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Tropical Storm Theta Forecast Discussion Number 11
2020-11-12 15:45:47| National Hurricane Center (Atlantic)
Issued at 300 PM GMT Thu Nov 12 2020 000 WTNT45 KNHC 121445 TCDAT5 Tropical Storm Theta Discussion Number 11 NWS National Hurricane Center Miami FL AL302020 300 PM GMT Thu Nov 12 2020 Although the cloud top temperatures across the broad comma-shaped convective shield have warmed this morning, there is some new convection that has been developing nearer to Theta's center over the past few hours. Unfortunately, the scatterometer passes this morning missed sampling the winds near the center of the cyclone. However, the partial ASCAT-A overpass showed that 45 kt winds are occurring nearly 100 n mi to the southwest of the center of Theta. Therefore it is assumed that stronger winds are still occurring closer to the center of the cyclone, and the initial intensity is being held at 55 kt. Theta has now turned to the right, and the initial motion is 080/10 kt. For about the next 36 h, the cyclone is expected to continue moving just north of east around the north side of a mid-level ridge. A slower east-southeastward motion is expected from 36-72 h as the mid-level ridge to the south weakens and mid- to upper-level northerly flow moves over Theta. After 72 h, Theta or its remnants are expected to turn northeastward or northward and accelerate in the low-level flow ahead of an approaching deep-layer mid-latitude cyclone over the northeastern Atlantic. The latest track forecast is little changed from the previous one and is near the multi-model consensus tracks. The shear across Theta is expected to relax somewhat over the day or so, while moving over cooler waters. The counteracting effects should allow the cyclone to maintain its intensity. By this weekend, strong northerly shear is expected to impact Theta, while stable air gets entrained into its circulation. This should cause the cyclone to weaken, with the system likely degenerating into a remnant low by Sunday. The latest NHC intensity forecast is just slightly above the guidance through 60 h, and is near the various consensus models thereafter. FORECAST POSITIONS AND MAX WINDS INIT 12/1500Z 31.6N 28.8W 55 KT 65 MPH 12H 13/0000Z 31.7N 27.0W 55 KT 65 MPH 24H 13/1200Z 31.8N 24.7W 55 KT 65 MPH 36H 14/0000Z 31.8N 22.6W 55 KT 65 MPH 48H 14/1200Z 31.5N 21.0W 50 KT 60 MPH 60H 15/0000Z 31.2N 20.2W 40 KT 45 MPH 72H 15/1200Z 31.1N 19.6W 30 KT 35 MPH...POST-TROP/REMNT LOW 96H 16/1200Z 32.7N 19.2W 30 KT 35 MPH...POST-TROP/REMNT LOW 120H 17/1200Z 37.6N 17.4W 30 KT 35 MPH...POST-TROP/REMNT LOW $$ Forecaster Latto
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