000 AXNT20 KNHC 050552 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 205 AM EDT FRI JUL 05 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 0445 UTC. ...TROPICAL WAVES... TROPICAL WAVE IS ALONG 23N28W TO 14N28W MOVING WEST AT 5-10 KT. THE WAVE IS EMBEDDED WITHIN AN AREA OF INCREASED MOISTURE PRESENT IN TOTAL PRECIPITABLE WATER IMAGERY. A LARGE SAHARAN AIR LAYER SURROUNDS A GOOD PORTION OF THE WAVE...WHICH IS INHIBITING ANY DEEP CONVECTION NEAR THE AXIS. TROPICAL WAVE IS ALONG 18N43W TO 7N55W MOVING WEST NEAR 15 KT. THE WAVE COINCIDES WITH A LARGE SURGE OF DEEP LAYER MOISTURE PRESENT IN TOTAL PRECIPITABLE WATER IMAGERY. AN ASCAT SCATTEROMETER PASS INDICATES THAT LOW LEVEL CYCLONIC FLOW IS AROUND THE WAVE AXIS. SCATTERED MODERATE CONVECTION IS FROM 12N- 14N BETWEEN 48W-51W. TROPICAL WAVE IS ALONG 21N74W TO 10N75W MOVING WEST THROUGH THE CENTRAL CARIBBEAN AT 15-20 KT. ONLY A WEAK MOISTURE SIGNAL IS EVIDENT NEAR THE WAVE WITH MUCH HIGHER MOISTURE CONTENT FARTHER WEST OVER THE WESTERN CARIBBEAN. DRY AIR IS OVER THE AREA ALOFT EXCEPT NEAR THE NORTHERN PORTION OF THE WAVE WHERE DIFFLUENT FLOW IS PRESENT AROUND A NARROW UPPER TROUGH NEAR 77W. ISOLATED MODERATE CONVECTION IS NEAR THE NORTHERN PORTION OF THE WAVE FROM 18N-22N BETWEEN 73W-76W. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM THE COAST OF GUINEA-BISSAU NEAR 12N16W TO 8N19W 8N30W. THE ITCZ BEGINS NEAR 8N30W AND CONTINUES ALONG 8N38W 11N45W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 7N-10N BETWEEN 21W-26W. ...DISCUSSION... GULF OF MEXICO... MOIST CONDITIONS REMAIN ACROSS MUCH OF THE GULF OF MEXICO. THIS IS DUE TO A COMBINATION OF MOIST SOUTHERLY FLOW AT THE SURFACE THROUGHOUT MUCH OF THE AREA...AND MOIST SOUTHWESTERLY AND DIFFLUENT FLOW ALOFT BETWEEN AN UPPER LEVEL TROUGH OVER THE CENTRAL CONUS...AND AN UPPER LEVEL RIDGE OVER THE BASIN EXTENDING FROM THE BAY OF CAMPECHE NEAR 21N91W TO 31N82W. ISOLATED SHOWERS AND POSSIBLE THUNDERSTORMS ARE MAINLY EAST OF 91W. A WEAK SURFACE TROUGH IS ALSO IN THE BAY OF CAMPECHE FROM 26N92W TO 19N93W. POSSIBLE ISOLATED SHOWERS ARE WITHIN 120 NM TO EITHER SIDE OF THE AXIS. A SECOND SURFACE TROUGH ALONG THE NW GULF COAST APPEARS TO HAVE DISSIPATED AS OF 0300 UTC. BROAD SURFACE TROUGHING WILL REMAIN OVER THE WESTERN GULF WITH MOISTURE CONTINUING TO FLOW OVER MUCH OF THE BASIN FOR THE NEXT DAY OR SO. CARIBBEAN SEA... MODERATE MOISTURE IS THROUGHOUT THE WESTERN CARIBBEAN INDICATED BY TOTAL PRECIPITABLE WATER IMAGERY. SOME OF