000 AXNT20 KNHC 311048 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 AM EDT SAT AUG 31 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. ...SPECIAL FEATURES... A TROPICAL WAVE ASSOCIATED WITH A 1008 MB LOW PRESSURE IS COMING OFF THE AFRICAN COAST. ITS AXIS EXTENDS FROM 20N16W TO THE LOW NEAR 15N16W TO 10N16N AND IS MOVING W NEAR 5 KT. THE SURFACE CYCLONIC CIRCULATION ASSOCIATED WITH THE LOW EXTENDS UP TO THE MIDDLE LEVELS. TOTAL PRECIPITABLE WATER IMAGERY SHOW THE WAVE IS WITHIN A MODERATE TO HIGH MOIST ENVIRONMENT. STRONG SOUTHEASTERLY WIND SHEAR IS KEEPING A CLUSTER OF MODERATE/ISOLATED STRONG CONVECTION NW OF THE LOW PRESSURE CENTER FROM 13N-18N BETWEEN 17W-22W. ENVIRONMENTAL CONDITIONS APPEAR CONDUCIVE FOR DEVELOPMENT AND THIS SYSTEM HAS THE POTENTIAL TO BECOME A TROPICAL DEPRESSION DURING THE NEXT COUPLE OF DAYS AS IT MOVES TOWARD THE CAPE VERDE ISLANDS. RAINSHOWERS AND THUNDERSTORMS ARE EXPECTED IN PORTIONS OF THE CAPE VERDE ISLANDS IN THE NEXT COUPLE OF DAYS. ...TROPICAL WAVES... A TROPICAL WAVE ASSOCIATED WITH A 1012 MB LOW EXTENDS AN AXIS FROM 18N50W TO THE LOW NEAR 15N52W TO 11N54W AND MOVES W-NW NEAR 10 KT. TOTAL PRECIPITABLE WATER IMAGERY SHOW A HIGH MOIST ENVIRONMENT NE OF THE LOW PRESSURE CENTER AND A MODERATE MOIST ENVIRONMENT ELSEWHERE. SCATTERED MODERATE CONVECTION AND ISOLATED TSTMS COINCIDE WITH THE AREA OF HIGH MOISTURE AND ARE FROM 14N-19N BETWEEN 48W-52W. A TROPICAL WAVE IS MOVING ACROSS THE WESTERN CARIBBEAN SEA WITH AXIS EXTENDING ALONG 22N78W TO 11N80W AND MOVING W-NW NEAR 15-20 KT. TOTAL PRECIPITABLE WATER IMAGERY SHOW THE WAVE IS WITHIN A MODERATE MOIST ENVIRONMENT. SCATTERED SHOWERS AND TSTMS ARE WITHIN 150 NM E OF THE AXIS FROM 18N-21N AND FROM 13N-16N. A SMALL CLUSTER OF MODERATE CONVECTION AND TSTMS IS FROM 10N-12N BETWEEN 79W-81W OR IN THE SOUTHERN AXIS REGION. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH AXIS EXTENDS FROM THE WEST AFRICAN COAST NEAR 15N16W TO 10N30W 08N40W 13N47W. BESIDES THE CONVECTION ASSOCIATED WITH THE TROPICAL WAVES ALREADY DISCUSSED...SCATTERED MODERATE CONVECTION IS FROM 03N-12N E OF 19W AS WELL AS FROM 04N- 08N BETWEEN 36W-44W AND FROM 12N-17N BETWEEN 38W-48W. ISOLATED SHOWERS ARE FROM 06N-12N BETWEEN 39W-42W. ...DISCUSSION... GULF OF MEXICO... WATER VAPOR IMAGERY INDICATE NORTHERLY UPPER LEVEL FLOW CONTINUES TO DOMINATE ACROSS MUCH OF THE GULF THIS MORNING WITH RELATIVELY DRY AND STABLE