000 AXNT20 KNHC 181140 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 705 AM EST SUN NOV 18 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. ...TROPICAL WAVES... TROPICAL WAVE IS IN THE E CARIBBEAN ALONG 65W S OF 17N MOVING W 15 KT. NIGHT CHANNEL VIS IMAGES SHOWS A FAINT AREA OF CYCLONIC TURNING IN THE THIN LOW-LEVEL CLOUD FIELD SURROUNDING THE AXIS. ISOLATED SHOWERS TRAIL THE WAVE AXIS OVER THE WINDWARD AND SRN LEEWARD ISLANDS. A MORE ORGANIZED AREA OF SHOWERS LIE TO THE W OF THE WAVE FROM 13N-15N BETWEEN 67W-71W...BUT ITS NOT CLEAR IF THIS IS DIRECTLY ASSOCIATED WITH THIS FEATURE. TROPICAL WAVE IS IN THE W CARIBBEAN ALONG 79W/80W S OF 17N MOVING W 10-15 KT. THE INTERACTION BETWEEN THIS WEAK WAVE...REMNANT TROUGHING FROM AN OLD FRONT AND OVERALL LOW-LEVEL CONFLUENCE NEAR THE ITCZ IS PRODUCING A LARGE CLUSTER OF SCATTERED MODERATE CONVECTION FROM 10N-12N BETWEEN 76W-83W AND SCATTERED SHOWERS AND ISOLATED TSTMS FROM 15N-18N BETWEEN 81W-84W. ...THE ITCZ... ITCZ IS CENTERED ALONG 10N14W 5N25W 6N40W 7N50W 7N60W. THE ITCZ IS ACTIVE THIS MORNING LIKELY AIDED BY AN UPPER JET N OF THE REGION. SCATTERED MODERATE CONVECTION IS WITHIN 90 NM OF THE AXIS BETWEEN 17W-28W. SIMILAR CONVECTION IS WITHIN 180 NM N AND 120 NM S OF THE AXIS BETWEEN 31W-40W AND WITHIN 150 NM N OF THE AXIS BETWEEN 44W-57W. DISCUSSION... THE GULF OF MEXICO... SFC HIGH PRESSURE HAS NOW MOVED E OF THE AREA CENTERED IN THE W ATLC. THIS HAS ALLOWED WINDS TO SHIFT E TO SE ACROSS THE REGION ...WHICH HAS GREATLY MODIFIED THE VERY COOL AIRMASS THAT WAS IN PLACE OVER THE PAST COUPLE OF DAYS. FAIR WEATHER DOMINATES ABOUT THREE-FOURTHS OF THE AREA WITH SAT IMAGES DEPICTING THINNING STRATOCUMULUS CLOUDS IN THE CENTRAL AND ERN GULF. DEEPER MOISTURE IS AVAILABLE OVER NE MEXICO...THE NW GULF AND PORTIONS OF E TEXAS AND W LOUISIANA ROUGHLY N OF 24N W OF 92W. THIS MOISTURE IS ASSOCIATED WITH DIFFLUENCE ALOFT TO THE E OF A SHARP SHORTWAVE TROUGH AIDED BY MOIST LOW-LEVEL RETURN FLOW. DOPPLER RADAR AND LIGHTNING DATA REVEAL A FAIRLY IMPRESSIVE MCS OVER WRN LOUISIANA WITH ACTIVITY MORE SCATTERED IN NATURE ACROSS THE WRN GULF WATERS. FLATTENED MID TO UPPER LEVEL RIDGING AND STABLE AIR CONTROL THE PATTERN ALOFT ACROSS THE REMAINDER OF THE REGION. THE CARIBBEAN SEA... THE INTERACTION BETWEEN REMNANT TROUGHING FROM AN OLD FRONT...A TROPICAL WAVE IN THE SW CARIB AND LOW-LEVEL CONVERGING FLOW NEAR THE COASTS OF PANAMA...COSTA RICA AND NICARAGUA ARE PRODUCING A LARGE CLUSTER OF SCATTERED MODERATE CONVECTION FROM 10N-12N BETWEEN 76W-83W. SCATTERED SHOWERS AND ISOLATED TSTMS ARE ALSO FROM 15N-18N BETWEEN 81W-84W. SWLY FLOW ALOFT ON THE UPWARD SIDE OF BROAD RIDGING IS ALSO SUPPORTING THIS ACTIVITY. A WEAKENING AREA OF CONVECTION S OF HISPANIOLA FROM 13N-15N BETWEEN 67W-71W COULD BE SOMEWHAT SUPPORTED BY LOW-LEVEL SPEED CONVERGENCE AS NOTED IN RECENT SCATTEROMETER PASSES. THESE PASSES INDICATE WINDS NEAR 25 KT IN THE VICINITY OF THE N COAST OF COLOMBIA. SCATTERED SHOWERS AND TSTMS HAVE INCREASED SLIGHTLY ALONG THE N COAST OF HISPANIOLA TIED TO THE AFOREMENTIONED FRONT. THE ATLANTIC OCEAN... FAIRLY ZONAL MID TO UPPER FLOW...BETWEEN RIDGING TO THE S AND TROUGHING TO THE N...DOMINATES MUCH OF THE W ATLC. AN UPPER SHORTWAVE DIPS ALONG 50W SUPPORTING A COLD FRONT THAT STRETCHES FROM 32N49W TO 22N60W THEN STATIONARY AND DISSIPATING ACROSS THE NRN SHORE OF HISPANIOLA. THE COMBINATION OF SFC HIGH PRES BEHIND THE FRONT AND A VERY DRY ENVIRONMENT ALOFT IS PROVIDING FAIR AND SEASONABLY COOL WEATHER ACROSS THE SW ATLC. SOME ACTIVE WEATHER LIES IN A DIFFLUENT ZONE ALOFT BETWEEN THE TROUGH AND A RIDGE AXIS ALONG 43W/43W. IR IMAGES AND LIGHTNING DATA REVEAL SCATTERED SHOWERS AND ISOLATED TSTMS N OF 28N BETWEEN 45W-50W. VERY NARROW DEEP LAYER RIDGING COVERS A SMALL PART OF THE ATLC BETWEEN 39W-46W. THE PATTERN QUICKLY CHANGES THEME IN THE E ATLC WHERE LARGE SCALE DEEP LAYER TROUGHING IS IN PLACE ANCHORED BY A WWD MOVING LOW NEAR 35N31W. A 1008 MB SFC LOW HAS BEEN SLOW TO MOVE W OF THE MADEIRA ISLANDS NEAR 36N20W WITH A COLD FRONT EXTENDING SW ALONG 25N23W 21N38W. SCATTERED SHOWERS AND ISOLATED TSTMS ARE WITHIN 90 NM OF THE FRONT N OF 26N AND NEAR THE MAIN LOW N OF 29N BETWEEN 24W-34W. A WEAK SFC TROUGH APPEARS TO HAVE BROKE OFF FROM THE TAIL END OF THE FRONT AND IS MOVING SLOWLY WWD ALONG 47W FROM 20N-25N. A SWLY JET BRANCH EXISTS NEAR THE BASE OF THE TROUGH AND THEN RUNS NE ALONG 13N50W 15N30W 30N15W. DIFFLUENCE TO THE SE OF THE JET IS GENERATING AND ADVECTING MID-HIGH LEVEL CLOUDINESS WITHIN 240 NM AND ENHANCING CONVECTION ALONG THE ITCZ. $$ CANGIALOSI