000 AXNT20 KNHC 090116 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT FRI JUN 08 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 ALONG 33W S OF 12N MOVING W 10-15 KT. THIS WAVE HAS LOST A GREAT DEAL OF ITS STRUCTURE AND CONVECTION SINCE YESTERDAY AND MAINLY CONSISTS OF WEAK TURNING IN LOW CLOUDS. THE PSN OF THE WAVE FOLLOWS CONTINUITY AND IS PLACED ON THE UPSHEAR SIDE OF ASSOCIATED SCATTERED SHOWERS AND ISOLATED TSTMS WITHIN 240 NM W OF THE AXIS. A TROPICAL WAVE IS ALONG 56W S OF 11N MOVING W NEAR 10 KT. WAVE PASSAGE WAS EVIDENT IN THE RAOBS AT CAYENNE FRENCH GUIANA BETWEEN 07/1100 UTC AND 07/2300 UTC. EARLIER CONVECTION NOTED WITH THE WAVE HAS DECREASED MARKEDLY OVER THE PAST SEVERAL HOURS WITH ONLY ISOLATED MODERATE CONVECTION NOTED FROM 8N TO 10N WITHIN 90-120 NM E OF THE WAVE AXIS. A TROPICAL WAVE SLIGHTLY RELOCATED ACROSS THE SRN CARIB ALONG 69W/70W S OF 15N IS MOVING W NEAR 15 KT. THE UPPER AIR TIME SECTION FROM TRINIDAD SHOWED A CLEAR WAVE PASSAGE EARLY IN THE DAY YESTERDAY. THIS WAVE REMAINS LARGELY VOID OF DEEP CONVECTION AS THE FEATURE PRESSES WESTWARD IN A STRONGLY SUBSIDENT ENVIRONMENT. HOWEVER...24-H PRES TENDENCIES IN THE SE CARIB SHOW A RATHER PRONOUNCED 2-3 MB DROP SHOWING THE STRENGTH OF THIS FEATURE. A TROPICAL WAVE OVER THE EPAC ALONG 90W S OF 13N MOVING W 10-15 KT. THIS WAVE WAS CHALLENGING TO TRACK OVER THE PAST FEW DAYS WITH LITTLE WAVE SIGNATURE NOTED IN SFC OBS OR SATELLITE IMAGES. HOWEVER...THIS MORNING'S VIS PICTURES SHOWS A FAIR AMOUNT OF LOW TO MID LEVEL CYCLONIC TURNING NEAR 10N90W...LEADING TO THE SHIFTED PSN. FOR MORE DETAILS REFER TO THE EAST PACIFIC TWD...MIATWDEP. ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 5N9W 5N31W 6N35W 4N44W 6N53W. CLUSTERS OF SCATTERED MODERATE TO STRONG CONVECTION IS WITHIN 240 NM N OF THE AXIS E OF 15W. THIS ACTIVITY IS OCCURRING AHEAD OF WHAT APPEARS TO BE A TROPICAL LARGE WAVE OF LARGE AMPLITUDE THAT IS STILL INLAND OVER AFRICA ROUGHLY ALONG 8W. TONIGHTS TIME SECTIONS SHOULD PROVIDE BETTER DETAIL ON THIS SYSTEM WHICH MAY BE ADDED TO THE TROPICAL SURFACE ANALYSIS WITHIN THE NEXT DAY OR TWO AS IT PUSHES OFF THE AFRICAN COAST. ELSEWHERE ALONG THE ITCZ...ONLY ISOLATED TO SCATTERED MODERATE CONVECTION WAS NOTED WITHIN 180 NM N OF THE AXIS BETWEEN 20W AND 30W. ...DISCUSSION... THE GULF OF MEXICO... THE WRN EXTENSION OF A W ATLC SFC RIDGE STRETCHES ACROSS FLORIDA INTO THE GULF ALONG 29N. THIS RIDGE IS PRODUCING MODERATE TO FRESH SELY RETURN FLOW IN THE MID AND W GULF...WITH LIGHTER WINDS IN THE E GULF CLOSER TO THE HIGH PRES CENTER. ALOFT...THE PATTERN IS CONFLUENT BETWEEN AN UPPER HIGH CENTERED OVER S MEXICO NEAR 18N100W