Hurricane LARRY (Text)

Hurricane Larry Discussion Number  40
NWS National Hurricane Center Miami FL       AL122021
1100 AM AST Fri Sep 10 2021
Larry remains a well organized hurricane at a high latitude, and it 
is quickly approaching southeastern Newfoundland.  Satellite images 
show a fairly tight inner core and large curved bands surrounding 
that feature.  However, there are some notable dry slots between the 
core and bands that have developed during the past several hours.  
The latest Dvorak numbers have nudged downward, with the CI values 
ranging between 65 kt and 72 kt.  Based on these estimates, and a 
very recent ASCAT pass that showed peak winds near 65 kt, the 
initial intensity is set at 70 kt for this advisory. The cyclone 
remains quite large, with hurricane-force winds and 
tropical-storm-force winds estimated to extend outward up to 80 and 
210 n mi from the center, respectively.
The hurricane is in the process of turning to the right, with the
latest initial motion estimated to be a fairly quick 015/25 kt.  An
even faster north-northeast to northeast motion is expected during
the next day or two as the hurricane moves in the fast flow between
a mid- to upper-level trough over the northeastern U.S./eastern
Canada and a mid-level ridge over the central Atlantic.  This motion
should take Larry across southeastern Newfoundland tonight.  Larry
is then expected to merge with a large extratropical low over the
Labrador Sea on Sunday.  The NHC track forecast is similar to the
previous one and near the middle of the guidance envelope.
Although Larry will be moving over cooler waters north of the Gulf
Stream Current later today, the hurricane will likely hold its
strength or weaken just a little before landfall.  After landfall,
the models show the inner core dissipating, and the combination of
land interaction, cooler waters, and an increase in shear should
cause weakening and lead to extratropical transition by early
Saturday.  The NHC intensity forecast is close to the GFS model,
which often performs well for hurricanes that transition to
extratropical cyclones.
Key Messages:
1. Larry is forecast to move over portions of southeastern
Newfoundland tonight as it undergoes transition to a
hurricane-force post-tropical cyclone.  Hurricane conditions, a
dangerous storm surge, and heavy rainfall are expected in portions
of southeastern Newfoundland where a Hurricane Warning in effect.
2. Large swells generated by Larry will continue to affect the
Bahamas, Bermuda, and the east coast of the United States and
Atlantic Canada through Saturday night. These swells will 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.
INIT  10/1500Z 40.0N  60.5W   70 KT  80 MPH
 12H  11/0000Z 45.1N  56.4W   70 KT  80 MPH
 24H  11/1200Z 52.0N  49.4W   60 KT  70 MPH...POST-TROP/EXTRATROP
 36H  12/0000Z 57.5N  44.0W   60 KT  70 MPH...POST-TROP/EXTRATROP
 48H  12/1200Z 61.1N  38.7W   55 KT  65 MPH...POST-TROP/EXTRATROP
 60H  13/0000Z...DISSIPATED
Forecaster Cangialosi

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Page last modified: Friday, 31-Dec-2021 12:09:27 UTC