[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 151728
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 PM EST FRI DEC 15 2006

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...
CENTRAL AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...
NORTHEASTERN SECTIONS OF SOUTH AMERICA...AND THE ATLANTIC
OCEAN TO THE AFRICAN COAST FROM THE EQUATOR TO 32N.
THE FOLLOWING INFORMATION IS BASED ON SATELLITE IMAGERY...
METEOROLOGICAL ANALYSIS...WEATHER OBSERVATIONS...AND RADAR.

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1715 UTC.

...THE ITCZ...
ITCZ AXIS IS ALONG 6N11W 4N39W EQ49W. SMALL CLUSTERS OF
SCATTERED MODERATE CONVECTION ARE WITHIN 120 NM S OF AXIS
BETWEEN 12W AND 15W...AND WITHIN 120 NM N OF AXIS BETWEEN 41W
AND 45W.

...DISCUSSION...
THE GULF OF MEXICO...
WATER VAPOR IMAGERY SHOWS WELL DEFINED SHORT WAVE TROUGH MOVING
OFF THE NRN GULF COAST OF MEXICO THIS MORNING. SURFACE
OBSERVATIONS SHOW 1017 MB HIGH PRES ANCHORED OVER THE LOWER
MISSISSIPPI VALLEY...MAINTAINING LIGHT TO MODERATE ELY FLOW
ACROSS THE GULF. SLIGHTLY LOWER SEA LEVEL PRESSURES OVER THE
WESTERN GULF ALONG WITH WEAK CYCLONIC TURNING HINT AT
DEVELOPMENT OF A WEAK SURFACE TROUGH NEAR THE MEXICAN COAST
ASSOCIATED WITH UPPER LEVEL SHORT WAVE.

MEANWHILE SURFACE OBSERVATIONS OVER THE EASTERN GULF OF MEXICO
AND THE FLORIDA PENINSULA ARE SHOWING A BETTER TEMPERATURE
GRADIENT FROM THE FLORIDA BIG BEND AREA TO S FLORIDA.
TEMPERATURES REMAIN IN THE LOWER TO MID 60S OVER NORTH
FLORIDA...AND EVEN IN THE 50S OVER THE WESTERN PANHANDLE...WHILE
GETTING ONLY TO THE LOWER TO MID 70S OVER THE EXTREME SE COAST
OF FLORIDA WITH NE FLOW. THIS INDICATES FRONTALGENESIS IS
STARTING ALONG THE EXISTING TROUGH LINE FROM SOUTH FLORIDA TO
THE NE AHEAD OF SHORT WAVE TROUGH MOVING ACROSS THE GULF WATERS.
SURFACE OBSERVATIONS AND QUIKSCAT IMAGERY SHOW NE TO E
CONVERGENCE ALONG THE TRAILING TROUGH FROM S FLORIDA TO THE
YUCATAN.


THE CARIBBEAN SEA...
MODERATE TO FRESH ELY FLOW PERSISTS ACROSS THE CARIBBEAN
BASIN...EXCEPT FOR LIGHT SE FLOW BETWEEN JAMAICA AND THE
YUCATAN. LIGHT SHOWERS AND BROKEN CLOUD DECKS ARE EVIDENT NEAR A
WEAK TROUGH IN THE YUCATAN CHANNEL AND AS FAR S AS THE BELIZE
COAST. SPEED CONVERGENCE OVER THE SW CARIBBEAN IS PROMOTING
SCATTERED SHOWERS FROM THE NRN COAST OF PANAMA TO THE NICARAGUAN
COAST. OTHERWISE GENERALLY FAIR CONDITIONS PREVAIL UNDER DRY
SUBSIDENT AIR ALOFT.

THE ATLANTIC OCEAN...
OCCLUDED LOW PRES COMPLEX SITUATED NEAR SW OF THE AZORES NEAR
27N32W WITH COLD FRONT EXTENDING TO AROUND 15N40W. AN EARLY
MORNING QUIKSCAT PASS SHOWS NEAR NLY GALE FORCE WINDS WRAPPING
AROUND THE LOW PRES APPROXIMATELY 240 NM TO THE W. LARGE NLY
SWELL PERSISTS IN THIS AREA AS WELL WITH COMBINED SEA HEIGHTS
OF 14 TO 18 FT. A LARGE FIELD OF STRATO CUMULUS CLOUDS EXTEND
BEHIND THE FRONT AS FAR W AS 55W. CONVERGENT FLOW IS GENERATING
AREAS OF SHOWERS AND MULTILAYER CLOUD DECKS ALONG THE FRONTAL
BOUNDARY AND WITHIN 60 NM OF A LINE EXTENDING TO THE LEEWARD
ISLANDS. DRY SUBSIDENT AIR AND FAIR CONDITIONS PERSIST OTHERWISE
ACROSS THE ATLC N OF THE ITCZ. 1032 MB HIGH PRES IS CENTERED
NEAR 38N42W. GRADIENT BETWEEN THIS HIGH AND THE OCCLUDED LOW IS
MAINTAINING FRESH NE TO E WINDS N OF 14N AND W OF 40W...WITH
MODERATE TO FRESH ELY WIND PREVAILING TO THE S OF THIS AREA.

FURTHER W...COLD FRONT IS EMERGING OFF THE SE COAST N OF THE
BAHAMAS...FOLLOWED BY 1024 MB HIGH PRES CELL SHIFTING E THROUGH
THE CAROLINAS. THE FRONT WILL PROGRESS EWD THROUGH THE WEEKEND
INTO THE CENTRAL ATLC AS THE HIGH PRES BUILDS OVER THE WRN ATLC.
WINDS AND SEAS WILL VEER MORE NE AND INCREASE SLIGHTLY W OF 60W
AS HIGH PRES BUILDS TO N. MEANWHILE THIS WILL WEAKEN THE 1032 MB
HIGH OVER THE CENTRAL ATLC...ALLOWING WINDS TO DIMINISH SLIGHTLY
TO THE S. THE HIGH PRES OVER THE WRN ATLC WILL CONTINUE TO BUILD
E THROUGH EARLY NEXT WEEK AS THE COMES IN PHASE WITH THE
OCCLUDED LOW AND LIFTS OUT TO THE NE.

$$
CHRISTENSEN



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