000 AXNT20 KNHC 221806 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT WED AUG 22 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1715 UTC. ...SPECIAL FEATURE... HURRICANE DEAN IS NOW INLAND OVER MEXICO AND BEGINNING TO WEAKEN...CENTERED NEAR 20.5N 97.3W...OR VERY NEAR POZA RICA MEXICO...AT 22/1800 UTC MOVING WNW AT 19 MPH. MAXIMUM SUSTAINED WIND SPEEDS HAVE DECREASED TO 85 MPH WITH HIGHER GUSTS. ESTIMATED MINIMUM CENTRAL PRESSURE IS 982 MB. PLEASE SEE THE LATEST NHC FORECAST ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT4/WTNT24 KNHC AND THE LATEST PUBLIC ADVISORY UNDER MIATCPAT4/WTNT34 KNHC FOR MORE DETAILS INCLUDING THE LATEST WATCH AND WARNING INFORMATION. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS OVER THE WRN BAY OF CAMPECHE AND INLAND OVER MEXICO S OF 25N W OF 94W. CONTINUED WEAKENING IS EXPECTED UNTIL DEAN DISSIPATES OVER THE MOUNTAINS OF CENTRAL MEXICO TONIGHT. DEAN IS EXPECTED TO PRODUCE STORM TOTAL RAINFALL OF 5 TO 10 INCHES OVER PARTS OF SOUTHERN AND CENTRAL MEXICO...WITH MAXIMUM AMOUNTS OF UP TO 20 INCHES. THESE RAINS COULD CAUSE LIFE-THREATENING FLASH FLOODS AND MUDSLIDES. ...TROPICAL WAVES... TROPICAL WAVE IS TILTED ALONG 22N59W 6N56W MOVING W 15-20 KT. VISIBLE IMAGERY SHOWS AN ELONGATED AND NARROW ZONE OF LOW LEVEL CYCLONIC TURNING IN ASSOCIATION WITH THIS WAVE JUST E OF THE LESSER ANTILLES. IN ADDITION...THE WAVE SHOWS UP WELL IN THE UW-CIMSS TPW PRODUCT AS A SECONDARY SURGE OF MOISTURE BEHIND THE LARGER WAVE TO ITS W. DEEP CONVECTION IS OVERALL MINIMAL AND DISORGANIZED WITH THIS WAVE...THOUGH A FEW ISOLATED TSTMS ARE NEAR THE NRN PORTION OF THE AXIS FROM 16N-20N BETWEEN 56W-60W. SCATTERED MODERATE CONVECTION IS ALSO FURTHER S...BEGINNING TO MOVE THROUGH TRINIDAD AND TOBAGO...WITHIN 120 NM EITHER SIDE OF THE AXIS FROM 10N-13N. TROPICAL WAVE IS ALONG 73W/74W S OF 30N MOVING W 15-20 KT. THIS WAVE HAS SHOWED UP WELL IN RECENT QUIKSCAT AND ASCAT PASSES. SATELLITE IMAGERY STILL SHOWS THAT THE FOCUS OF THE LOW LEVEL TURNING IS JUST E OF THE CENTRAL BAHAMAS FROM 23N-27N BETWEEN 71W-78W. BAHAMAS METAR DATA TO THE S OF THIS TURNING ARE STILL SHOWING LIGHT NE TO E WINDS...SO AM STILL NOT CONVINCED THERE IS A CLOSED SURFACE LOW WITH THIS FEATURE. THE ASSOCIATED SCATTERED SHOWERS AND ISOLATED TSTMS ARE A BIT LESS CONCENTRATED THAN THEY WERE EARLY THIS MORNING...AND NOW EXTEND NE FROM WRN CUBA ACROSS THE NW BAHAMAS AND INTO THE ATLC FOR A FEW HUNDRED NM. THE WAVE IS EXPECTED TO BRING SHOWERS AND THUNDERSTORMS TO THE FLORIDA PENINSULA OVER THE NEXT DAY OR SO. HOWEVER...UPPER-LEVEL WINDS ARE NOT FAVORABLE FOR TROPICAL CYCLONE FORMATION. SCATTERED MODERATE CONVECTION HAS ALSO PERSISTED WITH THE CARIBBEAN PORTION OF THE WAVE BETWEEN 73W-77W. THIS SRN BRANCH OF THE WAVE IS EXPECTED TO BRING MOISTURE/SHOWERS TO CENTRAL AMERICA AND THE YUCATAN AS WE MOVE THROUGH THE SECOND PART OF THE WEEK. ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 12N16W 9N30W 10N40W 9N47W 6N56W. THERE IS A LITTLE MORE CONVECTION ALONG THE AXIS TODAY BUT THE ITCZ REMAINS HIGHLY ZONAL ACROSS THE TROPICAL ATLC. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS NEAR THE COAST OF AFRICA FROM 8N-13N E OF 17W. NUMEROUS MODERATE/ISOLATED STRONG IS WITHIN 120 NM S OF THE AXIS BETWEEN 20W-28W. SCATTERED MODERATE IS WITHIN 90 NM S AND 120 NM N OF THE AXIS BETWEEN 29W-44W. SIMILAR ACTIVITY IS FROM 9N-11N BETWEEN 41W-55W. DISCUSSION... GULF OF MEXICO... THE MAIN FOCUS TODAY REMAINS WEAKENING HURRICANE DEAN THAT RECENTLY MADE LANDFALL IN MEXICO NEAR THE TOWN OF TECOLUTLA...SEE SPECIAL FEATURES ABOVE. DEAN IS BEING STEERED WWD BY A DEEP LAYER RIDGE TO ITS N/NE. TROPICAL MOISTURE FROM DEAN IS ROUNDING THIS RIDGE AND MOVING THROUGH TEXAS. DRY/STABLE AIR IS OVER THE ERN GULF KEEPING WEATHER MOSTLY FAIR...THOUGH MOISTURE/SHOWERS EXPECTED TO INCREASE THROUGH THU IN THE SE PORTION WITH THE APPROACHING TROPICAL WAVE AND MID TO UPPER LOW. SFC RIDGING WILL REMAIN QUASI STATIONARY OVER THE N GULF OVER THE NEXT FEW DAYS. CARIBBEAN SEA... THE MOST SIGNIFICANT AREA OF WEATHER IN THE CARIBBEAN IS IN THE SW PORTION...WITH SCATTERED SHOWERS AND TSTMS S OF 15N W OF 73W. THE CONVECTION IN THIS VICINITY IS IN PART DUE TO THE TROPICAL WAVE ALONG 74W AS DESCRIBED ABOVE...BUT IS ALSO BEING SUPPORTED BY DIFFLUENT FLOW ALOFT. MOISTURE WITH THIS WAVE...AND THE WAVE NEARING THE WINDWARD ISLANDS...WILL PUSH W THROUGH THE BASIN OVER THE NEXT COUPLE OF DAYS. ELSEWHERE AT THE SFC LIGHT TO MODERATE TRADES ARE IN PLACE AND GENERALLY EXPECTED TO PERSIST THROUGH THU. THE UPPER PATTERN IS DOMINATED BY THE LARGE AND ELONGATED UPPER LOW JUST S OF CUBA...AND THE SRN PERIPHERY OF AN UPPER RIDGE OVER THE ERN PORTION. LIFT WITH THE UPPER LOW IS ALSO SUPPORTING SCATTERED SHOWERS/ISOLATED TSTMS OVER THE NW CARIBBEAN N OF 15N BETWEEN 79W-84W. ATLANTIC OCEAN... SHOWERS AND TSTMS ARE MOVING THROUGH THE WRN ATLC WITH THE TROPICAL WAVE ALONG 74W AS DESCRIBED ABOVE. TROUGHING IS VERTICALLY STACKED IN THIS VICINITY...EXTENDING N FROM AN UPPER LOW JUST S OF CUBA. AN UPPER HIGH IS NEAR 30N68W THAT HAS RIDGING EXTENDING S TO THE ERN CARIBBEAN. THIS IS SUPPORTING A FEW ISOLATED TSTMS BETWEEN 65W-70W. BENIGN UPPER LOWS ARE NOTED NEAR 22N50W AND 32N36W...WHILE THE REMAINDER OF THE FAR ERN ATLC AREA IS DOMINATED BY TYPICAL UPPER RIDGING. ELSEWHERE AT THE SFC A 1023 MB HIGH IS NEAR 30N50W...EXPECTED TO SLIDE SW IN ADVANCE OF THE FRONTAL SYSTEM N OF THE AREA. LIGHT TO MODERATE TRADE WINDS AND FAIR WEATHER AROUND THIS RIDGING DOMINATE MUCH OF THE AREA N OF 13N E OF 50W. $$ WILLIS