000
AXNT20 KNHC 181713
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT TUE APR 18 2006

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL 
AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHEASTERN 
SECTIONS OF SOUTH AMERICA...AND THE ATLANTIC OCEAN TO THE 
AFRICAN COAST FROM THE EQUATOR TO 32N. THE FOLLOWING INFORMATION 
IS BASED ON SATELLITE IMAGERY...WEATHER OBSERVATIONS... 
RADAR...AND METEOROLOGICAL ANALYSIS.

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1645 UTC.

...ITCZ...

ITCZ AXIS IS ALONG 7N12W 2N32W 1S50W.  SCATTERED MODERATE 
CONVECTION IS FROM 2N-6N BETWEEN 14W-18W.  WIDELY SCATTERED 
MODERATE FROM 1N-3.5N BETWEEN 26W-32W.  ISOLATED MODERATE S OF 
1N W OF 40W AND WITHIN 60 NM OF 3N50W.  STRONG CLUSTERS OF TSTMS 
ARE S OF AFRICA WITHIN 45 NM OF A LINE 3N FROM 6W TO 9W.

...DISCUSSION...

GULF OF MEXICO...
SURFACE HIGH PRESSURE COVERS THE REGION WITH A RIDGE EXTENDING 
FROM NW CUBA TO SE LOUISIANA.  SSW TO WLY FLOW IS OVER A GOOD 
PORTION OF THE E GULF WITH ONE OF THE WARMEST DAYS OF THE YEAR 
EXPECTED IN S FLORIDA.  FARTHER W... SSE WINDS OVER THE W GULF 
ARE BRINGING PLENTY OF WARM MOIST AIR TOWARD THE TX/LOUISIANA 
COASTS.  HOWEVER THE MOISTURE LAYER IS RATHER SHALLOW WITH 
LITTLE CHANCE OF BREAKING THE STRONG CAP NEAR THE TX COAST WITH 
UPPER LEVEL RIDGING PRESENT.  ANY SIGNIFICANT MOISTURE WILL BE N 
OF THE AREA ALONG A WEAK COLD FRONT.  LITTLE CHANGE IN THE 
WEATHER IS LIKELY FOR THE NEXT SEVERAL DAYS AS THE PATTERN 
REMAINS STATIONARY. 

CARIBBEAN SEA...
LARGE UPPER RIDGE DOMINATES THE W & CENTRAL CARIBBEAN WITH 
TROUGHING ACROSS THE LEEWARD ISLANDS.  LOTS OF SUBSIDENCE IS 
PRESENT WITH DRY AIR ALOFT PRACTICALLY EVERYWHERE.  THE WEATHER 
IS RATHER PLEASANT WITH TRADES STILL A BIT RELAXED AND FEW 
TRADEWIND SHOWERS.  SOME INCREASE IN TSTMS IS POSSIBLE LATER 
TODAY IN THE SW CARIBBEAN S OF 11N.  OTHERWISE MOSTLY CLEAR 
SKIES ARE THE RULE WITH DRIER-THAN-TYPICAL CONDITIONS AS 
DEWPOINTS ARE BELOW 70F IN THE NE CARIBBEAN. 

ATLANTIC OCEAN...
MOST SIGNIFICANT FEATURE IS A COLD FRONT MOVING INTO THE W ATLC 
APPROACHING BERMUDA THRU 31N71W TO 29N75THEN WESTWARD TO JUST S 
OF JACKSONVILLE.  GALE CONDITIONS ARE JUST N OF THE AREA AHEAD 
OF THE FRONT ALONG WITHIN ISOLATED TSTMS WITHIN 60 NM OF THE 
BOUNDARY E OF 71W.  BROKEN LOW CLOUDS ARE BEHIND THE FRONT.. 
PRETTY MUCH THE MOST CLOUDINESS IN THE BASIN.  BROAD UPPER 
TROUGHING IS ACROSS MOST OF THE SUBTROPICAL ATLC WITH A FEW 
SHORTWAVES EMBEDDED WITHIN THE WLY FLOW.  ONE SHORTWAVE IS ALONG 
47W N OF 24N IS CAUSING A FEW SHOWERS/TSTMS ALONG A WEAK SURFACE 
TROUGH BETWEEN 22N-27N FROM 41W-48W.  ANOTHER SHORTWAVE IS ALONG 
27W N OF 25N CAUSING AN INCREASE IN HIGH CLOUDINESS BUT NO 
INCREASE IN SHOWERS.  THE AREA HAS A LOT LESS CLOUDINESS THAN 
AVERAGE IN GENERAL WITH PATCHY STRATOCUMULUS AT BEST.  FARTHER 
S... THE TROPICAL ATLC IS CONTROLLED BY A WELL-DEFINED MID/UPPER 
HIGH NEAR 5N35W RIDGING WNW TO 8N62W IN S AMERICA AND EASTWARD 
TO 4N22W.  TRADES ARE FAIRLY WEAK W OF 40W BUT HAVE PICKED UP IN 
THE FAR E ATLC NEAR THE COAST OF AFRICA.  SUBTROPICAL RIDGING 
HAS BEEN DISPLACED EASTWARD CAUSING NE WINDS TO NEAR 30 KT NEAR 
WESTERN SAHARA.  UPPER TROUGHING ALONG THE COAST OF W AFRICA IS 
CAUSING A FAIR AMOUNT OF TSTMS IN THE ITCZ E OF 20W OTHERWISE 
SUBSIDENCE DOMINATES.  

$$
BLAKE