000 AXNT20 KNHC 251804 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT WED JUL 25 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 1745 UTC. ...TROPICAL WAVES... TROPICAL WAVE IS TILTED ALONG 16N38W 11N40W 5N40W MOVING W NEAR 13 KT. THIS WAVE WAS ADJUSTED SLIGHTLY TO THE E BASED ON ITS APPEARANCE IN VISIBLE SATELLITE IMAGERY THIS MORNING. A BROAD ZONE OF LOW LEVEL CYCLONIC TURNING IS NOTED FROM 10N-15N BETWEEN 36W-44W. DEEP CONVECTION REMAINS MINIMAL. TROPICAL WAVE IS MOVING THROUGH THE WINDWARD ISLANDS ALONG 62W S OF 14N. THE WAVE IS MOVING QUICKLY W 20-25 KT AND EXHIBITS SOME SLIGHT LOW LEVEL CYCLONIC TURNING. ISOLATED MODERATE CONVECTION IS MOVING INTO AND THROUGH THE SE CARIBBEAN FROM 11N-14N BETWEEN 60W-66W. A WEST CARIBBEAN TROPICAL WAVE IS ALONG 87W S OF 21N MOVING W NEAR 20 KT. SCATTERED SHOWERS AND TSTMS ARE OVER MUCH OF THE NW CARIBBEAN N OF 15N W OF 82W...AND ARE NOW MOVING THROUGH BELIZE AND THE ERN YUCATAN PENINSULA. ANOTHER CLUSTER OF MODERATE CONVECTION IS FROM 14N-16N BETWEEN 80W-82W. ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 14N16W 11N35W 8N35W 9N43W 11N58W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS OVER THE COAST OF AFRICA AND ADJACENT WATERS FROM 11N-15N BETWEEN 14W-18W. SCATTERED MODERATE ALSO FROM 8N-11N BETWEEN 20W-23W. SIMILAR CONVECTION IS WITHIN 120NM EITHER SIDE OF THE AXIS BETWEEN 28W-34W...WHICH MAY BE ASSOCIATED WITH A LOW AMPLITUDE TROPICAL WAVE. ...DISCUSSION... GULF OF MEXICO... ANOTHER ACTIVE WEATHER DAY IN THE GULF TODAY ALTHOUGH THE FOCUS HAS SHIFTED W. LIGHTNING DATA...RADAR...AND SATELLITE DEPICT SCATTERED SHOWERS AND TSTMS OVER MOST OF THE BASIN W OF 88W. THE ACTIVITY IS MOST CONCENTRATED IN A CLUSTER OF SCATTERED MODERATE CONVECTION NOW DRIFTING N THROUGH THE BAY OF CAMPECHE AND THE YUCATAN...WITHIN 90NM EITHER SIDE OF THE LINE 26N88W 24N93W 21N96W. THERE MAY BE A SOME LOW LEVEL CONFLUENCE IN THE AREA BUT OVERALL THE SURFACE FLOW ON THE LARGE SCALE IS ANTICYCLONIC AROUND AN ATLC RIDGE ATTEMPTING TO BUST THROUGH. A HINT OF LOW LEVEL CYCLONIC TURNING IS ALSO NOTED JUST OFFSHORE TUXPAN MEXICO. THE UPPER SUPPORT...ON THE OTHER HAND...IS MUCH MORE FAVORABLE WITH THE FLOW HIGHLY DIFFLUENT BETWEEN THE BROAD UPPER LOW OVER TEXAS AND AN UPPER HIGH OVER WRN CUBA. SFC HIGH PRESSURE IS EXPECTED TO FORM OVER THE NE GULF THROUGH THU AND MOVE LITTLE THROUGH FRI. THIS WILL PRODUCE LIGHT WINDS OVER THE NE PORTION WITH MODERATE SE FLOW IN THE WRN PORTION. SHOWERS/TSTMS EXPECTED TO CONTINUE AFFECTING THE WRN GULF THROUGH THU WITH THE UPPER SUPPORT ONLY SLOWLY WEAKENING AND LOWER TO MID LEVEL ENERGY APPROACHING WITH THE TROPICAL WAVE NEAR THE YUCATAN. CARIBBEAN SEA... ASIDE FROM THE WEATHER ASSOCIATED WITH THE TWO TROPICAL WAVES OVER THE FAR E AND W PORTIONS...NOT TOO MUCH IS GOING ON. A CLUSTER OF MODERATE CONVECTION IS MOVING INTO COSTA RICA AND EXTENDS INTO THE SW CARIBBEAN S OF 12N AND W OF 79W. SKIES ARE MOSTLY CLEAR IN THE CENTRAL CARIBBEAN S OF HISPANIOLA TO THE COAST OF COLOMBIA. THIS IS ALSO WHERE THE TRADES ARE THE STRONGEST (20-25 KT) AND HAS PROMOTED A WELL MIXED LOWER ATMOSPHERE. TRADES ARE A FEW KTS LIGHTER ELSEWHERE WITH THIS SCENARIO EXPECTED TO STICK AROUND THROUGH FRI. ALOFT...AN UPPER HIGH OVER FAR WRN CUBA DOMINATES THE BASIN W OF 75W WHILE AN INVERTED UPPER TROUGH IS OVER THE ERN CARIB. ATLANTIC OCEAN... A WEAK SFC TROUGH EXTENDS NE FROM JUST OFFSHORE NORTH FLORIDA TO A FEW HUNDRED MILES OFFSHORE CAPE HATTERAS. THIS...ALONG WITH DIFFLUENCE ALOFT BETWEEN THE LARGE UPPER LOW OVER OHIO AND AN UPPER RIDGE EXTENDING INTO THE WRN ATLC FROM THE CARIBBEAN...IS SUPPORTING THE SCATTERED SHOWERS/ISOLATED TSTMS N OF 27N BETWEEN 68W-78W. SIMILAR ACTIVITY IS AFFECTING THE WRN BAHAMAS...S FLORIDA...AND THE STRAITS OF FLORIDA. THE CENTRAL ATLC IS DOMINATED BY A WELL DEFINED UPPER LOW NEAR 31N55W. LIGHTNING DATA DEPICTS SCATTERED TSTMS OCCURRING AROUND THE UPPER LOW N OF 28N BETWEEN 50W-57W. THERE ARE SEVERAL BENIGN UPPER FEATURES IN THE E ATLC BUT WHAT STANDS OUT THE MOST IS THE EXTREMELY DRY AIR NOTED IN THE UPPER CONFLUENT ZONE N OF 15N BETWEEN 32W-46W. A 1029 MB SFC HIGH NEAR 35N39W IS HELPING TO PRODUCE THE WIDESPREAD FAIR WEATHER AND MODERATE NE TRADES N OF 15N E OF 50W. $$ WILLIS