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Hurricane Lorenzo Forecast Discussion Number 18
2019-09-27 04:33:18| National Hurricane Center (Atlantic)
Issued at 1100 PM AST Thu Sep 26 2019 243 WTNT43 KNHC 270233 TCDAT3 Hurricane Lorenzo Discussion Number 18 NWS National Hurricane Center Miami FL AL132019 1100 PM AST Thu Sep 26 2019 Lorenzo has intensified even more this evening, with a clear eye characterized by warm temperatures of up to 17 degrees Celsius. The eye is now completely surrounded by a ring of convection with cold cloud tops less than minus 70 degrees Celsius. The subjective Dvorak intensity estimates from both TAFB and SAB, as well as the objective intensity estimate from UW-CIMSS ADT unanimously support increasing the initial intensity to 125 kt. Lorenzo is a very large hurricane, with tropical storm force winds extending over 200 n mi from the center in the northern semicircle, and a cirrus cloud canopy that spans greater than a 10 degree latitude by 10 degree longitude area. The initial motion is now north-northwest, or 330/12 kt. Model guidance is in very good agreement throughout the 5 day period on the future track of Lorenzo. The hurricane will move through a break in the subtropical ridge currently to its northwest over the next couple of days, gradually turning to the north then northeast as it rounds the periphery of a ridge to its east. Late in the forecast period, Lorenzo will begin to accelerate as it gets caught in southwesterly flow ahead of an approaching mid-latitude trough. The model guidance made a slight shift to the left since the previous advisory, but since the same guidance shifted right earlier today, I did not want to make much of a change to the track. The official forecast track is very near the previous one, and is now on the right side of the consensus guidance. The environment around Lorenzo is expected to change little over the next day or so. Both dynamical and statistical guidance are suggesting that the hurricane is nearing peak intensity. Therefore only fluctuations in strength due to eyewall replacement cycles are expected through about Friday night. Over the weekend, some moderate westerly shear ahead of the approaching mid-latitude trough could begin to slowly weaken the cyclone. Late in the forecast period, the combination of strong upper level southwesterly winds and cooler sea surface temperatures should cause a faster weakening trend. The official forecast is essentially an update of the previous one, and a little higher than most of the guidance through the first 48 hours. FORECAST POSITIONS AND MAX WINDS INIT 27/0300Z 17.6N 41.5W 125 KT 145 MPH 12H 27/1200Z 19.1N 42.3W 125 KT 145 MPH 24H 28/0000Z 21.0N 43.3W 120 KT 140 MPH 36H 28/1200Z 22.7N 43.8W 115 KT 130 MPH 48H 29/0000Z 24.4N 43.6W 110 KT 125 MPH 72H 30/0000Z 27.8N 41.8W 100 KT 115 MPH 96H 01/0000Z 31.8N 39.0W 95 KT 110 MPH 120H 02/0000Z 37.5N 33.2W 85 KT 100 MPH $$ Forecaster Latto
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