000 AXNT20 KNHC 170547 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 105 AM EST SAT NOV 17 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0515 UTC. ...TROPICAL WAVES... TROPICAL WAVE IS ALONG 56W S OF 17N MOVING W 15 KT. NIGHT CHANNEL VIS IMAGERY REVEALS SLIGHT LOW-LEVEL TURNING IN THE THIN LOW-LEVEL CLOUDS. THE ONLY AREA OF SHOWER ACTIVITY AT THE MOMENT IS NEAR THE INTERSECTION OF THE ITCZ FROM 9N-10N BETWEEN 57W-58W. BUOY DATA IN THE REGION SHOWS AN SLP MINIMUM NEAR THE WAVE AXIS AND A RECENT QSCAT PASS DEPICTS A SLIGHT INCREASE IN THE ELY TRADES ALONG AND TO THE E OF THE WAVE. TROPICAL WAVE IS IN THE CENTRAL CARIBBEAN ALONG 75W S OF 19N MOVING W 10-15 KT. THE MIMIC TPW ANIMATION PROVIDES A BIT OF HISTORY ON THIS WAVE SHOWING A WELL DEFINED...ALBEIT NARROW...MOISTURE PLUME TRACKING ACROSS THE CARIB THU AND EARLY FRI. THIS MOISTURE AREA...WHICH IS THOUGHT TO REPRESENT MUCH OF THE WAVE ENERGY...HAS BEEN PULLED TO THE NE BY A STRONG COLD FRONT OVER THE LAST SEVERAL HOURS. THE LEFT OVER PORTION OF THE WAVE APPEARS WEAK AND IS PRODUCING ISOLATED SHOWERS AT BEST IN ITS VICINITY. ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 8N13W 6N25W 7N40W 9N54W 8N62W. SCATTERED MODERATE CONVECTION IS WITHIN 120 NM N OF THE AXIS BETWEEN 26W-36W AND WITHIN 240 NM S OF THE AXIS BETWEEN 34W-38W. ISOLATED MODERATE IS WITHIN 90 NM EITHER SIDE OF THE AXIS BETWEEN 42W-48W. DISCUSSION... THE GULF OF MEXICO... SFC HIGH PRES CONTINUES TO SHIFT SE CENTERED JUST S OF THE FL PANHANDLE NEAR 30N87W...ANALYZED 1021 MB. IT IS A VERY CHILLY NIGHT ACROSS THE SOUTHEAST ON THE E SIDE OF THE HIGH WITH TEMPS NEAR THE FREEZING MARK IN INLAND PORTIONS OF NW FLORIDA. THE AIRMASS MODIFIES FURTHER W ESPECIALLY W OF 92W WHERE LOW-LEVEL RETURN FLOW HAS SET UP. FAIR WEATHER EXISTS ACROSS THE ENTIRE AREA WITH SATELLITE IMAGERY SHOWING COOL AIR STRATOCUMULUS CLOUDS AS THE PRIMARY MOISTURE SOURCE IN THE CENTRAL AND E GULF AND SOME PATCHY LOW TO MID LEVEL CLOUDS IN THE BAY OF CAMPECHE...POSSIBLY ASSOCIATED WITH A VERY WEAK SFC TROUGH. IN THE MID AND UPPER LEVELS...MODEST RIDGING AND ABUNDANT STABLE AIR COVERS THE REGION. THE CARIBBEAN SEA... STRONG COLD FRONT THAT SWEPT THROUGH THE GULF OF MEXICO THU AND FRI IS GRADUALLY LOSING ITS IDENTITY IN THE NW CARIBBEAN ...ANALYZED FROM WRN CUBA TO THE CENTRAL YUCATAN. COOL AIR HAS WORKED ITS WAY AS FAR S AS