000 AXNT20 KNHC 071805 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT THU MAY 07 2009 TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHERN SECTIONS OF SOUTH AMERICA...AND 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. ...THE ITCZ... THE ITCZ AXIS IS CENTERED ALONG 5N10W 2N19W CROSSING THE EQUATOR NEAR 24W AND CONTINUING S OF THE EQUATOR INTO NE BRAZIL NEAR 3S42W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 240 NM S OF THE AXIS BETWEEN 7W-10W. SIMILAR ACTIVITY IS ALONG THE EQUATOR BETWEEN 41W-46W. ...DISCUSSION... GULF OF MEXICO... WEAK MID AND UPPER LEVEL TROUGHING IS JUST EXITING THE GULF WITH THE TAIL END OF THE TROUGH EXTENDING FROM S CENTRAL FL SW TO THE STRAITS OF FL. IN ITS WAKE...MODERATE SUBSIDENCE WITH ASSOCIATED DRY STABLE AIR IN NW FLOW IS OBSERVED ACROSS THE GULF AS BROAD MID/UPPER LEVEL RIDGING W OF THE AREA SPREADS EWD KEEPING TRANQUIL CONDITIONS OVER THE GULF INTO THE WEEKEND. AT THE SURFACE A RIDGE WAS ANALYZED ALONG 29N E OF 95W. LATEST VISIBLE SATELLITE IMAGERY SHOWED GENERALLY MOSTLY CLEAR SKIES ACROSS THE GULF WITH THE EXCEPTION OF UPPER TEXAS AND SW LOUISIANA COASTS WHERE SCATTERED TO BROKEN LOW CLOUDS ARE BEING REPORTED. A FEW THIN STRANDS OF HIGH CIRRUS CLOUDS ARE MOVING EWD ACROSS THE FAR NRN PORTION OF THE NE GULF...WHILE A SMOKE PLUME FROM OVER SE MEXICO AND THE SW YUCATAN PENINSULA IS NOTED OVER THE SW GULF AND BAY OF CAMPECHE SW OF A LINE FROM FAR NE MEXICO TO CAMPECHE. VISIBILITIES OF 5-7 SM ARE BEING REPORTED BY MEXICAN REPORTING OBSERVATION SITES ALONG THE COAST. CARIBBEAN SEA... WEAK MID/UPPER LEVEL TROUGH IS MOVING E ACROSS THE FAR N CENTRAL PART OF THE SEA WHILE AT THE SAME TIME DAMPENING MID/UPPER LEVEL RIDGING TO ITS SW ACROSS CENTRAL AMERICA IS CREATING BASICALLY ZONAL FLOW OVER MUCH OF THE WRN AND CENTRAL CARIBBEAN. UPPER NW FLOW FROM THE GULF INTO THE NW PORTION OF THE SEA MERGES WITH THE ZONAL FLOW RESULTING IN UPPER LEVEL CONFLUENCE INTO THE BASE OF THE TROUGH WITH SUBSIDENCE PROVIDING STABLE A ENVIRONMENT TO THE CENTRAL AND WRN PORTIONS OF THE SEA. SCATTERED TO BROKEN SMALL CUMULUS CLOUDS WITH BRIEF PASSING ISOLATED SHOWERS AND WEAK ISOLATED TSTMS ARE NOTED OVER THE FAR WRN PORTION OF THE SW CARIBBEAN TO ALONG AND JUST INLAND THE ADJACENT CENTRAL AMERICA. TO THE E OF THE MID/UPPER LEVEL TROUGH...THE FLOW GRADUALLY BECOMES DIFFLUENT WHILE AT THE SURFACE A WEAK TROUGH EXTENDS FROM 17N74W N TO ACROSS THE WINDWARD PASSAGE AND INTO THE SE BAHAMAS. BOTH QUIKSCAT DATA AND BUOY OBSERVATIONS FROM THIS MORNING SHOWED MODERATE E-SE FLOW TO THE E OF THE TROUGH AND LIGHTER NE-E FLOW TO ITS W. THESE IS PRODUCING ENOUGH LOW-LEVEL SPEED CONVERGENCE UNDER THE DIFFLUENCE TO TRIGGER OFF A PERSISTENT BAND OF SCATTERED TO NUMEROUS SHOWERS AND TSTMS JUST S OF PUERTO RICO AND THE DOMINICAN REPUBLIC. LATEST MODEL GUIDANCE SUGGESTS THAT THIS ACTIVITY SHOULD PERSIST THROUGH THE WEEKEND...WITH LOCALLY HEAVY AMOUNTS OF RAIN POSSIBLE...UNTIL THE MID/UPPER TROUGH WEAKENS AS IT SLOWLY SHIFTS EWD INTO THE CENTRAL ATLC THROUGH SAT. ELSEWHERE S OF THE SHOWER AND TSTM ACTIVITY...THE ATMOSPHERE BECOMES DRY IN MODERATE SUBSIDENCE WITH VERY NARROW STREAMERS OF SMALL CUMULUS WITH POSSIBLE ISOLATED LIGHT SHOWERS EVIDENT S TO ABOUT 12N. CLEAR SKIES ARE SEEN S OF 12N. ATLANTIC OCEAN... THE REMAINDER OF THE MID/UPPER LEVEL TROUGH DESCRIBED UNDER GULF OF MEXICO EXTENDS NE TO BEYOND THE AREA AT 32N76W. TO ITS E...A MID/UPPER RIDGE EXTENDS FROM NEAR THE CENTRAL BAHAMAS NE TO NE OF THE AREA AT 32N71W. A SHARPENING SHORTWAVE TROUGH IS E OF THE RIDGE THROUGH 32N66W TO 25N67W. THE UPPER FLOW BECOMES ZONAL E OF THIS TROUGH...THEN RESPONDS TO A BROAD DEEP LAYER TROUGH OVER THE FAR ERN ATLC STRETCHING FROM 32N25W SW TO NEAR 24N32W. AT THE SURFACE...A TROUGH EXTENDS FROM 26N73W S THROUGH THE SE BAHAMAS AND INTO THE WINDWARD PASSAGE. SCATTERED SHOWERS AND A FEW TSTMS ARE WITHIN 90 NM NE OF THE TROUGH WHICH ARE ALSO ENHANCED BY THE MID/UPPER LEVEL TROUGH JUST TO THE W. A TINY VORT MAX SPUN OFF FROM THE TROUGH IS RACING N NEAR 30N75W WITH SCATTERED MODERATE CONVECTION WITHIN 45 NM OF IT. A 1030 MB HIGH CENTER IS JUST N OF THE AREA NEAR 33N54W WITH A RIDGE WSW TO 29N72W TO ACROSS NRN FL. PATCHES OF BROKEN LOW AND MID LEVEL CLOUDS WITH EMBEDDED SCATTERED SHOWERS AN ISOLATED WEAK CONVECTION ARE MOVING WWD IN MODERATE TO STRONG ESE FLOW S OF THE RIDGE AND E OF THE SURFACE TROUGH TO NEAR 52W. SOME SIGNS OF AFRICAN DUST/HAZE ARE NOTED OVER THE ERN ATLC S OF 25N E OF 56W...OTHERWISE THE ENVIRONMENT THERE REMAINS VERY SUPPRESSED WITH JUST THE TYPICAL SCATTERED TO BROKEN STRATOCUMULUS CLOUD FIELD PRESENT N OF THE ITCZ. $$ AGUIRRE