000 AXNT20 KNHC 041757 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT THU JUL 04 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. ...TROPICAL WAVES... TROPICAL WAVE EXTENDS FROM 14N26W TO 23N25W MOVING W-NW AT 10-15 KT. THE WAVE REMAINS EMBEDDED WITHIN A POLEWARD SURGE OF MODERATE TO DEEP MOISTURE AS SHOWN ON TOTAL PRECIPITABLE WATER IMAGERY WITH GREATEST DEFINITION OF THE WAVE AXIS NOTED ON GLOBAL MODEL DATA AT THE 700 MB LEVEL. SATELLITE WINDS ALSO CONFIRM THE PRESENCE OF THE WAVE NEAR THIS LOCATION. CONVECTION REMAINS NON-EXISTENT DUE TO SAHARAN DUST THAT COVERS MUCH OF THE TROPICAL ATLC N OF 10N E OF 40W. TROPICAL WAVE EXTENDS FROM 05N49W TO 10N46W TO 14N42W MOVING W AT 15 KT. SATELLITE PRESENTATION SHOWS THE WAVE AND ASSOCIATED SHOWER AND TSTM ACTIVITY COINCIDES WITH A BROAD MID-LEVEL 700 MB TROUGH S OF 22N BETWEEN 38W-54W. ISOLATED MODERATE CONVECTION IS WITHIN 150 NM WEST OF THE WAVE AXIS. TROPICAL WAVE EXTENDS FROM 12N71W TO 21N69W MOVING W AT 20 KT. THE WAVE REMAINS ASSOCIATED WITH A WEAK MID-LEVEL TROUGH PROGRESSING ACROSS THE CENTRAL CARIBBEAN SEA AND A SMALL PORTION OF THE SW NORTH ATLC. NO SIGNIFICANT CONVECTION IS NOTED WITH THE WAVE AT THIS TIME HOWEVER FAST-MOVING WESTWARD ISOLATED SHOWERS ARE OCCURRING N OF 15N BETWEEN 66W-73W. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 08N13W TO 09N18W TO 08N28W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 08N28W TO 08N36W TO 12N42W. SCATTERED MODERATE CONVECTION IS FROM 03N-10N BETWEEN 10W-29W. ISOLATED MODERATE CONVECTION IS FROM THE EQUATOR TO 05N BETWEEN 44W-52W. ...DISCUSSION... GULF OF MEXICO... AN RELATIVELY AMPLIFIED UPPER LEVEL PATTERN DOMINATES OVER THE CONUS THIS AFTERNOON WITH A MIDDLE TO UPPER LEVEL LOW CENTERED OVER MISSOURI THAT IS PROVIDING MUCH OF THE GULF WITH MOIST WEST- SOUTHWESTERLY FLOW ALOFT. THE TROUGHING SUPPORTS A 1013 MB LOW CENTERED NEAR 30N87W WHICH IS ALONG A SURFACE TROUGH AXIS EXTENDING FROM THE LOW CENTER W-SW TO 27N95W. MOST OF THE ACTIVE WEATHER IS LOCATED SOUTH AND EAST OF THIS BOUNDARY IN MAXIMIZED LOW-LEVEL MOISTURE CONVERGENCE AND MID-LEVEL DIFFLUENCE. NUMEROUS SHOWERS AND SCATTERED TSTMS ARE OCCURRING BETWEEN THE WESTERN COAST OF THE FLORIDA PENINSULA ALONG 81W TO 92W...ALSO INCLUDING AN AREA S OF 22N E OF 95W OFFSHORE OF THE YUCATAN PENINSULA. THE LOW IS FORECAST TO DRIFT NORTHWARD AND GRADUALLY DISSIPATE INLAND WITH THE REMNANT SURFACE TROUGHING DRIFTING WESTWARD THROUGH MONDAY. CARIBBEAN SEA... THE WESTERN CARIBBEAN SEA IS UNDER THE INFLUENCE OF AN UPPER LEVEL ANTICYCLONIC CIRCULATION CENTERED OVER SOUTHERM MEXICO NEAR 18N92W WHICH IS PROVIDING PRIMARILY NORTHERLY FLOW W OF 73W. DIFFLUENCE IS MAXIMIZED BENEATH THIS UPPER LEVEL FEATURE WITH SCATTERED SHOWERS AND TSTMS OCCURRING W OF 87W...INCLUDING INLAND PORTIONS OF THE SE YUCATAN PENINSULA...BELIZE... GUATEMALA...AND WESTERN HONDURAS. FARTHER SOUTH...THE MONSOON TROUGH IS ANALYZED ALONG 08N AND IS PROVIDING FOCUS FOR ISOLATED SHOWERS AND TSTMS WITHIN 90 NM OF A LINE FROM 09N80W TO 11N84W. EAST OF 73W...WATER VAPOR IMAGERY INDICATES DRIER AIR IS SLOWLY PROGRESSING WESTWARD FROM THE EASTERN CARIBBEAN OVER PORTIONS OF THE CENTRAL CARIBBEAN AND WESTERN VENEZUELA. FINALLY...A WEAK TROPICAL WAVE ALONG 71W IS FORECAST TO CONTINUE PROVIDING FOCUS FOR ISOLATED SHOWER ACTIVITY THE NEXT COUPLE DAYS AS IT TRACKS WEST. WATER VAPOR IMAGERY ALSO INDICATES AN UPPER LEVEL LOW IS CENTERED NEAR 24N76W DRAWING MOISTURE OVER EASTERN CUBA...THE WINDWARD PASSAGE...AND WESTERN HISPANIOLA. SCATTERED SHOWERS AND ISOLATED TSTMS ARE OCCURRING N OF 17N BETWEEN 73W-78W. HISPANIOLA... AN UPPER LEVEL LOW IS CENTERED N-NW OF THE ISLAND NEAR 24N76W AND EXTENDS AN UPPER LEVEL TROUGH AXIS S-SE TO 19N74W. EAST- SOUTHEASTERLY TRADES CONTINUE TO ADVECT LOW-LEVEL MOISTURE AND ALONG WITH MID-LEVEL LIFTING DYNAMICS...THE ATMOSPHERE IS SUPPORTING ISOLATED SHOWERS CURRENTLY. A TROPICAL WAVE ALONG 71W ALSO EXTENDS ACROSS THE ISLAND IS WILL PROVIDE FOR AFTERNOON SHOWERS AND TSTMS THROUGH THE OVERNIGHT HOURS. ATLANTIC OCEAN... AN UPPER LEVEL LOW IS NOTED ON WATER VAPOR IMAGERY CENTERED NEAR 24N76W THAT IS PROVIDING PORTIONS OF THE SW NORTH ATLC WITH SCATTERED SHOWERS AND ISOLATED TSTMS FROM 17N-25N BETWEEN 71W- 77W. THIS UPPER LEVEL FEATURE IS LOCATED ABOVE A SURFACE RIDGE ANCHORED BY A 1030 MB HIGH CENTERED NORTHWEST OF BERMUDA NEAR 34N67W. THE RIDGE IS FORECAST TO MOVE VERY LITTLE THROUGH LATE SATURDAY WITH A TROPICAL WAVE ALONG 71W TRACKING WESTWARD ON THE SOUTHERN PERIPHERY OF THE RIDGE ACROSS THE CENTRAL CARIBBEAN SEA AND GREATER ANTILLES. OTHERWISE...THE REMAINDER OF THE CENTRAL AND EASTERN ATLC IS UNDER THE INFLUENCE OF SURFACE RIDGING ANCHORED BY A 1027 MB HIGH CENTERED OVER THE AZORES NEAR 38N26W. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ HUFFMAN