000
AXNT20 KNHC 221745
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL  
205 PM EDT SUN MAY 22 2011

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...WEATHER OBSERVATIONS...RADAR...AND 
METEOROLOGICAL ANALYSIS.

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1715 UTC.

...TROPICAL WAVES...

THE TROPICAL WAVE PREVIOUSLY ALONG 23W/24W IS NO LONGER 
DISCERNIBLE ON SATELLITE IMAGERY...TOTAL PRECIPITABLE WATER 
IMAGERY...HOVMOLLER GRAPHICS...OR POTENTIAL VORTICITY AND WIND 
GRAPHICS. ALTHOUGH A PULSE WAS OBSERVED OVER DAKAR ON MAY 20TH 
WHICH WELL NORTH OF THE PREVIOUS POSITION...IT HAS BEEN DROPPED 
FROM THE 12Z ANALYSIS. 

...THE ITCZ...

ITCZ AXIS IS ANALYZED ALONG 6N10W 3N17W 4N26W 1N38W 2N46W TO 
INLAND OVER SOUTH AMERICA NEAR 51W. CLUSTERS OF SCATTRED 
MODERATE/ISOLATED STRONG CONVECTION ARE WITHIN 75/90 NM OF LINE 
FROM INLAND OVER LIBERIA NEAR 5N9W TO 2N17W...FROM 5N TO S OF 
THE EQUATOR W OF 37W TO INLAND OVER SOUTH AMERICA AND FROM 5N-8N 
BETWEEN 47W-54W. CLUSTERS OF SCATTERED MODERATE CONVECTION ARE 
FROM 3N-9N BETWEEN 14W-24W. 
 
...DISCUSSION...

GULF OF MEXICO...
AN UPPER LOW IS OVER THE W TIP OF CUBA/YUCATAN CHANNEL NEAR 
22N85W COVERING THE SE GULF AND GENERATING SCATTERED SHOWERS/ 
ISOLATED THUNDERSTORMS INLAND OVER W CUBA AND IN THE YUCATAN 
CHANNEL S OF 23N. A BROAD UPPER RIDGE COVERS THE W GULF W OF 89W 
ANCHORED IN THE E PACIFIC REGION NW OF ACAPULCO AND A SECOND 
UPPER RIDGE ANCHORED IN THE W ATLC ALONG THE COAST OF 
NORTH/SOUTH CAROLINA COVERS THE NE GULF. SOMEWHAT DRY STABLE AIR 
ALOFT REMAINS OVER MUCH OF THE GULF LIMITING SHOWER ACTIVITY. 
DENSE SMOKE ALSO REMAINS OVER THE W GULF W OF 90W WITH 
VISIBILITIES AS LOW AS 2 NM FROM FIRES REPORTED OVER S MEXICO 
AND THE YUCATAN PENINSULA AS INDICATED ON NOAA SSD FIRE 
PRODUCTS. A LESS DENSE AREA OF SMOKE IS OBSERVED ON VISIBLE 
SATELLITE IMAGERY OVER THE E GULF. A WEAK SURFACE RIDGE REMAINS 
OVER THE NE GULF WITH A 1018 MB HIGH NEAR 29N85W GIVING MOST OF 
THE GULF SE SURFACE FLOW AND LEAVING THE THE GULF UNDER MOSTLY 
CLEAR SKIES THIS AFTERNOON. WEAK SURFACE RIDGE OVER THE FAR NE 
GULF WILL REMAIN STATIONARY THROUGH LATE MON NIGHT. FRESH SE 
RETURN FLOW WILL CONTINUE OVER W GULF THROUGH TUE THEN DIMINISH 
WED AS COLD FRONT APPROACHES E TEXAS. THE SMOKE OVER MUCH OF THE 
W GULF IS EXPECTED TO PERSIST AT LEAST THROUGH MON NIGHT.

