000 AXNT20 KNHC 251141 TWDAT 16TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1045 UTC. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM THE COAST OF GUINEA-BISSAU NEAR 12N16W TO 7N20W. THE ITCZ BEGINS AT 7N20W AND CONTINUES ALONG 7N33W 2N50W 2N57W. SCATTERED MODERATE/STRONG CONVECTION IS FROM 4N-8N BETWEEN 20W-37W. ISOLATED MODERATE/STRONG CONVECTION IS FROM EQ-6N BETWEEN 42W-48W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 6N-9N BETWEEN 48W-57W. ...DISCUSSION... GULF OF MEXICO... UPPER LEVEL RIDGING SPREADS OVER THE GULF OF MEXICO TONIGHT WITH AXIS NEAR 93W SUPPORTING SURFACE RIDGING EXTENDING FROM A HIGH CEN TER 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 SCATTERED SHOWERS/THUNDERSTORMS ALONG THE EASTERN MEXICO COAST FROM 21N-26N BETWEEN 96W-100W. ISOLATED SHOWERS ARE ALSO IN THE BAY OF CAMPECHE NEAR A SURFACE TROUGH ALONG 20N93W TO 16N91W. 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 IN THE SW GULF. SURFACE RIDGING WILL DOMINATE THE AREA THROUGHOUT THE WEEKEND. CARIBBEAN SEA... CLEAR SKIES SPREAD ACROSS A LARGE AREA OF THE CARIBBEAN INCLUDING THE NW AND SE CORNERS. HOWEVER...A COUPLE AREAS OF SHOWERS/THUNDERSTORMS ARE STILL PRESENT. THE FIRST AREA IS IN THE SW CARIBBEAN WHERE SCATTERED SHOWERS/THUNDERSTORMS ARE FROM 9N-14N BETWEEN 78W-84W. THIS IS LIKELY INFLUENCED BY THE MONSOON TROUGH WHICH EXTENDS THROUGH COSTA RICA AND PANAMA TO NORTHERN COLOMBIA. 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 68W. 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... NO SHOWER ACTIVITY IS ACROSS HISPANIOLA AT THIS TIME. 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 73W SUPPORTS A COLD FRONT ALONG 32N72W 29N76W 28N80W. A SURFACE TROUGH IS TO THE EAST ALONG 32N71W TO 24N76W. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS EXTEND UP TO 230 NM EAST OF THE TROUGH AXIS TO THE NORTH OF 26N. AN UPPER LEVEL RIDGE DOMINATES THE CENTRAL ATLC ALONG 50W SUPPORTING BROAD SURFACE RIDGING ACROSS THIS AREA. AN UPPER LEVEL LOW NEAR 31N34W SUPPORTS A WEAK 1022 MB SURFACE LOW NEAR 30N38W WITH A SURFACE TROUGH EXTENDING FROM THE LOW CENTER ALONG 28N36W 22N44W. ISOLATED SHOWERS ARE POSSIBLE ALONG THE AXIS WITH AN AREA OF SCATTERED SHOWERS TO THE EAST FROM 26N-31N BETWEEN 31W-36W. 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