000
AXNT20 KNHC 210524
TWDAT 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT TUE APR 21 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY
THROUGH 0515 UTC.

...THE ITCZ... 
ITCZ AXIS IS CENTERED ALONG 6N10W 3N14W CROSSING THE EQUATOR 
NEAR 19W TO 4S33W TO 2S45W. ISOLATED MODERATE CONVECTION IS S OF 
3N BETWEEN 13W-22W.

...DISCUSSION...

THE GULF OF MEXICO...
A LARGE UPPER TROUGH OVER THE ERN CONUS IS SUPPORTING A COLD 
FRONT THAT EXTENDS FROM NEAR THE TAMPA AREA TO THE NW YUCATAN 
PENINSULA. UPPER DIFFLUENCE TO THE E OF THE TROUGH AXIS COUPLED 
WITH LOW-LEVEL CONVERGENCE ALONG THE FRONT IS PRODUCING A SWATH 
OF MOISTURE OVER THE SE GULF AND FLORIDA. DOPPLER RADAR AND 
LIGHTNING DATA ONLY SUGGEST EMBEDDED ISOLATED SHOWER AND TSTM 
ACTIVITY. A FASTER MOVING SECONDARY SURGE IS NOTED ON SATELLITE 
IMAGERY OVER THE FLORIDA PANHANDLE ADVECTING DRIER AIR BEHIND 
IT. THESE BOUNDARIES ARE EXPECTED TO CROSS THE REMAINDER OF THE 
AREA BY THIS AFTERNOON. W OF THE FRONT...N WINDS LIKELY PEAKED 
AROUND 25-30 KT OVER THE TOPOGRAPHICALLY ENHANCED SW PORTION OF 
THE BAY OF CAMPECHE MON. WINDS ARE DIMINISHING TONIGHT AS WEAK 
HIGH PRES HAS BUILT E OVER THE WRN GULF...WEAKENING THE PRESSURE 
GRADIENT. THIS HIGH IS FORECAST TO CONTINUE ITS E DRIFT ACROSS 
THE GULF OVER THE NEXT COUPLE OF DAYS.

THE CARIBBEAN SEA... 
A LARGE AREA OF CONVECTIVE ACTIVITY IS LOCATED INLAND OVER 
COLOMBIA TRIGGERED BY A SWLY UPPER JET AND LIKELY ENHANCED BY 
LOCAL FLOWS AND USUAL SFC LOW PRES. LATEST QUIKSCAT PASS REVEALS 
20-25 KT NE/E WINDS BETWEEN THE COAST OF COLOMBIA AND HISPANIOLA 
WITH 15-20 KT TRADES ELSEWHERE E OF 80W. WINDS ARE LIGHT AND 
VARIABLE OVER THE W PORTION DUE TO THE PRESENCE OF A WEAK 
PREFRONTAL TROUGH ALONG 83W/84W. SOME MOISTURE...LIKELY 
CONTAINING ONLY ISOLATED SHOWERS AND TSTMS...HAS MOVED INTO THE 
FAR NW CARIBBEAN AHEAD OF A COLD FRONT OVER THE E GULF. THIS 
FRONT MAY MOVE INTO THE AREA BUT SHOULD HAVE LITTLE SIGNIFICANT 
WEATHER IMPACTS.   

THE ATLANTIC OCEAN...
SCATTERED SHOWERS AND TSTMS ARE WITHIN 240 NM E OF THE N FLORIDA 
AND GEORGIA COASTS TRIGGERED BY AN UPPER DIFFLUENT FLOW AND A 
COLD FRONT OVER FLORIDA. SEE GULF OF MEXICO SECTION FOR MORE 
DETAILS. SLY WINDS HAVE INCREASED TO 20-25 KT NEAR THE N BORDER 
W OF 74W AND WILL LIKELY INCREASE TO 30 KT OVER THE NEXT 6-12 
HOURS AS THE FRONT NEARS. OVER THE CENTRAL ATLC...DEEP LAYER 
TROUGHING REMAINS WELL DEFINED PROVIDING LIMITED SUPPORT FOR A 
WEAK BOUNDARY FROM 32N46W TO 22N60W. A WEAK SMALL SCALE LOW IS 
POSITIONED W OF THE FRONT NEAR 27N55W PRODUCING LITTLE 
SIGNIFICANT WEATHER. A MORE AMPLIFIED TROUGH...SUPPORTING 
ANOTHER FRONT...IS EXPECTED TO SWEEP SE AND ABSORB OR MERGE WITH 
THE WEAK LOW/FRONT OVER THE NEXT COUPLE OF DAYS. A NARROW SWATH 
OF SCATTERED SHOWERS AND TSTMS ARE LOCATED IN THE UPPER 
DIFFLUENT ZONE N OF 24N BETWEEN 37W-42W. AN UPPER JET EXTENDING 
NE FROM THE WINDWARD ISLANDS TO 20N40W IS LIKELY PRODUCING 
SCATTERED SHOWERS AND TSTMS WITHIN 300 NM E OF THE JET AXIS. 
OTHERWISE...THE E ATLC IS DOMINATED BY A STRONG AZORES HIGH.  

$$
CANGIALOSI