[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 091750
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 PM EST MON FEB 09 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...

ITCZ IS CENTERED ALONG 5N9W 1N20W 1N40W CROSSING THE EQUATOR AT
47W...AND INTO NE BRAZIL NEAR 1S50W. A CLUSTER OF MODERATE TO
ISOLATED STRONG CONVECTION IS FROM 3N TO THE COAST OF AFRICA
BETWEEN 3W-8W. SCATTERED MODERATE CONVECTION IS WITHIN 60N S OF
AXIS BETWEEN 13W-17W...AND FROM 2S TO THE EQUATOR BETWEEN 30W
AND 36W.

...DISCUSSION...

GULF OF MEXICO...
THE WEATHER PATTERN HAS NOT EXPERIENCED MUCH CHANGE ACROSS THE
GULF REGION SINCE YESTERDAY. THE AREA CONTINUES UNDER THE
INFLUENCE OF A 1029 MB SFC HIGH CENTERED NEAR 29N80W AT 1500
UTC. THE RIDGE AXIS EXTENDS SW INTO THE BAY OF CAMPECHE AND SE
MEXICO INCLUDING THE YUCATAN PENINSULA. THIS SYSTEM IS PRODUCING
MOSTLY FAIR WEATHER AND SE-S RETURN FLOW WITH SPEEDS OF 20-25 KT
OVER MUCH OF THE GULF WATERS. THESE WINDS ARE EXPECTED TO
DIMINISH LATE TODAY AS THE SFC HIGH MOVES AWAY FROM THE FORECAST
AREA...AND THE PRES GRADIENT RELAXES. ALOFT...A MID/UPPER LEVEL
RIDGE DOMINATES THE ENTIRE GULF AND THE SE CONUS. THE NEXT COLD
FRONT IS FORECAST TO MOVE OFF TEXAS COAST EARLY WED. THE RETURN
FLOW WILL INCREASE AGAIN TO 20-25 KT LATER ON TUE IN ADVANCE OF
THE FRONT.

CARIBBEAN SEA...
A SFC TROUGH...REMNANTS OF AN OLD FRONTAL BOUNDARY...IS ANALYZED
ACROSS THE MONA PASSAGE ON THE 1200 UTC SFC MAP. A LARGE AREA OF
MOISTURE WITH SOME INVERTED-V CLOUD PATTERN AND EMBEDDED
MODERATE SHOWERS ARE ASSOCIATED WITH THE TROUGH. THIS ACTIVITY
IS AFFECTING THE UK/US VIRGIN ISLANDS...PUERTO RICO AND
DOMINICAN REPUBLIC WHICH HAS REPORTED SIGNIFICANT RAINFALL
AMOUNTS OF AROUND 2 INCHES IN SEVERAL PLACES FOR THE PAST 24 AND
48 HOURS. THE GFS COMPUTER MODEL HAS MOISTURE FROM THIS TROUGH
MOVING WWD ACROSS HISPANIOLA AND THE CARIBBEAN REGIONAL WATERS
DURING THE NEXT 24 HOURS OR SO WHICH MEANS A RISK OF ADDITIONAL
POTENTIALLY HEAVY RAINFALL OVER DOMINICAN REPUBLIC. DURING THE
24 HOURS...A TOTAL OF 1.06 INCHES OF RAIN FELL IN SAN
JUAN...WHILE 1.55 INCHES OF RAIN FELL IN ST THOMAS. POCKETS OF
MOISTURE WITH MAINLY LIGHT RAIN ARE ALSO AFFECTING MUCH OF
CENTRAL AMERICA. A TIGHT SURFACE GRADIENT BETWEEN THE SURFACE
HIGH N OF AREA AND LOWER PRES OVER S AMERICA IS PRODUCING FRESH
TO STRONG TRADE WINDS OVER THE CENTRAL AND W CARIBBEAN. AN
EARLIER QSCAT PASS SHOWED NE WINDS OF UP TO 30 KT JUST OFFSHORE
THE COAST OF COLOMBIA. THESE WINDS ARE EXPECTED TO DIMINISH
SLIGHTLY ON TUE...BUT WILL INCREASE AGAIN LATER ON TUE AND INTO
FRI AS NEW ATLC HIGH PRES BUILDS OVER THE SW N ATLC. ALOFT...A
SHORT-WAVE TROUGH IS OVER THE CENTRAL BAHAMAS AND CUBA EXTENDING
INTO THE CARIBBEAN SEA TO NEAR CABO GRACIAS A DIOS NICARAGUA. AN
UPPER-LEVEL HIGH CENTERED OVER NE BRAZIL EXTENDS A RIDGE NW
ENVELOPING THE EASTERN CARIBBEAN. SWLY FLOW BETWEEN THESE TWO
UPPER-LEVEL FEATURES IS ADVECTING SOME MID/UPPER LEVEL MOISTURE
FROM COLOMBIA INTO THE CARIBBEAN SEA.

ATLANTIC OCEAN...
THE MAIN FEATURE ACROSS THE FORECAST AREA IS A SFC TROUGH...
REMNANTS OF AN OLD FRONTAL BOUNDARY...THAT ENTERS THE REGION
NEAR 31N30W THEN CONTINUES SW ALONG 25N45W 20N66W INTO THE MONA
PASSAGE. SEE THE CARIBBEAN SEA SECTION FOR MORE DETAILS. A
PRETTY WELL DEFINED NARROW BAND OF CLOUDS IS RELATED TO THE
TROUGH ACROSS THE ATLC OCEAN. A WEAK SFC TROUGH IS ALSO ANALYZED
ALONG 57W SOUTH OF 12N TO THE COAST OF SURINAME. UPPER-LEVEL
DIFFLUENCE ASSOCIATED WITH THE ABOVE MENTIONED RIDGE OVER N
SOUTH AMERICA IS HELPING TO INDUCE SOME SHOWER ACTIVITY EITHER
SIDE OF THE TROUGH. A 1029 MB SFC HIGH IS CENTERED JUST E OF NE
FL NEAR 29N80W. THIS SYSTEM WILL MERGE WITH A STRONGER HIGH PRES
EXITING THE MID ATLC STATES. THIS WILL MAINTAIN A TIGHT PRES
GRADIENT OVER THE BAHAMAS...THE GREATER ANTILLES AND THE
CARIBBEAN SEA INCLUDING THE PASSAGES THROUGH EARLY WED. A COUPLE
OF 1025 MB SFC HIGHS ARE OVER THE REMAINDER OF THE DISCUSSION
AREA. ONE IS NEAR 35N37W WHILE THE SECOND IS EAST OF THE MADEIRA
ISLANDS NEAR 33N12W. ALOFT...A TROUGH/RIDGE/TROUGH PATTERN
DOMINATES THE AREA.

$$
GR





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