THE NRN YUCATAN WITH TEMPS IN THE LOWER 60'S F IN CANCUN. THERE IS SOME PATCHY LOW-LEVEL CLOUDINESS AND ISOLATED SHOWERS WITHIN 60 NM OF THE FRONT. FARTHER S...IR IMAGERY SHOWS SMALL CLUSTERS OF SHOWERS AND ISOLATED TSTMS IN THE SW CARIB FROM 9N-12N BETWEEN 79W-83W ASSOCIATED WITH LOW-LEVEL CONFLUENCE NEAR THE ITCZ. SIMILAR WEATHER IS OCCURRING OVER PUERTO RICO AND HISPANIOLA TIED TO THE TAIL END OF A PRE-FRONTAL TROUGH. SAN JUAN DOPPLER RADAR SHOWS MUCH OF THE STRONGER ACTIVITY BOTH N AND SW OF THE ISLAND AT THE MOMENT. SCATTERED SHOWERS ARE ALSO MAKING THEIR WAY TOWARD THE WINDWARD ISLANDS TRIGGERED BY APPROACHING WEAK TROPICAL WAVE. THE REMAINDER OF THE AREA IS RELATIVELY TRANQUIL WITH MODERATE DRY AIR AND SW TO ZONAL FLOW OVERHEAD. THE ATLANTIC OCEAN... MID AND UPPER LEVEL TROUGHING DOMINATES MUCH OF THE WRN ATLC EXTENDING SWD FROM A POLAR VORTEX. THIS UPPER SYSTEM IS SUPPORTING A FAIRLY STRONG COLD FRONT WHICH EXTENDS FROM 32N60W ACROSS THE SE BAHAMAS. THE COMBINATION OF SFC HIGH PRES BEHIND THE FRONT AND A VERY DRY ENVIRONMENT ALOFT IS PROVIDING FAIR AND COOL WEATHER ACROSS THE SW ATLC. NIGHT CHANNEL VIS IMAGERY SHOWS A LARGE AREA OF SCATTERED STRATOCUMULUS CLOUDS...INDICATIVE OF THE COOL AIRMASS IN PLACE. SOME ACTIVE WEATHER LIES IN A DIFFLUENT ZONE ALOFT BETWEEN THE TROUGH AND A RIDGE AXIS ALONG 51W/52W. IR IMAGES AND LIGHTNING DATA REVEAL SCATTERED SHOWERS AND TSTMS N OF 21N BETWEEN 53W-61W AND S OF 20N BETWEEN 64W-68W. A SFC TROUGH FROM 27N58W TO THE DOMINICAN REPUBLIC...WHICH SHOWED UP FAIRLY WELL IN AN EARLIER QSCAT PASS...IS ENHANCING SOME OF THIS WEATHER ESPECIALLY S OF 20N. PART OF THE CENTRAL ATLC...BETWEEN 40W AND 52W...IS DOMINATED BY DEEP LAYER RIDGING WHICH IS ONLY ADVECTING SOME DEBRIS HIGH LEVEL CLOUDINESS. THE PATTERN QUICKLY CHANGES THEME IN THE E ATLC WHERE LARGE SCALE DEEP LAYER TROUGHING IS IN PLACE ANCHORED BY AN UPPER LOW NEAR 36N29W. A MID-LEVEL DISTURBANCE TO THE S OF THE UPPER LOW IS GENERATING SCATTERED SHOWERS AND TSTMS FROM 24N-27N BETWEEN 29W-34W. THIS LARGE SCALE UPPER TROUGH IS SUPPORTING A 1006 MB LOW W OF THE MADEIRA ISLANDS WHICH HAS A TRAILING COLD FRONT ALONG 32N21W 25N29W 24N38W. A SWLY JET BRANCH HAS SET UP NEAR THE BASE OF THE TROUGH AND THEN RUNS NE ALONG 14N47W 17N30W 24N22W GENERATING AND ADVECTING MID HIGH LEVEL CLOUDINESS WITHIN 150 NM SE OF THE JET AXIS. $$ CANGIALOSI