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Hurricane Lorenzo Forecast Discussion Number 27
2019-09-29 04:35:27| National Hurricane Center (Atlantic)
Issued at 1100 PM AST Sat Sep 28 2019 000 WTNT43 KNHC 290235 TCDAT3 Hurricane Lorenzo Discussion Number 27 NWS National Hurricane Center Miami FL AL132019 1100 PM AST Sat Sep 28 2019 Lorenzo has rapidly strengthened this evening. An eyewall replacement cycle completed earlier today, with a recent SSMIS microwave overpass showing that a new eyewall about 30 n mi in diameter now completely encircles the eye. The cold cloud tops surrounding the eye have expanded, with a solid ring of temperatures measuring colder than minus 70 degrees Celsius. In addition, the eye has cleared, with satellite derived cloud-top temperatures now above 15 degrees Celsius. Throughout the evening, the objective and subjective intensity estimates have climbed, with 0130 UTC special classifications from TAFB and SAB as well as a recent UW-CIMSS ADT estimate unanimously agreeing on a 140-kt initial intensity. This makes Lorenzo an extremely dangerous category 5 hurricane. The initial motion is now northward at 9 kt. Lorenzo will be steered north through a break between two subtropical ridges through tonight, with a turn to the north-northeast expected on Sunday. After Sunday, Lorenzo will begin to get caught up in increasing southwesterly flow ahead of an approaching mid-latitude trough. This will cause the cyclone to accelerate northeastward through the end of the forecast period. The official track forecast is essentially an update of the previous one, and is near the middle of the consensus aids. Lorenzo will likely peak in intensity overnight as it remains in the current favorable environment. Some fluctuations in intensity are possible on Sunday mainly due to eyewall replacement cycles. By Sunday night, Lorenzo will begin to feel the effects of some southwesterly shear ahead of the approaching trough, while it also moves over waters of lower oceanic heat content. These factors should induce a steady weakening trend through 48 hours. After that time, SSTs below 26 C should cause a faster weakening trend. By 72 hours, the cyclone will begin interacting with the approaching trough and an associated cold front, which will begin a transition to an extratropical low. This transition is forecast to complete by 120 hours, but it could happen a little sooner than that. The official forecast was increased through the first 48 hours due to the increase in initial intensity, and then blends to near the previous official forecast by 72 hours. With this latest advisory intensity, Lorenzo becomes the strongest hurricane in history this far north and east in the Atlantic basin. Key Messages: 1. Lorenzo is a large hurricane, and its hurricane- and tropical-storm-force wind fields are expected to expand further during the next several days. Regardless of Lorenzo's exact track near the Azores, strong winds are becoming increasingly likely on the islands Tuesday night and Wednesday, and residents there should monitor the progress of the hurricane. 2. Large swells generated by Lorenzo will continue to spread across much of the western and northern parts of the Atlantic basin during the next few days. These swells will produce life-threatening surf and rip currents. FORECAST POSITIONS AND MAX WINDS INIT 29/0300Z 24.2N 44.9W 140 KT 160 MPH 12H 29/1200Z 25.5N 44.7W 135 KT 155 MPH 24H 30/0000Z 27.1N 44.1W 125 KT 145 MPH 36H 30/1200Z 28.8N 43.3W 115 KT 130 MPH 48H 01/0000Z 30.8N 42.0W 105 KT 120 MPH 72H 02/0000Z 36.7N 35.3W 95 KT 110 MPH 96H 03/0000Z 45.0N 23.5W 75 KT 85 MPH 120H 04/0000Z 52.2N 10.7W 60 KT 70 MPH...POST-TROP/EXTRATROP $$ Forecaster Latto
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