[Tropical] Tropical Cyclone Discussion

[EMWIN Server]

WTNT43 KNHC 012034
TCDAT3

Hurricane Lorenzo Discussion Number  38
NWS National Hurricane Center Miami FL       AL132019
500 PM AST Tue Oct 01 2019

The eye of Lorenzo, while still evident in both visible and infrared
satellite imagery, has become smaller and slightly less distinct
this afternoon, but the overall structure of the hurricane has not
changed much since the previous advisory.  Objective Dvorak
T-numbers crept up this morning when the eye cleared for a couple
of hours and are somewhat higher than the latest subjective
estimates from TAFB and SAB.  A blend of these estimates remains
around 85 kt, and this is the value used as the initial wind speed
for this advisory.  Lorenzo is heading toward colder waters and an
area of increasing vertical wind shear.  However, since the wind
field of the hurricane is quite large, only gradually weakening is
foreast during the next 12 to 24 hours.  After that time, Lorenzo
is forecast to merge with a front and become a strong extratropical
low over the northeastern Atlantic.  The global models indicate
that the post-tropical low will weaken more quickly when it moves
near Ireland and Great Britain in 2 to 3 days.

Lorenzo continues to accelerate northeastward, with an initial
motion estimate of 040/25 kt.  The forward speed of the hurricane
is predicted to increase further overnight and on Wednesday as it
is steered northeastward ahead of a mid-latitude trough over the
central Atlantic.  By late Thursday, the post-tropical cyclone
should slow down and turn eastward or east-southeastward within the
low-level westerly flow.  The track has continued to bend to the
right beyond 48 hours, and the official forecast has once again
been adjusted southward and eastward at that time period. The new
NHC track forecast is in good agreement with the latest ECMWF model.

Lorenzo is producing very large seas over the north Atlantic.  Full
information can be found in High Seas Forecasts from the following
agencies:

The NOAA Ocean Prediction Center under AWIPS header NFDHSFAT1, WMO
header FZNT01 KWBC, and online at
ocean.weather.gov/shtml/NFDHSFAT1.php

The UK Met Office under WMO header FQNT21 EGRR and online at
http://www.metoffice.gov.uk/public/weather/marine-high-seas/

Meteo France under WMO header FQNT50 LFPW and online at
http://www.meteofrance.com/previsions-meteo-marine/bulletin/
grandlarge/metarea2

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.  Swells generated by Lorenzo have spread across much of the
North Atlantic, and are affecting the east coast of the United
States, Atlantic Canada, the Bahamas, portions of the Greater and
Lesser Antilles, and portions of the coast of Europe.  These swells
will produce life-threatening surf and rip currents.


FORECAST POSITIONS AND MAX WINDS

INIT  01/2100Z 37.0N  35.5W   85 KT 100 MPH
 12H  02/0600Z 40.2N  31.3W   80 KT  90 MPH
 24H  02/1800Z 45.6N  24.8W   70 KT  80 MPH
 36H  03/0600Z 51.2N  18.4W   65 KT  75 MPH...POST-TROP/EXTRATROP
 48H  03/1800Z 54.4N  13.5W   60 KT  70 MPH...POST-TROP/EXTRATROP
 72H  04/1800Z 53.2N   3.0W   35 KT  40 MPH...POST-TROP/EXTRATROP
 96H  05/1800Z...DISSIPATED

$$
Forecaster Brown
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