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Tropical Storm Rene Forecast Discussion Number 21
2020-09-12 10:44:14| National Hurricane Center (Atlantic)
Issued at 500 AM AST Sat Sep 12 2020 000 WTNT43 KNHC 120844 TCDAT3 Tropical Storm Rene Discussion Number 21 NWS National Hurricane Center Miami FL AL182020 500 AM AST Sat Sep 12 2020 Deep convection associated with Rene appears to have lost some organization overnight. Although there have been several pulsating bursts of convection overnight, the convection that was persistent over the center during the evening is now confined to the southern portion of the circulation. A blend of the latest subjective and objective satellite intensity estimates yields an initial intensity of 35 kt, but this could be generous. ASCAT data later this morning should help to determine if Rene is still a topical storm. Mid-level dry air appears to be the primary reason why Rene has struggled to strengthen over the past few days, and although the shear is expected to remain low today, the dry air is likely to prevent strengthening. On Sunday, Rene is forecast to approach an area of strong west-northwesterly flow aloft, and this increase is shear is likely to cause the cyclone to weaken. Most of the global models continue to significantly weaken Rene early next week, and both the ECMWF and GFS suggest that the cyclone will degenerate into a trough of low pressure by days 4 or 5. The NHC forecast continues to maintain Rene as a tropical cyclone throughout the forecast period, but if the current trends it is becoming unlikely that Rene will survive as a tropical cyclone for the entire 5-day period. Rene has turned northwestward and is now moving at 305/13 kt. A northwestward motion around the western periphery of a mid-level ridge over the eastern Atlantic should continue for another 12 to 24 hours, but by late Sunday Rene is forecast to slow down as ridge of high pressure builds to the northwest and north of the cyclone. Later in the period, Rene is forecast to turn westward and then southwestward under the influence of the building ridge. The track guidance remains in fairly good agreement, and no significant changes to the official forecaster were required. FORECAST POSITIONS AND MAX WINDS INIT 12/0900Z 22.5N 43.5W 35 KT 40 MPH 12H 12/1800Z 23.7N 44.9W 35 KT 40 MPH 24H 13/0600Z 25.4N 46.3W 35 KT 40 MPH 36H 13/1800Z 26.6N 47.3W 35 KT 40 MPH 48H 14/0600Z 27.2N 47.7W 30 KT 35 MPH 60H 14/1800Z 27.1N 48.1W 30 KT 35 MPH 72H 15/0600Z 26.7N 49.1W 30 KT 35 MPH 96H 16/0600Z 25.5N 52.0W 30 KT 35 MPH 120H 17/0600Z 24.7N 55.0W 30 KT 35 MPH $$ Forecaster Brown
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