THIS IS MOISTURE ALOFT THAT IS STREAMING OVER THE AREA IN NORTHERLY FLOW AROUND AN UPPER LEVEL RIDGE OVER THE EASTERN GULF OF MEXICO. A NARROW UPPER TROUGH IS TO THE EAST ALONG 78W...WHICH IS PROVIDING DIFFLUENT FLOW ALOFT OVER THE NE CARIBBEAN. ISOLATED SHOWERS ARE CURRENTLY OVER CUBA WITH A FEW CLUSTERS OF THUNDERSTORMS TO THE SOUTH FROM 18N-21N BETWEEN 79W-81W. A TROPICAL WAVE TO THE EAST ALONG 75W IS ALSO PROVIDING SOME MOISTURE TO THE AREA. A FEW SHOWERS AND THUNDERSTORMS ARE NEAR THE NORTHERN PORTION OF THE WAVE OVER EASTERN CUBA AND WESTERN HAITI. DRY AIR ALOFT AROUND AN INVERTED UPPER TROUGH ALONG 72W IS LIMITING CONVECTION NEAR THE REMAINDER OF THE WAVE. DRY AIR ALOFT ALSO COVERS THE EASTERN CARIBBEAN WHERE VERY CLEAR SKIES ARE NOTED. SEVERAL STATIONS IN THE LESSER ANTILLES ARE REPORTING DUST. TRADEWIND FLOW OF 15-20 KT IS THROUGHOUT MUCH OF THE AREA WITH A SMALL AREA OF 25 KT WINDS NEAR THE COAST OF COLOMBIA IN THE CENTRAL CARIBBEAN. THE TROPICAL WAVE IS EXPECTED TO CONTINUE MOVING WEST WHERE MOIST CONDITIONS WILL REMAIN FOR AT LEAST THE NEXT 24 HOURS. HISPANIOLA... A TROPICAL WAKE CONTINUES TO IMPACT WESTERN HAITI. THE AXIS IS JUST WEST OF THE ISLAND...BUT A FEW SHOWERS/POSSIBLE THUNDERSTORMS REMAIN OVER THE SW CORNER. DRIER AIR IS BEGINNING TO MOVE OVER THE AREA AS THE WAVE TRACKS WEST...WHICH WILL KEEP CONVECTION TO A MINIMUM EXCEPT DURING PEAK DAYTIME HEATING WHERE AFTERNOON ACTIVITY WILL STILL LIKELY OCCUR. A DRIER AIRMASS WILL CONTINUE TO IMPACT THE ISLAND UNTIL THE NEXT TROPICAL WAVE APPROACHES EARLY NEXT WEEK. ATLANTIC OCEAN... BROAD SURFACE RIDGING DOMINATES THE WEST ATLC AROUND A 1027 MB HIGH NEAR 34N67W. THE RIDGE IS SUPPORTED BY BROAD UPPER RIDGING CENTERED NEAR 36N69W. HOWEVER...A NARROW UPPER TROUGH ALONG 79W IS SUPPORTING ISOLATED SHOWERS/THUNDERSTORMS OFF THE COAST OF FLORIDA WEST OF 77W. AN UPPER LEVEL LOW IS CENTERED NEAR 22N58W SUPPORTING A FEW POSSIBLE SHOWERS FROM 24N-29N BETWEEN 57W-62W. A DISSIPATING COLD FRONT ALSO EXTENDS INTO THE AREA ALONG 30N50W TO 27N59W. NO SHOWERS ARE ASSOCIATED WITH THE BOUNDARY. THE REMAINDER OF THE BASIN IS DOMINATED BY SURFACE RIDGING AROUND A 1026 MB AZORES HIGH NEAR 41N23W. BROAD UPPER RIDGING COVERS THE TROPICAL ATLC CENTERED NEAR 16N24W. AN UPPER LOW IS TO THE NORTH NEAR 34N19W...BUT IS NOT CAUSING ANY ACTIVE WEATHER IN THE AREA. VERY DRY AIR IS THROUGHOUT THIS AREA DUE TO THE PRESENCE OF A BROAD SAHARAN AIR LAYER. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ WALTON