000 AXNT20 KNHC 031147 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 705 AM EST MON DEC 03 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1115 UTC ...THE ITCZ... ITCZ IS CENTERED ALONG 7N12W 6N23W 7N35W 5N42W 3N51W. AXIS IS ACTIVE THIS MORNING WITH SCATTERED MODERATE/ISOLATED STRONG CONVECTION COVERING A LARGE AREA FROM 4N-8N BETWEEN 17W-31W. SIMILAR CONVECTION IS WITHIN 150 NM OF THE AXIS E OF 14W AND BETWEEN 31W-34W. A SFC TROUGH ALONG 43W/44W IS ENHANCING SCATTERED MODERATE/ISOLATED STRONG FROM 4N-9N BETWEEN 38W-47W. DISCUSSION... THE GULF OF MEXICO... A DIGGING MID TO UPPER SHORTWAVE OVER THE NW GULF IS SUPPORTING A COLD FRONT...WHICH AS OF 09Z EXTENDED FROM THE WRN FL PANHANDLE TO JUST S OF BROWNSVILLE TEXAS NEAR 25N98W. LOW-LEVEL CONVERGENCE NEAR THE BOUNDARY IS GENERATING A NARROW LINE OF SCATTERED SHOWERS AND TSTMS WITHIN 60 NM AS NOTED IN MOSAIC DOPPLER RADAR. NW GULF BUOYS SHOW NLY WINDS SIGNIFICANTLY INCREASING UP TO 30 KT WITH HIGHER GUSTS BEHIND THE FRONT. THIS STRONG FLOW IS ADVECTING A COOLER AND MUCH DRIER AIRMASS INTO THE NW WATERS. DEWPOINTS HAVE FALLEN INTO THE 20'S F ACROSS MUCH OF TEXAS AND A ONE HOUR 17 DEG F DEWPOINT DROP WAS REPORTED IN BROWNSVILLE. THE REMAINDER OF THE GULF IS VERY TRANQUIL AT THE MOMENT WITH LIGHT AND VARIABLE WINDS AND ONLY A FEW PATCHY CLOUDS SUPPRESSED BY WIDESPREAD STABLE AIR ALOFT. THE FRONT IS EXPECTED TO CONTINUE ITS SE PROGRESS ALLOWING THE AIRMASS CHANGE...ALBEIT MODIFYING ...TO SPREAD ACROSS MOST OF THE AREA WITHIN THE NEXT 24-36 HOURS. THE CARIBBEAN SEA... BRISK LOW-LEVEL NE WINDS TO THE W OF A LOW PRES SYSTEM IN THE CENTRAL ATLC IS DRIVING STREAMS OF LOW-LEVEL CLOUDS AND SHOWERS ACROSS THE LEEWARD ISLANDS AND INTO THE CENTRAL CARIB ROUGHLY FROM 14N-17N E OF 78W. THIS CLOUDINESS IS DEEPEST ROUGHLY MIDWAY BETWEEN SOUTH AMERICA AND HISPANIOLA LIKELY DUE TO WIND SPEED CONVERGENCE WHICH WAS CLEARLY EVIDENT IN EARLIER ASCAT DATA. HIGHLY ELONGATED MID TO UPPER TROUGHING AND VERY DRY AIR ALOFT COVERS MUCH OF THE CENTRAL AND E CARIB. THIS IS HELPING TO KEEP MOST OF THE MENTIONED SHOWER ACTIVITY FAIRLY SHALLOW. THE WRN CARIB IS EXPERIENCING FAIR WEATHER UNDER THE INFLUENCE OF MID TO UPPER RIDGING AND ABUNDANT SUBSIDENCE. NELY TRADE WIND FLOW IS STRONGEST...20-25 KT...IN THE N CENTRAL CARIB THIS MORNING. THESE WINDS ARE EXPECTED TO SLACKEN BELOW 20 KT BASIN WIDE AROUND THIS TIME TOMORROW. THE ATLANTIC OCEAN... VERTICALLY STACKED RIDGING IS THE THEME ACROSS THE W ATLC. WATER VAPOR IMAGERY SHOWS AN EXTENSIVE AREA OF DRY AIR S OF 22N W OF 55W BUT THIS IS SOMEWHAT DECEIVING AS SCATTERED TO BROKEN PATCHES OF CLOUDINESS/SHOWERS LIE UNDERNEATH THIS INVERSION. THE SFC HIGH CENTER IS ANALYZED 1023 MB VERY NEAR BERMUDA ALLOWING ELY WINDS TO BE LIGHT N OF 27N AND MODERATE TO FRESH S OF THERE. IN THE CENTRAL ATLC...A SLOWLY WEAKENING FRONTAL BOUNDARY IS ANALYZED FROM 32N43W TO 25N55W THEN DISSIPATING TO 23N69W. THIS FRONT APPEARS AS IF IS ABOUT TO MERGE WITH A QUASI-STATIONARY 1010 MB LOW NEAR 23N52W. SHIP BATFR13 JUST W OF THE LOW CENTER HAS BEEN VERY HELPFUL IN ANALYZING THE MIN PRES. CONVECTION HAS BEEN ON A STEADY DECREASE OVERNIGHT WITH ONLY ISOLATED MODERATE REMAINING FROM 21N-24N BETWEEN 48W-51W. A LARGER AREA OF CLOUDINESS AND EMBEDDED SCATTERED SHOWERS IS LOCATED TO THE E OF THE SFC LOW IN AN UPPER DIFFLUENT ZONE BETWEEN 37W-45W N OF 18N. ANOTHER QUASI-STATIONARY SFC TROUGH IS ALONG 55W/56W FROM 9N-16N. NIGHT CHANNEL VIS IMAGES AND ASCAT DATA SUGGESTS THAT AN ILL STRUCTURED 1010 MB LOW HAS FORMED ALONG THE TROUGH AXIS NEAR 13N. SCATTERED SHOWERS AND TSTMS ARE LOCATED TO THE E OF THE TROUGH/LOW... SHEARED BY UPPER SWLY FLOW...FROM 13N-15N BETWEEN 52W-54W. THE ERN ATLC IS DOMINATED BY SFC RIDGING EXTENDING SWD FROM A 1028 MB HIGH MIDWAY BETWEEN THE AZORES AND THE IBERIAN PENINSULA. NE TO ELY TRADES ARE STRONGEST FROM 14N-25N E OF THE CAPE VERDE ISLANDS AS SUGGESTED BY RECENT SCATTEROMETER PASSES. THE MID AND UPPER FLOW IS MAINLY W TO NW ACROSS THIS REGION BETWEEN RIDGING STRETCHING NWD FROM THE EQUATOR...AND A HIGHLY ELONGATED UPPER TROUGH EXTENDING SW FROM EUROPE THRU THE CANARY ISLANDS. STRONG FLOW BETWEEN THESE SYSTEMS IS ADVECTING HIGH LEVEL CLOUDINESS MAINLY S OF 22N. A WEAK UPPER LOW CENTERED NEAR 29N24W IS PRODUCING SIMILAR CLOUDINESS WITHIN 90 NM OF THE CENTER. $$ CANGIALOSI