000 AXNT20 KNHC 311801 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT MON AUG 31 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1715 UTC. ...SPECIAL FEATURES... A BROAD AREA OF LOW PRESSURE ASSOCIATED WITH A 1008 MB LOW IS CENTERED NEAR 15N52W. MAXIMUM VALUES OF LOW-LEVEL VORTICITY AND TOTAL PRECIPITABLE WATER ARE OBSERVED IN THE VICINITY OF THE LOW BASED ON CIMSS WAVETRAK MODEL GUIDANCE AND TPW IMAGERY. THE ASSOCIATED CONVECTION IS BEING ENHANCED AND MAINTAINED BY AN UPPER LEVEL RIDGE ALONG 17N THAT IS PROVIDING UPPER LEVEL DIVERGENCE AND A FAVORABLE ENVIRONMENT TO THE NW OF THE LOW CENTER. SCATTERED/NUMEROUS STRONG CONVECTION IS FROM 13N-17N BETWEEN 49W-53W. CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE ELSEWHERE FROM 13N-16N BETWEEN 54W-58W AND FROM 17N-20N BETWEEN 48W-52W. THIS SYSTEM HAS THE POTENTIAL TO BECOME A TROPICAL DEPRESSION DURING THE NEXT DAY OR SO AS IT MOVES WNW NEAR 12 KT. INTERESTS IN THE LESSER ANTILLES SHOULD MONITOR THE PROGRESS OF THIS SYSTEM. ...TROPICAL WAVES... TROPICAL WAVE IS ALONG 28W S OF 18N MOVING W NEAR 12 KT. THE WAVE REMAINS EMBEDDED WITHIN A BROAD AREA OF MID-LEVEL CYCLONIC CURVATURE IN THE VICINITY OF THE WAVE AXIS AND IS BEGINNING TO TRACK BENEATH A VERY DRY AND SUBSIDENT AIR MASS ASSOCIATED WITH THE ERN EXTENT OF AN UPPER LEVEL ANTICYCLONIC CIRCULATION CENTERED NEAR 16N34W. NO SIGNIFICANT CONVECTION OR SHOWER ACTIVITY ACCOMPANIES THE WAVE. TROPICAL WAVE IS ALONG 77W S OF 18N MOVING W NEAR 15 KT. THIS WAVE IS EMBEDDED IN LOW-LEVEL CYCLONIC TRADE WIND FLOW ACROSS THE WRN CARIBBEAN AND IS DIFFICULT TO DISCERN ON VISIBLE SATELLITE IMAGERY. MIDDLE TO UPPER LEVEL DRY STABLE AIR IN THE SW QUADRANT OF AN UPPER LEVEL ANTICYCLONIC CIRCULATION CENTERED OVER THE NW CARIBBEAN NEAR 20N80W IS INHIBITING ANY DEEP CONVECTION OR SHOWER ACTIVITY. ...ITCZ... THE ITCZ AXIS IS CENTERED ALONG 15N16W 12N24W 9N30W 14N46W 11N56W 10N62W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 11N-16N BETWEEN 14W-19W AND FROM 8N-11N BETWEEN 18W-22W. ...DISCUSSION... GULF OF MEXICO... AS OF 1500 UTC...A WEAK 1016 MB LOW IS CENTERED NEAR PANAMA CITY FLORIDA WITH A SLOW MOVING COLD FRONT DRAPED TO THE WSW ACROSS THE NRN GULF WATERS ALONG 28N90W TO NEAR CORPUS CHRISTI TEXAS. A SURFACE TROUGH IS ALSO ANALYZED ACROSS THE WRN GULF FROM 28N91W TO 23N96W. LOW-LEVEL CONVERGENCE NEAR THE COLD FRONT AND SURFACE TROUGH ARE GENERATING SCATTERED SHOWERS AND ISOLATED TSTMS NW OF A LINE FROM GAINESVILLE FLORIDA THROUGH 26N90W TO THE SRN MEXICO COAST