000 AXNT20 KNHC 062352 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT SAT JUL 06 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 2315 UTC. ...SPECIAL FEATURES... TROPICAL WAVE EXTENDS FROM A 1009 MB LOW CENTERED NEAR 08N35W TO 11N41W TO 16N42W MOVING W AT 20-25 KT. WHILE MOST OF THE WAVE AXIS ITSELF REMAINS EMBEDDED WITHIN SAHARAN DUST AND DOES NOT EXHIBIT ANY CONVECTION...THE LOW CENTER LOCATED ON THE SOUTHERN EXTENT OF THE WAVE AXIS REMAINS EMBEDDED WITHIN THE ITCZ AXIS AND EXHIBITS A RELATIVELY SMALL AREAL COVERAGE CYCLONIC SPIN ON SATELLITE IMAGERY. SCATTERED MODERATE CONVECTION IS OCCURRING WITHIN VERY CLOSE PROXIMITY...120 NM...TO THE LOW CENTER. THIS SYSTEM HAS A MEDIUM CHANCE OF TROPICAL CYCLONE DEVELOPMENT WITHIN THE NEXT 48 HOURS. ...TROPICAL WAVES... TROPICAL WAVE EXTENDS FROM 14N68W TO 20N63W MOVING W-NW AT 15 KT. THE WAVE COINCIDES WITH A GLOBAL MODEL INDICATED 700 MB TROUGH PROGRESSING ACROSS PORTIONS OF THE NE CARIBBEAN AND SW NORTH ATLC WHICH IS EXPECTED TO DRIFT W-NW ON THE SOUTHERN PERIPHERY OF A SW NORTH ATLC RIDGE ANCHORED OFF THE COAST OF THE CAROLINAS. THE WAVE ALSO REMAINS ON THE HEELS OF A MIDDLE TO UPPER LEVEL LOW CENTERED NORTH OF HISPANIOLA NEAR 23N68W THAT CONTINUES TO DRAW MOISTURE AND THE A PORTION OF THE WAVE IN THAT DIRECTION. CONVECTION REMAINS LIMITED AT THIS TIME WITH ISOLATED SHOWERS AND TSTMS OCCURRING EAST OF THE LEEWARD ISLANDS FROM 15N- 22N BETWEEN 56W-63W...AND WEST OF THE WAVE FROM 14N-17N BETWEEN 66W-73W...AND IN THE VICINITY OF PUERTO RICO. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 18N16W TO 12N26W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 12N26W TO A 1009 MB LOW CENTERED NEAR 08N35W TO 05N40W TO 03N51W. SCATTERED MODERATE CONVECTION IS FROM 07N-12N BETWEEN 08W-20W. ...DISCUSSION... GULF OF MEXICO... A MIDDLE TO UPPER LEVEL TROUGH AXIS EXTENDS FROM THE MID- MISSISSIPPI RIVER VALLEY SOUTH-SOUTHWEST TO NE MEXICO. THIS TROUGHING SUPPORTS A SURFACE TROUGH ANALYZED FROM THE PANHANDLE OF FLORIDA NEAR 31N88W TO THE GULF COAST NEAR 30N92W IN SW LOUISIANA TO THE EASTERN COAST OF MEXICO NEAR TAMPICO. WHILE THE SURFACE TROUGH IS PROVIDING LOW-LEVEL MOISTURE CONVERGENCE ACROSS THE WESTERN GULF...THE PRIMARY DYNAMICS AT WORK ARE MAXIMIZED MIDDLE TO UPPER LEVEL DIFFLUENCE EAST OF THE UPPER LEVEL TROUGH AXIS GENERATING NUMEROUS SHOWERS AND SCATTERED TSTMS ACROSS A LARGE PORTION OF THE BASIN THIS EVENING WITH THE EXCEPTION OF THE FAR NW CORNER ALONG THE TEXAS COAST AND A PORTION OF THE NE GULF N OF 26N E OF 83W. THE SURFACE TROUGH IS EXPECTED TO DRIFT NW OVER THE NEXT 24 TO 48 HOURS AS SURFACE RIDGING BUILDS IN FROM THE SW NORTH ATLC THROUGH LATE MONDAY. THEREAFTER EAST-SOUTHEAST WINDS ARE FORECAST TO PREVAIL FOR MUCH OF THE UPCOMING WEEK AHEAD. CARIBBEAN SEA... WATER VAPOR IMAGERY INDICATES THE WESTERN CARIBBEAN IS UNDER THE INFLUENCE OF NORTHEASTERLY FLOW ALOFT WEST OF A LINE FROM HISPANIOLA TO NICARAGUA. THIS AREA IS LARGELY UNDER THE INFLUENCE OF UPPER LEVEL DIFFLUENCE WITH WIDELY SCATTERED SHOWERS AND ISOLATED TSTMS OCCURRING OVER THE NW CARIBBEAN N OF 18N W OF 76W...INCLUDING JAMAICA...THE CAYMAN ISLANDS...AND CUBA. FARTHER TO THE SOUTH AS THE UPPER LEVEL FLOW