000 AXNT20 KNHC 211047 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 AM EDT WED AUG 21 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 1015 UTC. ...TROPICAL WAVES... TROPICAL WAVE EXTENDS FROM A 1010 MB LOW CENTERED NEAR 11N34W TO 15N35W TO 19N33W MOVING W AT 10-15 KT. THE LOW CENTER REMAINS THE FOCAL POINT FOR A BROAD AND ENLONGATED MONSOONAL GYRE CIRCULATION INFLUENCING THE TROPICAL ATLC FROM 08N-17N BETWEEN 27W-47W. NO SIGNIFICANT DEEP CONVECTION IS OCCURRING IN THE VICINITY OF THE WAVE HOWEVER SCATTERED MODERATE CONVECTION IS FROM 07N-10N BETWEEN 32W-40W IN ASSOCIATION WITH THE MONSOON TROUGH AXIS. TROPICAL WAVE EXTENDS FROM 10N73W TO 20N72W MOVING W AT 10 KT. THE WAVE REMAINS WITHIN BROAD LOW-LEVEL...700 MB...TROUGHING LOCATED ACROSS THE CENTRAL CARIBBEAN SEA WITH TOTAL PRECIPITABLE WATER IMAGERY INDICATING A LOCAL MAXIMUM FROM 11N-21N BETWEEN 66W-72W. SCATTERED MODERATE CONVECTION IS OCCURRING NEAR THE SOUTHERN EXTENT OF THE WAVE AXIS FROM 07N-11N BETWEEN 71W-76W AND IS LIKELY ENHANCED DUE TO THE CLOSE PROXIMITY OF THE MONSOON TROUGH AXIS EXTENDING ALONG 10N ACROSS NORTHERN COLOMBIA. TROPICAL WAVE EXTENDS FROM 18N93W TO 27N92W MOVING W AT 10 KT. THE WAVE IS BECOMING MORE AND MORE DIFFICULT TO DISCERN ON SATELLITE IMAGERY AND CONTINUES WEAKENING THIS MORNING. ANY REMAINING TROUGHING IS EXPECTED TO DRIFT WESTWARD AND DISSIPATE OVER THE NEXT 12 TO 24 HOURS ACROSS THE WESTERN GULF OF MEXICO. NO SIGNIFICANT DEEP CONVECTION IS ASSOCIATED WITH THE WAVE AT THIS TIME. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM 18N22W TO 11N34W TO 07N48W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 07N48W TO 07N58W. ISOLATED MODERATE CONVECTION IS FROM 08N-11N BETWEEN 14W- 18W...AND FROM 11N-13N BETWEEN 22W-27W. SCATTERED MODERATE CONVECTION IS FROM 07N-10N BETWEEN 32W-40W. ...DISCUSSION... GULF OF MEXICO... AN UPPER LEVEL LOW IS CENTERED OVER NORTHERN MEXICO NEAR 25N102W AND IS PROVIDING ADVECTION OF MOISTURE ACROSS CENTRAL MEXICO INTO THE WESTERN GULF. WHILE NO SURFACE FORCING FEATURE IS PRESENT...AMPLE MIDDLE TO UPPER LEVEL DYNAMICS ARE IN PLACE TO GENERATE ISOLATED SHOWERS AND TSTMS S OF 28N W OF 95W THIS MORNING. TO THE EAST...A TROPICAL WAVE WHICH IS BECOMING DIFFUSE IS ALONG 93W AND EXTENDS WEAK SURFACE TROUGHING FROM THE LOUISIANA COAST ALONG THE WAVE AXIS TO SOUTHERN MEXICO. THIS RELATIVELY NARROW AREA OF CYCLONIC TURNING IN THE LOWER LEVELS OF THE ATMOSPHERE IS GENERATING ISOLATED SHOWERS AND TSTMS FROM 22N-29N BETWEEN 88W-93W. FINALLY...OVER THE EASTERN GULF... NORTHERLY UPPER LEVEL FLOW DOMINATES ON THE WESTERN PERIPHERY OF AN UPPER LEVEL LOW CENTERED OVER THE NW CARIBBEAN SEA NEAR 20N84W THAT EXTENDS A TROUGH AXIS NORTHWARD OVER THE SOUTHERN FLORIDA PENINSULA TO 27N83W. OVERALL UPPER LEVEL CYCLONIC TURNING...A MID-LEVEL VORTICITY MAXIMUM IN THE VICINITY OF 26N85W...AND LACK OF ANY STRONG PRESSURE GRADIENT AT THE SURFACE IS GENERATING WIDELY SCATTERED SHOWERS AND ISOLATED TSTMS THIS MORNING E OF 88W...INCLUDING THE FLORIDA STRAITS. LOOKING AHEAD...GENERALLY EAST-SOUTHEAST WINDS ARE EXPECTED TO PREVAIL THROUGH THE REMAINDER OF THE WEEK AS A SURFACE RIDGE CONTINUES TO ANCHOR ITSELF IN THE SW NORTH ATLC WATERS NEAR 32N72W. CARIBBEAN SEA... AN UPPER LEVEL LOW IS