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Tropical Storm Earl Forecast Discussion


000
WTNT41 KNHC 041459
TCDAT1

Tropical Storm Earl Discussion Number   7
NWS National Hurricane Center Miami FL       AL062022
1100 AM AST Sun Sep 04 2022

This morning, Earl developed a large convective burst, with cold 
convective cloud tops below -80 C and the larger cirrus plume 
obscuring the low-level center. A NOAA-P3 mission has also be flying 
through Earl this morning, showing that the center may be in the 
process of reorganizing closer to this recent convective burst. 
WSR-88D radar imagery from Puerto Rico earlier showed a well-defined 
mid-level vortex associated with this convective burst up at 20 k 
feet, which matched the NOAA-P3 TDR data, but it is unclear how 
close the surface vortex is relative to this mid-level center. 
Subjective Dvorak estimates from TAFB and SAB are T3.0/45-kt and 
T3.5/55-kt respectively, though objective estimates are somewhat 
lower, with ADT only at 33-kt and SATCON at 44-kt. A blend of these 
estimates and the wind data from the NOAA-P3 mission support 
maintaining the intensity at 45 kt for this advisory.

Earl appears to have slowed down further this morning, and may be in 
the process of relocating closer to the convective burst, with the 
latest motion an uncertain 310/3 kt. As mentioned previously, there 
is a weakness in the mid-level ridging to the north of the storm, 
and this should enable Earl to make a gradual turn to the 
north-northwest and north over the next 24-72 hours. The mid-level 
ridging then shifts mostly east of the cyclone, allowing a continued 
slow north-northeastward motion thereafter. The latest track 
guidance has shifted east in the short term due in part to the 
initial position, and the latest NHC track forecast has been shifted 
in that direction and lies just west of TVCN consensus. However, the 
latest track forecast is not as far to the east as the HFIP 
Corrected Consensus (HCCA), GFS or HWRF forecasts, and additional 
eastward adjustments may be needed in subsequent forecasts.

The large convective burst this morning makes the short-term 
intensity forecast somewhat tricky. If the low-level center is able 
to reform and become better aligned with the mid-level center, some 
intensification could occur. If and when this occurs is important, 
with the latest HWRF and GFS forecasts suggesting this could occur 
as soon as later today, resulting in more significant 
intensification. However, the HMON, HAFS-S, and ECMWF suggest it may 
take a few days for a more aligned structure to occur, likely 
delayed by continued moderate (15-25 kts) southwesterly vertical 
wind shear, which is expected to persist for the next 2-3 days. The 
latest NHC intensity forecast opts to split the difference, now 
showing gradual intensification over the next 24-48 hours, making 
Earl a hurricane in 48 hours. This is higher than the previous NHC 
intensity forecast, but is under the latest HCCA, HWRF, and 
GFS-SHIPS guidance. After 72 h, shear is expected to decrease, and 
more robust intensification is possible thereafter, with the latest 
intensity forecast now making Earl a major hurricane by 120 h, in 
good agreement with the IVCN and HCCA consensus aids.

At this juncture, tropical-storm-force winds are still forecast to 
remain on the northern and eastern side of the circulation, and are 
not expected to move across the northern Leeward Islands, the Virgin 
Islands, or Puerto Rico.  However, gusty winds in squalls are 
possible at these locations through tonight.


KEY MESSAGES:

1.  Heavy rainfall from Earl is expected to lead to limited flash,
urban, and small stream flooding impacts over the Leeward Islands,
U.S. and British Virgin Islands, and Puerto Rico today.  Rapid
rises on rivers and mudslides in areas of steep terrain are possible
in Puerto Rico.

2.  Earl is forecast to pass to the north of the the Virgin Islands
and Puerto Rico today, but gusty winds, especially in squalls,
remain possible on those islands.


FORECAST POSITIONS AND MAX WINDS

INIT  04/1500Z 19.5N  64.4W   45 KT  50 MPH
 12H  05/0000Z 20.4N  65.0W   50 KT  60 MPH
 24H  05/1200Z 21.5N  65.2W   55 KT  65 MPH
 36H  06/0000Z 22.6N  65.4W   60 KT  70 MPH
 48H  06/1200Z 23.5N  65.5W   65 KT  75 MPH
 60H  07/0000Z 24.7N  65.4W   70 KT  80 MPH
 72H  07/1200Z 25.7N  65.0W   75 KT  85 MPH
 96H  08/1200Z 27.2N  64.0W   85 KT 100 MPH
120H  09/1200Z 29.6N  61.8W  100 KT 115 MPH

$$
Forecaster Papin



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