[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 221735
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 PM EST THU JAN 22 2009

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHERN SECTIONS
OF SOUTH AMERICA...AND 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...
FROM 1N10E ALONG THE COAST OF EQUATORIAL GUINEA TO THE EQUATOR
10W TO 2S33W INTO NORTHEASTERN BRAZIL NEAR 2S45W.  ISOLATED
MODERATE CONVECTION IS OCCURRING WITHIN 180 NM ON EITHER SIDE OF
THE AXIS FROM EQUATORIAL GUINEA TO 2E.  SCATTERED MODERATE TO
STRONG CONVECTION IS LOCATED WITHIN 60 NM SOUTH OF THE AXIS TO
180 NM NORTH OF THE AXIS FROM 16W TO THE COAST OF NORTHEASTERN
BRAZIL.

...DISCUSSION...
THE GULF OF MEXICO AND THE ATLANTIC OCEAN WEST OF 56W...
A VIGOROUS COLD FRONTAL BOUNDARY EXTENDS FROM 31N57W
SOUTHWESTWARD TO THE MONA PASSAGE NEAR 19N67W.  AHEAD OF THE
FRONT IS A PRE-FRONTAL TROUGH BETWEEN 22N AND 31N...THOUGH THE
TROUGH MAY BE MERGING WITH THE FRONTAL BOUNDARY.  NUMEROUS
SHOWERS AND ISOLATED DEEP CONVECTION ARE OCCURRING WITHIN 150 NM
EAST OF THE FRONTAL BOUNDARY.  A 1027 MB SURFACE HIGH IS
CENTERED OVER CENTRAL FLORIDA AS QUITE COLD...FOR
FLORIDA...CONDITIONS PREVAILED THIS MORNING.  WINDS THROUGHOUT
THE GULF ARE QUITE WEAK AS THE COLD AIR ADVECTION BEHIND THE
FRONT HAS ENDED THERE.  IN THE ATLANTIC REGION...NORTH TO
NORTHWEST WINDS UP TO 20 KT ARE OCCURRING.  WHILE WINDS WILL
REMAIN LIGHT IN THE GULF FOR THE NEXT TWO DAYS...THE WINDS IN
THE ATLANTIC REGION WILL SHIFT TO MORE NORTHEASTERLY AT 20 KT OR
LESS AS SURFACE RIDGING BUILDS IN TO THE EAST.  IN THE UPPER
LEVELS...THE STRONG SHORT-WAVE TROUGH HAS REACHED THE ATLANTIC
AND IS HELPING TO PRODUCE SUBSIDENT WESTERLY WINDS OF UP TO 90
KT.

THE CARIBBEAN SEA...
A FRONTAL BOUNDARY STRETCHES FROM THE MONA PASSAGE
WEST-SOUTHWESTWARD SOUTH OF HISPANIOLA AND JAMAICA...TO EAST OF
NICARAGUA.  THE PORTION OF THE FRONT NEAR CENTRAL AMERICA IS
WEAKENING.  A DISTINCT SURFACE TROUGH CONTINUES IN THE
NORTHWESTERN CARIBBEAN SEA...WHICH MAY HAVE A CLOSED CIRCULATION
CENTER NEAR 17N85W.  THIS TROUGH ALONG WITH THE COLD FRONT ARE
PRODUCING NO SIGNIFICANT AREAS OF DEEP CONVECTION...THOUGH SOME
LOW-TOPPED SHOWERS ARE OCCURRING WITHIN THE TROUGH AS WELL AS
ALONG LAND AREAS EXPERIENCING UPSLOPE NORTHERLY FLOW BEHIND THE
FRONT INCLUDING COSTA RICA...PANAMA...JAMAICA...EASTERN
CUBA...AND HISPANIOLA.  WINDS THROUGH THE EASTERN AND CENTRAL
CARIBBEAN ARE EAST TO NORTHEASTERLY UP TO 20 KT.  IN THE
NORTHWESTERN CARIBBEAN...WEAK NORTHWESTERLY SURFACE WINDS ARE
OCCURRING IN CONJUNCTION WITH THE TROUGH.  THE TROUGH IS NOT
EXPECTED TO DEVELOP INTO AN OFF-SEASON TROPICAL CYCLONE BECAUSE
OF THE STRONG SHEAR AND SUBSIDENT ATMOSPHERE.  MODEST EAST TO
NORTHEAST SURFACE WIND SHOULD PREVAIL IN THE CARIBBEAN DURING
THE NEXT TWO DAYS AS THE FRONTAL BOUNDARY DISSIPATES.  IN THE
UPPER LEVELS...SUBSIDENT SOUTHWESTERLY FLOW PREVAILS ON THE
SOUTH SIDE OF THE VIGOROUS AFOREMENTIONED SHORT-WAVE TROUGH OVER
THE EXTREME WESTERN ATLANTIC.

THE REST OF THE ATLANTIC OCEAN EAST OF 56W...
A LARGE SURFACE HIGH OF 1031 MB IS CENTERED NEAR 30N30W...WHICH
IS PRODUCING A WIDESPREAD AREA OF GENERALLY EASTERLY WINDS UP TO
25 KT.  THERE WILL BE NO SIGNIFICANT CHANGE IN THIS SYNOPTIC
PATTERN DURING THE NEXT TWO DAYS.  NO DEEP CONVECTION IS
OCCURRING IN THE REGION ASIDE FROM THAT ALONG AND NORTH OF THE
ITCZ AXIS.  IN THE UPPER LEVELS...A RIDGE AXIS LIES ALONG 24N56W
EAST-NORTHEASTWARD TO 34N18W.  A CLOSED UPPER LOW IS CENTERED AT
14N52W AND IS ADVECTING MID TO UPPER LEVEL CLOUDINESS AND
MOISTURE FROM THE ITCZ CONVECTIVE OUTFLOW ALONG ITS EASTERN
SEMICIRCLE.

$$
CWL




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