000 AXNT20 KNHC 040004 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT FRI AUG 03 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2345 UTC. ...TROPICAL WAVES... TROPICAL WAVE IS ALONG 19W S OF 21N ESTIMATED TO BE MOVING W NEAR 15 KT. THIS WAVE CONTINUES TO EXHIBIT A LARGE AREA OF CYCLONIC TURNING IN THE LOW AND MID LEVEL CLOUDS. THE GREATEST ROTATION IS NEAR 16/17N...WHICH IS FARTHER N THAN THE PAST SEVERAL WAVES. DEEP CONVECTION REMAINS MINIMAL NEAR THIS ROTATION THOUGH. THE ONLY NOTABLE SHOWER ACTIVITY IS CONFINED TO THE BASE OF THE WAVE NEAR ITS INTERSECTION WITH THE ITCZ. TROPICAL WAVE IS ALONG 36W S OF 18N MOVING W NEAR 15 KT. THIS WAVE REMAINS DIFFICULT TO LOCATE COMPARED TO THE OTHER TWO WAVES IN THE ATLC BASIN. HOWEVER...ONE CAN DETECT A WWD MOVING AREA OF CLOUDS/SHOWERS ON A METSAT-9 HOVMOLLER DIAGRAM ASSOCIATED WITH THIS FEATURE. DEEP CONVECTION IS OVERALL MINIMAL ON BOTH SIDES OF THE AXIS. HIGH AMPLITUDE TROPICAL WAVE IS ALONG 51W MOVING W NEAR 20 KT. WAVE REMAINS EASY TO LOCATE WITH A LARGE INVERTED V SHAPE NOTED IN THE STRATOCUMULUS FIELD FROM 12N-27N BETWEEN 47W-59W. HOWEVER...ALMOST NO DEEP CONVECTION EXISTS WITHIN SEVERAL HUNDRED NM EITHER SIDE OF THE WAVE AXIS. TROPICAL WAVE IS MOVING RAPIDLY INTO AND THROUGH THE WRN CARIBBEAN ALONG 77W S OF 21N. THIS WAVE HAS BEEN THE SPECIAL FEATURE THAT WE HAVE BEEN MONITORING OVER THE PAST SEVERAL DAYS. SCATTERED MODERATE/ISOLATED STRONG CONVECTION LIES FROM 14N-21N BETWEEN 75W-82W. TRAILING SCATTERED SHOWERS/ISOLATED TSTMS ALSO EXIST IN THE CENTRAL CARIBBEAN WITHIN 400NM E OF THE AXIS FROM 14N-19N. THE WAVE IS EXPECTED TO BRING CLOUDINESS AND SHOWERS TO JAMAICA...THE CAYMAN ISLANDS AND PORTIONS OF CENTRAL AMERICA TONIGHT AND SATURDAY. UPPER-LEVEL WINDS MAY BECOME A LITTLE MORE FAVORABLE FOR DEVELOPMENT DURING THE NEXT DAY OR SO...BUT DEVELOPMENT MAY BE HINDERED BY PROXIMITY TO LAND. TROPICAL WAVE IS ALONG 88W S OF 21N MOVING W 15-20 KT. UW-CIMSS TPW PRODUCT SHOWS A WEAK SURGE OF MOISTURE PROPAGATING W WITH THIS FEATURE. THE WAVE APPEARS TO BE ENHANCING THE SURGE OF SHOWERS/TSTMS NOW MOVING THROUGH NRN GUATEMALA AND THE YUCATAN PENINSULA. ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 11N20W 10N27W 13N40W 14N51W. ISOLATED MODERATE CONVECTION IS WITHIN 180 NM EITHER SIDE OF THE AXIS BETWEEN 19W-31W. ISOLATED SHOWERS AND TSTMS ARE S OF THE AXIS FROM 7N-12N W OF 40W. ...DISCUSSION... THE GULF OF MEXICO... A LINGERING SFC TROUGH OVER THE NRN GULF CONTINUES TO PRODUCE DISORGANIZED CLOUDINESS...SCATTERED SHOWERS...AND ISOLATED TSTMS THIS