000 AXNT20 KNHC 122351 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 705 PM EST MON NOV 12 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2315 UTC. ...TROPICAL WAVES... TROPICAL WAVE IS ALONG 70W/71W S OF 16N MOVING W NEAR 20 KT. THE MIMIC TPW ANIMATION SHOWS A WEAK NARROW QUICK MOVING MOISTURE SURGE ASSOCIATED WITH THIS FEATURE. HOWEVER...THERE IS NO SENSIBLE WEATHER APPARENT. ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 8N13W 6N30W 7N40W 5N52W. SCATTERED MODERATE CONVECTION IS WITHIN 120 NM OF THE AXIS BETWEEN 17W-19W. ISOLATED MODERATE IS FROM 3N TO 7N BETWEEN 28W-36W. DISCUSSION... GULF OF MEXICO... ABUNDANT DRY AIR IN THE MID AND UPPER LEVELS DOMINATES THE MAJORITY OF THE GULF ON THE NRN SIDE OF A MID-LEVEL RIDGE. THIS IS PROVIDING A VERY NICE LATE AFTERNOON AND EVENING ACROSS THE REGION. A SHORTWAVE TROUGH DIGS SWD OVER ALABAMA AND MISSISSIPPI GENERATING CLOUDINESS AND SHOWERS OVER PORTIONS OF THE SOUTHEAST U.S. AND OHIO VALLEY. THIS SHORTWAVE WILL LIKELY PUSH ACROSS THE NE PORTION OF THE REGION TOMORROW AND HELP DEEPEN THE W ATLC TROUGH. AT THE SFC...1027 MB HIGH PRES SYSTEM SITUATED NEAR THE CAROLINA COASTLINE CONTROLS THE PATTERN. ENHANCED PRES GRADIENT BETWEEN THE HIGH AND TROUGH OF LOW PRES IN THE CARIB IS PRODUCING MODERATE TO FRESH ENE WINDS ACROSS THE SE PORTION OF THE GULF. E TO SE WINDS ARE LIGHT TO MODERATE ELSEWHERE. VISIBLE IMAGERY REVEALS A NARROW AREA OF LOW LEVEL CLOUDINESS AND PERHAPS SHALLOW ISOLATED SHOWERS N OF 24N W OF 94W ASSOCIATED AND STEERED BY THE LOW-LEVEL RETURN FLOW. LOOKING AHEAD A DAY OR TWO...THE SFC HIGH PRES SYSTEM CURRENTLY NE OF THE AREA IS ANTICIPATED TO WEAKEN AND SHIFT SWD. THIS WILL ALLOW WINDS TO LIGHTEN...ESPECIALLY THE NRN HALF. CARIBBEAN SEA... AN AREA OF LOW PRES...ANALYZED 1008 MB...IS VERY NEAR THE SE COAST OF NICARAGUA. LAST FEW VISIBLE IMAGES OF THE DAY SHOWED A WEAK SMALL SWIRL OF LOW CLOUDS PUSHING TOWARD THE COAST. WHILE THE CENTER OF CIRCULATION AND MINIMUM PRES IS NEAR THE SE NICARAGUAN COAST...MUCH OF THE ASSOCIATED ACTIVITY LIES TO THE N. IR IMAGERY AND LIGHTNING DATA REVEAL CONSIDERABLE CLOUDINESS ...SCATTERED SHOWERS AND ISOLATED TSTMS FROM 11N-21N W OF 76W. MOST OF THE STRONGER TSTMS HAVE WEAKENED OVER THE PAST FEW HOURS WITH THE EXCEPTION OF THE CLUSTER N OF THE COLOMBIAN COAST FROM 11N-14N BETWEEN 76W-78W WHICH APPEARS TO HAVE BEEN ENHANCED IN AN UPPER DIFFLUENT ZONE. SINCE THE SYSTEM