000 AXNT20 KNHC 100517 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 105 AM EST SAT NOV 10 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 50W S OF 12N MOVING W NEAR 20 KT. THE MIMIC TPW ANIMATION CLEARLY SHOWS A LARGE DRY SURGE...ASSOCIATED AT LEAST IN PART WITH SAHARAN DUST...QUICKLY SPREADING WWD TO ABOUT 53W. THIS LOW AMPLITUDE WAVE IS NEAR THE SW EDGE OF THE SURGE...MARKED BY A FAINT MOISTURE BUMP ON THE PRODUCT AND IN SATELLITE IMAGES. SCATTERED SHOWERS AND ISOLATED TSTMS ARE WITHIN 120 NM EITHER SIDE OF THE AXIS. TROPICAL WAVE IS ALONG 64W S OF 13N MOVING W NEAR 15 KT. MUCH OF THIS WAVE IS INLAND OVER S AMERICA WITH VERY LITTLE SIGNATURE APPARENT IN ANY OF THE AVAILABLE DATA. ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 10N14W 5N30W 7N42W 6N49W 5N54W. SCATTERED MODERATE CONVECTION IS WITHIN 45 NM OF THE AXIS BETWEEN 27W-33W. WIDELY SCATTERED MODERATE IS WITHIN 30 NM OF THE AXIS BETWEEN 41W-44W. DISCUSSION... GULF OF MEXICO... MID TO UPPER LEVEL NWLY FLOW AND DRY STABLE AIR DOMINATES THE GULF TONIGHT. THE AIR IS DRIEST OVER THE SE PORTION WHERE THE FLOW BECOMES HIGHLY CONFLUENT ALOFT. THIS STABLE AIRMASS IS SUPPRESSING DEEP CLOUD FORMATION ACROSS THE REGION. IN THE LOWER LEVELS...WEAK HIGH PRES RIDGE ALONG 29N IS IN CONTROL. THIS HAS ALLOWED WINDS TO BE LIGHT TO MODERATE AND ANTICYCLONIC ACROSS THE REGION. BROKEN STRATOCUMULUS CLOUDS ARE EVIDENT OVER THE S CENTRAL PORTION...INDICATIVE OF THE COOL AIRMASS. THERE COULD BE A FEW QUICK MOVING SHALLOW SHOWERS IN THE W GULF ASSOCIATED WITH THE LOW-LEVEL RETURN FLOW BUT THE DOPPLER RADARS ARE ECHO-FREE ACROSS THE GULF COAST. THIS TRANQUIL PATTERN SHOULD PERSIST THRU SATURDAY ALLOWING THE PLEASANT FALL WEATHER TO CONTINUE. CARIBBEAN SEA... ACTIVE WEATHER PERSISTS IN THE SW CARIB ASSOCIATED WITH A NEARLY STATIONARY LOW-LEVEL TROUGH...ANALYZED ALONG 76W/77W S OF 17N. IR IMAGERY AND LIGHTNING DATA REVEAL DEEPENING AND EXPANDING CONVECTION S OF 15N BETWEEN 72W-83W. IN ADDITION TO LOW-LEVEL CONVERGENCE...AN UPPER DIFFLUENT PATTERN IS AIDING IN THE INSTABILITY AND SPREADING HIGH LEVEL CLOUDINESS TOWARD PUERTO RICO AND HISPANIOLA. THESE STRONG UPPER-LEVEL WINDS ARE UNFAVORABLE FOR SIGNIFICANT TROPICAL DEVELOPMENT. A QSCAT PASS AROUND 00Z SHOWED STRONG NLY WINDS IN THIS AREA...ESPECIALLY TO THE W OF THE TROUGH AXIS. THE NW CARIB...LIKE THE GULF OF MEXICO...IS EXPERIENCING RATHER PLEASANT WEATHER UNDER THE INFLUENCE OF ABUNDANT SUBSIDENCE AND LOW-LEVEL NLY FLOW. THE REMAINDER OF THE CENTRAL AND ERN CARIB IS FAIRLY TRANQUIL WITH LIGHT TO MODERATE TRADES AND MODEST DRY AIR EVIDENT ON WATER VAPOR IMAGES UNDER MID TO UPPER RIDGING. ATLANTIC OCEAN... LARGE MID AND UPPER TROUGH OVER THE W ATLC IS SUPPORTING A PAIR OF WEAK FRONTAL TROUGHS. THE ERN BOUNDARY ENTERS THE AREA NEAR 32N54W AND EXTENDS SW TO A 1011 MB LOW NEAR 21N68W. THE OTHER FEATURE STRETCHES FROM A 1012 MB LOW N OF THE AREA ALONG 32N73W TO THE NW BAHAMAS. THERE IS MINIMAL SHOWER ACTIVITY NEAR THE WRN BOUNDARY DUE TO THE VERY DRY ATMOSPHERE IT IS EMBEDDED IN. WIDESPREAD MID TO HIGH LEVEL CLOUDINESS AND LIKELY EMBEDDED SHOWERS AND ISOLATED TSTMS LIE OVER THE ERN BOUNDARY N OF 24N BETWEEN 50W-60W...IN AN UPPER DIFFLUENT ZONE BETWEEN THE AFOREMENTIONED TROUGH AND UPPER RIDGING TO THE E. IN THE CENTRAL AND E ATLC...THE UPPER PATTERN CONSISTS OF A RIDGE/TROUGH. THE RIDGE IS HIGHLY ELONGATED FROM A HIGH CENTER OVER THE LESSER ANTILLES EXTENDING NE TO 32N43W. AN UPPER LOW APPEARS TO HAVE OPENED INTO A SHARP TROUGH FROM 21N39W 4N47W. STRONG SW TO WLY FLOW IS GENERATING AND TRANSPORTING A BROKEN MID TO HIGH LEVEL CLOUD DECK S OF 17N E OF 42W. A LARGE DEEP LAYER LOW PRES SYSTEM...ANALYZED 1006 MB AT THE SFC...IS CENTERED N OF THE AREA OVER THE AZORES. A TRAILING SFC TROUGH EXTENDS FROM 32N23W TO 25N31W. THIS LARGE LOW PRES TROUGH IS ALLOWING WINDS TO BE LIGHT TO MODERATE ACROSS MUCH OF THE CENTRAL AND E ATLC. $$ CANGIALOSI