[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 012343
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
705 PM EST THU MAR 01 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
2315 UTC.

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

THE MONSOON TROUGH MEANDER ALONG ABOUT 11N ACROSS W AFRICA TO
THE COAST NEAR 12N16W WHERE IT TERMINATES. BROAD AND WEAK
CYCLONIC FLOW IS FOUND S OF THIS OFF THE COAST OF W AFRICA.
THE ITCZ BEGINS FROM NEAR 03N18W TO THE EQUATOR NEAR 43W THEN TO
THE NE COAST OF BRAZIL NEAR 01S47W. SCATTERED MODERATE ISOLATED
STRONG CONVECTION IS NOTED WITHIN 60 NM OF THE ITCZ AXIS E OF
29W. SCATTERED MODERATE TO STRONG CONVECTION IS NOTED WITHIN 150
NM N AND 120 NM S OF AXIS W OF 29W.

...DISCUSSION...

THE GULF OF MEXICO...
UPPER LEVEL RIDGING DOMINATING THE GULF DURING THE PAST FEW DAYS
HAS SHIFTED SLIGHTLY WWD AND FLATTENED DURING THE PAST 24 HOURS
AS SW N ATLC TROUGH AXIS HAS CONTINUED TO DIG S AND SW ACROSS
THE W HALF OF CARIBBEAN. CONDITIONS ALOFT ACROSS THE GULF HAVE
THUS DESTABILIZED SOMEWHAT TODAY. THE ATLC HIGH PRES RIDGE
EXTENDS W-SW ACROSS SRN FLORIDA THEN W ALONG 25N TO 93W...
YIELDING LIGHT TO MODERATE SLY RETURN FLOW ACROSS THE BASIN PER
RECENT SCATTEROMETER PASSES. MILD WINDS AND STRONG ANTICYCLONIC
TURNING ACROSS THE NE GULF AGAIN ALLOWED FOR LOW STRATUS AND FOG
TO LINGER INTO THE AFTERNOON HOURS ACROSS MUCH OF THE BIG BEND
REGION TODAY...WITH AREAS OF LOW STRATUS STILL LINGERING ACROSS
COASTAL ZONES FROM FROM JUST N OF TAMPA BAY TO THE FLORIDA
PANHANDLE. A FRONTAL SYSTEM HAS STALLED THIS AFTERNOON ACROSS
CENTRAL PORTIONS OF THE N GULF STATES BUT WILL LIFT N OF THE
REGION LATE TONIGHT AND FRI AS LLVL RETURN FLOW INCREASES IN
ADVANCE OF NEXT COLD FRONT APPROACHING SE TEXAS COASTAL WATERS
FRI AFTERNOON. SLY WINDS ARE EXPECTED TO INCREASE TO AROUND 20
KT ACROSS MOST OF THE W HALF OF THE BASIN FRI IN ADVANCE OF THIS
NEXT FRONT.

THE CARIBBEAN SEA...
IN THE UPPER LEVELS...A SHARP MID TO UPPER LEVEL TROUGH EXTENDS
FROM THE W CENTRAL ATLC SW ACROSS THE E END OF HISPANIOLA...
ACROSS NW COSTA RICA AND INTO THE TROPICAL EPAC. STRONG
SUBSIDENCE IS SEEN IN WATER VAPOR IMAGERY NW OF THE TROUGH FROM
S OF JAMAICA TO SRN NICARAGUA AND NW COSTA RICA. STRONG CYCLONIC
TURNING WITHIN THE TROUGH AXIS ACROSS THE MONA PASSAGE HAS ACTED
TO ENHANCE LLVL MOISTURE AND SHOWERS PASSING ACROSS ERN
HISPANIOLA...PUERTO RICO...THE FAR NW LEEWARD ISLANDS AND
ADJACENT WATERS THIS AFTERNOON...YIELDING ISOLATED TSTMS THAT
WERE CONTINUING ACROSS SW PUERTO RICO.

