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Post-Tropical Cyclone ALEX Forecast Discussion


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000
WTNT41 KNHC 152032
TCDAT1

POST-TROPICAL CYCLONE ALEX DISCUSSION NUMBER   9
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL012016
500 PM AST FRI JAN 15 2016

Geostationary and low-level microwave satellite images show the
cloud pattern becoming elongated and taking on a comma, i.e.
frontal, shape.  Short-term model forecasts show significant
thermal advection in the circulation, and this is also suggested by
surface data.  An earlier scatterometer pass showed that the system
was losing its inner-core wind maximum, with the strongest winds
well-removed to the northeast of the center.  Therefore Alex has
made the transition to an extratropical cyclone, and this will be
the last advisory.

Maximum winds are estimated to be just below hurricane strength,
and the post-tropical cyclone could re-intensify slightly in the
short term due to baroclinic energy sources. Within 48 hours, the
global models generally agree on the system merging with another
extratropical low over the north Atlantic.

The cyclone has accelerated greatly during the day and is now moving
slightly west of due north, or 350/35.  The dynamical guidance
shows the system rotating counterclockwise around a large gyre over
the north Atlantic during the next day or so.  This is also shown
in the official forecast, which is based mainly on input from the
NOAA Ocean Prediction Center.

Additional information on this system can be found in High Seas
Forecasts issued by the National Weather Service under AWIPS header
NFDHSFAT1, WMO header FZNT01 KWBC, and available on the Web at
http://www.opc.ncep.noaa.gov/shtml/NFDHSFAT1.shtml, and in high seas
forecasts issued by Meteo France under WMO header FQNT50 LFPW and
available on the web at
http://www.meteofrance.com/previsions-meteo-marine/bulletin.

FORECAST POSITIONS AND MAX WINDS

INIT  15/2100Z 43.0N  27.8W   60 KT  70 MPH...POST-TROP/EXTRATROP
 12H  16/0600Z 49.2N  29.4W   65 KT  75 MPH...POST-TROP/EXTRATROP
 24H  16/1800Z 56.3N  36.1W   65 KT  75 MPH...POST-TROP/EXTRATROP
 36H  17/0600Z 56.5N  47.0W   60 KT  70 MPH...POST-TROP/EXTRATROP
 48H  17/1800Z...ABSORBED BY ANOTHER EXTRATROPICAL LOW

$$
Forecaster Pasch