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| #1143931 (Received by flhurricane at: 11:06 AM 16.Jul.2023) TCDAT5 Subtropical Depression Don Discussion Number 10 NWS National Hurricane Center Miami FL AL052023 1100 AM AST Sun Jul 16 2023 Satellite images indicate that Don is producing a small area of convection in the southeastern quadrant, though it is stretch to call it very organized. Overall, the system is mostly a big swirl of low- to mid-level clouds with occasional bursts of modest convection. A 1250 UTC ASCAT-B scatterometer pass showed maximum winds of about 30 kt, so that will be the initial wind speed. Don has turned to the east-northeast this morning, and should gradually execute a large clockwise loop over the central Atlantic during the next few days, turning southeast, south and southwest. Model guidance is in good agreement on this course through midweek, and little change was made to the previous forecast. The long range forecast is more uncertain, however, with Don potentially becoming trapped in an area of lighter steering currents before moving more northward, rather than westward in the loop. The model spread is enormous by day 5, with about 1000 n mi of distance between some of the ECMWF ensemble members. The new forecast is trended westward toward the multi-model ensemble mean, with a majority suggesting a northwest track at the end of the forecast period, but that`s far from certain. The environment near Don is expected to be pretty hostile for the next few days, with any cold air aloft promoting convection being neutralized by cool waters, dry air surrounding the cyclone, and some shear. This should result in little intensity change during the next few days, and Don could also degenerate into a remnant low, especially tomorrow when conditions could be the most harsh. At long range, Don might have a chance to re-strengthen since it moves over warmer waters with more instability, but Don could also be too weak to take advantage of these factors. Considering the large track uncertainty, the new forecast is the same as the previous one at long range, below the model guidance. FORECAST POSITIONS AND MAX WINDS INIT 16/1500Z 39.0N 48.1W 30 KT 35 MPH 12H 17/0000Z 39.4N 46.8W 30 KT 35 MPH 24H 17/1200Z 38.9N 44.6W 30 KT 35 MPH 36H 18/0000Z 37.8N 42.5W 30 KT 35 MPH 48H 18/1200Z 36.2N 41.2W 30 KT 35 MPH 60H 19/0000Z 34.7N 41.2W 30 KT 35 MPH 72H 19/1200Z 33.5N 41.8W 30 KT 35 MPH 96H 20/1200Z 33.0N 43.6W 35 KT 40 MPH 120H 21/1200Z 35.0N 47.0W 35 KT 40 MPH $$ Forecaster Blake |