CENTERED OVER THE NW CARIBBEAN NEAR 20N84W THAT CONTINUES TO GENERATE ISOLATED SHOWERS AND TSTMS N OF 19N BETWEEN 78W-86W...INCLUDING THE CAYMAN ISLANDS AND CUBA THIS MORNING. OTHERWISE...TO THE SOUTHEAST OF THE UPPER LEVEL LOW...SOUTH-SOUTHWESTERLY FLOW ALOFT DOMINATES ACROSS THE SW CARIBBEAN. LOW-LEVEL MOISTURE CONVERGENCE ALONG WITH THE DIFFLUENT ENVIRONMENT PRESENT OVER THE REGION IS GENERATING SCATTERED SHOWERS AND WIDELY SCATTERED TSTMS S OF 16N BETWEEN 78W-89W. CONVECTION STRETCHES SOUTH OF THIS AREA ACROSS PORTIONS OF PANAMA AND COSTA RICA AS THE MONSOON TROUGH AXIS EXTENDS ALONG 10N FROM NORTHERN COLOMBIA INTO THE EAST PACIFIC REGION. ACROSS THE CENTRAL CARIBBEAN...A TROPICAL WAVE IS ALONG 73W AND REMAINS EMBEDDED WITHIN BROAD LOW-LEVEL TROUGHING. WITH DEEP TROPICAL MOISTURE NOTED ON TOTAL PRECIPITABLE WATER IMAGERY... ISOLATED SHOWERS AND TSTMS ARE OCCURRING S OF 20N BETWEEN 68W- 75W. THE WAVE IS EXPECTED TO CONTINUE MOVING WESTWARD AND INCREASE PRECIPITATION CHANCES FOR THE WESTERN CARIBBEAN OVER THE NEXT 24 TO 48 HOURS. FINALLY...A WEAK SURFACE TROUGH ANALYZED FROM 12N58W TO 16N59W CONTINUES TO PROVIDE ISOLATED SHOWERS AND TSTMS FOR THE LESSER ANTILLES AND ADJACENT COASTAL WATERS S OF 18N BETWEEN 57W-65W. THIS AREA OF CONVECTION IS LIKELY ENHANCED DUE TO MARGINAL MIDDLE TO UPPER LEVEL DIFFLUENCE LOCATED OVER THE TROPICAL ATLC AND EASTERN CARIBBEAN. HISPANIOLA... EARLIER LATE EVENING AND OVERNIGHT CONVECTION CONTINUES TO DIMINISH WITH ONLY A FEW REMAINING ISOLATED SHOWERS OCCURRING ACROSS THE ISLAND THIS MORNING. WESTERLY FLOW ALOFT REMAINS OVER THE ISLAND ON THE NORTHERN PERIPHERY OF AN UPPER LEVEL ANTICYCLONIC CIRCULATION CENTERED OVER THE CENTRAL CARIBBEAN. WITH MARGINAL MIDDLE TO UPPER LEVEL LIFT PRESENT AND A TROPICAL WAVE ALONG 73W...ISOLATED SHOWERS AND TSTMS ARE EXPECTED OVER THE NEXT 24 HOURS WITH STRONGER SCATTERED CONVECTION EXPECTED TO INITIATE DURING THE AFTERNOON HOURS DUE TO PEAK DAYTIME HEATING AND INSTABILITY. ANY ACTIVITY THAT FORMS WILL LIKELY LAST INTO THE EVENING HOURS AND DIMINISH THEREAFTER. ATLANTIC OCEAN... A WEAK UPPER LEVEL LOW IS CENTERED OVER THE SOUTHERN FLORIDA PENINSULA NEAR 26N82W THAT CONTINUES TO PRODUCE ENHANCEMENT FOR WIDELY SCATTERED SHOWERS AND ISOLATED TSTMS OCCURRING S OF 29N W OF 72W ACROSS PORTIONS OF THE SW NORTH ATLC. THIS ACTIVITY REMAINS ON THE SOUTHWESTERN PERIPHERY OF A SURFACE RIDGE ANCHORED BY A 1021 MB HIGH CENTERED WEST OF BERMUDA NEAR 32N69W. THE SURFACE HIGH IS LARGELY SUPPORTED BY A MIDDLE TO UPPER LEVEL ANTICYCLONIC CIRCULATION CENTERED OVERHEAD NEAR 31N70W. FARTHER EAST...AN UPPER LEVEL LOW IS CENTERED NEAR 27N56W WITH A TROUGH AXIS EXTENDING NORTHEAST TO BEYOND 32N51W AND SOUTHWEST TO A BASE NEAR 20N67W. MID-LATITUDE MOISTURE ASSOCIATED WITH A COLD FRONTAL BOUNDARY ALONG 31N/32N BETWEEN 55W-65W CONTINUES TO ADVECT SOUTHWARD ON THE WESTERN PERIPHERY OF THE UPPER LEVEL LOW PRODUCING ISOLATED SHOWERS FROM 27N-32N BETWEEN 55W-65W. OTHERWISE...THE REMAINDER OF THE CENTRAL AND EASTERN ATLC IS UNDER THE INFLUENCE OF A SURFACE RIDGE ANCHORED BY A 1021 MB HIGH CENTERED SOUTH OF THE AZORES NEAR 34N28W. THE RIDGE AXIS EXTENDS SOUTHWEST FROM THE HIGH TO NEAR 27N50W. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ HUFFMAN