[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 282341
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
705 PM EST TUE FEB 28 2012

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...WEATHER OBSERVATIONS...RADAR...AND METEOROLOGICAL
ANALYSIS.

BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2245 UTC.

...THE ITCZ/THE MONSOON TROUGH...

THE MONSOON TROUGH MEANDERS ACROSS W AFRICA ALONG 09-10N AND
EXITS THE COAST OF GUINEA NEAR 10N13W CONTINUING SW TO NEAR
04N20W...WHERE IT TRANSITIONS TO ITCZ...CONTINUING TO THE
EQUATOR NEAR 33W AND THEN EXTENDING JUST S OF THE EQUATOR ALONG
0.5S TO THE COAST OF BRAZIL AT THE MOUTH OF THE AMAZON. ISOLATED
TO SCATTERED MODERATE/ISOLATED STRONG CONVECTION WAS NOTED
01.5S-02N BETWEEN 27W AND 33W...AND FROM 03S-03N BETWEEN 31W AND
43W. SCATTERED MODERATE TO STRONG CONVECTION WAS NOTED S OF 06N
W OF 45W TO COASTAL ZONES OF S AMERICA.

...DISCUSSION...

THE GULF OF MEXICO...
A HIGH AMPLITUDE UPPER LEVEL RIDGE CONTINUES TO DOMINATE THE
GULF OF MEXICO THIS AFTERNOON...EXTENDING FROM THE TROPICAL
EASTERN PACIFIC ALONG 95W...N-NE ACROSS SE MEXICO AND THROUGH
THE SW LOUISIANA COAST...CONTINUING BEYOND THE GREAT LAKES
REGION. RIDGE AXIS GENERALLY SPANS THE GULF BETWEEN 78W AND
105W...AND IS MAINTAINING A VERY STABLE MIDDLE TO UPPER
ENVIRONMENT ACROSS ALL BUT NORTHEASTERN MEXICO. AT THE
SURFACE...HIGH PRESSURE CENTERED OVER WESTERN MARYLAND-NE W VA
EXTENDS SW AND WEAKLY ACROSS THE NE GULF TO SOUTHERN MEXICO
ALONG THE COAST OF VERA CRUZ. HI RES VISIBLE SATELLITE IMAGERY
SHOWS THE TYPICAL COASTAL TROUGH JUST OFFSHORE BETWEEN TUXPAN
AND TAMPICO MEXICO. OTHERWISE...LIGHT TO MODERATE ANTICYCLONIC
FLOW PREVAILS ACROSS THE BASIN...WITH SOUTHERLY RETURN FLOW TO
15 KT OCCURRING N OF 24N W OF 87W. SATELLITE IMAGERY SHOWS
BROKEN TO OVERCAST LOW CLOUDS LINGERING ACROSS THE NE
GULF...WITH AREAS OF DENSE FOG AND LOW VISIBILITIES STILL BEING
REPORTED ACROSS PORTIONS OF THE FLORIDA PANHANDLE AND NORTHERN
FLORIDA...AND ARE LIKELY OCCURRING ACROSS THE FAR NE GULF WATERS
ATTM. EXPECT THIS SURFACE RIDGING TO REMAIN OVER THE BASIN FOR
THE NEXT COUPLE OF DAYS....WITH LITTLE CHANGE IN SURFACE WIND
SPEED AND DIRECTION EXPECTED THROUGH THU NIGHT.

