/HMON now showing Hector at category 4 strength in the central Pacific Ocean. I would prefer to see more consistency from these models before showing such a large increase, but the new forecast is raised from the previous one and is higher than the model consensus. The storm is moving west-northwestward at 11 kt. Hector should turn to the west tomorrow and even move a little south-of-west for the next few days thereafter as the subtropical ridge builds to the north and west of the cyclone. The largest uncertainty is the location of Hector in a few days as an inverted upper-level trough forms to the north or northeast of the cyclone. For now there is enough separation of Hector and this trough to prevent the cyclone from gaining much latitude. While the model guidance doesn't show a lot of spread for now, and the new forecast is close to the previous one, it is worth keeping an eye on the trough to make sure it stays separate from Hector at long range. FORECAST POSITIONS AND MAX WINDS INIT 01/1500Z 13.8N 120.4W 40 KT 45 MPH 12H 02/0000Z 14.2N 122.0W 50 KT 60 MPH 24H 02/1200Z 14.5N 124.1W 55 KT 65 MPH 36H 03/0000Z 14.6N 126.4W 60 KT 70 MPH 48H 03/1200Z 14.5N 128.7W 65 KT 75 MPH 72H 04/1200Z 14.4N 133.5W 75 KT 85 MPH 96H 05/1200Z 13.9N 138.2W 90 KT 105 MPH 120H 06/1200Z 13.7N 142.0W 90 KT 105 MPH $$ Forecaster Blake
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