000 AXNT20 KNHC 242351 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT MON AUG 24 2009 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...METEOROLOGICAL ANALYSIS...WEATHER OBSERVATIONS...AND RADAR. BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2315 UTC. ...SPECIAL FEATURES... TROPICAL WAVE EXTENDS FROM 10N57W ALONG 18N58W TO 24N61W MOVING W NEAR 20 KT. THIS TROPICAL WAVE CONTINUES TO INTERACT WITH AN NORTH-SOUTH ELONGATED UPPER LEVEL LOW CENTERED NEAR 25N65W THAT STRETCHES UPPER LEVEL TROUGHING SWD ACROSS THE NE CARIBBEAN SEA. DEEP LAYER MOISTURE COINCIDES WITH THE WAVE AXIS AND PAIRED WITH MOIST S-SW UPPER LEVEL FLOW AND UPPER DIFFLUENCE LOCATED EAST OF THE TROUGH AXIS IS GENERATING SCATTERED MODERATE/ISOLATED STRONG CONVECTION FROM 16N-24N BETWEEN 55W-63W. ...TROPICAL WAVES... TROPICAL WAVE IS ALONG 30W S OF 20N MOVING W NEAR 15 KT. SATELLITE IMAGERY DEPICTS AN INVERTED-V CLOUD SIGNATURE AND THE CIMSS WAVETRAK GUIDANCE INDICATES LOW TO MIDDLE LEVEL CYCLONIC FLOW IN THE VICINITY OF THE WAVE AXIS. THIS WAVE ALSO COINCIDES WITH A DEEP LAYER MOISTURE MAXIMUM OBSERVED IN THE TOTAL PRECIPITABLE WATER IMAGERY. SCATTERED SHOWERS ARE NOTED COVERING THE AREA FROM 10N-21N BETWEEN 26W-34W. TROPICAL WAVE IS ALONG 78W S OF 17N MOVING W NEAR 18 KT. THIS WAVE HAS BEEN REPOSITIONED A FEW DEGREES WEST FROM THE PREVIOUS ANALYSIS AND BETTER COINCIDES WITH A DEEP LAYER MOISTURE MAXIMUM OBSERVED IN THE TOTAL PRECIPITABLE WATER IMAGERY ACROSS THE SW CARIBBEAN. THE CIMSS WAVETRAK GUIDANCE INDICATES A BROAD AREA OF LOW PRESSURE AND ASSOCIATED LOW TO MIDDLE LEVEL ATMOSPHERIC INSTABILITY AND LIFT WHICH IS GENERATING SCATTERED MODERATE/ ISOLATED STRONG CONVECTION MOVING W LOCATED FROM 8N-16N BETWEEN 78W-85W. ...ITCZ... THE ITCZ AXIS IS CENTERED ALONG 10N14W 16N27W 14N32W 7N47W 11N56W 11N59W 9N65W. CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE ALONG THE W AFRICA COAST FROM 11N-15N BETWEEN 13W-19W. A SMALLER AREA OF SCATTERED MODERATE CONVECTION IS OVER THE NRN CAPE VERDE ISLANDS FROM 16N-18N BETWEEN 22W-26W. ELSEWHERE...SCATTERED SHOWERS ARE WITHIN 120 NM EITHER SIDE OF THE AXIS BETWEEN 34W-42W LOCATED SE OF THE TROPICAL WAVE ALONG 30W. ...DISCUSSION... GULF OF MEXICO... AS OF 2100 UTC...A STATIONARY FRONT IS OVER THE CENTRAL FLORIDA PENINSULA FROM ORLANDO TO NEAR SARASOTA CONTINUING SW INTO THE SE GULF ALONG 25N85W 23N90W TO 24N95W. THIS FRONTAL BOUNDARY IS SUPPORTED BY AN UPPER LEVEL TROUGH ACROSS THE SE CONUS WITH AXIS EXTENDING FROM CENTRAL ALABAMA TO 26N97W IN THE NW GULF. SCATTERED SHOWERS AND ISOLATED TSTMS ARE OCCURRING OVER THE SRN FLORIDA PENINSULA AND ALSO WITHIN 60 NM