THE CARIBBEAN SEA...
THE UPPER FLOW ACROSS THE CARIBBEAN IS GENERALLY CHARACTERIZED
BY CONFLUENCE BETWEEN THE NW FLOW DOWNSTREAM OF THE GULF OF
MEXICO RIDGE...SW FLOW ACROSS THE TOP OF UPPER RIDGING ACROSS
NRN S AMERICA...AND W FLOW ASSOCIATED WITH A SHORT WAVE TROUGH
MOVING ACROSS THE SW N ATLC. THIS IS PRODUCING BROAD SCALE
CONFLUENT FLOW ALOFT AND LEADING TO SUBSIDENCE ACROSS ALL BUT
THE FAR ERN CARIBBEAN. AT THE SURFACE...THE 1031 MB HIGH PRES
MENTIONED ABOVE ACROSS THE CENTRAL APPALACHIANS IS REINFORCING
THE W FLANK OF THE WEAKENED ATLC RIDGE...AND PRODUCING A TIGHT
PRES GRADIENT AND FRESH TO STRONG NE TO E TRADEWINDS ACROSS THE
CARIBBEAN. THE PRES GRADIENT BETWEEN HIGH PRES ALONG THE EASTERN
SEABOARD AND SEMI-PERMANENT LOW PRES OVER COLOMBIA HAS ENHANCED
TRADEWIND FLOW ACROSS THE BASIN...WITH A BROAD ZONE OF 20-25 KT
TRADES FOUND S OF 18N AND E OF 82W...WHILE THE TYPICALLY STRONG
TRADES OFF THE COAST OF COLOMBIA CONTINUE AT GALE FORCE. AREAS
OF LOW LEVEL MOISTURE EMBEDDED IN THIS ENHANCED LOW LEVEL FLOW
WERE PRODUCING AN ELONGATED ZONE OF BROKEN TO OVERCAST LOW AND
MID LEVEL CLOUDS WITH SCATTERED SHOWERS MOVING ACROSS THE SE
CARIBBEAN...ACROSS THE EXTREME NE CARIBBEAN AND ADJACENT
ISLANDS...AND DOWNSTREAM OF JAMAICA AND INLAND ACROSS
HONDURAS...BELIZE...AND GUATEMALA. THESE STABLE CONDITIONS ALOFT
LIMITED DIURNAL CONVECTION ACROSS THE GREATER ANTILLES TO JUST
ISOLATED MODERATE TOPPED CELLS.
EXPECT LITTLE CHANGE IN THIS OVERALL PATTERN DURING THE NEXT 24
HOURS.

THE ATLANTIC OCEAN...
A VERY PROGRESSIVE UPPER LEVEL PATTERN PREVAILS ACROSS THE ATLC
THIS AFTERNOON...WITH A SHORTWAVE TROUGH GENERALLY N OF 20N AND
ALONG 69W/70W...AND A SECOND WEAKER SHORTWAVE DOWNSTREAM N OF
18N AND ALONG 42W. AN OLD COLD FRONT HAS TRAVERSED MUCH OF THE
ATLC BASIN AND WAS ACROSS THE ERN ATLC...ENTERING THE DISCUSSION
AREA NEAR 31N31W AND EXTENDING W-SW TO NEAR 26N50W AND CONTINUED
W TO NEAR 67W. SCATTERED TO LOCALLY NUMEROUS SHOWERS WERE NOTED
ALONG AND WITHIN 30 NM N OF THE FRONT...WHILE NUMEROUS WELL
DEFINED LLVL VORTICES COULD BE SEEN ALONG THIS LINGERING
BOUNDARY BETWEEN 40W AND 60W...GENERATED BY HORIZONTAL SHEAR TO
THE N. THE WEAK ATLC SURFACE RIDGE WAS CENTERED ON A 1026 MB
HIGH NEAR 35N44W AND EXTENDED W-SW TO NEAR THE FLORIDA ATLC
COASTAL WATERS...WHERE A N-S ALIGNED SURFACE TROUGH CONTINUED
ALONG 79W/80W. ILL DEFINED REMNANTS OF THE W END OF THE FRONT
COULD BE SEEN IN THE FORM OF CLUSTERS OF LOW AND MID CLOUDS AND
EMBEDDED SHOWERS MOVING W ACROSS THE NW BAHAMAS. FARTHER E...AN
UPPER LEVEL RIDGE WAS CENTERED OVER W TROPICAL AFRICA...
SANDWICHED BETWEEN ELY FLOW ALOFT S OF 10N...AND SW FLOW ALOFT N
OF 10N AND E OF 35W. AT THE SURFACE...THE 1026 MB HIGH IS
PRODUCING A MODERATE PRES GRADIENT TO THE S ACROSS THE CENTRAL
AND E TROPICAL ATLC...YIELDING A BROAD ZONE OF FRESH TRADES
GENERALLY BETWEEN 10N AND 20N. THE MOST RECENT OUTBREAK OF SAL
AND EMBEDDED DUST CAN STILL BE DETECTED IN SATELLITE IMAGERY
FROM THE W AFRICAN COAST NEAR 14N...W-SW TO NEAR 06N44W. JUST TO
THE W OF THIS...A MID LEVEL TROUGH AXIS INTERACTED WITH THE ITCZ
IN THE PAST 48 HOURS TO AID IN PRODUCING A LARGE AREA OF
TROPICAL MOISTURE S OF 13N BETWEEN 45W AND 56W...WHERE SCATTERED
SHOWERS ARE OCCURRING BETWEEN 07N AND 14N...AND SCATTERED TO
LOCALLY NUMEROUS TSTMS ARE OCCURRING BETWEEN 07N AND THE ITCZ.

FOR ADDITIONAL INFORMATION PLEASE VISIT
HTTP://WWW.HURRICANES.GOV/MARINE

$$
STRIPLING





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