000 AXNT20 KNHC 262335 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT TUE JUN 26 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 2315 UTC. ...TROPICAL WAVES... A TROPICAL WAVE IS ALONG 34.5W S OF 16N MOVING W 12 KT. SCATTERED MODERATE AND ISOLATED STRONG CONVECTION IS NOTED WITHIN 150 NM W AND WITHIN 180 NM E OF THE WAVE AXIS. A TROPICAL WAVE IS ALONG 69.5W S OF 23N MOVING W AT 12 KT. UPPER DIFFLUENCE...BETWEEN AN UPPER TROUGH NEAR THE BAHAMAS AND AN UPPER RIDGE OVER THE NE CARIBBEAN...ENHANCED AFTERNOON CONVECTION OVER HISPANIOLA...WESTERN PUERTO RICO AND NEAR 23N69W. THESE CONVECTIVE FLARE UPS MASK THE TRUE WAVE AXIS POSITION. SUBSIDENCE OVER THE CENTRAL CARIBBEAN IS SUPPRESSING CONCENTRATED CONVECTION AND ONLY TRADE WIND CUMULUS IS NOTED. AN ELY SURGE IN THE LOW LEVEL FLOW ACCOMPANIES THIS WAVE AS WELL AS A LARGE AREA OF SAHARAN DUST...WHICH HAS ITS WESTERN EDGE ALONG 72.5W AT THE MOMENT...AND EXTENDS E ACROSS THE WINDWARDS WITH MOST ISLANDS REPORTING OBSTRUCTIONS TO VISIBILITY...DUR E TO EITHER DUST OR HAZE. A TROPICAL WAVE EXTENDS FROM COSTA RICA TO THE N COAST OF CUBA AT 23N...ESTIMATED TO BE MOVING W AT 12 KT. SEABREEZE CONVECTION OVER W CUBA APPEARS TO HAVE BEEN ENHANCED BY THE WAVE WITH A CELLS PROPAGATING W INTO THE YUCATAN CHANNEL...IN THE DISSIPATING STAGE AT THE MOMENT. A LARGE CLUSTER OF STRONG CONVECTION IS NOTED OVER CHIRIQUI PANAMA EXTENDING W THROUGH EASTERN COSTA RICA...AND EXTENDING N INTO THE CARIBBEAN TO NEAR 11N81W. CONCENTRATED CONVECTION...BUT ONLY TOWERING CUMULUS... ARE OVER THE CARIBBEAN NEAR 19.5N81.5W...VERIFIED BY A LACK OF LIGHTNING HITS. ...THE ITCZ... THE ITCZ AXIS IS CENTERED ALONG 10N14W 8N23W 8N34W 6N54W AND IS FOR THE MOST PART LOCATED SLIGHTLY N OF ITS ASSOCIATED CLOUDS AND CONVECTION. OTHER THAN CONVECTION ASSOCIATED WITH THE WAVE NEAR 35W...ONLY ISOLATED MODERATE CONVECTION IS NOTED WITHIN 180 NM S OF THE ITCZ AXIS BETWEEN 13W AND 32W AND THEN W OF THE TROPICAL WAVE BETWEEN 38W AND 44W. ...DISCUSSION... THE GULF OF MEXICO... AN UPPER ANTICYCLONE HAS MOVED W ACROSS CENTRAL OLD MEXICO INTO THE E PAC TO A POSITION NEAR 19N104W...BUT ITS ENVELOPE OF ANTICYCLONIC FLOW STILL EXTENDS E ACROSS CENTRAL MEXICO AND OVER THE GULF OF MEXICO TO THE W OF 91W. UPPER DEBRIS MOISTURE...THAT ORIGINATED FROM CONVECTION OVER INTERIOR OLD MEXICO AND OVER NE TEXAS AND THE MISSISSIPPI DELTA OF THE UNITED STATES...CONTINUES TO SPREAD S IN THE ANTICYCLONIC FLOW TO ALONG 18N OVER BETWEEN 87W AND 95W WHERE THE MOISTURE EVAPORATES. AN UPPER TROUGH LIES ACROSS THE CENTRAL GULF...FROM 31N85W S THROUGH A WEAK UPPER CYCLONE AT 22N88W AND CONTINUING S OVER THE YUCATAN PENINSULA TO BASE NEAR 17N89W. THE UPPER TROUGH HAS INDUCED A LOW LEVEL TROUGH FROM 21N87W TO 28N84W WHICH IS MOVING W WITH TIME. SCATTERED MODERATE CONVECTION...WITH TSTMS ACTIVITY CONCENTRATED NEAR 25N85W BASED ON LIGHTNING DATA...ACCOMPANIES THE TROUGH. THE NORTHERN