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Hurricane Lee Forecast Discussion



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WTNT43 KNHC 101444
TCDAT3

Hurricane Lee Discussion Number  21
NWS National Hurricane Center Miami FL       AL132023
1100 AM AST Sun Sep 10 2023

Earlier SSMIS and GMI microwave overpasses along with reports from 
a NOAA Hurricane Hunter aircraft indicate that Lee has a larger 
banded-type eye as compared to yesterday.  The ragged eye has 
become apparent in visible and infrared satellite images within 
the past hour or so.  The NOAA aircraft has measured a peak 700-mb 
flight-level wind of 106 kt and SFMR winds of 95 kt, and the minimum 
pressure has been oscillating in the 956-958 mb range during the 
flight.  Based on these data, and the recent improvement in 
structure, the initial intensity has been raised to 95 kt. 

The vertical wind shear over Lee appears to have relaxed some since 
yesterday as there has been an expansion of the upper-level outflow 
over the southern and southwestern portions of the storm.  Most of 
the guidance suggests that the shear will decrease more over the 
next couple of days, allowing Lee to re-strengthen.  The expected 
slow motion of the hurricane could cause some upwelling, especially 
in the 2-3 day time period when Lee is forecast to be moving at only 
around 5 kt.  The NHC wind speed forecast calls for steady 
restrengthening during the next 24-48 hours, then shows some gradual 
weakening after that time due to the potential for upwelling. Later 
in the forecast period, increasing southwesterly shear is likely to 
cause additional weakening, however Lee is forecast to remain a 
strong hurricane through most of this week. 

Recent aircraft center fixes show that the hurricane is beginning 
to slow down.  The initial motion is now west-northwest or 300 
degrees at 7 kt. A high pressure ridge to the northwest of Lee is 
forecast to build southwestward during the next couple of days, 
further slowing Lee's progress.  By midweek, a mid-latitude trough 
moving into the northeastern United States is expected to weaken 
the western extent of the ridge, allowing Lee to turn northward. 
There is still significant uncertainty in the global model guidance 
regarding the forward speed of Lee later in the forecast period.  
The NHC track forecast continues to lie between the faster GFS and 
slower ECMWF, close to the various consensus models. 


KEY MESSAGES:

1. Lee's core is expected to pass well north of the northern
Leeward Islands, the Virgin Islands, and Puerto Rico during the 
next couple of days.

2. Dangerous surf and life-threatening rip currents are affecting
portions of the northern Leeward Islands, the British and U.S. 
Virgin Islands, Puerto Rico, Hispaniola, the Turks and Caicos 
Islands, the Bahamas, and Bermuda. 

3. It remains too soon to know what level of impacts, if any, Lee
might have along the U.S. East Coast, Atlantic Canada, or Bermuda
late next week, especially since the hurricane is expected to slow
down considerably over the southwestern Atlantic.  Regardless,
dangerous surf and rip currents are expected along most of the U.S.
East Coast beginning later today and continuing through the week as 
Lee grows in size. Users should continue to monitor updates to the
forecast of Lee during the next several days.


FORECAST POSITIONS AND MAX WINDS

INIT  10/1500Z 21.6N  61.0W   95 KT 110 MPH
 12H  11/0000Z 22.3N  62.1W  105 KT 120 MPH
 24H  11/1200Z 23.0N  63.3W  110 KT 125 MPH
 36H  12/0000Z 23.4N  64.5W  115 KT 130 MPH
 48H  12/1200Z 23.8N  65.6W  115 KT 130 MPH
 60H  13/0000Z 24.2N  66.5W  110 KT 125 MPH
 72H  13/1200Z 24.7N  67.2W  105 KT 120 MPH
 96H  14/1200Z 27.3N  67.9W   95 KT 110 MPH
120H  15/1200Z 31.3N  67.7W   80 KT  90 MPH

$$
Forecaster Brown



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