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Tropical Storm Kristy Forecast Discussion Number 4
2018-08-07 22:33:07| National Hurricane Center (East Pacific)
Issued at 200 PM PDT Tue Aug 07 2018 103 WTPZ43 KNHC 072033 TCDEP3 Tropical Storm Kristy Discussion Number 4 NWS National Hurricane Center Miami FL EP132018 200 PM PDT Tue Aug 07 2018 Geostationary satellite and microwave images indicate that Kristy has well-defined curved bands, but the convection in these bands has decreased during the past several hours. A recent ASCAT pass showed maximum winds of about 40 kt. Based on that data and Dvorak classifications, the initial intensity is again held at 45 kt. Kristy has been moving just south of due west during the past 12 hours, and the initial motion estimate is 260/11 kt. The models agree that a decrease in forward speed and a turn to the west-northwest is expected to begin tonight or on Wednesday, but that is about all they agree on for the future track of Kristy. There remains significant spread in the models about how the storm will interact with Hurricane John to its northeast. The GFS continues to show Kristy being pulled northward and then northeastward into the outer circulation of John. On the other hand, the ECMWF has been consistent in showing little interaction between the tropical cyclones, and keeps Kristy moving on a westward or west-northwestward path. The NHC official track forecast lies between these scenarios and is close to the recent run of the UKMET model. This forecast has been adjusted to the north and east of the previous one to get closer to the middle of the guidance envelope. It should be noted that the track forecast is of low confidence given the very different model solutions. Kristy's struggles are likely due to the influences of dry air and moderate shear. The SHIPS model shows the shear decreasing during the next couple of days, which could allow the storm to gradually strengthening during that time period. Beyond a couple of days, however, cooler waters and a more stable airmass should end the strengthening trend and result in weakening. The NHC intensity forecast is largely an update of the previous one and lies close to the HCCA model. FORECAST POSITIONS AND MAX WINDS INIT 07/2100Z 13.7N 127.1W 45 KT 50 MPH 12H 08/0600Z 13.9N 128.2W 50 KT 60 MPH 24H 08/1800Z 14.5N 129.2W 55 KT 65 MPH 36H 09/0600Z 15.4N 129.9W 60 KT 70 MPH 48H 09/1800Z 16.4N 130.2W 65 KT 75 MPH 72H 10/1800Z 18.5N 130.2W 60 KT 70 MPH 96H 11/1800Z 21.0N 130.8W 55 KT 65 MPH 120H 12/1800Z 23.0N 132.5W 45 KT 50 MPH $$ Forecaster Cangialosi
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