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Hurricane Earl Forecast Discussion


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WTNT41 KNHC 071453
TCDAT1

Hurricane Earl Discussion Number  19
NWS National Hurricane Center Miami FL       AL062022
1100 AM AST Wed Sep 07 2022

While it is evident that westerly vertical wind shear continues to 
affect the overall satellite presentation of Earl, useful data 
from the NOAA-P3 Hurricane Hunter aircraft indicates that the 
hurricane is holding its own and has even strengthened a bit. Part 
of this resilience could be due to the fact that the low and 
mid-level centers of Earl are now vertically stacked with the wind 
field relatively symmetric per the most recent set of Tail Doppler 
Radar from the aircraft. However, the westerly shear is still 
affecting the inner-core structure of the system, with its large 40 
n mi wide eye open in the southern semicircle. The highest flight- 
level winds from this morning's mission was 82 kt at 700 mb with 
SFMR at 75 kt. The initial intensity was increased to 75 kt at the 
8am intermediate advisory and remains this value for this advisory.

Fixes from this morning indicate that Earl has been moving just east 
of due north, with the motion estimated at 005/6 kt. The hurricane 
is caught in between a mid-level ridge now centered to its 
southeast, with a positively-tilted upper-level trough located to 
the northwest. This synoptic setup should enable Earl to begin 
recurving north-northeastward and then northeastward as it 
accelerates over the next 24-48 hours. The track guidance remains 
tightly clustered during the early portion of the forecast, with the 
GFS and ECMWF tracks now nearly identical during this period. The 
official track forecast was only adjusted a touch east of the prior 
one during this period. However, as noted previously, there is 
increasing model support that the upper-level trough will ultimately 
phase with Earl after 72 hours, resulting in the cyclone slowing 
down significantly and potentially turning more northward in days 
4-5. The official track forecast during this period now shows a bit 
more of a northward bend and further slowdown compared to the prior 
track, favoring a blend of the latest GFS and ECMWF forecast.  

The persistent deep-layer westerly vertical wind shear that has been 
impacting Earl the last several days is finally forecast to subside 
later today, dropping below 10 kt in 24 hours. This decreasing 
shear, in combination with very warm sea-surface temperatures, 
favorable positioning in the right-entrance region of an upper-level 
jet streak, and significant acceleration in the storm motion, is 
likely to result in substantial strengthening of the surface wind 
field and the latest NHC intensity forecast now shows a peak at 115 
kt in 60-h, in good general agreement with the latest HCCA, yet 
still under the LGEM intensity aid. After that, a significant 
trough interaction is likely to rapidly increase baroclinicity, with 
Earl forecast to become an extratropical-low as it phases with the 
upper-level trough between days 3-4 in the forecast period.


KEY MESSAGES:

1.  Although Earl's center is forecast to pass southeast of Bermuda,
the wind field is expected to grow, with tropical-storm-force winds
forecast to spread across the island beginning Thursday afternoon
and continuing through Friday morning.

2.  Swells generated by Earl are expected to reach Bermuda by 
tonight and the U.S. East Coast shortly thereafter.  These swells 
are likely to cause life-threatening surf and rip current 
conditions through the weekend.  Please consult products from your 
local weather office.


FORECAST POSITIONS AND MAX WINDS

INIT  07/1500Z 25.7N  65.7W   75 KT  85 MPH
 12H  08/0000Z 26.8N  65.6W   80 KT  90 MPH
 24H  08/1200Z 28.5N  65.2W   90 KT 105 MPH
 36H  09/0000Z 30.4N  64.1W  100 KT 115 MPH
 48H  09/1200Z 33.0N  61.5W  110 KT 125 MPH
 60H  10/0000Z 36.4N  57.3W  115 KT 130 MPH
 72H  10/1200Z 40.1N  53.1W  100 KT 115 MPH
 96H  11/1200Z 45.0N  49.0W   60 KT  70 MPH...POST-TROP/EXTRATROP
120H  12/1200Z 47.0N  47.9W   45 KT  50 MPH...POST-TROP/EXTRATROP

$$
Forecaster Papin



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