EVENING...MAINLY WITHIN 90 NM OF A LINE FROM BROWNSVILLE TEXAS TO TALLAHASSEE FLORIDA. THIS TROUGH HAS BECOME A LITTLE MORE DIFFICULT TO FIND OVER THE LAST SEVERAL HOURS DUE TO THE SEA BREEZE CIRCULATION ALONG THE GULF COAST. DEVELOPMENT OF THIS SYSTEM IS NOT ANTICIPATED. MOST OF THE SHOWERS/CLOUDS APPEAR TO BE JUST AHEAD OF AN UPPER TROUGH AXIS EXTENDING SW FROM ERN LOUISIANA TO 27N94W. A LARGE UPPER HIGH OVER THE SW U.S. INTERACTING WITH AN INVERTED UPPER TROUGH NEAR THE YUCATAN IS PRODUCING E TO NE FLOW ELSEWHERE OVER THE WRN GULF. ANOTHER UPPER HIGH IN THE WRN ATLC IS ADVECTING A SWATH OF VERY DRY MID TO UPPER AIR NW THROUGH THE STRAITS OF FLORIDA AND FAR SE FLORIDA...THOUGH COLLIDING BOUNDARIES HAS LED TO SOME FAIRLY STRONG TSTMS NEAR LAKE OKEECHOBEE OVER THE LAST FEW HOURS. THE CARIBBEAN SEA... THE MAIN FEATURE IN THE CARIB IS THE TROPICAL WAVE MOVING INTO THE WRN PORTION. FOR DETAILS REFER TO THAT SECTION ABOVE. IN THE WRN CARIB...AN UPPER LOW IS DRIFTING TO THE NW NEAR THE COAST OF BELIZE. LIFT TO THE E OF THIS UPPER LOW IS ALSO SUPPORTING THE CONVECTION NEAR THE TROPICAL WAVE. IN THE ERN CARIB...CONDITIONS ARE FAIRLY TRANQUIL IN RESPONSE TO MODERATE SUBSIDENCE. THERE ARE TYPICAL QUICK MOVING SHALLOW SHOWERS AND SOME PATCHES OF HIGH LEVEL CIRRUS ACROSS THE REGION...BUT NOT MUCH OF SIGNIFICANCE. AN INCREASE IN MOISTURE IS LIKELY OVER THE NEXT COUPLE OF DAYS AS THE LARGE TROPICAL WAVE IN THE TROPICAL ATLC APPROACHES. TRADES ARE ON THE FRESH TO STRONG SIDE IN THE CENTRAL CARIB N OF 12N BETWEEN 70W-80W...LIKELY ENHANCED SOME BY THE TROPICAL WAVE. THE ATLANTIC OCEAN... THE FRONT THAT HAS BEEN ALONG OUR NRN BORDER FOR THE PAST COUPLE OF DAYS HAS DRIFTED N AS IT HAS LOST MUCH OF ITS UPPER SUPPORT TO A STRENGTHENING UPPER RIDGE CENTERED NEAR 29N75W. THIS RIDGE IS SUPPLYING THE BAHAMAS AND FAR SE FLORIDA WITH FAIR WEATHER. DEBRIS MOISTURE...FROM THE ACTIVITY ALONG THE FRONT...IS GETTING PUSHED SWD BY STRONG NLY WINDS BETWEEN THE UPPER HIGH AND AN UPPER LOW NEAR 27N57W. THE REMAINDER OF THE UPPER PATTERN IS RATHER BENIGN WITH OVERALL LITTLE SIGNIFICANT MOISTURE BEING PRODUCED. THE SFC PATTERN IS DOMINATED BY A 1027 MB HIGH NEAR 35N36W. THE COMBINATION OF THIS HIGH PRES AND A LARGE AREA OF STABLE AIR ALOFT IS PRODUCING WIDESPREAD FAIR WEATHER N OF 18N E OF 55W. TYPICAL STABLE SCATTERED LOW-LEVEL STRATOCUMULUS ARE THE MAIN SOURCE OF CLOUD COVER ACROSS THIS REGION. TRADES ARE MODERATE...EXCEPT NEAR THE CARIB ISLANDS AND THE COAST OF NW AFRICA WHERE THE TIGHTENED PRES GRAD IS PRODUCING STRONGER WINDS. $$ WILLIS