TRANSITIONS TO AN INVERTED TROUGH OVER THE SW CARIBBEAN...ISOLATED SHOWERS AND TSTMS ARE OCCURRING S OF 13N BETWEEN 79W-87W...INCLUDING SOUTHERN NICARAGUA...COSTA RICA...AND PANAMA. THE MIDDLE TO UPPER LEVEL LIFT GENERATING THIS CONVECTION IS PARTIALLY AIDED BY THE CLOSE PROXIMITY TO THE MONSOON TROUGH AXIS ALONG 09N/10N BETWEEN NORTHERN COLOMBIA AND WESTERN PANAMA. FINALLY...A TROPICAL WAVE EXTENDS FROM THE US/UK VIRGIN ISLANDS TO NORTH OF THE ABC ISLANDS NEAR 14N68W. SIGNFICANT DEEP CONVECTION REMAINS LIMITED AS WATER VAPOR IMAGERY INDICATES MODERATELY DRY AIR ALOFT...HOWEVER...A FEW LOW-TOPPED ISOLATED SHOWERS ARE OCCURRING OVER THE NORTH-CENTRAL CARIBBEAN...PUERTO RICO...AND US/UK VIRGIN ISLANDS THIS EVENING. THESE SHOWERS ARE EXPECTED TO CONTINUE DRIFTING WESTWARD AS E-SE TRADES PERSIST THROUGH EARLY NEXT WEEK. HISPANIOLA... CURRENTLY A FEW ISOLATED SHOWERS AND TSTMS ARE OCCURRING OVER INTERIOR PORTIONS OF THE ISLAND...BUT THIS CONVECTION IS ANTICIPATED TO DIMINISH OVER THE NEXT FEW HOURS WITH THE LOSS OF DAYTIME HEATING. LOOKING AHEAD...AN UPPER LEVEL LOW IS CENTERED NORTH OF HISPANIOLA NEAR 23N68W WHICH CONTINUES TO DRAW MOISTURE AND A TROPICAL WAVE ALONG 66W WESTWARD. WHILE MOST OF THE UPPER LEVEL DYNAMICS ASSOCIATED WITH THE LOW WILL KEEP PRECIPITATION OVER PORTIONS OF THE SW NORTH ATLC...THE TROPICAL WAVE IS EXPECTED TO PASS ACROSS THE REGION DURING THE NEXT DAY OR TWO INCREASING THE PROBABILITY OF PRECIPITATION FOR THE ISLAND. MOST CONVECTION ASSOCIATED WITH THE TROPICAL WAVE CURRENTLY REMAINS SHALLOW...HOWEVER WITH ADDED OROGRAPHIC LIFT AND PEAK INSTABILITY ACROSS INLAND LOCATIONS...WIDELY SCATTERED SHOWERS AND TSTMS ARE EXPECTED THROUGH MONDAY. ATLANTIC OCEAN... A MIDDLE TO UPPER LEVEL ANTICYCLONIC CIRCULATION IS CENTERED OFF THE COAST OF THE CAROLINA NEAR 35N70W THAT SUPPORTS A STATIONARY 1026 MB HIGH CENTERED NEAR 34N73W. OVERALL THESE SYNOPTIC FEATURES ARE PROVIDING MUCH OF THE SW NORTH ATLC WITH RELATIVELY TRANQUIL CONDITIONS THIS EVENING...HOWEVER A MIDDLE TO UPPER LEVEL LOW IS CENTERED NEAR 23N68W WITH A SURFACE TROUGH ANALYZED FROM 22N70W TO 26N69W. ASIDE FROM THE IMMEDIATE ISOLATED SHOWERS ASSOCIATED WITH THE UPPER LEVEL LOW OCCURRING FROM 21N-26N BETWEEN 64W-71W...ISOLATED SHOWERS CONTINUE TO ADVECT ACROSS THE BAHAMAS AND INLAND ACROSS PORTIONS OF THE FLORIDA PENINSULA. A TROPICAL WAVE EXTENDING NORTHEAST FROM THE NE CARIBBEAN SEA TO 20N63W IS ALSO PROVIDING PORTIONS OF THE SW NORTH ATLC WITH ISOLATED SHOWERS AND TSTMS N OF 15N BETWEEN 56W-64W. OTHERWISE...THE LAST AREA OF SIGNIFICANT WEATHER IS NOTED ACROSS THE CENTRAL ATLC AS A MID-LEVEL SHORTWAVE TROUGH PROGRESSES EASTWARD IN THE VICINITY OF 32N44W. THIS TROUGHING SUPPORTS A DISSIPATING STATIONARY FRONT ANALYZED FROM 32N40W W-SW TO 28N60W. ISOLATED SHOWERS AND TSTMS ARE OCCURRING SOUTH OF THE FRONT FROM 28N-31N BETWEEN 40W-51W. THE REMAINDER OF THE EASTERN ATLC IS UNDER THE INFLUENCE OF A SURFACE RIDGE WITH AXIS EXTENDING FROM 32N31W TO 25N37W THEN WESTWARD TO 23N53W. A LARGE PORTION OF THE EASTERN AND CENTRAL ATLC ARE ALSO INFLUENCED BY A SAHARAN AIR LAYER...SUSPENDED DUST...N OF 10N E OF 45W. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ HUFFMAN