000 AXNT20 KNHC 231748 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT TUE APR 23 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1715 UTC. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 07N11W TO 01N20W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 01N20W TO THE EQUATOR NEAR 25W TO 01N33W TO THE EQUATOR NEAR 38W. SCATTERED MODERATE AND ISOLATED STRONG CONVECTION IS FROM THE EQUATOR TO 06N BETWEEN THE PRIME MERIDIAN AND 13W. SCATTERED MODERATE CONVECTION IS FROM THE EQUATOR TO 06N BETWEEN 21W-30W. ...DISCUSSION... GULF OF MEXICO... WATER VAPOR IMAGERY INDICATES GENERALLY WEST-NORTHWESTERLY MIDDLE TO UPPER LEVEL FLOW IS OVER THE GULF BASIN THIS AFTERNOON AS RIDGING ALOFT WITH AXIS ALONG 96W CONTINUES TO SLIDE EASTWARD. THIS UPPER LEVEL FEATURE SUPPORTS A SURFACE RIDGE WITH AXIS EXTENDING FROM THE MID-ATLC COAST THROUGH THE SE CONUS TO THE SW GULF NEAR 20N96W. THE RIDGE IS PROVIDING GENERALLY EAST TO SOUTHEASTERLY WINDS IN THE RANGE OF 10 TO 20 KT WITH THE HIGHER OF THESE WIND VALUES LOCATED W OF 90W WHERE LOW-LEVEL MOISTURE AND RETURN FLOW IS MAXIMIZED. THE SURFACE RIDGE WILL GRADUALLY SAG SOUTHEASTWARD FROM THE DELMARVA REGION INTO THE SW NORTH ATLC WITH A COLD FRONT FORECAST TO EMERGE OFF THE TEXAS AND LOUISIANA COAST MIDDAY WEDNESDAY. THE FRONT WILL QUICKLY BECOME DIFFUSE BY LATE THURSDAY INTO EARLY FRIDAY WITH SURFACE HIGH PRESSURE RE-ESTABLISHING ITSELF OVER THE SE CONUS AND GULF BASIN FOR THE UPCOMING WEEKEND. CARIBBEAN SEA... OVERALL DRY AND STABLE AIR IN WEST-NORTHWESTERLY FLOW ALOFT DOMINATES OVER MUCH OF THE CARIBBEAN THIS AFTERNOON KEEPING CONDITIONS ACROSS THE BASIN FAIRLY TRANQUIL. SATELLITE AND TOTAL PRECIPITABLE WATER IMAGERY INDICATE A SWATH OF LOWER LEVEL MOISTURE AND CLOUDINESS EXTENDING FROM THE WINDWARD ISLANDS WESTWARD TO 72W WITH ISOLATED LOW-TOPPED SHOWERS OCCURRING FROM 12N-15N BETWEEN 60W-72W. ANOTHER AREA OF ISOLATED SHOWERS IS OCCURRING IN THE VICINITY OF THE WINDWARD PASSAGE AND AREAS SURROUNDING THE SOUTHERN APPROACH TO THE PASSAGE BETWEEN WESTERN HISPANIOLA AND JAMAICA. THIS PRECIPITATION IS LARGELY DUE TO VERY WEAK SURFACE TROUGHING...AN EXTENSION OF A SW NORTH ATLC FRONTAL TROUGH...AND THE BASE OF A MIDDLE TO UPPER LEVEL TROUGH WITH AXIS ALONG 75W. OTHERWISE...TRADE WINDS REMAIN IN THE RANGE OF 10 TO 20 KT THIS AFTERNOON AND ARE EXPECTED TO PERSIST IN THAT RANGE THROUGH EARLY FRIDAY. ATLANTIC OCEAN... A MIDDLE TO UPPER LEVEL TROUGH IS OVER THE SW NORTH ATLC WITH AXIS ALONG 75W THAT SUPPORTS A 1008 MB LOW CENTERED OFF THE CAROLINAS NEAR 35N73W. THE ASSOCIATED COLD FRONT EXTENDS S-SW FROM THE LOW TO 29N75W WITH THE FRONT BECOMING A SURFACE TROUGH TO 25N80W. WITHIN THE WARM-SECTOR OF THIS SYSTEM...SCATTERED SHOWERS AND ISOLATED TSTMS ARE OCCURRING WITHIN 60 NM EITHER SIDE OF THE FRONT AND N OF 21N BETWEEN 65W-76W PRIMARILY TO THE EAST OF THE TROUGHING IN THE AREA OF MAXIMUM UPPER LEVEL DIFFLUENCE. THE REMAINDER OF THE SW NORTH ATLC BETWEEN 43W-65W IS UNDER THE INFLUENCE OF A MIDDLE TO UPPER LEVEL ANTICYCLONIC CIRCULATION CENTERED NEAR 26N59W THAT SUPPPORTS SURFACE RIDGING AND OVERALL FAIR CONDITIONS THIS AFTERNOON. FARTHER EAST...A BROAD MIDDLE TO UPPER LEVEL LOW IS CENTERED NEAR 34N33W THAT SUPPORTS A 1006 MB SURFACE LOW CENTERED NEAR 34N32W. THE ASSOCIATED COLD FRONT CONTINUES TO DEVELOP AS THE UPPER LEVEL TROUGH STRENGTHENS WITH MOST OF THE PRECIPITATION GENERATED BY THIS SYSTEM LOCATING WITHIN THE NE QUADRANT. SCATTERED SHOWERS AND ISOLATED TSTMS ARE OCCURRING FROM 31N-38N BETWEEN 25W-32W. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ HUFFMAN