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Hurricane Lorenzo Discussion Number  36
NWS National Hurricane Center Miami FL       AL132019
500 AM AST Tue Oct 01 2019

Lorenzo's eye has become less distinct on satellite images over the
past several hours, but the system remains very well organized with
tightly curved convective bands.  The upper-level outflow remains
quite well-defined.  The advisory intensity, 85 kt, is a blend of
subjective Dvorak estimates from TAFB and SAB along with ADT values
from UW-CIMSS.  Sea-surface temperatures beneath the cyclone are
likely to fall below 20 deg C within 36 hours, along with a large
increase in vertical shear.  Since Lorenzo has such a large
circulation, it will probably be slow to weaken, however.  In 48
hours or less, the global models show the system merging with a
frontal zone, indicating the transition to an extratropical
cyclone.  The NHC intensity forecast is on the high side of the
numerical guidance but still weakens the cyclone below hurricane
strength when it nears Ireland and Great Britain.  By 96 hours, the
cyclone should dissipate over Europe.

The hurricane continues to accelerate, and is now moving
northeastward near 19 kt.  Continued acceleration on the southeast
and east side of a large mid-tropospheric trough over the central
north Atlantic should occur over the next day or two.  In 72 hours
or so, the cyclone is expected to turn east-northeastward while
moving in the westerly flow ahead of the north Atlantic trough.
There is still significant track model divergence around this time,
and the official 3-day forecast is somewhat southeast of the model
consensus.  This leans toward the latest ECMWF solution, which
continues to be on the southeast side of the track guidance
envelope.

Lorenzo is producing huge seas over the north Atlantic.  Full
information on the High Seas Forecasts can be found at the Ocean
Prediction Center under AWIPS header NFDHSFAT1, WMO header FZNT01
KWBC, and online at ocean.weather.gov/shtml/NFDHSFAT1.php.
The UK Met Office also has information in High Seas Forecasts issued
by under WMO header FQNT21 EGRR and on the web at
http://www.metoffice.gov.uk/public/weather/marine-high-seas/


Key Messages:

1.  Lorenzo is expected to bring hurricane and tropical storm force
winds to the Azores beginning tonight, and these conditions
will continue into Wednesday.  Hurricane and Tropical Storm Warnings
are in effect for the Azores.

2.  Large swells generated by Lorenzo will continue to spread across
much of the north Atlantic basin during the next few days.  These
swells will produce life-threatening surf and rip currents,
especially across the Azores.


FORECAST POSITIONS AND MAX WINDS

INIT  01/0900Z 33.4N  39.7W   85 KT 100 MPH
 12H  01/1800Z 35.9N  36.7W   85 KT 100 MPH
 24H  02/0600Z 40.2N  31.3W   80 KT  90 MPH
 36H  02/1800Z 45.5N  24.5W   75 KT  85 MPH
 48H  03/0600Z 51.0N  18.5W   70 KT  80 MPH...POST-TROP/EXTRATROP
 72H  04/0600Z 56.5N   8.5W   50 KT  60 MPH...POST-TROP/EXTRATROP
 96H  05/0600Z...DISSIPATED

$$
Forecaster Pasch

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