CARIBBEAN SEA...
AN UPPER LOW IS OVER THE W TIP OF CUBA/YUCATAN CHANNEL NEAR 
22N85W WITH AN UPPER TROUGH EXTENDING S TO OVER THE GULF OF 
HONDURAS COVERING THE NW CARIBBEAN W OF 80W WITH SCATTERED 
SHOWERS/ISOLATED THUNDERSTORMS N OF 21N TO OVER W CUBA AND 
THROUGH THE YUCATAN CHANNEL BETWEEN 82W-87W. DRY STABLE AIR 
ALOFT REMAINS OVER THE REMAINDER OF THE NW CARIBBEAN LEAVING THE 
AREA W OF 80W UNDER MOSTLY CLEAR SKIES THIS AFTERNOON. A BROAD 
UPPER RIDGE COVERS THE REMAINDER OF THE CARIBBEAN E OF 80W 
ANCHORED SE OF THE WINDWARD ISLANDS. A SURFACE TROUGH IS BENEATH 
THIS UPPER RIDGE EMBEDDED WITHIN PERSISTENT DEEP LAYERED 
MOISTURE AS DEPICTED ON THE TOTAL PRECIPITABLE WATER IMAGERY 
EXTENDING FROM THE S COAST OF HISPANIOLA NEAR 17N71W TO THE 
COAST OF COLOMBIA NEAR 11N74W WITH SCATTERED SHOWERS/ISOLATED 
THUNDERSTORMS WITHIN 150/175 NM NW OF THE TROUGH AXIS BETWEEN 
13N-18N. SMOKE IS OBSERVED ON VISIBLE SATELLITE IMAGERY OVER THE 
GULF OF HONDURAS S OF 17N W OF 85W. SURFACE TROUGH WILL MOVE 
INTO THE W CARIBBEAN MON TO INLAND OVER CENTRAL AMERICA WED AS 
WEAK SURFACE RIDGE BUILDS W OVER THE W TROPICAL ATLC. A SURFACE 
TROUGH CURRENTLY IN THE W TROPICAL ATLC WILL MOVE INTO THE E 
CARIBBEAN LATER THIS EVENING AND INTO THE CENTRAL CARIBBEAN BY 
WED. 

ATLANTIC OCEAN...
A SMALL UPPER RIDGE COVERS THE AREA OF THE W ATLC N OF 26N W OF 
75W TO OVER THE NE GULF OF MEXICO. AN UPPER TROUGH COVERS THE 
REMAINDER OF THE W ATLC N OF 23N BETWEEN 60W-75W SUPPORTING A 
COLD FRONT N OF THE REGION AND A SURFACE TROUGH THAT ENTERS THE 
DISCUSSION AREA NEAR 32N66W TO 28N71W. SCATTERED SHOWERS/ 
ISOLATED THUNDERSTORMS ARE MOVING RAPIDLY E WITHIN 225/250 NM E 
OF THE TROUGH AXIS. A SURFACE TROUGH IS OVER THE W/CENTRAL ATLC 
EXTENDING FROM 27N61W TO 21N66W ALONG THE W SIDE OF A BROAD 
UPPER RIDGE THAT EXTENDS FROM THE TROPICS OFF THE COAST OF SOUTH 
AMERICA NEAR 9N56W TO BEYOND 32N51W SUPPLYING DIFFLUENT FLOW 
ALOFT AND ENHANCING SCATTERED SHOWERS WITHIN 250/300 NM OF LINE 
FROM 22N58W TO 30N52W. A BROAD SURFACE RIDGE DOMINATES THE ATLC 
N OF 15N W OF 55W ANCHORED BY A 1030 MB HIGH NEAR THE AZORES. A 
SURFACE TROUGH IS IN THE W TROPICAL ATLC ALONG 54W S OF 15N TO 
THE COAST OF SOUTH AMERICA WITH POSSIBLE ISOLATED SHOWERS WITHIN 
75 NM EITHER SIDE OF THE TROUGH AXIS. A SURFACE RIDGE WILL BUILD 
OVER THE W ATLC THROUGH TUE NARROWING ON WED. THE SURFACE TROUGH 
IN THE W TROPICAL ATLC WILL MOVE ACROSS THE LESSER ANTILLES INTO 
THE E CARIBBEAN LATER THIS EVENING. 

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

$$
PAW