AND AN UPPER LOW OVER SE FLORIDA. THIS PATTERN IS LEADING TO A DRY STABLE AIRMASS ACROSS THE MAJORITY OF THE REGION AIDING IN THE WIDESPREAD FAIR WEATHER. HOWEVER... INSTABILITY NEAR THE UPPER LOW IS FUELING SCATTERED SHOWERS AND TSTMS ACROSS THE SRN THIRD OF THE FLORIDA PENINSULA...RADAR DATA FROM MIAMI INDICATED CYCLONIC TURNING IN THE REFLECTIVITY OVER ERN MIAMI-DADE COUNTY MOVING SW TOWARD THE UPPER KEYS. ADDITIONAL STORMS WITH FREQUENT LIGHTNING STRIKES WERE NOTED OVER THE FLORIDA STRAITS. THE WEEKEND LOOKS TRANQUIL OVER THE GULF WITH SFC WINDS ANTICIPATED TO RELAX AS WEAK HIGH PRES DEVELOPS AND SETTLES IN THE N CENTRAL GULF. THE CARIBBEAN SEA... THE MOST ACTIVE WEATHER IN THE REGION REMAINS OVER PANAMA... COSTA RICA AND THE EXTREME SW CARIB WHERE SATELLITE IMAGERY AND LIGHTNING DATA DEPICT SCATTERED MODERATE/STRONG CONVECTION S OF 11N W OF 77W. THIS ACTIVITY APPEARS MOSTLY TIED TO THE ITCZ WITH SOME ENHANCEMENT FROM DIFFLUENCE ALOFT. OTHERWISE...TROPICAL WAVES ARE THE MAIN ISSUE OVER THE REGION WITH ONE IN THE SE CARIB AND THE OTHER APPROACHING THE WINDWARD ISLANDS. THE LATTER IS AIDING IN SCATTERED SHOWERS AND TSTMS ACROSS THE LESSER ANTILLES. FOR MORE DETAILS REFER TO THE TROPICAL WAVES SECTION ABOVE. OTHERWISE...MODERATE TO FRESH TRADES AND FAIR WEATHER DOMINATE AS A LARGE AREA OF DRY SINKING AIR LIES ALOFT ASSOCIATED WITH WEAK UPPER RIDGING. ATLANTIC OCEAN... INSTABILITY ASSOCIATED WITH A WELL DEFINED UPPER LOW SPINNING OVER S FLA IS FUELING SCATTERED SHOWERS AND TSTMS OVER THE BAHAMAS...S FLORIDA AND THE FLORIDA STRAITS MAINLY IN AN AREA S OF 26N W OF 74W. THE STRONGEST ACTIVITY IS NOW LOCATED S OF THE UPPER LOW MAINLY ACROSS THE FLORIDA STRAITS AND ANDROS ISLAND. OTHERWISE...SFC HIGH PRES RIDGE RULES WITH A 1021 MB CENTER NEAR 31N72W. FARTHER NE...A LARGE VERTICALLY STACKED LOW PRES AREA IS LOCATED NEAR 38N60W. THIS SYSTEM IS PROVIDING LIMITED SUPPORT FOR A WEAKENING COLD FRONT WHICH EXTENDS FROM 32N55W TO 26N63W. SCATTERED SHOWERS ARE WITHIN 120 NM E OF THE FRONT AND N OF 24N BETWEEN 47W-52W IN AN ASSOCIATED UPPER DIFFLUENT ZONE. MUCH OF THE CENTRAL AND EASTERN ATLC DISCUSSION AREA IS UNDER THE INFLUENCE OF WEAK SFC HIGH PRES RIDGING RESULTING IN LIGHT WINDS. UPPER LOW WITH MEAN CENTER NEAR 29N42W IS BECOMING ELONGATED AND MAY OPEN UP INTO A TROUGH. THIS FEATURE APPEARS TO BE GENERATING ISOLATED TSTMS NEAR 28N43W AND AN AREA OF CIRRUS CLOUDS WITHIN A DIFFLUENT AXIS. A S-SWLY JET ORIGINATES NEAR THE BASE OF THE ASSOCIATED TROUGH NEAR 14N49W AND CONTINUES NE ALONG 22N40W 31N37W THEN TURNS EWD TO THE S OF A LARGE DEEP LAYERED OCCLUDED LOW PRES SYSTEM E OF THE AZORES NEAR 40N21W. $$ COBB