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Hurricane LARRY

Hurricane Larry Discussion Number  24
NWS National Hurricane Center Miami FL       AL122021
1100 AM AST Mon Sep 06 2021

Larry currently has an annular structure, with a 60 n-mi diameter 
eye and a relatively thick eyewall.  High-resolution visible imagery 
shows several meso-vortices rotating within the eye, which is 
typically observed in strong hurricanes.  The upper-level outflow 
has become better defined over the western portion of the 
circulation, indicative of decreased shear in comparison to 
yesterday. The advisory intensity is kept at 105 kt, in reasonable 
agreement with the latest Dvorak estimates from TAFB and SAB.
Larry has slowed its forward speed a bit, and is now moving 
northwestward near 9 kt.  There are no important changes in the 
track forecast or reasoning from the previous advisory.  During the 
next few days, the hurricane is expected to move around the western 
periphery of a subtropical anticyclone over the central Atlantic, 
turning northward and northeastward.  At this time, Larry is 
forecast to pass east of Bermuda and make its closest approach to 
the island on Thursday.  Given Larry's large size, some impacts 
could be felt even if the center remains well east of the island as 
forecast.  In 3-5 days, the cyclone should accelerate northeastward 
ahead of a large mid-tropospheric trough moving through the 
northeastern United States.  The official track forecast follows the 
latest dynamical model consensus, and remains close to the previous 
one.  Since the model guidance is in good agreement, this continues 
to be a high-confidence track forecast.

Vertical shear is expected to remain low and the system will 
continue to traverse warm SSTs for the next few days.  However, the 
presence of dry mid-level air and the broad nature of the 
hurricane's inner core will probably mitigate against significant 
restrengthening.  Some fluctuations in intensity are possible for 
the next 48 hours or so.  In 3-5 days, cooler waters and increasing 
shear should cause gradual weakening.  Around the end of the 
forecast period, the global models show the system beginning to 
merge with a frontal zone near Newfoundland.  The official forecast 
is on the high side of the model guidance suite and close to the 
latest Decay-SHIPS prediction.
Key Messages:
1. Large swells generated by Larry are affecting the Lesser Antilles
and will spread to portions of the Greater Antilles, the Bahamas,
and Bermuda today through Tuesday.  Significant swells should reach
the east coast of the United States and Atlantic Canada by midweek
and continue affecting these shores through the end of the week.
These swells will likely cause life-threatening surf and rip current
conditions, and beachgoers and other interests along these coasts
are urged to follow the guidance of lifeguards and local officials
this week.
2. Larry is forecast to approach Bermuda during the next few days as
a large and powerful hurricane, bringing a risk of strong winds,
heavy rainfall, and coastal flooding to the island by the middle of
this week.  While it is too soon to determine the magnitude of these
hazards and potential impacts on Bermuda, interests there should
closely monitor the latest forecast updates during the next several
INIT  06/1500Z 22.1N  52.9W  105 KT 120 MPH
 12H  07/0000Z 23.1N  54.0W  110 KT 125 MPH
 24H  07/1200Z 24.5N  55.3W  110 KT 125 MPH
 36H  08/0000Z 25.9N  56.6W  105 KT 120 MPH
 48H  08/1200Z 27.5N  58.0W  100 KT 115 MPH
 60H  09/0000Z 29.3N  59.6W  100 KT 115 MPH
 72H  09/1200Z 31.6N  61.2W   95 KT 110 MPH
 96H  10/1200Z 38.6N  60.0W   85 KT 100 MPH
120H  11/1200Z 49.0N  49.0W   70 KT  80 MPH...POST-TROP/EXTRATROP
Forecaster Pasch