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Hurricane Larry Discussion Number  29
NWS National Hurricane Center Miami FL       AL122021
500 PM AST Tue Sep 07 2021
 
After becoming rather ragged-looking in earlier satellite images,
Larry's eye has become a little better defined recently, and the
surrounding deep convection is more or less maintaining its
strength.  Observations from a NOAA Hurricane Hunter aircraft show
that the central pressure has fallen slightly, to 965 mb.  Peak
flight-level winds from the aircraft were 110 kt so the advisory
intensity is kept at 100 kt.  This is also consistent with a Dvorak 
Current Intensity number from TAFB.
 
Larry continues its northwestward motion at about 320/8 kt.  The
hurricane should move around the western side of a deep-layer
subtropical anticyclone during the next 48-60 hours.  After passing
Bermuda, the system is likely to accelerate northeastward while
moving into the mid-latitude westerlies ahead of a trough moving
from the northeastern United States to Atlantic Canada, and move
into the far north Atlantic by day 5.  The official track forecast
stays close to the previous NHC prediction, and remains in good
agreement the various model consensus solutions.

The hurricane continues to exhibit well-defined upper-level outflow, 
indicative of weak vertical shear.  Over the next couple of days, 
Larry will be traversing waters of gradually decreasing oceanic heat 
content.  This, combined with some dry mid-level air in the 
environment, should lead to a gradual decrease in intensity through 
48-60 hours.  Later in the forecast period, colder waters and strong 
shear should cause more rapid weakening.  By day 4, the global 
models show Larry merging with a frontal zone.  Therefore, the NHC 
forecast calls for extratropical transition by that time.  The 
official intensity forecast is generally below the 
statistical-dynamical guidance and above the coupled dynamical 
hurricane models through 72 hours, but in good agreement with the 
model consensus aids.

 
Key Messages:
 
1. Large swells generated by Larry will continue to affect the
Lesser Antilles, portions of the Greater Antilles, and the Bahamas
through midweek.  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. The center of Larry is forecast to pass east of Bermuda on
Thursday, but given Larry's large size, tropical storm conditions
are possible there Thursday, along with a risk of heavy rainfall
and coastal flooding.  A Tropical Storm Watch is in effect for
Bermuda and interests there should closely monitor the latest
forecast updates.

3. Larry is forecast to move near or over portions of southeastern 
Newfoundland late Friday and Friday night as it transitions to a 
hurricane-force post-tropical cyclone. There is a risk of impacts 
from high winds, rainfall, and storm surge in portions of 
Newfoundland, and interests there should monitor the progress of 
Larry and updates to the forecast. 
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  07/2100Z 25.1N  56.3W  100 KT 115 MPH
 12H  08/0600Z 26.5N  57.4W   95 KT 110 MPH
 24H  08/1800Z 28.3N  58.8W   95 KT 110 MPH
 36H  09/0600Z 30.5N  60.5W   90 KT 105 MPH
 48H  09/1800Z 33.3N  61.7W   90 KT 105 MPH
 60H  10/0600Z 36.8N  61.2W   85 KT 100 MPH
 72H  10/1800Z 41.7N  58.2W   80 KT  90 MPH
 96H  11/1800Z 53.0N  48.0W   65 KT  75 MPH...POST-TROP/EXTRATROP
120H  12/1800Z 60.0N  38.0W   50 KT  60 MPH...POST-TROP/EXTRATROP
 
$$
Forecaster Pasch
 
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