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Tropical Storm Douglas Forecast Discussion Number 7
2020-07-22 04:33:27| National Hurricane Center (East Pacific)
Issued at 500 PM HST Tue Jul 21 2020 000 WTPZ43 KNHC 220233 TCDEP3 Tropical Storm Douglas Discussion Number 7 NWS National Hurricane Center Miami FL EP082020 500 PM HST Tue Jul 21 2020 This afternoon's satellite presentation reveals a tropical cyclone that's struggling with the inhibiting factors from mid-level dry air intrusion. Cloud tops near the center of circulation have warmed considerably during the past few hours, and the primary convective band in the east semicircle has become a bit fragmented. A blend of an earlier SATCON of 52 kt, an ADT objective estimate of 51 kt and a Dvorak satellite classification of T3.5 from both TAFB and SAB supports holding the initial intensity at 55 kt, although the aforementioned recent changes in the cloud pattern may consider this as a bit generous. The better performing HFIP HCCA and IVCN multi-model intensity guidance still show Douglas shaking off the dry air invasion and strengthening into a hurricane in 12 hours, and the official forecast reflects this. The consensus intensity models and the FV3/GFS SHIPS show the cyclone reaching a peak intensity in around two days. Afterward, Douglas will be moving over 25-deg-C oceanic temperatures and into stable air mass. These negative contributions should, therefore, induce a slow weakening trend through day 5. The initial motion is estimated to be westward, or 270/12 kt within the mid-tropospheric easterly steering flow provided by a subtropical ridge anchored to the north of Douglas. This ridge is forecast to gradually build westward in response to a retreating large cut-off low near the Hawaiian Islands. As a result, Douglas should progressively turn West-northwestward by late Wednesday. and this general motion is forecast to continue for the remainder of the 5-day forecast period. The official NHC forecast is quite similar to the previous one with only a slight adjustment to the right beyond 72 hours through 120 hours in order to conform to the various consensus models. FORECAST POSITIONS AND MAX WINDS INIT 22/0300Z 12.1N 126.7W 55 KT 65 MPH 12H 22/1200Z 12.1N 128.5W 70 KT 80 MPH 24H 23/0000Z 12.6N 130.8W 80 KT 90 MPH 36H 23/1200Z 13.6N 133.2W 85 KT 100 MPH 48H 24/0000Z 15.1N 136.0W 90 KT 105 MPH 60H 24/1200Z 16.4N 138.8W 80 KT 90 MPH 72H 25/0000Z 17.5N 141.7W 70 KT 80 MPH 96H 26/0000Z 18.8N 147.3W 60 KT 70 MPH 120H 27/0000Z 19.4N 153.1W 50 KT 60 MPH $$ Forecaster Roberts
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