[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 201104
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
705 AM EST FRI FEB 20 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0930 UTC.

...THE ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 5N6W CROSSES THE EQUATOR NEAR
14W THEN ALONG 2S20W 3S30W AND INTO NE BRAZIL NEAR 4S39W.
SCATTERED MODERATE CONVECTION IS FROM 2S-5S BETWEEN2W-7W.
SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM THE
EQUATOR TO 5N BETWEEN 7W-19W.

...DISCUSSION...

GULF OF MEXICO...
A DEEP-LAYER TROUGH OVER THE EASTERN SEABOARD SUPPORTS A COLD
FRONT ACROSS THE W ATLANTIC...BAHAMAS...AND GULF OF MEXICO. AS
OF 0900 UTC...THE FRONT ENTERS THE GULF THROUGH THE STRAIGHTS OF
FLORIDA AND CONTINUES ALONG 23N85W TO 23N90W WHERE IT BECOMES
STATIONARY THROUGH THE WESTERN BAY OF CAMPECHE AND CROSSES
INLAND OVER MEXICO NEAR COATZACOALCOS. MOST OF THE CONVECTIVE
ACTIVITY ASSOCIATED WITH THE FRONT HAS DIMINISHED..HOWEVER
MULTI-LEVEL CLOUDS AND ISOLATED SHOWERS REMAIN ALONG THE
BOUNDARY. STRONG N TO NE WINDS OF 20-25 KT CONTINUE TO USHER A
COOLER AND DRIER AIRMASS ACROSS THE GULF IN THE WAKE OF THE
FRONT. A 1027 MB HIGH OVER TEXAS IS PRODUCING FAIR WEATHER AND
CLEAR SKIES ACROSS THE NW GULF N OF 27N. THIS HIGH IS EXPECTED
TO SHIFT EAST AS THE FRONTAL BOUNDARY MOVES OUT OF THE REGION
TONIGHT.

CARIBBEAN SEA...
HIGH PRESSURE OVER THE CENTRAL ATLANTIC IS MAINTAINING FRESH TO
STRONG TRADE WIND FLOW ACROSS THE CARIBBEAN WITH THE STRONGEST
WINDS...UP TO 30 KT...OBSERVED ALONG THE COAST OF COLOMBIA.
ISOLATED SHOWERS ARE MOVING ACROSS PUERTO RICO...THE MONA
PASSAGE...THE LESSER ANTILLES...AND THE CARIBBEAN WATERS E OF
67W. LOW LEVEL WIND CONVERGENCE IS GENERATING SCATTERED SHOWERS
ALONG THE COAST OF COSTA RICA. CONVECTION IN THE CARIBBEAN
REMAINS SHALLOW DUE TO STRONG SUBSIDENCE AROUND AN UPPER-LEVEL
RIDGE THAT EXTENDS FROM SOUTH AMERICA TO THE NW CARIBBEAN.

ATLANTIC OCEAN...
A COLD FRONT ASSOCIATED WITH A DEEP-LAYER TROUGH OVER THE
EASTERN SEABOARD STRETCHES ACROSS THE W ATLC. AS OF 0900
UTC...THE FRONT ENTERS THE W ATLC NEAR 31N69W AND CONTINUES
ACROSS THE BAHAMAS AND THROUGH THE FLORIDA STRAIGHTS INTO THE
GULF OF MEXICO. SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS ARE
OBSERVED WITHIN 50 NM OF THE FRONT N OF 26N. THE STRONG PRESSURE
GRADIENT ACROSS THE FRONT IS GENERATING SOUTHWESTERLY GALE FORCE
WINDS N OF 29N BETWEEN THE BOUNDARY AND 66W. FAIR WEATHER AND
STRATOCUMULUS CLOUDS SURROUND A 1028 MB SFC HIGH CENTERED NEAR
32N45W. A DISSIPATING FRONTAL BOUNDARY ASSOCIATED WITH A LOW
PRESSURE SYSTEM WELL NORTH OF THE AREA ENTERS THE CENTRAL ATLC
NEAR 31N35W BECOMING DIFFUSE NEAR 27N40W TO 21N57W. SURFACE
CONFLUENCE NEAR THIS BOUNDARY IS SUPPORTING INCREASED CLOUDINESS
AND ISOLATED SHOWERS WITHIN 40 NM EITHER SIDE OF THE FRONT. FAIR
WEATHER ASSOCIATED WITH A SFC RIDGE COVERS THE ATLC E OF 34W. IN
THE TROPICS... DEEP-LAYER DRY AIR AT THE BASE OF AN UPPER TROUGH
IS SUPPRESSING CONVECTION OVER THE WRN HALF OF THE ITCZ WHILE
UPPER LEVEL DIVERGENCE E OF THIS TROUGH IS ENHANCING THE
CONVECTION OVER THE ERN HALF OF THE ITCZ.

$$
WADDINGTON






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