000 AXNT20 KNHC 191747 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT FRI JUL 19 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 10N42W TO 21N39W MOVING W AT 15-20 KT. THE WAVE COINCIDES WITH A BROAD GLOBAL MODEL INDICATED 700 MB TROUGH AXIS ALONG 40W AND A MAXIMUM IN TOTAL PRECIPITABLE WATER IMAGERY FROM 10N-19N BETWEEN 32W-42W...PRIMARILY TO THE EAST OF THE WAVE AXIS. NO SIGNIFICANT DEEP CONVECTION IS ASSOCIATED THE WAVE AT THIS TIME DUE TO THE STABLING EFFECT OF THE SAHARAN AIR LAYER ACROSS THE EASTERN ATLC. TROPICAL WAVE EXTENDS FROM 09N75W TO 18N75W MOVING W AT 15-20 KT. THE WAVE IS ASSOCIATED WITH BROAD LOWER LEVEL TROUGHING ACROSS THE EASTERN CARIBBEAN WITH TOTAL PRECIPITABLE WATER IMAGERY INDICATING THE WAVE ENERGY CONTINUES TO STRETCH TO THE NORTH AS A SURFACE TROUGH IS ANALYZED FROM THE NORTHERN TIP OF THE WAVE AXIS NEAR 19N75W TO 24N72W. ISOLATED MODERATE CONVECTION IS FROM 19N-22N BETWEEN 75W-77W...WITH WIDELY SCATTERED SHOWERS COVERING A LARGER AREA FROM 16N-23N BETWEEN 68W-77W. THIS WAVE PRODUCED A 24 HOUR RAINFALL TOTAL OF 8.91 INCHES AT SAN JUAN PUERTO RICO FROM 18/1200 UTC TO 19/1200 UTC. TROPICAL WAVE EXTENDS FROM 07N85W TO 17N83W MOVING W AT 10-15 KT. THE WAVE CONTINUES TO PROGRESS ACROSS CENTRAL AMERICA THIS AFTERNOON BENEATH NORTHERLY AND DIFFLUENT FLOW ALOFT...WHICH IS GENERATING SCATTERED MODERATE CONVECTION FROM 10N-18N BETWEEN 83W-87W. THE WAVE IS EXPECTED TO CONTINUE ACROSS THE REMAINDER OF CENTRAL AMERICA THROUGH THIS EVENING AND EMERGE INTO THE EASTERN PACIFIC REGION THEREAFTER. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 14N17W TO 06N24W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 06N24W TO 05N31W TO 10N41W TO 06N57W. ISOLATED MODERATE CONVECTION IS FROM 04N-08N BETWEEN 44W-53W. ...DISCUSSION... GULF OF MEXICO... WATER VAPOR IMAGERY INDICATES A UPPER LEVEL LOW IS CENTERED OVER THE NORTH-CENTRAL GULF NEAR 29N91W THAT CONTINUES TO CREATE LIFT AND ADVECT MOISTURE OVER A MAJORITY OF THE BASIN...INCLUDING PORTIONS OF THE FLORIDA PENINSULA THIS AFTERNOON. MUCH OF THE PRECIPITATION AND CONVECTION IS FOCUSED ALONG A SURFACE TROUGH ANALYZED FROM THE FLORIDA PANHANDLE NEAR 30N85W TO 23N94W WITH NUMEROUS SHOWERS AND SCATTERED TSTMS OCCURRING FROM 23N-30N BETWEEN 82W-89W...AND WITHIN 120 NM EITHER SIDE OF THE SURFACE TROUGH. ISOLATED SHOWERS AND TSTMS ARE ALSO DRIFTING SOUTHWARD OFF THE EASTERN TEXAS GULF COAST FROM N OF 27N BETWEEN 92W-96W. THE SURFACE TROUGH IS EXPECTED TO DRIFT WESTWARD IN TANDEM WITH THE UPPER LEVEL LOW OVER THE NEXT FEW DAYS WITH THE SURFACE FEATURE EVENTUALLY DISSIPATING ALONG THE LOUISIANA AND TEXAS GULF COAST IN THE NW GULF SATURDAY. THEREAFTER...SURFACE RIDGING ANCHORED IN THE SW NORTH ATLC WILL EXTEND WESTWARD AND ONCE AGAIN RE-ESTABLISH SE TO S WINDS ACROSS THE BASIN OVER THE REMAINDER OF THE WEEKEND. CARIBBEAN SEA... A WEAK UPPER LEVEL LOW IS CENTERED OVER THE SOUTHERN CARIBBEAN NEAR 11N72W WITH CYCLONIC FLOW ALOFT INFLUENCE STRETCHING TO 20N BETWEEN 