CONDITIONS ALOFT W OF 88W. THIS OVERALL STABILITY IS SUPPORTING A 1014 MB HIGH CENTERED NEAR 26N89W WHICH IS PROVIDING ANTICYCLONIC WIND RANGING FROM 5-10 KT N OF 22N. AN UPPER LEVEL TROUGH OFF THE EASTERN SEABOARD SUPPORTS A STATIONARY FRONT AND A 1012 MB LOW PRESSURE CENTER OVER NORTHERN FLORIDA. THIS FRONTAL SYSTEM IS GENERATING SCATTERED SHOWERS AND TSTMS OVER THE NE GULF N OF 28N BETWEEN 84W-88W. OTHERWISE...A SURFACE TROUGH IS IN THE BAY OF CAMPECHE ALONG 22N90W TO 17N93W AND IS GENERATING ISOLATED SHOWERS S OF 20N. FAIR WEATHER IS EXPECTED TO DOMINATE ACROSS THE GULF THIS WEEKEND SUPPORTED BY SURFACE RIDGING AND STABLE DRY AIR. CARIBBEAN SEA... A TROPICAL WAVE IS MOVING ACROSS THE WESTERN CARIBBEAN SEA WITH AXIS EXTENDING ALONG 22N78W TO 11N80W. EXCEPT FOR TWO SMALL AREAS OF HIGH MOISTURE...TOTAL PRECIPITABLE WATER IMAGERY SHOW THE WAVE IS WITHIN A MODERATE MOIST ENVIRONMENT. SCATTERED SHOWERS AND TSTMS COINCIDE WITH THOSE TWO AREAS OF HIGH MOISTURE FROM 13N-16N BETWEEN 77W-80W AND FROM 10N-12N BETWEEN 79W-81W. UPPER LEVEL DIFFLUENCE FROM AN UPPER LOW CENTERED IN THE STRAITS OF FLORIDA AND A RIDGE CENTERED OVER THE SW GULF IS ENHANCING ISOLATED SHOWERS WITHIN 120 NM OFF THE HONDURAS COAST W OF 83W. AN UPPER LEVEL LOW CENTERED N OF PUERTO RICO EXTENDS A TROUGH AXIS OVER THE CENTRAL-EASTERN BASIN WHICH IS SUPPORTING SCATTERED SHOWERS N OF 16N BETWEEN 61W-69W. A TROPICAL WAVE IS EXPECTED TO MOVE ACROSS THE LESSER ANTILLES SUNDAY NIGHT GENERATING RAINSHOWERS. HISPANIOLA... ISOLATED SHOWERS ASSOCIATED WITH THE PASSAGE OF A TROPICAL WAVE LINGER ACROSS HAITI AND ADJACENT WATERS OF THE WINDWARD PASSAGE. AN UPPER LEVEL LOW CENTERED N OF PUERTO RICO IS SUPPORTING SCATTERED SHOWERS N OF 16N BETWEEN 61W-69W INCLUDING THE MONA PASSAGE AND EASTERN DOMINICAN REPUBLIC. THE UPPER LEVEL LOW N OF PUERTO RICO IS EXPECTED TO DRIFT WESTWARD OVER HISPANIOLA WHICH MAY ENHANCE CONVECTIVE ACTIVITY OVER THE WEEKEND. ATLANTIC OCEAN... UPPER LEVEL TROUGHINESS OVER THE SW N ATLC IS SUPPORTING ISOLATED SHOWERS AND TSTMS N OF 22N W OF 74W. FARTHER EAST...AN UPPER LEVEL ELONGATED LOW SUPPORTS A SURFACE TROUGH ALONG 28N60W TO 23N72W AND NUMEROUS MODERATE CONVECTION FROM 23N-28N BETWEEN 58W-63W. OTHERWISE...BESIDES THE TROPICAL WAVES ALREADY DISCUSSED...SURFACE RIDGING AND DRY STABLE AIR DOMINATES THE REMAINDER BASIN SUPPORTING FAIR WEATHER. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ NR