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| #984481 (Received by flhurricane at: 4:39 AM 29.Sep.2019) TCDAT3 Hurricane Lorenzo Discussion Number 28 NWS National Hurricane Center Miami FL AL132019 500 AM AST Sun Sep 29 2019 The satellite appearance of Lorenzo is not quite as impressive as it was several hours ago. Although the eye is still very distinct, the cloud tops are not as cold in the eyewall and there are a few dry slots evident beyond the inner core. The initial wind speed is lowered just slightly to 135 kt, but based on the latest satellite estimates this is probably generous. The NOAA Hurricane Hunters are scheduled to investigate Lorenzo later today, and the data they collect should provide a better assessment of the hurricane`s intensity and structure. Very intense hurricanes like Lorenzo are usually not able to maintain their intensity for very long. Since Lorenzo will be moving toward cooler waters and into an environment of drier air and higher wind shear during the next several days, steady weakening is forecast. Lorenzo is now expected to become extratropical by day 4, when the cyclone will be over SSTs colder than 20 C. The NHC intensity forecast is in good agreement with the consensus models, IVCN, IVDR, and HCCA. Lorenzo is still moving northward at 9 kt through a break in the Atlantic subtropical ridge. A mid- to upper-level trough currently over eastern Canada is expected to amplify when it reaches the central Atlantic, which should cause Lorenzo to accelerate to the northeast during the next few days. This motion should take the core of Lorenzo near or just west of the Azores late Tuesday and Wednesday. After that time, there are significant differences in the models on whether or not Lorenzo interacts with an extratropical low over the north Atlantic. The ECMWF and UKMET models show little interaction with that low and show Lorenzo moving east-northeastward in the westerlies toward northwestern France, Ireland, and the United Kingdom. On the other hand, the GFS, HWRF, and HMON models show Lorenzo rotating around the eastern side of the low and remaining over the Atlantic. The spread in the models is incredibly large, about 1300 n mi by day 5. Given the high uncertainty at this time, only small changes were made to the NHC track forecast, and this one favors the UKMET and ECMWF solutions. However, confidence in the long-term track is very low and adjustments may be needed later today. The Tropical Analysis and Forecast Branch here at NHC provided input that the large wind field of Lorenzo and its expected faster forward motion in a few days will likely lead to extreme enhancement of the wave field and wave growth over the southeastern portion of the circulation. 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 several days. Regardless of Lorenzo`s exact track near the Azores, strong winds are becoming increasingly likely on those 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 north Atlantic basin during the next few days. These swells will produce life-threatening surf and rip currents. FORECAST POSITIONS AND MAX WINDS INIT 29/0900Z 25.1N 44.6W 135 KT 155 MPH 12H 29/1800Z 26.4N 44.2W 125 KT 145 MPH 24H 30/0600Z 28.0N 43.5W 115 KT 130 MPH 36H 30/1800Z 29.9N 42.5W 110 KT 125 MPH 48H 01/0600Z 32.2N 40.5W 105 KT 120 MPH 72H 02/0600Z 39.4N 32.1W 90 KT 105 MPH 96H 03/0600Z 47.8N 20.0W 70 KT 80 MPH...POST-TROP/EXTRATROP 120H 04/0600Z 53.5N 10.0W 55 KT 65 MPH...POST-TROP/EXTRATROP $$ Forecaster Cangialosi |
