ZCZC MIATCDAT4 ALL TTAA00 KNHC DDHHMM Subtropical Storm Alpha Special Discussion Number 1 NWS National Hurricane Center Miami FL AL242020 430 PM GMT Fri Sep 18 2020 The small low pressure area that has been rotating around a larger extratropical low in the far northeastern Atlantic has become better organized this morning. Moderate-to-deep convection has persisted near the center since last night, scatterometer data shows a closed 40-kt low, and radar images from Portugal show a definite organized convective pattern. While the system is still in the cyclonic envelope of the large extratropical low and likely neutral- or cold-core, it has developed enough tropical characteristics to be considered a subtropical storm. The initial intensity is set to 45 kt in accordance with the scatterometer data, assuming some undersampling for this small system. Little change in strength is forecast until landfall in Portugal during the next couple of hours. Global models show the small low moving northeastward at about 15 kt for the next 24 hours before dissipating over northern Spain or the Bay of Biscay. The track and intensity forecasts are consistent with the consensus guidance. Additional information on the hazards from this system can be found in products from the Portuguese Institute for Sea and Atmosphere at www.ipma.pt. FORECAST POSITIONS AND MAX WINDS INIT 18/1630Z 39.9N 9.3W 45 KT 50 MPH 12H 19/0000Z 41.5N 7.5W 30 KT 35 MPH...POST-TROP/INLAND 24H 19/1200Z 44.2N 4.2W 30 KT 35 MPH...POST-TROP/EXTRATROP 36H 20/0000Z...DISSIPATED $$ Forecaster Blake NNNN
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