000 AXNT20 KNHC 101144 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 705 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1115 UTC. ...TROPICAL WAVES... TROPICAL WAVE IS ALONG 51W S OF 13N MOVING W 15-20 KT. THE MIMIC TPW ANIMATION CLEARLY SHOWS A LARGE DRY SURGE...ASSOCIATED AT LEAST IN PART WITH SAHARAN DUST...QUICKLY SPREADING WWD TO ABOUT 55W. THIS LOW AMPLITUDE WAVE IS NEAR THE SW EDGE OF THE SURGE...MARKED BY A SUBTLE MOISTURE BUMP ON THE PRODUCT AND IN SATELLITE IMAGES. AT 06Z...SHIP C6UG4 REPORTED 20 KT SE WINDS JUST E OF THE WAVE AXIS. 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 7N12W 6N25W 4N40W 4N49W 5N58W. SCATTERED MODERATE CONVECTION IS WITHIN 90 NM N OF THE AXIS BETWEEN 26W-34W. ISOLATED MODERATE IS FROM 6N-8N BETWEEN 42W-48W. DISCUSSION... GULF OF MEXICO... MID TO UPPER LEVEL NWLY FLOW AND DRY STABLE AIR DOMINATES THE GULF THIS MORNING. THE AIR IS DRIEST OVER THE SE PORTION WHERE THE FLOW BECOMES HIGHLY CONFLUENT ALOFT TOWARD THE BASE OF AN ATLC TROUGH. THIS STABLE AIRMASS IS SUPPRESSING DEEP CLOUD FORMATION ACROSS THE REGION. IN THE LOWER LEVELS...WEAK 1020 MB HIGH PRES AREA NEAR 29N87W 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 BRIEF SHALLOW ISOLATED SHOWER IN THE W GULF ASSOCIATED WITH THE LOW-LEVEL RETURN FLOW BUT NOT MUCH MORE AS DOPPLER RADARS REMAIN ECHO-FREE ACROSS THE GULF COAST. THIS TRANQUIL PATTERN IS EXPECTED TO PERSIST THRU THE DAY 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 16N. SFC OBSERVATIONS AND NIGHT CHANNEL VIS IMAGES REVEAL A BROAD ENVELOPE OF LOW TO MID LEVEL CYCLONIC TURNING SUGGESTING AN ILL-DEFINED 1009 MB LOW CENTERED JUST N OF PANAMA. IR IMAGERY AND LIGHTNING DATA INDICATE SCATTERED MODERATE TO STRONG CONVECTION S OF 16N BETWEEN 72W-84W. IN ADDITION TO LOW-LEVEL CONVERGENCE NEAR THE LOW/TROUGH...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 FEW WEAK FRONTAL TROUGHS. ONE OF THESE IS A COLD FRONT WHICH EXTENDS SW INTO THE AREA ALONG 32N71W 29N76W. A PREFRONTAL TROUGH LIES AHEAD OF THIS FEATURE ALONG 32N63W 26N70W. BOTH OF THESE ARE ONLY PRODUCING A THIN LINE OF LOW CLOUDS...LIKELY SUPPRESSED BY THE VERY DRY ATMOSPHERE THEY ARE EMBEDDED IN. THE ERN-MOST BOUNDARY...ANALYZED AS A TROUGH...ENTERS THE AREA NEAR 32N54W AND EXTENDS SW TO A 1011 MB LOW 150 NM NNW OF PUERTO RICO NEAR 21N67W. WIDESPREAD MID TO HIGH LEVEL CLOUDINESS AND LIKELY EMBEDDED SHOWERS AND ISOLATED TSTMS LIE OVER THIS BOUNDARY ADVECTED BY SWLY UPPER FLOW FROM THE CARIB. SCATTERED SHOWERS AND ISOLATED TSTMS ARE CONFINED TO N OF 26N BETWEEN 48W-53W...IN AN UPPER DIFFLUENT ZONE BETWEEN THE AFOREMENTIONED TROUGH AND UPPER RIDGING TO THE E. THIS BROAD LOW-LEVEL TROUGHING PATTERN IS CREATING LIGHT AND SOMEWHAT VARIABLE WINDS ACROSS MUCH OF THE W ATLC. 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 32N41W. AN UPPER LOW APPEARS TO HAVE OPENED INTO A SHARP TROUGH FROM 20N39W 4N48W. STRONG SW TO WLY FLOW IS GENERATING AND TRANSPORTING A BROKEN MID TO HIGH LEVEL CLOUD DECK S OF 18N E OF 43W. A LARGE DEEP LAYER LOW PRES SYSTEM...ANALYZED 1007 MB AT THE SFC...IS CENTERED N OF THE AREA OVER THE WRN AZORES. A TRAILING SFC TROUGH EXTENDS FROM 32N18W TO 22N27W. THIS LARGE LOW PRES TROUGH IS ALLOWING WINDS TO BE LIGHT TO MODERATE ACROSS MUCH OF THE CENTRAL AND E ATLC AS NOTED IN RECENT SCATTEROMETER PASSES. $$ CANGIALOSI