000 AXNT20 KNHC 211734 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT THU JUN 21 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. ...TROPICAL WAVES... A TROPICAL WAVE IS ALONG 29W S OF 12N MOVING W NEAR 20 KT. THIS WAVE IS LESS DEFINED THAN THE PAST FEW WHEN IN THIS VICINITY. SATELLITE IMAGES SHOW ONLY SLIGHT TURNING IN THE LOW-MID LEVELS ABOUT THE WAVE AXIS. ASSOCIATED SHOWER ACTIVITY IS MINIMAL AND MOSTLY AHEAD OF THE WAVE EMBEDDED IN THE ITCZ. A TROPICAL WAVE IS ALONG 43W S OF 12N MOVING W 15-20 KT. THIS WAVE HAS BECOME MORE CHALLENGING TO TRACK TODAY WITH THE CLOUDS/CONVECTION TAKING A LINEAR SHAPE SHUNTED BY LOW-LEVEL NELY FLOW AND ABSORBED BY THE ITCZ. A TROPICAL WAVE IS IN THE CENTRAL CARIBBEAN TITLED ALONG 71W/72W S OF 21N MOVING W NEAR 15 KT. MUCH OF THIS WAVE'S MOISTURE FIELD HAS BEING DRIVEN FAR TO THE NE ACROSS THE DOMINICAN REPUBLIC AND INTO THE ATLANTIC SHEARED BY STRONG MID-UPPER SWLY FLOW AHEAD OF A TROUGH. SIMILARLY TO THE WAVE IN THE CENTRAL ATLC...THIS FEATURE HAS BECOME LESS DEFINED TODAY WITH THE CURRENT PSN BASED MOSTLY ON FORWARD CONTINUITY. ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 8N13W 7N22W 8N27W 7N37W 5N52W. SCATTERED MODERATE CONVECTION IS WITHIN 150 NM N OF THE AXIS BETWEEN 34W-43W. ISOLATED MODERATE IS WITHIN 90 NM S OF THE AXIS BETWEEN 19W-22W AND WITHIN 60 NM N E OF 15W. ...DISCUSSION... THE GULF OF MEXICO... WEAK LOW PRES TROUGHING COVERS THE E GULF ASSOCIATED WITH A SLOW MOVING 1013 MB LOW CENTERED OVER NE FLORIDA. ISOLATED SHOWERS AND TSTMS ARE STARTING TO FIRE UP OVER THE FL PENINSULA SUPPORTED BY THIS LOW-LEVEL TROUGH. MODEST RIDGING EXTENDS SW FROM A 1021 MB CENTER IN THE MIDWEST TOWARD THE BAY OF CAMPECHE. THIS OVERALL WEAK PRES PATTERN IS PROVIDING THE AREA WITH LIGHT WINDS AND LOW SEAS. ALOFT...THE FLOW IS PRIMARILY NLY ON THE WRN PERIPHERY OF A HIGH CENTERED OVER SRN MEXICO NEAR 20N99W. A WEAK INVERTED TROUGH ALONG 87W/88W IS INTERRUPTING THE RIDGING ALLOWING MOST OF THE UPPER FLOW TO BE LIGHT IN ITS VICINITY. THIS UPPER PATTERN IS NOT GENERATING MUCH MOISTURE WITH ONLY A MID-HIGH LEVEL CLOUD DECK AND EMBEDDED ISOLATED SHOWER/TSTM ACTIVITY W OF 93W. LOOKING AHEAD...NWP MODELS GENERALLY SHOW LITTLE MOVEMENT OF THE LOW OR REMNANT TROUGH. THIS WILL ALLOW THE SFC FLOW TO REMAIN LIGHT FOR ANOTHER DAY OR SO. THEREAFTER...SFC WINDS AND MOISTURE MAY INCREASE ACROSS THE SRN WATERS AS THE NRN EXTENSION