EXTENSION OF A TROPICAL WAVE IS CURRENT MOVING THROUGH W CUBA...AND WILL MOVE THROUGH THE YUCATAN CHANNEL TONIGHT AND WILL LIKELY BE ACCOMPANIED BY CONVECTION ENHANCED E OF THE UPPER TROUGH. OTHERWISE RIDGING FROM THE ATLC DOMINATES THE LOW LEVELS. THE CARIBBEAN SEA... AN UPPER TROUGH EXTENDS S THROUGH THE NW BAHAMAS TO AN UPPER CYCLONE NEAR THE YUCATAN PENINSULA AND CONTINUES S TO NEAR BELIZE. AN UPPER ANTICYCLONE IS OVER NW VENEZUELA. THUS...THE UPPER FLOW IS SOUTHWESTERLY OVER MOST OF THE CARIBBEAN. DEBRIS MOISTURE...FROM CONVECTION ASSOCIATED WITH A TROPICAL WAVES OVER THE W CARIBBEAN THE CENTRAL CARIBBEAN...AND AFTERNOON SEABREEZE CONVECTION OVER CUBA AND HISPANIOLA...IS ADVECTED ENE INTO THE SUBTROPICAL SW ATLC. A BAND OF DRY UPPER AIR IS INDICATED ACROSS THE CENTRAL CARIBBEAN AND IS SUPPRESSING CONVECTION. THE LOW LEVEL FLOW IS ELY AND QUITE BRISK...STREAMING BANDS OF TRADE WIND CUMULUS AND BRIEF LIGHT SHOWERS...ACROSS THE AREA TO THE S AND E OF JAMAICA. WIDESPREAD DUST IS ALSO SPREADING W ACROSS THE AREA...CURRENTLY E OF 74W. ALTHOUGH BARBADOS IS STILL EXPERIENCING REDUCED VISIBILITY...THE LAST HIGH RESOLUTION VISIBLE IMAGERY OF THE DAY INDICATES THE THE EASTERN EDGE OF THE DUST IS ALONG 58W...SO VISIBILITY CONDITIONS SHOULD IMPROVE IN THE WINDWARDS ON WED. THE ATLANTIC OCEAN... AN UPPER CYCLONE HAS NEARLY CUT OFF...FROM ITS PARENT MID ATLC UPPER TROUGH...OVER THE BAHAMAS NEAR 26N78W. AN ASSOCIATED SURFACE LOW THAT SPUN OVER THE ATLC WATERS E OF N FLORIDA FOR SEVERAL DAYS HAS WEAKENED INTO A SURFACE TROUGH...AND IS STILL EVIDENT OVER THE NW BAHAMAS. BOTH SYSTEMS ARE SLOWLY SHIFTING WESTWARD WITH TIME. INITIALLY...DRY UPPER AIR AND RESULTANT SUBSIDENCE...WILL SUPPRESS CONVECTION OVER FLORIDA...BUT AS THE UPPER DIFFLUENCE LOCATED OF THE UPPER LOW...MOVES OVER THE NW BAHAMAS AND FLORIDA...CONDITIONS WILL BECOME FAVORABLE FOR AN INCREASE IN CONVECTION...ESPECIALLY DURING AFTERNOON PEAK HEATING. A TROPICAL WAVE OVER THE ATLC E OF THE EXTREME SE BAHAMAS NEAR HISPANIOLA IS ALSO MOVING WESTWARD. THE NORTHERN EXTENSION OF THIS WAVE WILL MOVE THROUGH THE BAHAMAS AND THE STRAITS OF FLORIDA THROUGH THE REMAINDER OF THE WEEK...AND LIKELY ALSO INCREASE THE CHANCE FOR RAIN E OF ITS AXIS. AN UPPER RIDGE EXTENDS N FROM THE E CARIBBEAN INTO THE SW ATLC BETWEEN 73W AND 58W AND ADVECTS UPPER DEBRIS CIRRIFORM CLOUDS NE OVER THE SUBTROPICAL ATLC UNDER THE RIDGE. ANOTHER UPPER TROUGH EXTENDS ACROSS THE CENTRAL ATLC INTO THE AREA FROM 31N47W TO AN UPPER CYCLONE NEAR 19N51W WITH THE TROUGH CONTINUING S TO BASE AT 10N56W. DRY UPPER AIR ACCOMPANIES THIS TROUGH WITHIN 150 NM EITHER SIDE OF LINE 31N47W 23N51W AND ELSEWHERE FROM 23N TO 7N BETWEEN 54W AND 63W. ANOTHER UPPER TROUGH IS NOTED OVER THE FAR E ATLC ALONG 31N14W TO 23N30W. AN UPPER RIDGE EXTENDS W OFF THE AFRICAN COAST ALONG 17N10W TO 17N20W. SCATTERED TO LOCALLY BROKEN LOW CLOUDS ARE NOTED N OF THE ITCZ E OF 50W. $$ NELSON