NEAR VERACRUZ. THIS ACTIVITY IS FURTHER ENHANCED BY UPPER LEVEL DIFFLUENCE ASSOCIATED WITH AN ANTICYCLONIC CIRCULATION CENTERED OVER CENTRAL MEXICO NEAR 21N102W. THE UPPER RIDGE EXTENDS NE ACROSS THE NRN GULF TO THE BIG BEND REGION OF FLORIDA. A SHORTWAVE UPPER TROUGH IS OVER THE FLORIDA PENINSULA AND STRAITS OF FLORIDA WHICH IS CONTINUING TO GENERATE ISOLATED SHOWERS AND TSTMS OVER EXTREME SRN FLORIDA AND THE FLORIDA KEYS THIS AFTERNOON AND EVENING. CARIBBEAN SEA... AN UPPER LEVEL TROUGH IS OVER THE FAR NW CARIBBEAN AND NRN PORTIONS OF CENTRAL AMERICA WITH AXIS ALONG 88W FROM THE YUCATAN CHANNEL SWD TO EL SALVADOR. ISOLATED SHOWERS AND TSTMS ARE OBSERVED ON SATELLITE IMAGERY FROM 15N-21N W OF 87W. AN UPPER ANTICYCLONIC CIRCULATION IS OVER THE REMAINDER OF THE WRN CARIBBEAN W OF 70W AND UPPER LEVEL DIFFLUENCE ASSOCIATED WITH THIS FEATURE IS GENERATING AN AREA OF NUMEROUS SHOWERS AND SCATTERED TSTMS FROM 11N-16N BETWEEN 82W-87W...INCLUDING PORTIONS OF INTERIOR NICARAGUA AND ERN HONDURAS. AN UPPER LEVEL TROUGH IS OVER THE FAR SRN PORTION OF THE SW NORTH ATLC AND DIPS TROUGHING INTO THE NE CARIBBEAN TO 14N E OF 70W. THIS TROUGHING IS PRODUCING A FEW ISOLATED SHOWERS MOVING ACROSS PUERTO RICO AND HISPANIOLA...INCLUDING THE MONA PASSAGE. MODERATE TO STRONG ELY TRADE WINDS REMAIN ACROSS THE BASIN. THE SPECIAL FEATURES AREA OF LOW PRESSURE OVER THE TROPICAL NORTH ATLC IS EXPECTED TO IMPACT THE LESSER ANTILLES WEDNESDAY INTO THURSDAY. ATLANTIC OCEAN... A NARROW UPPER RIDGE IS OVER THE FAR W ATLC EXTENDING FROM CUBA ACROSS THE NW BAHAMAS TO 30N75W AND PROVIDING AMPLE UPPER LEVEL DIFFLUENCE TO GENERATE SCATTERED SHOWERS AND TSTMS FROM 26N-32N BETWEEN 74W-80W. AN UPPER TROUGH EXTENDS FROM A CENTRAL ATLC UPPER LOW CENTERED NEAR 29N57W TO A STRONGER UPPER LOW CENTERED N OF THE MONA PASSAGE NEAR 20N68W. THIS UPPER LEVEL FEATURE SUPPORTS A SURFACE TROUGH THAT EXTENDS FROM 19N73W TO 27N71W. LOW-LEVEL CONVERGENCE COUPLED WITH MIDDLE TO UPPER LEVEL DIFFLUENCE NEAR THE UPPER LOW CENTERED IS GENERATING SCATTERED SHOWERS AND TSTMS COVERING AN AREA FROM 19N-28N BETWEEN 64W-72W. AN UPPER LEVEL TROUGH IS ACROSS THE NE ATLC FOCUSED NEAR AN UPPER LOW CENTERED NEAR 30N23W. UPPER LEVEL DIFFLUENCE LOCATED E OF THE UPPER TROUGH IS PRODUCING MIDDLE LEVEL CLOUDINESS AND POSSIBLE ISOLATED SHOWERS N OF 20N E OF 27W. ELSEWHERE ACROSS THE REMAINDER OF THE CENTRAL AND ERN ATLC...A SURFACE RIDGE DOMINATES THE BASIN ANCHORED BY A 1028 MB HIGH N OF THE DISCUSSION AREA CENTERED NEAR 39N41W. $$ HUFFMAN