|#1150709 (Received by flhurricane at: 10:57 PM 31.Aug.2023)|
Post-Tropical Cyclone Idalia Discussion Number 22
NWS National Hurricane Center Miami FL AL102023
1100 PM EDT Thu Aug 31 2023
Satellite images indicate that Idalia continues to exhibit the
appearance of an extratropical cyclone with a frontal boundary
extending from the center northeastward. There is almost no deep
convection associated with the system, but there continues to be
areas of heavy rain along the front extending to near the coast of
North Carolina. The initial intensity remains 55 kt.
The cyclone is moving eastward at about 20 kt. A slightly slower
motion to the east-southeast is expected during the next day or two
as the system continues to move near the base of a mid- to
upper-level trough. However, the steering currents are expected to
weaken over the weekend as the storm approaches Bermuda, which
should cause a significant slow down. A turn to the northeast is
forecast late in the weekend when another shortwave trough
approaches the system. The guidance is slower this cycle, and the
NHC track forecast has been adjusted accordingly.
Gradual weakening is expected through early Saturday as the system
separates from the mid- to upper-level trough. However, as Idalia
transitions back to a tropical cyclone near Bermuda, slow
strengthening seems likely. Based on the GFS and ECMWF models,
Idalia will likely transition back to an extratropical cyclone in
about 5 days. The intensity forecast is similar to the previous
one and fairly close to the GFS model.
1. Tropical storm conditions are possible in Bermuda by Saturday.
Heavy rainfall will likely lead to areas of flash and urban
flooding on the island.
2. Water levels are expected to subside and winds are expected to
diminish along the coast of North Carolina through early Friday.
FORECAST POSITIONS AND MAX WINDS
INIT 01/0300Z 33.1N 71.5W 55 KT 65 MPH...POST-TROPICAL
12H 01/1200Z 32.3N 69.1W 50 KT 60 MPH...POST-TROP/EXTRATROP
24H 02/0000Z 31.1N 67.2W 45 KT 50 MPH...POST-TROP/EXTRATROP
36H 02/1200Z 30.6N 65.9W 40 KT 45 MPH...POST-TROP/EXTRATROP
48H 03/0000Z 31.3N 64.5W 40 KT 45 MPH...TROPICAL CYCLONE
60H 03/1200Z 32.3N 63.0W 45 KT 50 MPH
72H 04/0000Z 34.3N 61.0W 50 KT 60 MPH
96H 05/0000Z 36.8N 59.0W 50 KT 60 MPH
120H 06/0000Z 38.7N 61.0W 45 KT 50 MPH...POST-TROP/EXTRATROP