000 AXNT20 KNHC 170548 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 205 AM 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0515 UTC. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 12N16W TO 05N23W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 05N23W TO 01N32W. ISOLATED MODERATE CONVECTION IS FROM 01N-05N BETWEEN 22W-29W. ...DISCUSSION... GULF OF MEXICO... A MIDDLE TO UPPER LEVEL RIDGE IS NOTED ON WATER VAPOR IMAGERY WITH AXIS ALONG 86W THAT CONTINUES TO SUPPORT SURFACE RIDGING AND PRIMARILY EAST-SOUTHEASTERLY WINDS IN THE RANGE OF 10 TO 20 KT EAST OF 90W AND 15 TO 25 KT WEST OF 90W. AN UPPER LEVEL TROUGH AXIS EXTENDS FROM OVER SE TEXAS NEAR 29N98W TO A BASE OVER SOUTHERN MEXICO NEAR 17N95W. WHILE THIS REMAINS AN UPPER LEVEL FEATURE...THE TROUGHING IS ENHANCING CLOUDINESS OVER THE WESTERN GULF N OF 20N W OF 90W. THE SURFACE RIDGE IS EXPECTED TO PERSIST THROUGH LATE THURSDAY WHEN INTO EARLY FRIDAY THE NEXT COLD FRONT IS FORECAST TO EMERGE OFF THE TEXAS AND LOUISIANA COAST. WINDS WILL SHIFT NORTH-NORTHEASTERLY WEST OF THE FRONT AS IT MOVES EASTWARD OVER THE UPCOMING WEEKEND. CARIBBEAN SEA... AN UPPER LEVEL ANTICYCLONIC CIRCULATION IS CENTERED OVER THE SW CARIBBEAN NEAR 11N79W THAT IS PROVIDING MOSTLY WEST- NORTHWESTERLY FLOW ALOFT OVER MUCH OF THE BASIN. WATER VAPOR IMAGERY INDICATES THAT DRY AIR AND OVERALL SUBSIDENCE CONTINUES TO PROVIDE TRANQUIL CONDITIONS WITH THE EXCEPTION OF AN AREA OF WIDELY SCATTERED SHOWERS OCCURRING IN THE VICINITY OF THE LESSER ANTILLES FROM 14N-20N BETWEEN 57W-63W. OTHERWISE...TRADES PERSIST IN THE RANGE OF 10 TO 20 KT WITH THE HIGHEST WINDS ANTICIPATED S OF 15N BETWEEN 68W-78W...AND IN CLOSE PROXIMITY TO THE COAST OF COLOMBIA. THIS OVERALL SYNOPTIC PATTERN IS EXPECTED TO CONTINUE THROUGH EARLY THURSDAY AND INTO THE WEEKEND WITH TRADES GRADUALLY INCREASING E OF 80W BY EARLY FRIDAY DUE TO AN INCREASED PRESSURE GRADIENT AND HIGH PRESSURE RIDGE ANCHORED OVER THE SW NORTH ATLC REGION. ATLANTIC OCEAN... AS MIDDLE TO UPPER LEVEL RIDGING BUILDS EASTWARD FROM THE GULF OF MEXICO INTO THE SW NORTH ATLC...DRY AND SUBSIDENT NORTHWEST FLOW DOMINATES THIS EVENING HOWEVER...AN AREA OF WEAK LOW PRESSURE EXISTS ALONG 30N WITH TWO DIFFERENT 1019 MB LOW CENTERS...ONE NEAR 30N75W AND THE OTHER NEAR 30N68W. THESE LOWS ARE CONNECTED BY WAY OF A STATIONARY FRONT WITH POSSIBLE ISOLATED LOW-TOPPED SHOWERS OCCURRING N OF 30N BETWEEN 62W-78W. FARTHER EAST...LONGWAVE TROUGHING IS NOTED ON WATER VAPOR IMAGERY BETWEEN 35W-65W WITH AXIS EXTENDING FROM 37N45W TO A BASE NEAR 20N67W. THIS TROUGHING SUPPORTS A COLD FRONT ANALYZED FROM 32N36W TO 28N50W TO 29N60W AND INTO THE EASTERN-MOST 1019 MB LOW NEAR 30N68W. ISOLATED SHOWERS ARE OCCURRING WITHIN 90 NM EITHER SIDE OF THE COLD FRONT AND N OF 24N BETWEEN 50W-67W. THE REMAINDER OF THE EASTERN ATLC SOUTH AND EAST OF THE COLD FRONT IS UNDER THE INFLUENCE OF A WEAKENING AND NARROW SURFACE RIDGE ANCHORED BY A 1022 MB HIGH CENTERED NEAR 29N33W. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ HUFFMAN