000
AXNT20 KNHC 182343
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL  
805 PM EDT SAT JUN 18 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
2815 UTC.

...TROPICAL WAVES...

E TROPICAL ATLC TROPICAL WAVE IS ALONG 26W/27W S OF 11N MOVING W 
15-20 KT. WAVE IS EMBEDDED WITHIN AN AREA OF DEEP LAYER MOISTURE 
AS INDICATED BY THE TOTAL PRECIPITABLE WATER IMAGERY AND IS 
ALONG THE EASTERN EXTENT OF THE ITCZ. NO ASSOCIATED DEEP 
CONVECTION. 

TROPICAL WAVE IS E OF THE LESSER ANTILLES ALONG 55W/56W S OF 17N 
MOVING NW 15-20 KT. WAVE IS PRECEDING A DEEP LAYER MOISTURE 
SURGE AS INDICATED BY THE TOTAL PRECIPITABLE WATER IMAGERY. 
SCATTERED MODERATE/STRONG CONVECTION IS W OF THE WAVE FROM 
10N-14N BETWEEN THE WAVE AXIS AND 63W INCLUDING THE LESSER 
ANTILLES S OF SAINT LUCIA. 

TROPICAL WAVE IS ALONG 88W/89W S OF 23N MOVING NW 15-20 KT. WAVE 
HAS MOVED INLAND OVER THE YUCATAN PENINSULA AND CENTRAL AMERICA. 
WAVE IS ALONG THE WESTERN EDGE OF AN UPPER HIGH WHICH IS 
RESPONSIBLE FOR THE ACTIVITY JUST E OF THE WAVE AXIS AND 
SCATTERED MODERATE CONVECTION ASSOCIATED WITH THIS WAVE IS 
INLAND OVER THE YUCATAN AND BELIZE. 

...THE ITCZ/THE MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS ACROSS AFRICA INTO THE E ATLC NEAR 
13N16W TO 9N23W WHERE THE ITCZ CONTINUES ALONG 7N37W TO INLAND 
OVER SOUTH AMERICA NEAR 4N52W. SCATTERED/NUMEROUS STRONG 
CONVECTION IS INLAND OVER W AFRICA MOVING INTO THE E TROPICAL 
ATLC WITHIN 90/120 NM ALONG THE COAST OF GUINEA AND SIERRA LEONE 
BETWEEN 8N-11N. SMALL CLUSTERS OF SCATTERED MODERATE CONVECTION 
ARE WITHIN 225 NM S OF THE ITCZ BETWEEN 30W-37W. CLUSTERS OF 
SCATTERED MODERATE/ISOLATED STRONG CONVECTION WITHIN 90/120 NM 
OF LINE FROM 5N38W TO TO 9N53W. 

...DISCUSSION...

GULF OF MEXICO...
A SURFACE RIDGE EXTENDS FROM THE W ATLC ACROSS FLORIDA OVER THE 
GULF N OF 25N TO 94W WITH A TROPICAL WAVE OVER THE YUCATAN 
PENINSULA. A BROAD UPPER RIDGE DOMINATES MUCH OF THE GULF 
ANCHORED ALONG THE W COAST OF MEXICO IN THE E PACIFIC REGION 
COVERING ALL OF MEXICO...THE CENTRAL PLAIN STATES AND THE GULF 
OF MEXICO TO 87W WITH DRY STABLE AIR COVERING THE GULF NW OF A 
LINE FROM FORT MYERS FLORIDA TO THE NW TIP OF THE YUCATAN 
PENINSULA. A SHORTWAVE UPPER TROUGH IS MOVING ACROSS THE NE 
GULF EXTENDING AN AXIS OVER TALLAHASSEE TO NEAR 25N86W. AN UPPER 
HIGH IN THE NW CARIBBEAN IS DRAWING DENSE CLOUD COVER WITH 
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS OVER THE SE GULF S OF 
25N E OF 87W THROUGH THE STRAITS OF FLORIDA INCLUDING THE 
FLORIDA KEYS. A WEAK OUTFLOW BOUNDARY IS OBSERVED ON SATELLITE 
IMAGERY IN THE E BAY OF CAMPECHE PRODUCING ISOLATED SHOWERS S OF 
22N E OF 93W TO OVER THE YUCATAN PENINSULA LEAVING THE REMAINDER 
OF THE GULF UNDER CLEAR SKIES THIS EVENING. TROPICAL WAVE WILL 
MOVE INTO THE SW GULF LATE TONIGHT/EARLY SUN REACHING THE COASTS 
OF MEXICO/TEXAS ON MON. SURFACE RIDGE WILL REMAIN ACROSS THE N 
GULF THROUGH MON THEN LIFT N OF THE AREA TUE.

CARIBBEAN SEA...
ONE TROPICAL WAVE IS EXITING THE CARIBBEAN THIS EVENING AS 
ANOTHER APPROACHES THE LESSER ANTILLES. AN UPPER HIGH IS OVER 
THE W CARIBBEAN NEAR 13N82W PROVIDING A DIFFLUENT ENVIRONMENT TO 
GENERATE SCATTERED SHOWERS/ISOLATED THUNDERSTORMS OVER A BROAD 
AREA FROM OVER THE SE GULF OF MEXICO ACROSS CUBA INTO THE 
CARIBBEAN TO PANAMA E OF 78W TO OVER CENTRAL AMERICA AND THE 
YUCATAN PENINSULA. AN UPPER RIDGE EXTENDS FROM THE W TROPICAL 
ATLC ACROSS THE LESSER ANTILLES TO 70W. A TROPICAL WAVE IS  
APPROACHING THE LESSER ANTILLES GENERATING CONVECTION OVER THE 
SE CARIBBEAN...SEE ABOVE. THE REMAINDER OF THE CARIBBEAN IS 
UNDER CLEAR SKIES THIS EVENING WITH THE EXCEPTION OF AFTERNOON 
THUNDERSTORMS THAT DEVELOPED OVER E CUBA AND HAITI. THE TROPICAL 
WAVE ALONG 55W/56W WILL MOVE INTO THE E CARIBBEAN EARLY SUN TO 
THE CENTRAL CARIBBEAN ON MON REACHING THE W CARIBBEAN TUE. 

ATLANTIC OCEAN...
AN UPPER HIGH IS ANCHORED OVER THE W ATLC NEAR 28N76W W OF 66W 
WITH A BROAD UPPER TROUGH COVERING THE REMAINDER OF THE W INTO 
THE CENTRAL ATLC N OF 26N BETWEEN 45W-66W SUPPORTING A COLD 
FRONT THAT ENTERS THE CENTRAL ATLC NEAR 32N48W EXTENDING SW TO 
27N62W THEN DISSIPATES TO 27N66W. ISOLATED SHOWERS ARE WITHIN 
60 NM OF THE FRONT. THIS FRONT SPLITS A BROAD SURFACE RIDGE 
THAT COVERS THE ATLC THEN NARROWS W OF 70W INTO THE GULF OF 
MEXICO. A 1022 MB HIGH IS NW OF THE COLD FRONT NEAR 33N57W WITH 
A 1025 MB HIGH OVER THE NE ATLC N OF THE DISCUSSION AREA JUST S 
OF THE AZORES LEAVING THE ATLC E OF 50W UNDER FAIR CONDITIONS 
THIS EVENING. SURFACE RIDGE WILL PREVAIL ACROSS THE AREA THROUGH 
THU.

F0R ADDITIONAL INFORMATION PLEASE VISIT
HTTP://WWW.HURRICANES.GOV/MARINE

$$
PAW