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Tropical Storm Melissa Forecast Discussion Number 9
2019-10-13 16:34:37| National Hurricane Center (Atlantic)
Issued at 1100 AM AST Sun Oct 13 2019 000 WTNT44 KNHC 131434 TCDAT4 Tropical Storm Melissa Discussion Number 9 NWS National Hurricane Center Miami FL AL142019 1100 AM AST Sun Oct 13 2019 After an overnight convective hiatus, likely due to Melissa passing over a narrow band of cold water, deep convection has increased near the center and a curved band of broken convection has developed in the eastern semicircle. A 12Z TAFB shear pattern satellite intensity estimate resulted in 45 kt while the curved band pattern produced 35 kt. An average of these estimates yields 40 kt, which is close to the most recent UW-CIMSS SATCON and ADT estimates of 44 kt and 43 kt, respectively. Therefore, the initial intensity remains at 40 kt. Melissa is beginning to accelerate east-northeastward and the initial motion estimate is now 075/15 kt. A further increase in forward speed combined with an eastward motion is expected over the next couple of days as Melissa moves around the northern periphery of the deep-layer Bermuda-Azores high. By late Tuesday and Wednesday, Melissa is forecast to turn toward the east-southeast as a weakening extratropical low pressure system. The new NHC track forecast was nudged a little to the right of the previous advisory, and lies near the middle of the tightly-packed consensus guidance envelope. The westerly wind shear across Melissa is currently around 20 kt and the cyclone is moving over sub-25 degree C sea-surface temperatures (SST). Water temperatures ahead of the cyclone are forecast to decrease to 21-22 deg C within 12 hours, while the shear is expected to increase to 25-30 kt. The combination of these two negative factors will result in weakening by this evening, which will continue throughout the remainder of the forecast period, with Melissa becoming a post-tropical remnant by Monday and merging with a frontal system or larger extratropical low by Wednesday. The new official intensity forecast is similar to the previous advisory, and closely follows a blend of the HCCA and IVCN intensity models. FORECAST POSITIONS AND MAX WINDS INIT 13/1500Z 39.8N 60.9W 40 KT 45 MPH 12H 14/0000Z 40.5N 57.7W 35 KT 40 MPH 24H 14/1200Z 41.4N 53.0W 30 KT 35 MPH...POST-TROP/REMNT LOW 36H 15/0000Z 41.9N 47.8W 30 KT 35 MPH...POST-TROP/REMNT LOW 48H 15/1200Z 41.8N 41.9W 30 KT 35 MPH...POST-TROP/REMNT LOW 72H 16/1200Z...DISSIPATED $$ Forecaster Stewart
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