000
AXNT20 KNHC 182346
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL  
805 PM EDT MON APR 18 2011

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL 
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHERN SECTION
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 2300 UTC.

...THE ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 5N10W EQ18W 1S30W 3S43W. A LARGE 
BURST OF STRONG CONVECTION IS JUST OFFSHORE OF W AFRICA FROM 
3N-7N BETWEEN 12W-17W. ISOLATED MODERATE/STRONG CONVECTION IS 
FROM 1N-4N BETWEEN 33W-40W...AND FROM 5N-7N BETWEEN 42W-44W.

...DISCUSSION...

THE GULF OF MEXICO...
THE GULF OF MEXICO REMAINS CLEAR AS SURFACE RIDGING EXTENDS WWD 
ACROSS THE BASIN FROM THE FAR W ATLC. MODERATE DRY AIR ALOFT IN 
ZONAL WLY FLOW IS ALSO CONTRIBUTING TO THE FAIR CONDITIONS. 
LIGHT SE-S WINDS ARE ACROSS THE BASIN WITH STRONGER RETURN FLOW 
REACHING 15-20 KTS ACROSS THE FAR NW CORNER NEAR THE 
TEXAS/MEXICO COASTLINE. THE ONLY NOTABLE PRECIPITATION IS A 
LARGE CONVECTION BURST OVER SOUTH FLORIDA NEAR THE CENTER OF THE 
PENINSULA. EXPECT SURFACE RIDGING TO REMAIN ACROSS THE BASIN 
WITH SOME SURFACE TROUGHING DEVELOPING OVER THE YUCATAN 
PENINSULA WHICH MAY PROVIDE ENOUGH SUPPORT FOR A FEW ISOLATED 
SHOWERS.

THE CARIBBEAN SEA...
MOSTLY FAIR WEATHER IS ACROSS THE CARIBBEAN AS MOSTLY DRY AIR 
ALOFT COVERS THE BASIN IN ZONAL WLY FLOW. LIGHT TO MODERATE 
TRADEWINDS ARE ACROSS MUCH OF THE AREA WITH STRONG WINDS AROUND 
THE COAST OF COLOMBIA. A FEW ISOLATED AFTERNOON THUNDERSTORMS 
STILL REMAIN OVER PORTIONS OF THE ISLANDS INCLUDING 
JAMAICA...HISPANIOLA...AND PUERTO RICO. EXPECT LITTLE CHANGE 
OVER THE NEXT 24 HOURS. 

THE ATLANTIC OCEAN...
MUCH OF THE FAR SW NORTH ATLANTIC IS UNDER CLEAR CONDITIONS 
INFLUENCED BY A 1022 MB HIGH CENTERED NEAR 36N68W. HOWEVER...A 
STATIONARY FRONT EXTENDS INTO THE FAR NRN EXTENT OF THE 
DISCUSSION AREA ALONG 32N67W 29N74W SUPPORTING SCATTERED SHOWERS 
WITHIN 60 NM EITHER SIDE THE AXIS. A FEW CONVECTIVE STORMS HAVE 
ALSO POPPED UP OVER NW BAHAMAS. A WEAK SHORTWAVE UPPER LEVEL 
TROUGH EMBEDDED IN A LARGE SCALE UPPER TROUGH IS SUPPORTING THE 
AFOREMENTIONED SURFACE BOUNDARY. A SURFACE TROUGH IS IMPACTING 
PORTIONS OF THE CENTRAL ATLC EXTENDING ALONG 24N60W 17N56W 
12N57W. SATELLITE IMAGERY SHOWS CLEAR CYCLONIC FLOW AROUND THE 
AXIS WITH POSSIBLE CLOSED LOWS TRYING TO FORM. TOTAL 
PRECIPITABLE WATER IMAGERY ALSO INDICATES A SURGE OF MOISTURE TO 
THE E SIDE OF THE TROUGH. THIS COINCIDES WITH THE AREAS OF 
PRECIPITATION. SCATTERED SHOWERS/POSSIBLE THUNDERSTORMS ARE FROM 
18N-25N BETWEEN 46W-58W. EAST OF THE TROUGH...WEAK SURFACE 
RIDING EXTENDS FROM A SURFACE HIGH WELL N OF THE AREA SUPPORTED 
BY A NARROW UPPER LEVEL RIDGE BETWEEN 35W-50W. FARTHER E...A 
CUTOFF UPPER LOW IS SPINNING NEAR 31N27W SUPPORTING AN OCCLUDED 
SURFACE LOW NEAR 29N30W. AN OCCLUDED FRONT WRAPS AROUND THE LOW 
CENTER ALONG 32N28W 29N26W CONTINUING AS A COLD FRONT ALONG 
26N28W 23N36W. ISOLATED SHOWERS ARE WITHIN 120 NM EITHER SIDE OF 
THE FRONT. A WEAK SURFACE TROUGH IS TO THE E OF THIS SYSTEM 
ACROSS THE CANARY ISLANDS WITH POSSIBLE ISOLATED SHOWERS ALONG 
IT.  

FOR ADDITIONAL INFORMATION PLEASE VISIT
HTTP://WWW.HURRICANES.GOV/MARINE

$$
WALTON