AT LOWER LEVELS...A PRONOUNCED SURFACE PRESSURE GRADIENT FROM AN
EXTENSION OF THE BERMUDA HIGH WELL NORTHEAST OF THE CARIBBEAN TO
A 1006 MB LOW ALONG THE COLOMBIAN COAST NEAR 6N76W HAS WEAKENED
SLIGHTLY TODAY...BUT CONTINUES TO YIELD A BROAD ZONE OF
TRADEWINDS 20 KT AND HIGHER S OF 16N AND E OF 80W. A GALE
WARNING IS CURRENTLY IN EFFECT FOR THE AREA OF STRONGEST WINDS
OFF THE COAST OF COLOMBIA...BUT RECENT SCATTEROMETER PASSES
SUGGEST THAT WINDS MAY HAVE DIMINISHED TO BELOW GALE FORCE
THERE. GLOBAL MODEL GUIDANCE SUGGEST WINDS PULSING TO GALE FORCE
DURING THE LATE NIGHT AND EARLY MORNING HOURS ACROSS THIS AREA
EACH OF THE NEXT SEVERAL DAYS. A LARGE AREA OF MULTI LAYERED
CLOUDS WITH SCATTERED TO NUMEROUS SHOWERS AND SCATTERED TSTMS
CONTINUES TO AFFECT THE SE CARIBBEAN AND WINDWARD ISLANDS S OF
ANTIGUA THIS AFTERNOON. THIS IS ASSOCIATED WITH A WEAK LOW-LEVEL
DISTURBANCE ALONG 63W/64W...AND A LOW LEVEL WIND SURGE BEHIND
IT. TOTAL PRECIPITABLE WATER IMAGERY INDICATES ENHANCED MOISTURE
BETWEEN 54W AND 67W SOUTH OF 15N...BUT HAS BECOME SHEARED TO THE
NE TO 17N JUST E OF THE LEEWARDS DUE TO THE MID TO UPPER TROUGH.
SCATTERED TO NUMEROUS CONVECTION IS EXPECTED DURING THE NEXT 24
HOURS ACROSS THE CARIBBEAN S OF 15N AND PORTIONS OF NORTHERN
VENEZUELA AS THE WEAK DISTURBANCE MOVES WESTWARD. STRONG
CONVECTION IS EXPECTED THROUGH LATE THIS EVENING ACROSS THE
WINDWARDS...SOUTHERN LEEWARDS AND ADJACENT WATERS.

THE ATLANTIC OCEAN...
A MODEST AZORES-BERMUDA RIDGE EXTENDS ACROSS THE NORTH ATLANTIC
ALONG ABOUT 32N THEN CONTINUES SW ACROSS OUR NORTHERN BORDER
NEAR 52W AND THROUGH SOUTHERN FLORIDA...INTERRUPTED BY A LLVL
TROUGH ALONG 62W/63W. GENERALLY WEAK TO MODERATE NE TO E
TRADEWINDS PREVAIL ACROSS THE AREA N OF 20N...BECOMING SE TO S
WINDS W OF 67W. S OF 20N...NE TRADEWINDS NEAR 20 KT PREVAIL N OF
10N...WHILE ACTIVE CONVECTION DESCRIBED ABOVE IN THE E CARIBBEAN
EXTENDS E TO 55W AND CONTINUES TO AFFECT THE WATERS E OF THE
LESSER ANTILLES. E OF THIS ACTIVE WEATHER...VERY STABLE LLVL
CONDITIONS PREVAIL N OF THE ITCZ EWD TO THE COAST OF AFRICA AS A
WELL ESTABLISHED E TO W LLVL RIDGE ACROSS THE CENTRAL AND E ATLC
HAVE ALLOWED FOR RECENT LARGE PLUMES OF SAL TO MOVE ACROSS THE
TROPICS. A NEW PLUME OF SAL AND VERY DRY AIR HAS MOVED OFF OF W
AFRICA AND ACROSS THE CAPE VERDES TODAY...WITH SKIES NEARLY
CLEAR THERE. DRIER AIR AND IMPROVING WEATHER CONDITIONS ARE
EXPECTED ACROSS THE TROPICAL N ATLC WATERS W OF 55W AND INTO THE
LEEWARD ISLANDS BY LATE SAT.

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

$$
STRIPLING





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