000
AXNT20 KNHC 042327
TWDAT 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT SAT APR 04 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY
THROUGH 2315 UTC.

...THE ITCZ...
THE ITCZ AXIS IS CENTERED ALONG 5N10W 3N16W CROSSING THE EQUATOR 
NEAR 22W TO 2S30W TO 3S40W. SCATTERED MODERATE CONVECTION IS 
WITHIN 90 NM OF AXIS BETWEEN 25W-29W.  

...DISCUSSION...

THE GULF OF MEXICO...
A WEAKENING WARM FRONT IS LIFTING N FROM FORT MYERS FLORIDA TO 
26N92W. SHALLOW CLOUDINESS AND EMBEDDED ISOLATED SHOWERS ARE 
WITHIN 120 NM N OF THE FRONT. THE PRESSURE GRADIENT BETWEEN THE 
BOUNDARY AND A 1016 MB HIGH OVER S GEORGIA IS PRODUCING SE 
15-20 KT FLOW N OF THE FRONT. S OF THE FRONT...CONDITIONS ARE 
MAINLY FAIR ENHANCED BY WIDESPREAD STABLE AIR ALOFT...WITHIN A 
SPRAWLING MID-UPPER HIGH CENTERED JUST S OF GUATEMALA. A LARGE 
UPPER TROUGH OVER THE ROCKIES IS EXPECTED TO DEEPEN AS IT MOVES 
E...DRAGGING A COLD FRONT INTO THE NW GULF TOMORROW AFTERNOON. 
THIS PATTERN LOOKS MORE LIKE WINTER WITH HIGH PRES SURGING S 
FROM CANADA IN ITS WAKE. FOR THAT REASON...NLY GALE CONDITIONS 
ARE EXPECTED FOR THE SW WATERS BEHIND THE FRONT. THE BOUNDARY IS 
ANTICIPATED TO CROSS THE ENTIRE AREA BY MON NIGHT.
 
THE CARIBBEAN SEA...
A SFC TROUGH IS CENTERED NEAR THE VIRGIN ISLANDS ALONG 64W 
MOVING WNW ABOUT 10 KT. HIS FEATURE HAS PRODUCED A FAIR AMOUNT 
OF RAIN OVER THE LEEWARD ISLANDS DURING THE PAST 24 HOURS. 
VISIBLE IMAGERY AND SFC OBSERVATIONS SHOW CYCLONIC TURNING IN 
THE LOW-LEVEL WIND FIELD AND SCATTERED SHOWERS N OF 14N E OF 
65W. THIS WEAK DISTURBANCE IS EXPECTED TO CONTINUE WESTWARD 
OVER THE NEXT COUPLE OF DAYS BRINGING AN INCREASE IN MOISTURE 
OVER PUERTO RICO SUN AND HISPANIOLA MON. THE REMAINDER OF THE 
REGION IS EXPERIENCING MAINLY FAIR WEATHER ENHANCED BY A 
STRONGLY SUBSIDENT ENVIRONMENT. TRADE WINDS ARE GENERALLY E TO 
SE 15-20 KT...EXCEPT TO 25 KT OVER THE GULF OF HONDURAS. LOOKING 
AHEAD...A STRONG FRONT FOR THIS TIME OF YEAR IS EXPECTED TO MOVE 
INTO THE NW CARIBBEAN MON NIGHT/TUE.  

THE ATLANTIC OCEAN...
THE TROPICAL PORTION OF THE ATLC IS DOMINATED BY A MID-UPPER 
HIGH CENTERED NEAR 8N26W. SLY FLOW ALOFT AND AN OVERALL 
DIFFLUENT UPPER PATTERN TO THE W OF THE ANTICYCLONE IS 
GENERATING AND SPREADING MOISTURE N FROM THE ITCZ. THIS IS 
LEADING TO A SWATH OF SCATTERED SHOWERS AND TSTMS S OF 5N 
BETWEEN 40W-53W...STRONGEST INLAND OVER SOUTH AMERICA WHERE 
HEATING AND LOCAL FLOWS ARE PROVIDING AN ENHANCEMENT. THERE ARE 
A COUPLE AREAS OF DISTURBED WEATHER IN THE SUBTROPICS. ONE OF 
THESE IS ASSOCIATED WITH A DEEP LAYER LOW PRES SYSTEM CENTERED 
NEAR 30N40W...ANALYZED 1014 MB AT THE SFC. AN ASSOCIATED SFC 
TROUGH EXTENDS FROM 30N37W TO 21N46W. SCATTERED SHOWERS AND 
TSTMS ARE WITHIN 180 NM E OF THE TROUGH N OF 26N AND ELSEWHERE 
WITHIN 420 NM NE QUADRANT OF THE LOW. GLOBAL MODELS ARE IN 
GENERAL AGREEMENT IN SHOWING THE SFC LOW OPEN INTO A TROUGH OVER 
THE NEXT 24-36 HOURS AS IT DRIFTS SW. A COLD FRONT EXTENDS FROM 
31N67W TO 27N76W THEN BECOMES STATIONARY TO SOUTH FLORIDA. 
LOW-LEVEL CONVERGENCE ALONG THE BOUNDARY COUPLED WITH UPPER 
DIFFLUENCE IS PRODUCING SCATTERED SHOWERS AND TSTMS WITHIN 240 
NM E OF THE FRONT N OF 27N. ISOLATED SHOWERS ARE POSSIBLE 
ELSEWHERE ALONG THE BOUNDARY. THIS FEATURE IS EXPECTED TO WEAKEN 
OVER THE NEXT DAY OR TWO AS ITS UPPER SUPPORT PULLS AWAY. 
MEANWHILE...A STRONGER FRONT IS FORECAST TO MOVE OFF THE SE 
CONUS COAST MON. 

$$
CANGIALOSI