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Hurricane Lee Discussion Number  24
NWS National Hurricane Center Miami FL       AL132023
500 AM AST Mon Sep 11 2023
 
The eye of the hurricane became more ragged and less distinct
overnight, but in recent satellite images there appears to be some
warming near the center once again. A 0619 UTC AMSR2 microwave pass
showed the eyewall was open to the south, but a new convective burst
is currently wrapping around the western portion of the eyewall. The
latest objective and subjective satellite intensity estimates have
leveled off due to recent fluctuations in the structure of the
hurricane. The initial intensity is held at 105 kt, which is
consistent with the earlier aircraft data. This intensity also lies
between the latest subjective Dvorak data-T and current intensity
estimates from TAFB and SAB that range from 90-115 kt.
 
Lee is moving slowly northwestward (310/6 kt) while being steered by
a mid-level ridge over the western and central subtropical Atlantic.
A slow west-northwestward to northwestward motion should continue
for the next day or two before a deep-layer trough moves across the
eastern U.S. and begins eroding the steering ridge by midweek. This
should allow Lee to gradually turn northward by 72 h. The guidance
is in good agreement through midweek with little cross-track spread
noted, and the updated NHC forecast lies just a bit right of the
previous prediction. This takes the core of Lee to the west of
Bermuda, although its expanding tropical-storm-force wind field
could bring some impacts to the island during the latter part of the
week. On days 4-5, Lee should continue moving generally northward
with a ridge positioned to its east. For this portion of the
forecast, the NHC prediction was adjusted slightly west, keeping the
forecast track near the center of the guidance envelope and in best
agreement with the TVCA simple consensus aid.
 
In the near term, very warm SSTs of 29-30C and weaker deep-layer 
shear appear conducive for at least modest strengthening of the 
hurricane, although inner-core structural changes and bouts of dry 
air entrainment could cause some short-term intensity fluctuations. 
Most of the intensity models support an intensity peak within the 
next day or so, and this is reflected in the latest NHC forecast. 
Thereafter, the large wind field and slow motion of Lee could cause 
upwelling of cooler waters. In addition, the hurricane is likely to 
encounter increasing southwesterly shear from the aforementioned 
trough later in the period, as well as the cool wake left behind by 
recent western Atlantic hurricanes (Idalia and Franklin). All of 
these factors point toward weakening later this week, and the NHC 
forecast follows the IVCN and HCCA trends with gradual weakening 
beyond 48 h. Although the peak winds are forecast to decrease, the 
outer wind field is expected to expand as the hurricane interacts 
with the upper trough and gains latitude over the western Atlantic, 
with strong winds extending far from the center of the cyclone.
 
 
KEY MESSAGES:
 
1. Dangerous surf and life-threatening rip currents will affect
portions of the northern Leeward Islands, the Virgin Islands, Puerto
Rico, Hispaniola, the Turks and Caicos Islands, the Bahamas, and
Bermuda through much of the week.
 
2. Lee could bring wind, rainfall, and high surf impacts to
Bermuda later this week. Although it is too soon to determine the
specific timing and level of those impacts, interests on Bermuda
should monitor the latest forecasts for Lee.
 
3. It remains too soon to know what level of impacts, if any,
Lee might have along the U.S. East Coast and Atlantic Canada late
this 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 this 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  11/0900Z 23.1N  62.6W  105 KT 120 MPH
 12H  11/1800Z 23.5N  63.5W  115 KT 130 MPH
 24H  12/0600Z 24.0N  64.8W  115 KT 130 MPH
 36H  12/1800Z 24.5N  65.8W  115 KT 130 MPH
 48H  13/0600Z 25.1N  66.7W  110 KT 125 MPH
 60H  13/1800Z 26.1N  67.3W  100 KT 115 MPH
 72H  14/0600Z 27.6N  67.6W   95 KT 110 MPH
 96H  15/0600Z 31.8N  67.6W   85 KT 100 MPH
120H  16/0600Z 37.5N  67.0W   70 KT  80 MPH
 
$$
Forecaster Reinhart
 
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