000 AXNT20 KNHC 310542 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 AM EDT MON JUL 30 2007 TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHERN SECTIONS OF SOUTH AMERICA...AND THE 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0515 UTC. ...SPECIAL FEATURES... NEWLY FORMED TROPICAL DEPRESSION THREE CENTERED NEAR 36.1N 66.0W AT 31/0300 UTC OR 235 NM NORTH-NORTHWEST OF BERMUDA AND ABOUT 385 NM SOUTH-SOUTHEAST OF CHATHAM MASSACHUSETTS MOVING NNE 14 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1007 MB. MAXIMUM SUSTAINED WINDS ARE 30 KT WITH GUSTS TO 40 KT. SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT3/WTNT23 KNHC FOR ADDITIONAL DETAILS. THE SYSTEM IS IN A SHEARED ENVIRONMENT WITH THE THUNDERSTORM ACTIVITY WITHIN 120 NM NORTHEAST OF THE EXPOSED LOW LEVEL CENTER. ALTHOUGH THE SYSTEM IS EXPECTED TO REMAIN IN THIS ENVIRONMENT UNTIL IT TRANSITIONS TO AN EXTRATROPICAL SYSTEM WITHIN 24 HOURS...THERE IS THE POTENTIAL FOR THE DEPRESSION TO REACH STORM STRENGTH WITHIN THAT TIME. 1010 MB LOW NEAR 10N49W IN ASSOCIATION WITH THE TROPICAL WAVE ALONG 49N WAS LOCATED ABOUT 750 NM ESE OF THE WINDWARD ISLANDS IS FAIRLY WELL ORGANIZED WITH A CLUSTER OF SCATTERED STRONG THUNDERSTORMS DEVELOPING WITHIN 120-150 NM OF THE LOW LEVEL CENTER IN THE NE SEMICIRCLE. THIS SYSTEM IS IN A FAVORABLE ENVIRONMENTAL FOR SOME DEVELOPMENT OVER THE NEXT COUPLE OF DAYS. ...TROPICAL WAVES... TROPICAL WAVE ALONG 29W S OF 18N WITH A 1009 MB LOW ALONG THE WAVE NEAR 12N MOVING W NEAR 10 KT. BROAD CYCLONIC TURNING IN THE STRATOCUMULUS FIELD WAS NOTED WITH THE SYSTEM WITH A FEW EMBEDDED SHOWERS IN THE W SEMICIRCLE OF THE SYSTEM. SCATTERED MODERATE THUNDERSTORMS WERE NOTED MAINLY WITHIN 90 NM OF THE INTERSECTION OF THE WAVE AND ITCZ BETWEEN 26W AND 37W. TROPICAL WAVE IN THE E-CENTRAL CARIBBEAN AND SW N ATLANTIC IS TILTED FROM 23N67W THROUGH 15N69W TO INLAND OVER SOUTH AMERICA NEAR 5N70W MOVING W NEAR 15 KT. BROAD LOW LEVEL INVERTED-V SIGNATURE NOTED IN TRADE WIND CUMULUS FIELD GENERALLY IN THE ARE BETWEEN 65W-75W. ISOLATED SHOWERS ARE MOVING FROM THE LESSER ANTILLES ACROSS THE E CARIBBEAN BUT NO ASSOCIATED DEEP CONVECTION IS NOTED. ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 13N17W 10N28W 9N38W 11N46W 9N51W 6N57W. EXCEPT AS NOTED ABOVE...SCATTERED MODERATE/STRONG CONVECTION IS MOVING OFF W AFRICA WITHIN 90 NM OF THE COAST FROM 9N-16N. CLUSTERS OF SCATTERED MODERATE CONVECTION ARE WITHIN 90 NM OF THE ITCZ AXIS E OF 26W TO THE AREA OF CONVECTION ALONG THE AFRICAN COAST. ...DISCUSSION... GULF OF MEXICO... LARGE MID TO UPPER LEVEL ANTICYCLONE WITH SEVERAL CENTERS OVER THE RIO GRANDE VALLEY...E TEXAS AND