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000
AXNT20 KNHC 152344
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT SUN MAR 15 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 5N10W 2N20W CROSSING THE EQUATOR
NEAR 29W EXTENDING TO 3S35W AND INTO NE BRAZIL NEAR 5S40W.
SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS S OF 3N BETWEEN
8W-17W. ISOLATED MODERATE CONVECTION IS S OF 2N BETWEEN 30W-36W.

...DISCUSSION...

GULF OF MEXICO...
A SLOWLY PROGRESSING COLD FRONT EXTENDS INTO THE N/CENTRAL GULF
FROM A WEAK 1017 MB SFC LOW CENTERED OVER WESTERN GEORGIA TO
NEAR 28N89W. AT THIS POINT...THE FRONT BECOMES STATIONARY AND
STRETCHES ALONG 27N92W 23N99W INTO THE CENTRAL SECTION OF THE
BAY OF CAMPECHE NEAR 19N94W. IT CONTINUES INLAND ALONG THE ERN
SLOPE OF THE SIERRA MADRE ORIENTAL MOUNTAINS. THE FRONT IS
LOCATED AT THE LEADING EDGE OF A WIDE BAND OF MULTILAYERED
CLOUDS WITH EMBEDDED AREAS OF RAIN AND POSSIBLE ISOLATED TSTMS.
LOW LEVEL CONVERGENCE AND DEEP LAYERED ATMOSPHERIC LIFT ARE
SUPPORTING THIS ACTIVITY WHICH IS AFFECTING MAINLY THE FAR
WESTERN GULF AND THE N GULF STATES BETWEEN GEORGIA AND EASTERN
TEXAS INCLUDING ALSO THE FLORIDA PANHANDLE. N-NE SURFACE WINDS
OF 10 TO 15 KT ARE OBSERVED BEHIND THE FRONT. TO THE SE OF THE
FRONT...MODERATE SUBSIDENCE IS RESULTING IN GENERALLY FAIR
WEATHER CONDITIONS ACROSS MUCH OF THE S-CENTRAL AND ERN GULF...
INCLUDING THE FLORIDA PENINSULA. MODERATE SE WINDS ARE BLOWING
AHEAD OF THE FRONT. AN UPPER-LEVEL TROUGH EXTENDING OVER WESTERN
TEXAS AND NW MEXICO IS PRODUCING STRONG SWLY WINDS ALOFT OVER
MUCH OF THE GULF REGION. THESE WINDS ARE ADVECTING CONSIDERABLE
MID/UPPER LEVEL MOISTURE N OF LINE BETWEEN TAMPA BAY FLORIDA AND
TAMPICO MEXICO. ACCORDING TO THE GFS COMPUTER MODEL...THE FRONT
WILL CONTINUE TO SLOWLY MOVE SE APPROACHING SOUTH FLORIDA LATE
ON TUESDAY.

CARIBBEAN SEA...
THE COMBINATION OF STRONG HIGH PRESSURE OVER THE W ATLC AND
LOWER SURFACE PRESSURE OVER NRN SOUTH AMERICA IS PRODUCING FRESH
TO STRONG WINDS ACROSS MUCH OF THE BASIN. AN EARLIER ASCAT PASS
SHOWED THE STRONGEST WINDS OF 20 TO 30 KT JUST OFFSHORE THE
COAST OF COLOMBIA. THESE WEATHER CONDITIONS ARE EXPECTED TO
PERSIST THROUGH MON WHEN THE SFC HIGH WILL BEGIN TO SHIFT E AND
GRADUALLY WEAKEN. IN THE MEANTIME...GENERALLY FAIR WEATHER
CONDITIONS ARE OBSERVED AND EXPECTED TO CONTINUE OVER THE NEXT
24 HOURS ACROSS THE CARIBBEAN REGION AS DEEP LAYERED DRY AIR IS
PRESENT ON WATER VAPOR IMAGERY. HOWEVER...SHALLOW MOISTURE
EMBEDDED IN THE TRADE WIND FLOW IS MOVING ACROSS THE REGION
PRODUCING ISOLATED TO SCATTERED PASSING SHOWERS. THESE PATCHES
OF LOW LEVEL MOISTURE ARE MOST IMPACTING THE NE CARIBBEAN FROM
THE N LEEWARD ISLANDS TO DOMINICAN REPUBLIC. SIMILAR CLOUDINESS
ARE ALSO AFFECTING PARTS OF JAMAICA.

ATLANTIC OCEAN...
A 1027 MB SURFACE HIGH IS LOCATED SE OF BERMUDA NEAR 30N59W WITH
A RIDGE ENVELOPING MOST OF THE WEST AND CENTRAL ATLC...INCLUDING
THE BAHAMAS...THE STATE OF FLORIDA AND GREATER ANTILLES. IN THE
UPPER LEVELS...A RIDGE EXTENDS FROM THE NW CARIBBEAN ACROSS THE
FLORIDA PENINSULA INTO THE WESTERN ATLC WHILE A SHORT-WAVE
TROUGH IS DEVELOPING OVER THE SE BAHAMAS AND THE WINDWARD
PASSAGE. MODERATE TO STRONG SUBSIDENCE AND THE ASSOCIATED DRY
AIR MASS IS RESULTING IN MOSTLY FAIR WEATHER ACROSS THE REGION.
FARTHER TO THE E...AN UPPER LEVEL LOW LOCATED NEAR 32N28W
SUPPORTS A 1007 MB SURFACE LOW SITUATED NEAR 31N31W. A SURFACE
TROUGH EXTENDS FROM THE LOW ALONG 30N28W 27N27W 21N30W. UPPER
LEVEL DIFFLUENCE AND LOW LEVEL CONVERGENCE IN THE VICINITY OF
THE SURFACE LOW AND TROUGH ARE GENERATING AN AREA OF SCATTERED
SHOWERS WITHIN 80-100 NM E OF THE TROUGH N OF 26N. THE REMAINDER
OF THE E ATLC IS UNDER THE INFLUENCE OF A NARROW SURFACE RIDGE
ANCHORED WELL N OF THE FORECAST AREA. ACROSS THE DEEP TROPICS...
A BROAD UPPER LEVEL RIDGE ANCHORED ON A HIGH NEAR 6N49W WITH
AXIS ORIENTED W-E ALONG 6N IS ENHANCING CONVECTION ASSOCIATED
WITH THE ITCZ. MOSTLY ZONAL FLOW IS NOTED FROM 10-20N BETWEEN
THE WEST COAST OF AFRICA AND THE LESSER ANTILLES. A JET STREAM
BRANCH WITH CORE WINDS OF 70-100 KT IS LOCATED MIDWAY BETWEEN
THE CANARY AND THE CAPE VERDE ISLANDS ENTERING WEST AFRICA
THROUGH THE SOUTHERN PORTION OF WESTERN SAHARA. A BAND OF
TRANSVERSE HIGH CLOUDS IS NOTED ON SATELLITE IMAGERY ASSOCIATED
WITH THE JET.

$$
GR






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