000 AXNT20 KNHC 291726 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT THU MAR 29 2007 TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHEASTERN 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. ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 6N10W 3N23W EQ37W 1N50W. SCATTERED MODERATE CONVECTION IS WITHIN 150 NM EITHER SIDE OF THE AXIS BETWEEN 31W-41W. ISOLATED MODERATE IS WITHIN 150 NM EITHER SIDE W OF 41W. ...DISCUSSION... THE GULF OF MEXICO... A MID TO UPPER LEVEL RIDGE REMAINS WELL ESTABLISHED ACROSS THE AREA ALIGNED ALONG 87W. THIS RIDGE IS SUPPLYING THE REGION WITH ABUNDANT DRY AIR/SUBSIDENCE AS NOTED ON WV IMAGES. THE DRIEST AIR IS OVER THE NE GULF ALONG AND E OF THE RIDGE AXIS WHERE SOUNDING DATA FROM SEVERAL COASTAL SITES SHOW A STRONG CAP NEAR 850 MB. AT THE SFC...HIGH PRES IS ALSO IN CONTROL ANALYZED 1023 MB IN SE ALABAMA. THIS RIDGE IS PRODUCING 10 TO 20 KT E-SE WINDS ACROSS THE REGION...STRONGEST IN THE NW GULF WHERE THE PRES GRAD IS TIGHTENED IN RESPONSE TO LOW PRES OVER THE CENTRAL U.S. LOW-LEVEL CLOUD PATCHES AND EMBEDDED VERY LIGHT ISOLATED SHOWERS ARE PUSHING W ACROSS SE FLA...OTHERWISE FAIR TO MOSTLY CLEAR SKIES ARE THE RULE. LOOKING AHEAD INTO THE FIRST HALF OF THE WEEKEND...A BACK DOOR COLD FRONT WILL SURGE S DISSIPATING JUST E OF THE AREA. THIS FRONT MAY INCREASE CLOUD COVER SLIGHTLY TOMORROW OVER FL AND THE EXTREME ERN GULF BUT THE MAIN EFFECT IS THE REINFORCEMENT OF HIGH PRES BEHIND IT. THE STRONG HIGH IS FORECAST TO QUICKLY BUILD SWD FROM CANADA ON FRI AND THEN DRIFT E OFF THE SE U.S. COAST ON SAT. THIS PATTERN WILL INCREASE THE WINDS ACROSS THE GULF OVER THE NEXT COUPLE OF DAYS. THE CARIBBEAN SEA... MOST OF THE CARIB IS IN AN UPPER LEVEL CONFLUENT ZONE BETWEEN EXTENSIVE BROAD RIDGING OVER THE TROPICAL ATLC AND PRONOUNCED TROUGHING OVER A LARGE PORTION OF THE WRN ATLC. THIS HAS RESULTED IN ABUNDANT VERY DRY STABLE AIR ACROSS THE MAJORITY OF THE REGION. HOWEVER...THERE ARE THREE PATCHES OF CLOUDS/MOISTURE THAT CLIP A PORTION OF THE REGION. THE MOST SIGNIFICANT IS AN AREA OF WEAKENING MODERATE CONVECTION OVER ERN COLOMBIA AND WRN VENEZUELA. DEBRIS HIGH LEVEL MOISTURE IS STREAMING N AND E FROM THIS AREA OF RAIN STAYING CONTAINED S OF 14N E OF 76W. SIMILAR CLOUDINESS IS OVER EL SALVADOR...GUATEMALA AND THE YUCATAN PENINSULA IN A WEAK UPPER LEVEL DIFFLUENT ZONE. THE THIRD AREA IS ALMOST ENTIRELY N OF THE ERN CARIB ASSOCIATED WITH A 1011 MB LOW AND TROUGH 60 NM N OF THE NRN COAST OF PUERTO RICO. DOPPLER RADAR FROM SAN JUAN SHOWS SMALL LINES OF SHOWERS BEING DRIVEN TO THE S ON THE BACK SIDE OF THE LOW. THE TRADES ARE GENERALLY MODERATE ACROSS THE CARIB TODAY BUT THEY ARE SET TO INCREASE FROM W TO E INTO THIS WEEKEND AS CANADIAN HIGH PRES BUILDS SE. THE ATLANTIC OCEAN... STRONG UPPER LEVEL TROUGHING...EXTENDING SWD FROM A LARGE VORTEX OVER NEWFOUNDLAND...COVERS THE ATLC W OF ABOUT 50W. A PRONOUNCED SHORTWAVE IS ROTATING AROUND THE LARGE TROUGH CURRENTLY EXTENDING FROM 29N56W TO 19N64W. THIS SHORTWAVE TROUGH MAY BE STARTING TO ENERGIZE A 1011 MB SFC LOW JUST N OF PUERTO RICO NEAR 20N66W. A SFC TROUGH STRETCHES NE FROM THE LOW ALONG 20N66W 23N58W 27N49W. ALL OF THESE ELEMENTS ARE PRODUCING AN AREA OF SCATTERED SHOWERS WITHIN 120 NM W AND 180 NM E OF THE SFC TROUGH. FURTHER NW...A COLD FRONT IS PUSHING SWD DRAPED FAIRLY HORIZONTALLY ALONG 31N/32N BETWEEN 60W-75W THEN STATIONARY ACROSS THE SE U.S. A PRE-FRONTAL TROF LIES 120 NM AHEAD OF THE FRONT FROM 30N62W TO BEYOND 32N53W. NWP MODELS SHOW THIS FRONT MERGING WITH THE LOW/TROUGH OVER THE NEXT DAY OR TWO WHICH WILL SWEEP THE MOISTURE PLUME OFF TO THE E. AS THIS OCCURS...STRONG SFC HIGH PRES WILL BUILD SSE FROM CANADA INCREASING THE WINDS ACROSS MUCH OF THE W ATLC AND CARIB. THE REMAINDER OF THE ATLC...E OF 50W...IS UNDER THE INFLUENCE OF SLIGHT UPPER LEVEL RIDGING AND SCATTERED MID-HIGH LEVEL CLOUDS...ESPECIALLY N OF 20N. AT THE SFC...STRONG 1030 MB HIGH E OF THE AZORES CONTROLS THE PATTERN PRODUCING A LARGE AREA OF MODERATE TO STRONG TRADES. BASED ON THE PRES ANALYSIS AND THE AVAILABLE DATA THE STRONGEST WINDS ARE LIKELY E OF 30W FROM 15N-30N. $$ CANGIALOSI