OF THE STATIONARY FRONT TO 90W. A MORE WIDESPREAD AREA OF SIMILAR CONVECTION IS S OF 24N W OF 92W OVER THE SW GULF AND WRN BAY OF CAMPECHE. THIS AREA IS FURTHER AIDED BY AN UPPER LEVEL RIDGE AXIS PROVIDING UPPER LEVEL DIFFLUENCE OVER THE YUCATAN PENINSULA AND BAY OF CAMPECHE. NORTH OF THE FRONTAL BOUNDARY...A MUCH DRIER AIRMASS IS IN PLACE ACROSS THE NRN GULF WHICH IS PROMOTING SUBSIDENCE...SINKING AIR AND MOSTLY FAIR WEATHER CONDITIONS. CARIBBEAN SEA... A BROAD UPPER LEVEL RIDGE DOMINATES THE CARIBBEAN W OF 71W WITH THE ANTICYCLONIC CIRCULATION CENTERED S OF CENTRAL CUBA NEAR 20N79W. UPPER LEVEL DIFFLUENCE ON MOIST SWLY FLOW ALOFT BETWEEN THIS RIDGE AND THE UPPER LEVEL TROUGHING OVER THE WRN GULF OF MEXICO IS SUPPORTING SCATTERED SHOWERS AND TSTMS ACROSS THE YUCATAN PENINSULA AND PORTIONS OF WRN CUBA. ON THE SRN PERIPHERY OF THE UPPER LEVEL RIDGE...UPPER LEVEL DIFFLUENCE IS ENHANCING THE CONVECTION ASSOCIATED WITH THE TROPICAL WAVE OVER THE SW CARIBBEAN ALONG 78W. AS THE TROPICAL WAVE CONTINUES TRACKING WWD...EXPECT INCREASED SHOWER AND TSTM ACTIVITY OVER CENTRAL AMERICA DURING THE NEXT 24-36 HOURS. CURRENTLY THIS ACTIVITY IS FOUND S OF 16N W OF 78W INCLUDING PORTIONS OF PANAMA...COSTA RICA AND NICARAGUA. FARTHER TO THE E...UPPER LEVEL TROUGHING EXTENDS FROM THE CENTRAL ATLC OVER THE NE CARIBBEAN. MOIST SWLY FLOW ALOFT ALONG WITH THE APPROACHING TROPICAL WAVE APPROXIMATELY 200 NM E OF THE LESSER ANTILLES IS GENERATING SCATTERED SHOWERS AND ISOLATED TSTMS NE OF A LINE FROM SAINT LUCIA TO SW HISPANIOLA. ATLANTIC OCEAN... A STATIONARY FRONT EXTENDS OVER THE SW NORTH ATLC TO NEAR TITUSVILLE FLORIDA AND ACROSS THE CENTRAL FLORIDA PENINSULA INTO THE GULF OF MEXICO. A PRE-FRONTAL TROUGH IS ANALYZED FROM 31N78W TO 25N83W. SCATTERED SHOWERS AND ISOLATED TSTMS ACCOMPANY THIS FRONTAL BOUNDARY AND ARE WITHIN 150 NM E OF THE FRONT... INCLUDING A PORTION OF THE SE FLORIDA PENINSULA AND FLORIDA KEYS. THIS ACTIVITY IS PRIMARILY SUPPORTED ALOFT BY AN UPPER LEVEL TROUGH ACROSS THE SE CONUS AND THE ASSOCIATED UPPER LEVEL DIFFLUENCE LOCATED E OF THE TROUGH AXIS TO 74W. FARTHER TO THE E OVER THE REMAINDER OF THE SW NORTH ATLC AND INTO THE CENTRAL ATLC...A TROPICAL WAVE IS POSITIONED FROM 10N57W TO 24N61W WITH AN UPPER LEVEL LOW LOCATED NW OF THE WAVE AXIS NEAR 25N65W. THESE TWO FEATURES ARE INTERACTING AND ENHANCING A LARGE AREA OF RATHER UNORGANIZED CONVECTION FROM 16N-24N BETWEEN 55W-63W. THE REMAINDER OF THE CENTRAL AND ERN ATLC IS DOMINATED BY A SURFACE RIDGE ANCHORED BY A 1026 MB HIGH CENTERED NEAR 34N52W. THIS SURFACE RIDGE IS PROVIDING THE BASIN E OF 50W WITH NE TRADES OF UP TO 25 KT. $$ HUFFMAN