Hurricane Lorenzo Forecast Discussion Number 40

By | October 2, 2019

Issued at 500 AM AST Wed Oct 02 2019


000
WTNT43 KNHC 020835
TCDAT3

Hurricane Lorenzo Discussion Number  40
NWS National Hurricane Center Miami FL       AL132019
500 AM AST Wed Oct 02 2019

Lorenzo passed near Flores in the Azores a few hours ago where
hurricane-force winds, at least in gusts, were observed.  Winds
are now decreasing across those islands.  The current intensity
estimate, 75 kt, assumes only slow weakening since late yesterday.
The cloud pattern is becoming increasingly asymmetric in
appearance, suggestive that transition to an extratropical cyclone
is well underway.  The global models indicate that Lorenzo will soon
become embedded in a frontal zone, and simulated satellite imagery
from the ECMWF and GFS models show an extratropical-looking cloud
pattern later today.  The official forecast calls for a gradual
weakening trend over the next couple of days and is above the
intensity guidance.  Although the system is forecast to become
extratropical in 12 hours, it is still likely be a fairly vigorous
cyclone when it reaches Ireland late Thursday.  After crossing
England, the low is likely to dissipate over continental Europe.

Lorenzo accelerated significantly late Tuesday, and the motion is
rapidly northeastward, or 040/37 kt.  Over the next day or so,
the system should continue to move northeastward ahead of a large
mid-tropospheric trough over the north Atlantic.  Then, the cyclone
is forecast to turn eastward and a little south of eastward in the
weaker westerly flow ahead of the trough.  The official track
forecast is close to the model consensus, but leans a bit toward
the ECMWF forecast.

Lorenzo's expansive circulation 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.  Winds across the Azores will continue to decrease, and watches
and warnings for those islands will likely be discontinued later
today.

2.  Lorenzo is expected to be a strong extratropical cyclone when
it approaches Ireland Thursday afternoon or evening.

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  02/0900Z 42.3N  29.4W   80 KT  90 MPH
 12H  02/1800Z 46.4N  24.1W   75 KT  85 MPH...POST-TROP/EXTRATROP
 24H  03/0600Z 51.6N  16.9W   70 KT  80 MPH...POST-TROP/EXTRATROP
 36H  03/1800Z 54.3N  11.1W   65 KT  75 MPH...POST-TROP/EXTRATROP
 48H  04/0600Z 53.5N   6.5W   55 KT  65 MPH...POST-TROP/EXTRATROP
 72H  05/0600Z 51.5N   3.5E   30 KT  35 MPH...POST-TROP/EXTRATROP
 96H  06/0600Z...DISSIPATED

$$
Forecaster Pasch

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