000 AXNT20 KNHC 081041 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 AM EDT THU AUG 08 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1022 UTC. ...TROPICAL WAVES... A TROPICAL WAVE IS NEAR THE CAPE VERDE ISLANDS WITH AXIS EXTENDING FROM 21N26W TO 07N27W MOVING W NEAR 5 KT. THE SOUTHERN PART OF THE WAVE IS EMBEDDED WITHIN THE MONSOON TROUGH WHERE TOTAL PRECIPITABLE WATER IMAGERY SHOW A MODERATE TO HIGH MOIST ENVIRONMENT AND WHERE SCATTERED MODERATE CONVECTION IS OBSERVED FROM 06N-10N BETWEEN 25W-32W. NORTH OF THE MONSOON TROUGH AXIS...SAHARAN DRY AIR SPREADS OVER THE WAVE ENVIRONMENT HINDERING CONVECTION. A TROPICAL WAVE IS OVER THE CENTRAL CARIBBEAN WITH AXIS EXTENDING FROM 21N73W TO 09N74W MOVING W NEAR 10 KT. THE WAVE IS EMBEDDED IN A LIGHT TO MODERATE MOIST ENVIRONMENT AS DEPICTED ON TOTAL PRECIPITABLE WATER IMAGERY. AN UPPER LEVEL LOW CENTERED NEAR 23N74W WHICH EXTENDS A TROUGH ACROSS THE CENTRAL-SOUTHERN CARIBBEAN SUPPORTS LOW VALUES OF DEEP LAYER ENVIRONMENTAL WIND SHEAR...THUS ENHANCING SCATTERED MODERATE CONVECTION AND TSTMS OVER NORTHERN HAITI...THE WINDWARD PASSAGE AND EASTERN CUBA. S OF 18N...THERE IS NO CONVECTION ASSOCIATED WITH THIS WAVE UNFAVORED BY DRY AIR SUBSIDENCE AND HIGH VALUES OF DEEP LAYER ENVIRONMENTAL WIND SHEAR. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH AXIS EXTENDS FROM THE WEST AFRICAN COAST NEAR 16N16W TO 10N27W 07N38W. THE INTERTROPICAL CONVERGENCE ZONE AXIS STARTS NEAR 07N38W AND CONTINUES ALONG 06N47W TO 06N56W. BESIDES THE CONVECTION ASSOCIATED WITH THE WAVE NEAR THE CAPE VERDE ISLANDS ALREADY DISCUSSED...SCATTERED MODERATE CONVECTION IS FROM 06N-16N E OF 25W. ...DISCUSSION... GULF OF MEXICO... AS OF 0900 UTC...WIND IN THE RANGE OF 5-15 KT SPREADS ACROSS THE BASIN. ANTICYCLONIC FLOW IS OVER THE NW GULF ANCHORED BY A 1013 MB HIGH CENTERED NEAR 27N92W. SURFACE TROUGHINESS IS E OF 90 W WHERE A TROUGH AXIS EXTENDS FROM 29N87W TO 19N86W IN THE W CARIBBEAN. THERE IS A MODERATE TO HIGH MOIST ENVIRONMENT AND LOW VALUES OF DEEP LAYER ENVIRONMENTAL WIND SHEAR IN THIS REGION OF THE GULF WHICH IS SUPPORTING SCATTERED RAINSHOWERS/TSTMS E OF THE AXIS AS WELL AS WITHIN 120 NM W OF THE TROUGH AXIS S OF 26N. OTHERWISE...DRY AIR SUBSIDENCE IS SUPPORTING FAIR WEATHER OVER THE WESTERN GULF. THE CENTER OF HIGH PRESSURE IS EXPECTED TO DISSIPATE LATER THIS MORNING. THE SURFACE TROUGH WILL CONTINUE TO MOVE WESTWARD PROVIDING TROUGHINESS ACROSS THE WESTERN GULF UNTIL FRIDAY NIGHT. RAINSHOWERS ASSOCIATED WITH THE TROUGH ARE EXPECTED TO CONTINUE IN THE CENTRAL GULF AND BUILD OVER THE WESTERN GULF