000
AXNT20 KNHC 281743
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 PM EST SAT FEB 28 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.

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 5N8W CROSSING THE EQUATOR NEAR 
17W EXTENDING TO 1S30W 1S40W INTO NE BRAZIL NEAR 2S45W. 
SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 120 NM 
EITHER SIDE OF THE AXIS BETWEEN 10W-25W. SCATTERED MODERATE 
CONVECTION IS WHERE THE ITCZ MEETS THE COAST OF BRAZIL.  

...DISCUSSION...

GULF OF MEXICO...
A NEW COLD FRONT HAS ENTERED THE GULF OF MEXICO. AT 1500 UTC...
THE FRONT STRETCHES FROM SE LOUISIANA TO 28N95W ENTERING MEXICO 
JUST SOUTH OF BROWNSVILLE/MATAMOROS. A STRONG BAND OF SHOWERS 
AND TSTMS IS ASSOCIATED WITH THE FRONT OVER THE SE CONUS WHERE 
SOME TORNADO WATCHES/WARNINGS HAVE BEEN ISSUED. A DEEP LAYERED 
TROUGH ACROSS THE CENTRAL AND SOUTHERN PLAINS OF U.S. SUPPORTS 
THIS FRONT WHICH WILL EXTEND FROM THE FLORIDA PANHANDLE TO THE 
SW PORTION OF THE BAY OF CAMPECHE TONIGHT...AND FROM TAMPA BAY 
TO THE YUCATAN PENINSULA SUN MORNING. IN THE WAKE OF THE COLD 
FRONT...INCREASED NORTHERLY WINDS ARE FORECAST TO OCCUR OVER THE 
GULF WATERS...WITH GALE CONDITIONS EXPECTED SATURDAY NIGHT AND 
SUNDAY OVER PORTIONS OF THE SW GULF. ALSO...A RELATIVELY COOLER 
AND DRIER AIR MASS WILL FOLLOW THE FRONT BRINGING ANOTHER ROUND 
OF COLDER TEMPERATURES ACROSS SOUTH FLORIDA...PARTICULARLY 
MONDAY AND TUESDAY MORNINGS. LOWEST WIND CHILL READINGS ARE 
EXPECTED TO BE IN THE UPPER 30S/LOWER 40S. ACROSS THE REMAINDER 
OF THE GULF...GENERALLY FAIR WEATHER PERSISTS UNDER THE 
INFLUENCE OF A SFC RIDGE EXTENDING SWWD FROM THE CENTRAL ATLC 
ACROSS THE STATE OF FLORIDA INTO THE GULF WATERS...AND NWLY FLOW 
ALOFT THAT IS SUPPORTING ATMOSPHERIC SUBSIDENCE AND STABLE 
ATMOSPHERIC CONDITIONS. HOWEVER...SOME UPPER LEVEL MOISTURE IS 
STREAMING SOUTHEASTWARD ACROSS PORTIONS OF THE N AND CENTRAL 
GULF. AHEAD OF THE COLD FRONT...SE TO S SURFACE WINDS OF 20 TO 
25 KT ARE NOTED PER SFC DATA AND A QSCAT PASS FROM AROUND 1130 
UTC. 

CARIBBEAN SEA...
GENERALLY FAIR WEATHER CONDITIONS ARE OCCURRING ACROSS MUCH OF 
THE CARIBBEAN REGION...WHERE SUBSIDENCE IS BEING SUPPORTED BY 
CONFLUENCE IN WESTERLY FLOW ALOFT. AS USUAL FOR THIS TIME OF THE 
YEAR...SHALLOW MOISTURE EMBEDDED IN THE TRADE WIND FLOW IS 
MOVING ACROSS THE BASIN PRODUCING ISOLATED TO SCATTERED PASSING 
SHOWERS. IN ADDITION...INCREASED UPPER LEVEL MOISTURE IS 
STREAMING NORTHEASTWARD ACROSS SECTIONS OF THE E AND CENTRAL  
CARIBBEAN. MODERATE TO FRESH TRADE WINDS ARE BLOWING ACROSS THE 
REGION WITH THE STRONGEST WINDS JUST OFFSHORE THE COAST OF 
COLOMBIA WHERE AN EARLIER QSCAT PASS SHOWED NE WINDS OF UP TO 25 
KT. THE COLD FRONT CURRENTLY MOVING ACROSS THE GULF OF MEXICO IS 
EXPECTED TO REACH WESTERN CUBA AND THE NW CARIBBEAN LATE SUN 
MORNING...AND WEAKEN ACROSS THE WINDWARD PASSAGE ON MON.  

ATLANTIC OCEAN...
A STATIONARY FRONT REMAINS MAINLY OVER THE CENTRAL ATLC 
EXTENDING FROM 31N45W TO 27N59W TO 24N64W. LOW LEVEL CONVERGENCE 
IS SUPPORTING SCATTERED SHOWERS WITHIN 120 NM EITHER SIDE OF 
THE FRONT. THIS ACTIVITY IS BEING ENHANCED BY ATMOSPHERIC 
LIFT ASSOCIATED WITH UPPER LEVEL DIVERGENCE IN THE SW QUADRANT 
OF A 110-120 KT UPPER LEVEL JET MAXIMUM OVER THE CENTRAL ATLC. 
VIS SATELLITE IMAGERY INDICATES THAT A FRONTAL WAVE/SFC LOW IS 
LIKELY FORMING ALONG THE FRONTAL BOUNDARY NEAR 27N59W. THE GFS 
COMPUTER MODEL IS PREDICTING THE DEVELOPMENT OF A PAIR OF LOWS 
ALONG THIS FRONTAL SYSTEM DURING THE NEXT DAY OR SO. ALSO... 
AN UPPER-LEVEL LOW IS NOTED ON WV IMAGERY OVER THIS SAME AREA. 
TO THE W OF THIS STATIONARY FRONT...FAIR WEATHER CONDITIONS 
PREVAIL THANKS TO 1038 MB SFC HIGH LOCATED NEAR 4N45W. A RIDGE 
EXTENDS FROM THIS HIGH SWWD ACROSS THE W ATLC INTO FLORIDA AND 
THE EASTERN GULF. THIS RIDGE ALSO ENVELOPS MOST OF CUBA AND THE 
NW CARIBBEAN. SE OF THE STATIONARY FRONT...SUBSIDENCE ASSOCIATED 
WITH A SURFACE RIDGE IS ALSO SUPPORTING FAIR WEATHER CONDITIONS. 
THIS RIDGE EXTENDS SOUTHWARD FROM A 1025 MB SURFACE HIGH 
SITUATED NEAR 29N36W. THIS HIGH IS FORECAST TO DISSIPATE IN 
ABOUT 24 HOURS. A DEEP LAYERED TROUGH DOMINATES THE FAR E ATLC 
AND WEST AFRICA WHILE AN UPPER-LEVEL RIDGE COVERS MUCH OF THE 
E-CENTRAL ATLC. THIS RIDGE...ANCHORED ON A HIGH NEAR 3N24W...IS 
ENHANCING THE CONVECTION ASSOCIATED WITH THE ITCZ. ANOTHER WIND 
MAXIMA OF 90-110 KT ASSOCIATED WITH A JET-STREAM BRANCH IS 
OBSERVED ON THE NORTHERN SIDE OF THE RIDGE EXTENDING FROM 
HISPANIOLA ALONG 23N60W 25N40W THEN CROSSING OVER THE CAPE VERDE 
ISLANDS INTO W AFRICA NEAR 17N16W.  

$$
GR