61W-75W. WATER VAPOR IMAGERY INDICATES THIS UPPER LEVEL FEATURE REMAINS MODERATELY DRY WITH CONDITIONS AT THE SURFACE CONTINUING TO EXPERIENCE FAIR SKIES AND AN OVERALL LACK OF ANY SIGNIFICANT DEEP CONVECTION. A FEW ISOLATED SHOWERS ARE NOTED N OF 17N BETWEEN 71W-75W...IMPACTING HISPANIOLA AND THE ADJACENT COASTAL WATERS. OTHERWISE...THE MAIN FEATURES ARE TWO TROPICAL WAVE PROGRESSING WESTWARD OVER THE WESTERN CARIBBEAN. ONE WAVE IS ALONG 76W WITH A PORTION OF ITS ENERGY FRACTURING NORTHWARD AS A SURFACE TROUGH ANALYZED FROM THE WINDWARD PASSAGE N-NE TO 24N72W. WIDELY SCATTERED SHOWERS AND ISOLATED TSTMS ARE OCCURRING N OF 19N BETWEEN 74W-77W. THE OTHER TROPICAL WAVE IS ALONG 84W AND IS LARGELY INLAND ACROSS NICARAGUA AND COSTA RICA. A SMALL PORTION EXTENDS INTO THE NW CARIBBEAN NEAR 17N83W. SCATTERED SHOWERSE AND TSTMS ARE OCCURRING OVER THE NW CARIBBEAN NORTH OF THE HONDURAS COAST FROM 15N-18N BETWEEN 82W-86W. STRONGER CONVECTION...SCATTERED SHOWERS AND TSTMS ARE OCCURRING S OF 13N BETWEEN 78W-86W IN THE VICINITY OF THE TROPICAL WAVE AND MORE LIKELY ASSOCIATED WITH THE MONSOON TROUGH AXIS EXTENDING ALONG 09N BETWEEN NORTHERN COLOMBIA AND SOUTHERN COSTA RICA. HISPANIOLA... REMNANT MOISTURE LEFT FROM THE PASSAGE OF A TROPICAL WAVE YESTERDAY AND OVERNIGHT CONTINUES TO PRODUCE ISOLATED SHOWERS AND TSTMS THIS AFTERNOON ACROSS THE ISLAND AND ADJACENT COASTAL WATERS FROM 17N-22N BETWEEN 69W-75W. WITH SE WINDS DOMINATING AND OVERALL CLEARING SKIES TO THE EAST...CONDITIONS SHOULD IMPROVE OVER THE NEXT 24 HOURS WITH A SLIGHT CHANCE FOR AFTERNOON ISOLATED SHOWERS DUE TO PEAK DAYTIME HEATING AND INSTABILITY. OTHERWISE...THE WEEKEND SHOULD REMAIN FAIRLY TRANQUIL DUE TO SURFACE RIDGING BUILDING OVER THE REGION THROUGH MONDAY. THE NEXT TROPICAL WAVE...CURRENTLY ANALYZED OVER THE CENTRAL ATLC...IS FORECAST TO IMPACT HISPANIOLA LATE MONDAY INTO TUESDAY. ATLANTIC OCEAN... A BROAD UPPER LEVEL LOW IS CENTERED OVER THE NORTH-CENTRAL GULF OF MEXICO NEAR 29N91W THAT SUPPORTS A SURFACE TROUGH ANALYZED ACROSS THE GULF OF MEXICO. MOISTURE ADVECTING FROM THE GULF OF MEXICO OVER THE FLORIDA PENINSULA AND INTO THE SW NORTH ATLC IS PROVIDING FOR SCATTERED SHOWERS AND TSTMS N OF 22N W OF 74W AND CONTINUES TO BE ENHANCED BY MARGINAL MIDDLE TO UPPER LEVEL DIFFLUENCE. THE APPROACH OF A SURFACE TROUGH...FRACTURED ENERGY FROM A TROPICAL WAVE ACROSS THE CENTRAL CARIBBEAN SEA...IS ALSO BEGINNING TO IMPACT THIS AREA AND WILL LIKELY SUSTAIN GENERATION OF CONVECTION OVER THE NEXT 24 TO 36 HOURS ACROSS THE BAHAMAS AND PORTIONS OF THE FLORIDA PENINSULA...INCLUDING ADJACENT COASTAL WATERS. OTHERWISE...THE REMAINDER OF THE CENTRAL AND EASTERN ATLC IS UNDER THE INFLUENCE OF A SURFACE RIDGE ANCHORED BY A 1025 MB HIGH CENTERED NEAR 28N58W AND A 1023 MB HIGH CENTERED NEAR 30N29W. SATELLITE IMAGERY INDICATES THE SAHARAN AIR LAYER CONTINUES TO IMPACT MUCH OF THE EASTERN AND CENTRAL ATLC GENERALLY N OF 12N E OF 60W. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ HUFFMAN