000 AXNT20 KNHC 231137 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 AM EDT SAT JUL 23 2011 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. ...SPECIAL FEATURES... NONE. ...TROPICAL WAVES... TROPICAL WAVE IS ANALYZED FROM 10N31W TO 17N29W MOVING W AT 10 KT. SATELLITE IMAGERY AND SATELLITE DERIVED WINDS INDICATE BROAD CYCLONIC LOW-LEVEL FLOW IN THE VICINITY OF THE WAVE AXIS WHICH REMAINS EMBEDDED WITHIN THE ITCZ AXIS. TOTAL PRECIPITABLE WATER IMAGERY ALSO INDICATES A NORTHWARD EXTENSION OF LOW-LEVEL MOISTURE TO 18N BETWEEN 27W-35W. WIDELY SCATTERED MODERATE CONVECTION IS FROM 10N-14N BETWEEN 30W-35W. TROPICAL WAVE IS ANALYZED FROM 13N59W TO 20N57W MOVING W-NW AT 15 KT. SHORTWAVE INFRARED SATELLITE IMAGERY INDICATES CYCLONIC TURNING OF THE LOW-LEVEL CLOUD FIELD IN THE VICINITY OF THE WAVE AXIS. TOTAL PRECIPITABLE WATER IMAGERY ALSO SHOWS A MAXIMUM OF DEEP LAYER MOISTURE ASSOCIATED WITH THE WAVE ACROSS THE NE CARIBBEAN SEA AND LESSER ANTILLES. AN AREA OF SCATTERED MODERATE CONVECTION IS OCCURRING WITH THE WAVE FROM 14N-21N BETWEEN 56W-66W THAT IS EXPECTED TO IMPACT THE LESSER ANTILLES...NE CARIBBEAN SEA...AND PUERTO RICO THROUGH LATE SATURDAY INTO SUNDAY. TROPICAL WAVE IS ANALYZED FROM 18N93W TO 23N92W MOVING W AT 15 KT. THE WAVE IS EMBEDDED WITHIN MARGINAL LOW-LEVEL MOISTURE ACROSS THE YUCATAN PENINSULA AND SW GULF OF MEXICO AND LACKS ANY SIGNIFICANT CONVECTION. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 12N16W TO 08N20W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 08N20W TO 12N31W TO 06N44W TO 07N54W. SCATTERED MODERATE CONVECTION IS FROM 05N-09N BETWEEN 13W-26W. ...DISCUSSION... GULF OF MEXICO... WATER VAPOR IMAGERY INDICATES AN UPPER LEVEL ANTICYCLONE COVERS MUCH OF THE EASTERN CONUS AND THE RIDGING EXTENDS SOUTHWARD ACROSS MUCH OF THE GULF N OF 23N. THIS STRONG SUBSIDENCE REACHES TO THE SURFACE IN THE FORM OF A RIDGE AXIS EXTENDING FROM THE W ATLC NEAR 30N70W ACROSS THE CENTRAL FLORIDA PENINSULA TO THE MEXICO COAST NEAR 25N97W. THIS MORNING A FEW ISOLATED SHOWERS AND TSTMS ARE OCCURRING ACROSS THE NE GULF N OF 26N E OF 91W... BUT OVER THE NEXT SEVERAL DAYS THE SURFACE RIDGE IS FORECAST TO HOLD STRONG WITH THE AXIS SHIFTING SLIGHTLY NORTHWARD TO 29N BY EARLY MONDAY. ELSEWHERE...THE TROPICAL WAVE WILL MOVE ACROSS THE SW GULF SATURDAY AND MOVE INLAND AND DISSIPATE OVER CENTRAL MEXICO SUNDAY. CARIBBEAN SEA... AN ELONGATED UPPER LEVEL LOW IS ACROSS THE WESTERN CARIBBEAN CENTERED NEAR 17N79W. MIDDLE TO UPPER LEVEL LIFT ASSOCIATED WITH THIS FEATURE IS GENERATING A FEW OVERNIGHT ISOLATED SHOWERS AND TSTMS S OF EASTERN CUBA NEAR 20N76W. WESTWARD MOVING ISOLATED SHOWERS LINGER ACROSS THE NW CARIBBEAN N OF 17N BETWEEN 80W-87W AND ARE EXPECTED TO MOVE ONSHORE ACROSS BELIZE AND THE YUCATAN PENINSULA THROUGH LATE SATURDAY. FARTHER EAST...AN UPPER LEVEL ANTICYCLONIC CIRCULATION IS CENTERED IN THE TROPICAL N ATLC NEAR 18N44W THAT EXTENDS A RIDGE AXIS WESTWARD ALONG 18N TO OVER PUERTO RICO NEAR 18N66W. THIS UPPER LEVEL DIFFLUENT ENVIRONMENT IS LIKELY ENHANCING THE CONVECTION ASSOCIATED WITH THE APPROACHING TROPICAL WAVE ALONG 59W. ELSEWHERE THE REMAINDER OF THE CENTRAL CARIBBEAN IS UNDER MOSTLY CLEAR SKIES AND FAIR CONDITIONS DUE TO MODERATE SUBSIDENCE ALOFT BETWEEN 66W-80W. HOWEVER...A FEW ISOLATED SHOWERS AND TSTMS ARE OCCURRING FROM 15N-18N BETWEEN 67W-73W. THE MONSOON TROUGH ALSO EXTENDS ALONG 09N OVER THE SW CARIBBEAN AND CONTINUES TO GENERATE SCATTERED SHOWERS AND TSTMS S OF 12N AND OVER INTERIOR PORTIONS OF PANAMA...COSTA RICA...AND NICARAGUA. ATLANTIC OCEAN... A BROAD SURFACE RIDGE COVERS THE MAJORITY OF THE ATLC ANCHORED BY A 1028 MB AZORES HIGH NEAR 41N27W AND A 1025 MB HIGH NEAR 31N54W PROVIDING MOSTLY FAIR WEATHER BASIN-WIDE. WITH AN UPPER LEVEL LOW CENTERED NEAR 17N79W IN THE WESTERN CARIBBEAN SEA...A FEW ISOLATED SHOWERS AND TSTMS ARE NOTED ACROSS THE FLORIDA STRAITS. A FEW ISOLATED SHOWERS ARE ALSO NOTED FROM 26N-29N BETWEEN 71W-77W ASSOCIATED WITH AN UPPER LEVEL LOW NEAR 30N70W. OTHERWISE THE AZORES HIGH PRESSURE IS LARGE IN AREAL COVERAGE AND PROVIDING FAIR WEATHER N OF 20N...WITH THE EXCEPTION OF THE TROPICAL WAVE ALONG 59W AND THE ASSOCIATED CONVECTION IN THE VICINITY OF 19N58W. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ HUFFMAN