LATER TODAY. CARIBBEAN SEA... TOTAL PRECIPITABLE WATER IMAGERY SHOW A MODERATE TO HIGH MOIST ENVIRONMENT OVER THE WESTERN CARIBBEAN WHERE UPPER LEVEL DIFFLUENCE FROM A BROAD HIGH CENTERED OVER LOUISIANA AND A LOW ACROSS THE CENTRAL-SOUTHERN CARIBBEAN IS ENHANCING ISOLATED MODERATE CONVECTION/ISOLATED TSTMS. IN THE SOUTHERN BASIN...A 1008 MB LOW CENTER OVER NORTHERN COLOMBIA IS SUPPORTING A CLUSTER OF MODERATE CONVECTION WITH EMBEDDED TSTMS THAT EXTENDS WITHIN 80 NM OFF THE COAST. A TROPICAL WAVE IS MOVING ACROSS THE CENTRAL CARIBBEAN WITH THE NORTHERN PART OF ITS AXIS CURRENTLY OVER THE WINDWARD PASSAGE WHERE UPPER LEVEL DIFFLUENCE IS ENHANCING SCATTERED MODERATE CONVECTION AND TSTMS WHICH EXTENDS TO HAITI AND EASTERN CUBA. S OF 18N...THERE IS NO CONVECTION ASSOCIATED WITH THIS WAVE UNFAVORED BY DRY AIR AND HIGH VALUES OF DEEP LAYER ENVIRONMENTAL WIND SHEAR. A SURFACE TROUGH ASSOCIATED WITH A 1009 MB LOW EXTENDS FROM 17N66W TO 11N64W. A CLUSTER OF SCATTERED MODERATE CONVECTION AND TSTMS IS FROM 11N-14N BETWEEN 65W-67W. IN ADDITION...RAINSHOWERS HAS BEEN REPORTED WITHIN THE LAST COUPLE OF HOURS BY MANY OF THE LESSER ANTILLES. BOTH THE WAVE AND THE TROUGH ARE EXPECTED TO CONTINUE MOVING WESTWARD WITHIN THE NEXT 48 HOURS GENERATING RAINSHOWERS OVER THE CENTRAL AND SOUTHERN CARIBBEAN. ANOTHER SURFACE TROUGH IS EXPECTED TO MOVE ACROSS THE LESSER ANTILLES FRIDAY NIGHT INCREASING THE CHANCES OF PRECIPITATION. HISPANIOLA... A TROPICAL WAVE IS MOVING ACROSS THE CENTRAL CARIBBEAN WITH THE NORTHERN PART OF ITS AXIS CURRENTLY OVER THE WINDWARD PASSAGE WHERE UPPER LEVEL DIFFLUENCE IS SUPPORTING SCATTERED MODERATE CONVECTION AND TSTMS THAT EXTENDS TO HAITI. RAINSHOWERS ARE EXPECTED TO CONTINUE TO AFFECT THE ISLAND THROUGH LATE THURSDAY...HOWEVER WEATHER CONDITIONS IMPROVE ON EARLY FRIDAY WHEN A DRY AIRMASS IS EXPECTED TO MOVE ACROSS THE ISLAND. ATLANTIC OCEAN... A BROAD UPPER LEVEL TROUGH N OF 30N AND THE ELONGATED LOW CENTERED OVER THE BAHAMAS SUPPORT A SURFACE TROUGH THAT AS OF 0900 UTC EXTENDS FROM 30N56W TO 29N66W 27N72W 23N75W. SCATTERED MODERATE CONVECTION AND TSTMS ARE FROM 28N-31N BETWEEN 53W-61W AS WELL AS WITHIN 50 NM EITHER SIDE OF THE TROUGH AXIS BETWEEN 67W-76W. ANOTHER SURFACE TROUGH EXTENDS FROM 13N54W TO 08N54W WITH ISOLATED MODERATE CONVECTION WITHIN 220 NM EITHER SIDE OF ITS AXIS FROM 08N-11N. OTHERWISE...BESIDES THE TROPICAL WAVE ALREADY DISCUSSED...SURFACE RIDGING AND FAIR WEATHER SUPPORTED BY LOWER-MIDDLE LEVELS DRY AIR DOMINATE THE REMAINDER BASIN. FOR ADDITIONAL INFORMATION PLEASE VISIT WWW.HURRICANES.GOV/MARINE $$ RAMOS