[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 191740
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 PM EST THU FEB 19 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...

THE ITCZ AXIS IS CENTERED ALONG 5N9W 2N20W 1N30W EQ40W 1S50W.
SCATTERED MODERATE TO STRONG CONVECTION IS WITHIN 180 NM E OF
THE AXIS E OF 14W AND WITHIN 90 NM EITHER SIDE OF THE AXIS
BETWEEN 14W-20W. ISOLATED MODERATE CONVECTION IS WITHIN 180 NM
OF THE AXIS W OF 44W.

...DISCUSSION...

GULF OF MEXICO...
STRONG WESTERLY FLOW ALOFT COVERS THE GULF IN THE BASE OF A DEEP
TROUGH OVER THE E CONUS. A COLD FRONT ASSOCIATED WITH THIS
TROUGH EXTENDS FROM THE FLORIDA BIG BEND INTO THE NW GULF NEAR
25N96W TO THE COAST OF VERACRUZ NEAR 22N98W. THIS FRONT HAS
SURGED SOUTHWARD OVER THE FAR WESTERN GULF...WHERE LOCAL
TOPOGRAPHY CONTINUES TO FUNNEL THE COLDER AIRMASS NORTH OF THE
REGION SOUTHWARD. THIS FUNNELING HAS RESULTED IN THE DEVELOPMENT
OF A 1011 MB SURFACE LOW NEAR 20N96W. LOW LEVEL CONVERGENCE
SUPPORTING SCATTERED SHOWERS WITHIN 90 NM EITHER SIDE OF THE
FRONT...WITH EMBEDDED ISOLATED THUNDERSTORMS E OF 86W. SOUTH OF
THE FRONT...SOUTHERLY AND EASTERLY DIFFLUENT FLOW AT THE SURFACE
IS SUPPORTING FAIR WEATHER CONDITIONS...WHERE ATMOSPHERIC
STABILITY IS IN PLACE. N OF THE FRONT...STRATOCUMULUS CLOUD
DEVELOPMENT IS UNDERWAY IN RESPONSE TO COLD AIR ADVECTION OVER
RELATIVELY WARMER GULF WATERS. THE 19/1200 UTC QUIKSCAT PASS
DEPICTS N TO NE WINDS OF 20 TO 25 KT IN THE WAKE OF THE FRONT
THAT CONTINUE TO USHER A COOLER AND DRIER AIRMASS INTO THE GULF
REGION. THIS FRONT IS FORECAST TO CONTINUE MOVING SOUTHWARD
DURING THE NEXT DAY WHILE WEAKENING...WITH SHOWER AND
THUNDERSTORM ACTIVITY GRADUALLY DIMINISHING AS THE STRONGER
UPPER LEVEL SUPPORT SHIFTS NORTH OF THE DISCUSSION AREA.

CARIBBEAN SEA...
FRESH TRADE WINDS CONTINUE ACROSS A LARGE PART OF THE CENTRAL
AND E CARIBBEAN WITH A RIDGE PRESENT IN THE CENTRAL ATLC. THE
STRONGEST WINDS...UP TO 30 KT...ARE FOUND ALONG THE COAST OF
COLOMBIA. GENERALLY FAIR WEATHER CONDITIONS ARE PRESENT ACROSS
THE CARIBBEAN REGION WITH AN UPPER RIDGE DOMINATING THE REGIONAL
WEATHER...THOUGH PATCHES OF LOW LEVEL MOISTURE CONTINUE TO BE
ADVECTED EASTWARD ACROSS THE CARIBBEAN ON EASTERLY TRADE WINDS.

ATLANTIC OCEAN...
A DEEP TROUGH OVER THE E CONUS CONTINUES TO PROGRESS EASTWARD
WITH AN ASSOCIATED COLD FRONT MOVING OFF THE SE GEORGIA COAST.
THE STRONG PRESSURE GRADIENT ASSOCIATED WITH THIS FRONT IS
SUPPORTING SOUTHWESTERLY GALES AHEAD OF THE FRONT BASED ON
RECENT SHIP OBSERVATIONS. THIS FRONT WILL CONTINUE MOVING
EASTWARD DURING THE NEXT DAY...THOUGH WILL WEAKEN AS THE
ATTENDANT UPPER SUPPORT MOVES NORTH OF THE DISCUSSION AREA.
SCATTERED SHOWERS AND THUNDERSTORMS ARE OCCURRING WITHIN 90 NM
EITHER SIDE OF THE FRONT. FARTHER TO THE E...A 1025 MB SURFACE
HIGH IS CENTERED NEAR 30N57W. SUBSIDENCE ASSOCIATED WITH THIS
FEATURE IS RESULTING IN FAIR WEATHER CONDITIONS ACROSS A LARGE
PART OF THE CENTRAL ATLC. FARTHER TO THE E...SURFACE COLD FRONT
ENTERS THE DISCUSSION AREA NEAR 31N41W AND EXTENDS TO 23N49W
BECOMING STATIONARY SOUTHWESTWARD TO 17N62W. SURFACE CONFLUENCE
DEPICTED BY THE 19/1200 UTC ASCAT PASS NEAR THIS BOUNDARY IS
SUPPORTING INCREASED CLOUDINESS AND ISOLATED SHOWERS WITHIN 60
NM EITHER SIDE OF THESE FRONTS. ACROSS THE E ATLC...SUBSIDENCE
ASSOCIATED WITH A SURFACE RIDGE AND A 1030 MB SURFACE HIGH NEAR
33N29W IS RESULTING IN GENERALLY FAIR WEATHER CONDITIONS. ACROSS
THE TROPICAL ATLC...DEEP LAYER DRY AIR EMBEDDED WITHIN AN UPPER
TROUGH THAT EXTENDS SOUTHWARD FROM THE CENTRAL ATLC IS
SUPPRESSING CONVECTION OVER THE WESTERN HALF OF THE ITCZ. UPPER
LEVEL DIVERGENCE E OF THIS TROUGH IS ENHANCING THE CONVECTION
OVER THE E HALF OF THE ITCZ.

$$
COHEN



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