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Hurricane Lorenzo Forecast Discussion Number 32
2019-09-30 10:38:48| National Hurricane Center (Atlantic)
Issued at 500 AM AST Mon Sep 30 2019 000 WTNT43 KNHC 300838 TCDAT3 Hurricane Lorenzo Discussion Number 32 NWS National Hurricane Center Miami FL AL132019 500 AM AST Mon Sep 30 2019 The satellite presentation of Lorenzo has generally changed little during the last several hours. The hurricane continues to maintain a well-defined inner core with a ragged cloud-filled eye. The outer bands are well established to the north and east of the center, but are restricted on the south side of the circulation due to some southwesterly shear and drier air being wrapped into that portion of the cyclone. The initial intensity estimate is set at 90 kt based on T5.0/90 kt Dvorak classifications from TAFB and SAB. Lorenzo is moving north-northeastward at 11 kt through a break in the Atlantic subtropical ridge. The models generally agree that Lorenzo should pick up forward speed and move northeastward during the next day or two as a trough amplifies over the central Atlantic. This flow should take the core of Lorenzo near or to the west of the western Azores late Tuesday and early Wednesday. After that time, the spread in the guidance increases with several of the models including the GFS, HWRF, and HMON showing Lorenzo turning north-northeastward or northward as it moves around the east side of a large extratropical low. The new ECMWF run has shifted closer to the GFS/HWRF/HMON solutions, but it still is considerably to the east of those models as it shows less interaction with the extratropical low. The NHC track forecast has been adjusted a little to the left to come into better agreement with the latest consensus aids. Although the spread in the models is not as large as it was yesterday, the forecast beyond 48 hours is still of low confidence given the uncertainty in the longer-term steering flow. The intensity forecast appears to be more straightforward than the track forecast. The bulk of the guidance shows the hurricane maintaining its intensity or weakening slightly during the next day or two while it remains over relatively warm waters and in moderate wind shear conditions. It seems likely that Lorenzo will be a significant hurricane when it passes near the Azores in about 2 days. After that time, more notable weakening should occur due to a significant drop off in SSTs, drier air, and much stronger shear. In fact, these conditions should ultimately lead to extratropical transition, which is expected to be complete by 72 hours. Dissipation is now predicted to occur by day 5 following the global model guidance. Key Messages: 1. Lorenzo is a large and powerful hurricane, and its hurricane- and tropical-storm-force wind fields are expected to expand further during the next few days. Hurricane and Tropical Storm Watches are in effect for the Azores, and Hurricane and Tropical Storm Warnings could be required later today for those islands. 2. Large swells generated by Lorenzo will continue to spread across much of the north Atlantic basin during the next few days. These swells will produce life-threatening surf and rip currents. FORECAST POSITIONS AND MAX WINDS INIT 30/0900Z 28.7N 43.1W 90 KT 105 MPH 12H 30/1800Z 30.3N 42.3W 85 KT 100 MPH 24H 01/0600Z 32.7N 40.3W 85 KT 100 MPH 36H 01/1800Z 36.0N 36.6W 85 KT 100 MPH 48H 02/0600Z 40.5N 31.0W 80 KT 90 MPH 72H 03/0600Z 52.0N 20.0W 65 KT 75 MPH...POST-TROP/EXTRATROP 96H 04/0600Z 57.0N 13.5W 50 KT 60 MPH...POST-TROP/EXTRATROP 120H 05/0600Z...DISSIPATED $$ Forecaster Cangialosi
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