[Tropical] Tropical Cyclone Discussion

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WTNT41 KNHC 050852
TCDAT1

Tropical Storm Earl Discussion Number  10
NWS National Hurricane Center Miami FL       AL062022
500 AM AST Mon Sep 05 2022

Satellite imagery this morning shows that Earl continues to produce
strong convection to the northeast of the center.  However, data
from the SHIPS model and analyses from CIMSS at the University
of Wisconsin indicate that there is now 20-25 kt of southwesterly
vertical shear impacting the cyclone.  As a result, the low-level
center remains located near or just outside of the southwestern
edge of the main convective mass.  Satellite intensity estimates
have changed little since the last advisory, and data from NOAA
buoy 41043 suggests the central pressure is still in the 998-1000
mb range.  Based on this, the initial intensity remains 45 kt.
Earlier scatterometer data showed that the circulation center was
elongated from northeast to southwest, and recent wind obs suggest
the northeast end of the elongation is near the NOAA buoy.

Earl is turning more northward, with the initial motion now 335/4
kt.  For the next three days or so, the storm should move slowly
northward in the flow between the subtropical ridge to the east and
a mid- to upper-level trough to the west and northwest.  After
that, a motion more toward the northeast is expected as Earl
reaches the southern edge of the mid-latitude westerlies.  The
large-scale models are in poor agreement on the features in the
westerlies that Earl will encounter, with the GFS showing stronger
flow and a faster motion than the UKMET and ECMWF.  The new
forecast track is changed little through 60 h, then it is nudged a
little westward based on a shift in the guidance envelope.  The
track lies close to the various consensus models, and the speed at
the end is a compromise between the faster GFS and the slower
UKMET/ECMWF.

The large-scale models suggest that the current shear will persist
for about the next 48 h.  After 48-60 h, Earl may find a region of
lighter shear that could allow more significant strengthening.
The new intensity forecast is a little slower to intensify Earl
through 48 h based on the shear forecast, and it is possible that
Earl could strengthen less than forecast during this time.  Later
on, the new forecast is similar to the previous forecast.  It
should be noted that if Earl does find a more favorable environment
later in the forecast period, there are several models with a higher
120-h forecast intensity than the current official forecast of 105
kt.

While tropical-storm-force winds are still forecast to stay north of
the northern Leeward Islands, the Virgin Islands, and Puerto Rico,
training rainbands are producing heavy rainfall over portions of
these islands.  Users should refer to products issued by local
weather offices in these areas.

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.  Considerable flood impacts cannot be ruled out in
areas that receive heavier rainfall totals.

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


FORECAST POSITIONS AND MAX WINDS

INIT  05/0900Z 20.9N  65.3W   45 KT  50 MPH
 12H  05/1800Z 21.7N  65.5W   50 KT  60 MPH
 24H  06/0600Z 22.9N  65.7W   55 KT  65 MPH
 36H  06/1800Z 24.0N  65.8W   60 KT  70 MPH
 48H  07/0600Z 25.1N  65.9W   60 KT  70 MPH
 60H  07/1800Z 26.2N  65.7W   70 KT  80 MPH
 72H  08/0600Z 27.3N  65.4W   75 KT  85 MPH
 96H  09/0600Z 30.0N  64.0W   90 KT 105 MPH
120H  10/0600Z 33.5N  60.0W  105 KT 120 MPH

$$
Forecaster Beven
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