538 
AXNT20 KNHC 250542
TWDAT 

TROPICAL WEATHER DISCUSSION 
NWS NATIONAL HURRICANE CENTER MIAMI FL 
205 AM EDT SAT MAY 25 2013

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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0515 UTC.

...ITCZ/MONSOON TROUGH...                                     
THE MONSOON TROUGH EXTENDS FROM THE COAST OF GUINEA NEAR 10N14W 
TO 8N19W. THE ITCZ BEGINS AT 8N19W AND CONTINUES ALONG 6N35W 
6N48W. SCATTERED MODERATE/STRONG CONVECTION IS FROM 5N-6N 
BETWEEN 19W-23W...AND FROM 3N-7N BETWEEN 25W-36W. SCATTERED 
MODERATE/ISOLATED STRONG CONVECTION IS FROM 4N-7N BETWEEN 43W-
45W...EQ-2N BETWEEN 41W-46W...AND FROM 3N-6N BETWEEN 48W-52W.  

...DISCUSSION...

GULF OF MEXICO...                                                
UPPER LEVEL RIDGING SPREADS OVER THE GULF OF MEXICO TONIGHT WITH 
AXIS NEAR 94W SUPPORTING SURFACE RIDGING EXTENDING FROM A HIGH 
CENTER OVER THE GREAT LAKES REGION. DRY AIR ALOFT COVERS A GOOD 
PORTION OF THE BASIN PROVIDING FAIR CONDITIONS AND CLEAR SKIES. 
DIFFLUENT FLOW ALOFT AROUND THE WEST SIDE OF THE UPPER RIDGE 
CONTINUES TO PRODUCE A LARGE AREA OF SHOWERS/THUNDERSTORMS OVER 
NE MEXICO NEAR A SQUALL LINE FROM 26N98W TO 24N101W...AS OF 0300 
UTC. LIGHT NE WINDS OF 5-10 KT SPREAD ACROSS THE EASTERN GULF 
BECOMING EASTERLY ACROSS THE CENTRAL AND WESTERN PORTIONS AND 
REACHING 15 KT. A FEW 20 KT WINDS ARE POSSIBLE ALONG THE WEST 
COAST OF THE YUCATAN PENINSULA. A FEW SHOWERS/THUNDERSTORMS ARE 
STILL ACROSS SOUTHERN MEXICO AS WELL FROM 17N-19N BETWEEN 91W-
95W. SURFACE RIDGING WILL DOMINATE THE AREA THROUGHOUT THE 
WEEKEND. 

CARIBBEAN SEA...                                             
MUCH OF THE LATER AFTERNOON CONVECTION HAS DIED DOWN NOW. 
HOWEVER...SEVERAL AREAS OF SHOWERS/THUNDERSTORMS ARE STILL 
PRESENT. THE FIRST AREA IS OFF THE COAST OF NICARAGUA WHERE 
SCATTERED SHOWERS/THUNDERSTORMS ARE FROM 11N-15N BETWEEN 78W-
83W. THIS AREA LIES NEAR THE BASE OF A BROAD UPPER LEVEL TROUGH 
ACROSS THE AREA. IT ALSO COINCIDES WITH AN AREA OF MAXIMUM 
MOISTURE IN TOTAL PRECIPITABLE WATER IMAGERY. SCATTERED 
SHOWERS/ISOLATED THUNDERSTORMS ARE ALSO OVER THE NE CARIBBEAN 
FROM 16N-19N EAST OF 66W. THIS ACTIVITY IS ALSO WITHIN AN AREA 
OF ENHANCED MOISTURE EVIDENT IN TOTAL PRECIPITABLE WATER 
IMAGERY. THE REMAINDER OF THE AREA HAS MOSTLY CLEAR SKIES WITH 
ONLY A FEW LOW-LEVEL ISOLATED SHOWERS MOVING WITHIN TRADEWIND 
FLOW OF 15-20 KT. LITTLE CHANGE IS EXPECTED ACROSS THE BASIN. 
MOISTURE IS EXPECTED TO REMAIN OVER THE SW CARIBBEAN AS WELL AS 
THE NE CORNER. A SURFACE TROUGH/FRONTAL BOUNDARY IN THE WEST 
ATLC WILL MOVE EASTWARD JUST NORTH OF THE BASIN AND MAY 
INFLUENCE SHOWERS/THUNDERSTORMS ACROSS THE NORTHERN ISLANDS. 

HISPANIOLA...                                                 
DEEP CONVECTION FROM AFTERNOON HEATING AND INSTABILITY HAS NOW 
DIED DOWN WITH ONLY POSSIBLE LOW-LEVEL ISOLATED SHOWERS 
REMAINING. WATER VAPOR IMAGERY INDICATES MODERATE MOISTURE 
ALOFT...AND TOTAL PRECIPITABLE WATER IMAGERY INDICATES A SIMILAR 
SCENARIO WITH HIGHER MOISTURE JUST TO THE EAST. MODEL GUIDANCE 
INDICATES THAT THIS AREA OF HIGHER MOISTURE TO THE EAST WILL 
DRIFT WEST TOWARDS THE ISLAND...WHICH COINCIDES WITH SURFACE 
TROUGHING TO THE NORTH. THIS COMBINATION MAY LEAD TO A GREATER 
CHANCE OF SHOWERS/THUNDERSTORMS BY THE END OF THE WEEKEND. 

ATLANTIC OCEAN...                                                
AN UPPER LEVEL TROUGH ALONG 75W SUPPORTS A FRONTAL BOUNDARY JUST 
NORTH OF THE DISCUSSION AREA ALONG WITH A SURFACE TROUGH TO THE 
EAST ALONG 32N72W TO 85N79W. SCATTERED SHOWERS/ISOLATED 
THUNDERSTORMS EXTEND UP TO 230 NM EAST...75 NM WEST OF THE AXIS 
TO THE NORTH OF 29N. AN UPPER LEVEL RIDGE DOMINATES THE CENTRAL 
ATLC ALONG 50W SUPPORTING BROAD SURFACE RIDGING ACROSS THIS 
AREA. AN UPPER LEVEL LOW NEAR 31N35W SUPPORTS A DISSIPATING 
STATIONARY FRONT THAT ENTERS THE AREA NEAR 31N37W AND CONTINUES 
ALONG 28N35W 22N45W. ISOLATED SHOWERS ARE POSSIBLE ALONG THE 
AXIS WITH AN AREA OF SCATTERED SHOWERS TO THE EAST FROM 28N-32N 
BETWEEN 29W-34W. THE REMAINDER OF THE BASIN IS ALSO INFLUENCED 
BY SURFACE RIDGING SUPPORTED BY BROAD UPPER RIDGING ACROSS WEST 
AFRICA. BROAD UPPER RIDGING ALSO COVERS THE TROPICAL ATLC. 

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

$$
WALTON