cieldumort
(Moderator)
Sun Dec 30 2007 09:11 AM
Re: 2550SM East of Central Florida

95L has gotten battered and squeezed a bit tonight by the encroaching shear from the west. Deep convective banding that had been making some respectable inroads to fully encircling the LLC while developing an upper-level anticyclone in a fashion at times more tropical-like than subtropical, has been getting shunted northeast and east in the process, leaving once again a rather well-defined mid to upper level center rather barren of any deep convection.

For what it's worth, 95L quite possibly spent about 12-18 hours as a subtropical storm Saturday, just not "standard-enough" for what NHC likes to see before they enter it into the history books with a name. I think that the TWD that went up early Saturday night earns high marks for plain talk and candor, and speaks well to this point:

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
705 PM EST FRI DEC 29 2007

BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC

...SPECIAL FEATURE...

THE WELL-DEFINED NON-BAROCLINIC CYCLONE CONTINUES IN THE
NORTHEAST ATLANTIC NEAR 28N38W. THE SYSTEM HAS BEEN DRIFTING
NORTH-NORTHEASTWARD DURING THE DAY AND HAS DEVELOPED PRONOUNCED
ANTICYCLONIC OUTFLOW IN THE UPPER TROP. DESPITE WATER
TEMPERATURES NEAR THE CYCLONE OF AROUND 22-23C...MODERATE
CONVECTION HAS BEEN PERSISTENT ON THE NORTHEAST SEMICIRCLE.
SATELLITE CLASSIFICATIONS SUGGEST THAT THE SYSTEM COULD BE A
MINIMAL SUBTROPICAL STORM. QUIKSCAT WINDS...WHILE HAVING THE
USUAL AMBIGUITY ISSUES IN RAINY CONDITIONS...INDICATE THAT GALE
FORCE WINDS LIKELY ARE OCCURRING IN THE NORTHERN SEMICIRCLE.
TROPOSPHERIC VERTICAL SHEAR IS ABOUT 20 KT AS THE STRONGEST
UPPER TROP WESTERLIES ARE BYPASSING THE CYCLONE TO THE NORTH AND
THE SOUTH. THE CYCLONE SHOULD MEANDER OVER THE NEXT 36 HOURS
BEFORE BEING PUSHED OFF TOWARD THE WEST OR SOUTHWEST BY A
DEVELOPING MID-OCEAN RIDGE ON MONDAY. GIVEN THAT THE VERTICAL
SHEAR SHOULD INCREASE SUBSTANTIALLY TOMORROW...TONIGHT MAY BE
THE LAST OPPORTUNITY FOR THIS SYSTEM TO GAIN A BIT MORE
ORGANIZATION TO ITS CONVECTION AND MAKE THE TRANSITION TO A
NAMED SUBTROPICAL STORM.

The most recent batch of model runs were a little interesting. At 18Z both GFDL and HWRF suggested a meandering cyclone generally heading WSW or SW, and peaking out at about 55-60 knots at the surface, with pressure down to as low as the mid-upper 990s. I'm guessing that if the 00Z runs have had time to ingest the interaction with the increased shear this may now be in play some.



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