OF THE CARIB TROPICAL WAVE APPROACHES. THE CARIBBEAN SEA... ACTIVE WEATHER IS IN THE SW CARIB WHERE LARGE CLUSTERS OF NUMEROUS MODERATE/SCATTERED STRONG CONVECTION IS S OF 16N W OF 79W. THERE APPEARS TO BE SEVERAL ELEMENTS CONTRIBUTING TO THIS STRONG ACTIVITY. ONE FACTOR IS UPPER DIFFLUENCE BETWEEN AN UPPER HIGH CENTERED OVER SRN MEXICO AND ANOTHER CENTER OVER THE WINDWARD ISLANDS. ANOTHER FACTOR IS FORCING IN THE LOW TO MID LEVELS. WHILE THE ITCZ IS PROVIDING SOME OF THIS FORCING...I AM A LITTLE MORE CONVINCED THAT THERE IS A TROPICAL WAVE PROVIDING SUPPORT FOR MAINTAINING THIS WWD PROPAGATION OF CONVECTION. THIS WILL BE FURTHER ANALYZED AND POSSIBLY ADDED TO THE 18Z ANALYSIS. ELSEWHERE...SKIES ARE MOSTLY FAIR BESIDES FOR SHEARED LIGHT SHOWER ACTIVITY OVER THE DOMINICAN REPUBLIC AND WINDWARD PASSAGE...ASSOCIATED WITH THE CENTRAL CARIB TROPICAL WAVE. TRADE WINDS REMAIN ON THE STRONG SIDE...20 TO 30 KT...IN THE CENTRAL CARIB AS INDICATED BY A 1022 UTC QSCAT PASS. THESE STRONG WINDS ARE ANTICIPATED TO PERSIST AND EXPAND WWD SLIGHTLY OVER THE NEXT COUPLE DAYS. THE ATLANTIC OCEAN... INTERESTING AREA OF LOW PRES...ANALYZED 1013 MB...HAS BROKEN OFF THE TAIL END OF AN ATLC FRONT CENTERED JUST S OF ST AUGUSTINE FLA. 88-D DATA FROM JAX SHOWS SCATTERED SHOWERS AND TSTMS FLARING UP A BIT ON THE E SIDE OF THE CIRCULATION N OF 29N BETWEEN 77W-80W. IN GENERAL...NWP MODELS FORECAST LITTLE MOVEMENT OR DEVELOPMENT OF THIS SYSTEM. FARTHER E...AN UPPER TROUGH CUTS ACROSS THE AREA FROM 32N62W SW ACROSS THE SE BAHAMAS. DIFFLUENCE AND SWLY FLOW E OF THE TROUGH AXIS IS SHEARING THE TROPICAL WAVE IN THE CENTRAL CARIB AND GENERATING MOISTURE...MOSTLY SCATTERED SHOWERS...S OF 25N BETWEEN 52W-70W. OTHERWISE...A SFC HIGH PRES RIDGE IS IN CONTROL RUNNING FROM A 1029 MB HIGH S OF THE AZORES NEAR 35N24W TO A 1022 MB CENTER NEAR 27N62W. THIS NARROW RATHER LOW-LATITUDE RIDGE IS ALLOWING WINDS TO BE LIGHT TO MODERATE ACROSS MOST OF THE ATLC DISCUSSION AREA. THE EXCEPTION IS NEAR THE AFRICAN COAST WHERE THE PRES GRADIENT IS TIGHTENED BETWEEN THE AZORES HIGH AND INVERTED TROUGHING OVER THE CONTINENT. THE COMBINATION OF THIS HIGH PRES ALONG WITH DRY STABLE AIR ALOFT ASSOCIATED WITH AN UPPER RIDGE ALONG 24W/25W IS PROVIDING TRANQUIL CONDITIONS ACROSS THE E AND MOST OF THE TROPICAL ATLC. ENHANCING STABILITY FURTHER IS A PLUME OF SAHARAN DUST LOCATED BEHIND THE TROPICAL WAVE ALONG 29W. $$ CANGIALOSI