SE LOUISIANA DOMINATED THE FLOW OVER THE GULF OF MEXICO. ASSOCIATED RIDGE EXTENDED ESEWD ACROSS THE NE GULF TO CENTRAL FLORIDA. A SMALL CYCLONIC CIRCULATION NEAR 26N96W WAS UNDERCUTTING THE RIDGE. MODERATE BUT SOMEWHAT DIFLUENT NELY UPPER LEVEL FLOW WAS ADVECTING HIGH LEVEL CLOUD DEBRIS ACROSS THE ERN HALF OF THE GULF AND ALSO MAINTAINING WIDELY SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS IN THE AREA. AT THE SURFACE...WEAK RIDGE EXTENDS FROM THE W ATLC ACROSS THE STRAITS OF FLORIDA TO A DISSIPATING 1015 MB HIGH OVER N-CENTRAL CUBA NEAR 23N81W. THIS OVERALL PATTERN IS EXPECTED TO REMAIN IN PLACE FOR THE NEXT SEVERAL DAYS OR SO. THE PRESENCE OF DIFLUENT FLOW SE OF THE ANTICYCLONE AND AN APPROACHING UPPER LEVEL TROUGH/ASSOCIATED FRONTAL SYSTEM OVER THE DEEP SOUTH HOLDS THE POTENTIAL FOR ADDITIONAL SCATTERED THUNDERSTORMS OVER THE NE GULF. CARIBBEAN... AN UPPER RIDGE EXTENDS FROM NW COLOMBIA NEAR 9N78W NW TO THE YUCATAN PENINSULA NEAR BELIZE. WEAK UPPER LEVEL INVERTED TROUGH COUPLED WITH DRY STABLE AIR DOMINATES THE REMAINDER OF THE CARIBBEAN WITH WIDELY SCATTERED TRADE WIND SHOWERS AND A FEW THUNDERSTORMS IN THE EASTERN CARIBBEAN PER SAN JUAN WSR-88D DATA. ATLANTIC... SEE SPECIAL FEATURES FOR TROPICAL DEPRESSION THREE. VERY AMPLIFIED PATTERN IN PLACE OVER THE N ATLANTIC WITH IMPLICATIONS FOR THE NEWLY FORMED TROPICAL DEPRESSION. BROAD TROUGH COMPLEX OVER THE NW ATLANTIC WITH FIRST NEGATIVELY TILTED SHORTWAVE EXTENDING FROM NEW ENGLAND SEWD THROUGH 38N70W TO 34N65W. UPPER LEVEL DIFFLUENCE E OF THE TROUGH AXIS IS ALLOWING DEEP CONVECTION TO PERSIST NE OF THE EXPOSED LOW LEVEL CENTER AS THE DEPRESSION MOVES NNE 14 KT. A SECOND POTENT SHORTWAVE TROUGH SWINGING IN FROM THE W AND CUTTING ACROSS THE CAROLINAS TO GEORGIA HAS ALLOWED SCATTERED STRONG THUNDERSTORMS TO PERSIST AROUND ANOTHER AREA OF LOW PRESSURE NEAR 33N77W. THE FLOW IS STRONGLY DIFLUENT AS WELL ON THIS AREA. FURTHER S...AN ELONGATED RIDGE AXIS FROM 32N60W SWWD TO THE WRN BAHAMAS WITH SOME MODERATE SUBSIDENCE NOTED S OF THE RIDGE. CYCLONIC CIRCULATION NEAR 30N50W MOVING WWD 10 KT HAS ASSOCIATED SHEAR AXIS EXTENDING SWWD TO A SMALL CYCLONIC CIRCULATION NEAR 20N64W. ANTICYCLONES NEAR 16N47W AND 26N37W AND ASSOCIATED FLOW PREVAIL OVER THE REMAINDER OF THE ATLANTIC WITH DEEP EASTERLY FLOW IN PLACE OVER THE AREA. UW CIMSS SAL ANALYSIS INDICATES SAHARAN DUST CONTINUES OVER THE ATLANTIC E OF 40W THROUGH THE COVERAGE IS NOT AS EXTENSIVE AS PREVIOUS DAYS. AT THE SURFACE...DRY STABLE AIR E OF 60W AND A SURFACE RIDGE ANCHORED BY A 1026 MB HIGH WELL N OF THE REGION NEAR 41N41W DOMINATE THE ATLC GIVING THE AREA FAIR CONDITIONS TONIGHT. $$ COBB