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Tropical Storm Theta Forecast Discussion Number 20
2020-11-14 21:38:07| National Hurricane Center (Atlantic)
Issued at 900 PM GMT Sat Nov 14 2020 890 WTNT45 KNHC 142038 TCDAT5 Tropical Storm Theta Discussion Number 20 NWS National Hurricane Center Miami FL AL302020 900 PM GMT Sat Nov 14 2020 A persistent band of deep convection to the southeast of Theta's center continues to keep it classifiable as a tropical cyclone, with the edge of the convection at one point today reaching within 60 n mi of the center of the cyclone. Over the past couple of hours this convection has become farther displaced from Theta's center, as the system gets blasted by over 40 kt of northerly shear. Since the cyclone's appearance has changed little today, the initial intensity is being held at 35 kt based off data from an ASCAT-A overpass this morning. Very strong shear and dry air entrainment should cause the deep convection to weaken and become even farther displaced from the center tonight, with Theta anticipated to degenerate into a remnant low by 12 h. The cyclone should also weaken under this regime, and open into a trough by 72 h. The latest NHC intensity forecast is unchanged from the previous one, and is in good agreement with the intensity guidance. Theta continues moving just south of due east, but now at a slower pace of around 5 kt. A mid-level ridge located to the south of Theta is weakening, which will result in a continued slow east-southeastward motion through tonight. As Theta becomes a shallow system on Sunday, the low-level flow is forecast to become southwesterly, and this flow is expected to increase on Monday ahead of an approaching cold front. This will cause Theta to turn to the northeast by late Sunday and accelerate until it dissipates in a few days. The latest NHC track forecast is similar to the previous one and lies near the track consensus models. FORECAST POSITIONS AND MAX WINDS INIT 14/2100Z 31.7N 19.2W 35 KT 40 MPH 12H 15/0600Z 31.7N 18.3W 30 KT 35 MPH...POST-TROP/REMNT LOW 24H 15/1800Z 32.1N 17.5W 30 KT 35 MPH...POST-TROP/REMNT LOW 36H 16/0600Z 33.2N 17.0W 25 KT 30 MPH...POST-TROP/REMNT LOW 48H 16/1800Z 35.1N 16.4W 20 KT 25 MPH...POST-TROP/REMNT LOW 60H 17/0600Z 38.1N 14.7W 20 KT 25 MPH...POST-TROP/REMNT LOW 72H 17/1800Z...DISSIPATED $$ Forecaster Latto
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