000 AXNT20 KNHC 172341 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT WED APR 17 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2245 UTC. ...THE ITCZ/THE MONSOON TROUGH... THE MONSOON TROUGH PASSES THROUGH COASTAL SENEGAL NEAR 12N16W TO 6N19W 3N22W. THE ITCZ BEGINS AT 3N22W AND CONTINUES ALONG 1N30W 1S35W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 3N- 5N BETWEEN 10W-13W. ...DISCUSSION... THE GULF OF MEXICO... MOSTLY FAIR CONDITIONS ARE ACROSS MUCH OF THE GULF OF MEXICO THIS EVENING ASSOCIATED WITH DRY AIR ALOFT AROUND BROAD UPPER LEVEL RIDGING. A WEAK UPPER TROUGH IS EMBEDDED WITHIN THE LARGER SCALE UPPER RIDGE WITH AXIS ALONG 88W. SOME UPPER LEVEL MOISTURE IS STREAMING AROUND THE EAST SIDE OF THE UPPER TROUGH PROVIDING HIGH CLOUD COVER ACROSS THE EASTERN GULF. RADAR IMAGERY ONLY INDICATES A FEW AREAS OF ISOLATED SHOWERS ALONG THE SW FLORIDA COAST. AT THE SURFACE...BROAD RIDGING CONTINUES EXTENDING FROM A 1023 MB HIGH OVER EASTERN TENNESSEE. THIS PATTERN IS PROVIDING EAST TO SOUTHEAST WINDS RANGING FROM 15-20 KT. LITTLE CHANGE IS EXPECTED OVER THE NEXT 24 HOURS. THEN A COLD FRONT IS EXPECTED TO MOVE OFF THE TEXAS COAST LAST THURSDAY OR EARLY FRIDAY. THE CARIBBEAN SEA... AN UPPER LEVEL RIDGE WITH AXIS ALONG 80W COVERS THE CARIBBEAN PROVIDING DRY AIR ALOFT ACROSS THE AREA. THIS SUPPORTS MOSTLY CLEAR SKIES THROUGHOUT EXCEPT FOR A FEW ISOLATED SHOWERS/THUNDERSTORMS ACROSS THE NORTHERN ISLANDS INCLUDING CUBA...JAMAICA...HISPANIOLA...AND PUERTO RICO. MORE SCATTERED ACTIVITY IS ACROSS THE NORTHERN LEEWARD ISLANDS ASSOCIATED WITH A SMALL AREA OF LOW-LEVEL MOISTURE PRESENT IN TOTAL PRECIPITABLE WATER IMAGERY. TRADEWIND FLOW OF 15-20 KT BLOWS THROUGHOUT MUCH OF THE EASTERN AND CENTRAL CARIBBEAN REACHING 25 KT NEAR THE COAST OF COLOMBIA. LITTLE CHANGE IS EXPECTED OVER THE NEXT 24 HOURS. SHOWERS/POSSIBLE THUNDERSTORMS ARE LIKELY TO REMAIN ACROSS THE NORTHERN LEEWARD ISLANDS. THE ATLANTIC OCEAN... THE UPPER LEVEL RIDGE ALONG 80W CONTINUES UP THE EASTERN SEABOARD. AN UPPER LEVEL TROUGH TO THE EAST CONTINUES TO SUPPORT A PAIR OF WEAK 1019 MB SURFACE LOWS NEAR 29N76W AND 30N69W. A SURFACE TROUGH EXTENDS FROM THE WESTWARD LOW ALONG 29N74W 26N76W 25N80W. WIDELY ISOLATED SHOWERS ARE ALONG THE TROUGH AXIS. A DISSIPATING COLD FRONT IS EAST OF THE EASTWARD LOW ALONG 31N66W TO 30N67W. IT CONNECTS TO A DISSIPATING OCCLUDED FRONT THAT WRAPS INTO THE LOW CENTER. THE LOWS ARE EXPECTED TO DISSIPATE WITHIN THE NEXT 24 HOURS. THE UPPER TROUGH SUPPORTING THE SYSTEM CONTINUES INTO THE NE ATLC. IT ALSO SUPPORTS A FRONTAL BOUNDARY THAT SPREADS FROM NEAR NORTHERN PORTUGAL TO A WEAK FRONTAL LOW NEAR 32N39W. A COLD FRONT EXTENDS FROM THE LOW CENTER TO NEAR 27N55W WHERE IT BECOMES A DISSIPATING STATIONARY FRONT AND CONNECTS INTO THE AFOREMENTIONED OCCLUDED LOW IN THE WEST ATLC. ISOLATED SHOWERS ARE WITHIN 100 NM NORTH OF THE COLD FRONT. AN AREA OF SHOWERS AND POSSIBLE THUNDERSTORMS REMAINS NEAR THE NORTHERN LEEWARD ISLANDS FROM 15N-19N BETWEEN 55W-62W ASSOCIATED WITH AN AREA OF ENHANCED LOW-LEVEL MOISTURE PRESENT IN TOTAL PRECIPITABLE WATER IMAGERY. THE REMAINDER OF THE EAST ATLC IS COVERED BY WEAK SURFACE RIDGING. BROAD UPPER RIDGING ALONG 21W SUPPORTS THE SURFACE HIGH PRESSURE. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ WALTON