IS VERY NEAR OR OVER LAND...TROPICAL CYCLONE DEVELOPMENT IS NOT EXPECTED. HOWEVER...LOCALLY HEAVY RAINFALL IS POSSIBLE OVER PORTIONS OF CENTRAL AMERICA DURING THE NEXT COUPLE OF DAYS AS THIS SYSTEM MOVES WESTWARD NEAR 10 TO 15 MPH. THE TAIL END OF A CENTRAL ATLC SFC TROUGH...REMNANTS OF AN OLD FRONT...IS PRODUCING SCATTERED SHOWERS AND TSTMS OVER PUERTO RICO AND HISPANIOLA. SAN JUAN DOPPLER RADAR SHOWS THE ACTIVITY WEAKENING AND PUSHING NWD WITH THE SLOW MOVING BOUNDARY. THE REMAINDER OF THE AREA IS RATHER TRANQUIL UNDER MODERATE TRADE WIND FLOW AND UPPER RIDGING CENTERED JUST E OF TRINIDAD. THE MOST STABLE AIR ALOFT IS E OF 64W CLOSER TO THE UPPER HIGH. ATLANTIC OCEAN... STRONG SFC HIGH PRES CENTERED OFF THE SOUTHEAST U.S. COAST DOMINATES THE SW ATLC PRODUCING MODERATE NE TO E TRADES. THESE BRISK WINDS ARE GENERATING ENOUGH INSTABILITY TO STIR UP AND STEER STREAMS OF LOW CLOUDS AND QUICK MOVING SHALLOW SHOWERS. SOME OF THESE ISOLATED SHOWERS HAVE MADE IT TO THE E COAST OF S FLORIDA AS NOTED IN DOPPLER RADAR. ALOFT...A NARROW AMPLIFIED RIDGE LIES OVER THE ERN SEABOARD AND A BROAD LONGWAVE TROUGH COVERS THE ATLC WATERS BETWEEN 50W-75W N OF 23N. A SERIES OF UPPER SHORTWAVES OVER THE U.S. WILL LIKELY MOVE INTO THE REGION OVER THE NEXT COUPLE OF DAYS TEMPORALLY SHARPENING THE TROUGH. THE UPPER TROUGH IS SUPPORTING A PAIR OF WEAK LOW-LEVEL BOUNDARIES. ONE OF THESE IS A COLD FRONT WHICH BARELY CLIPS THE N PORTION OF THE AREA ENDING NEAR 31N53W. THE OTHER IS A STRETCHED OUT TROUGH ANALYZED ALONG 31N45W 23N55W TO HISPANIOLA. LOW-LEVEL CONVERGENCE NEAR THE TROUGH COUPLED WITH EXTENSIVE MID AND UPPER LEVEL SWLY FLOW IS PRODUCING SCATTERED SHOWERS AND TSTMS FROM 25N-31N BETWEEN 42W-46W. ISOLATED ACTIVITY IS ELSEWHERE WITHIN 90 NM OF THE BOUNDARY. THE REMAINDER OF THE CENTRAL AND E ATLC IS UNDER A VERY WEAK PRES PATTERN CONSISTING OF A 1017 MB HIGH NEAR 29N37W AND A 1013 MB LOW JUST S OF THE AZORES. THIS PATTERN IS ALLOWING WINDS TO BE LIGHT ACROSS THE REGION. IN THE MID AND UPPER LEVELS...A BROAD RIDGE/TROUGH PATTERN IS IN PLACE. THERE IS SOME INSTABILITY WITHIN THE TROUGH PRODUCING CLOUDINESS AND EMBEDDED SCATTERED SHOWERS FROM THE CANARY ISLANDS SWD TO 24N E OF 22W. A SWLY JET ORIGINATES JUST E OF THE TROUGH BASE NEAR 13N28W AND EXTENDS NE TO AFRICA NEAR 18N16W. DIFFLUENCE TO THE SE OF THE JET IS PRODUCING ABUNDANT CLOUDINESS AND ENHANCING CONVECTION IN THE ITCZ. $$ CANGIALOSI