000 AXNT20 KNHC 241131 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 705 AM EST MON NOV 24 2008 TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHERN SECTIONS OF SOUTH AMERICA...AND 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. ...SPECIAL FEATURE... IN THE SW CARIBBEAN...A 1007 MB SURFACE LOW IS CENTERED N OF PANAMA NEAR 10N80W. LOW LEVEL CONVERGENCE IN THE VICINITY OF THIS SURFACE LOW IS INTERACTING WITH DEEP LAYER MOISTURE OVER THE W CARIBBEAN TO RESULT IN NUMEROUS SHOWERS AND THUNDERSTORMS OVER THE CARIBBEAN S OF 15N W OF 77W...INCLUDING PORTIONS OF COSTA RICA...PANAMA...AND E NICARAGUA. THIS SHOWER AND THUNDERSTORM ACTIVITY CONTINUES TO BECOME BETTER ORGANIZED... AND A TROPICAL DEPRESSION MAY FORM IN THE NEXT DAY OR TWO IF THE SYSTEM REMAINS OVER WATER AS IT DRIFTS SLOWLY WESTWARD. HEAVY RAINFALL AND LOCALIZED FLOODING WILL BE POSSIBLE OVER PORTIONS OF PANAMA...COSTA RICA...AND NICARAGUA DURING THE NEXT COUPLE OF DAYS EVEN IF NO TROPICAL CYCLONE FORMS. ...TROPICAL WAVES... TROPICAL WAVE IS OVER THE CENTRAL CARIBBEAN ALONG 75W S OF 17N MOVING W 10-15 KT. SATELLITE IMAGERY DEPICTS A DISTINCT AREA OF CYCLONIC CIRCULATION COINCIDING WITH THIS WAVE...WHERE A MAXIMUM IN DEEP LAYER MOISTURE IS PRESENT BASED ON TOTAL PRECIPITABLE WATER PRODUCT FROM CIMSS. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS OCCURRING WITHIN 90 NM EITHER SIDE OF THE WAVE AXIS S OF 15N. THIS WAVE IS BECOMING ABSORBED BY THE BROAD LOW LEVEL CYCLONIC CIRCULATION ASSOCIATED WITH THE 1007 MB SURFACE LOW NEAR 10N80W. THIS IS THE SAME 1007 MB LOW PRESSURE CENTER WHICH MAY DEVELOP INTO A TROPICAL CYCLONE. ...THE ITCZ... THE ITCZ AXIS IS ANALYZED ALONG 9N12W 5N22W 6N33W 8N45W 6N58W. SCATTERED MODERATE IS FROM 5N-8N BETWEEN 19W-26W. SIMILAR CONVECTION IS WITHIN 120 NM EITHER SIDE OF THE ITCZ AXIS BETWEEN 40W-49W. ...DISCUSSION... GULF OF MEXICO... STRONG SOUTHWESTERLY AND WESTERLY UPPER LEVEL WINDS COVER THE GULF REGION...WITH UPPER LEVEL MOISTURE STREAMING ACROSS THE N GULF REGION FROM THE E PACIFIC REGION. AT THE SURFACE... A RELATIVELY COOL AND DRY AIRMASS IS IN PLACE ACROSS THE GULF REGION...WITH TEMPERATURES GENERALLY BELOW SEASONAL AVERAGES. THIS AIRMASS IS BEING SUPPORTED BY A 1030 MB SURFACE HIGH OVER SOUTH CAROLINA NEAR 33N82W...WITH AN ASSOCIATED SURFACE RIDGE EXTENDING ACROSS THE NE GULF. SUBSIDENCE AND STABLE ATMOSPHERIC CONDITIONS ARE INHIBITING DEEP CONVECTION ACROSS THE GULF REGION. FARTHER NORTH...A VIGOROUS UPPER TROUGH IS OVER THE PLAINS OF THE CONUS...WITH AN ASSOCIATED SURFACE FRONT EXTENDING FROM THE SOUTHERN PLAINS OF THE CONUS TO THE ROCKY MOUNTAINS. AS THIS UPPER TROUGH TRANSLATES SOUTHEASTWARD OVER THE NEXT DAY... THE FRONT WILL BEGIN TO MOVE ACROSS THE GULF REGION. IN THE WAKE OF THIS FRONT...A REINFORCING COOLER AND DRIER AIRMASS... CHARACTERIZED AS A MODIFIED CONTINENTAL POLAR AIRMASS...WILL AFFECT THE GULF REGION. CARIBBEAN SEA... IN THE SW CARIBBEAN...A 1007 MB SURFACE LOW NEAR 10N80W IS SUPPORTING SHOWER AND THUNDERSTORM ACTIVITY. THIS AREA OF LOW PRESSURE MAY BECOME A TROPICAL CYCLONE DURING THE NEXT DAY OR TWO. THE INCREASED SURFACE PRESSURE GRADIENT ASSOCIATED WITH THIS SURFACE LOW IS SUPPORTING N TO NE SURFACE WINDS OF 20 TO 30 KT FOR MUCH OF THE CARIBBEAN...WITH THE STRONGEST WINDS OVER THE SW CARIBBEAN AND AROUND THE WINDWARD PASSAGE. THE SHOWER AND THUNDERSTORM ACTIVITY ASSOCIATED WITH THE SURFACE LOW IS BEING ENHANCED BY STRONG UPPER LEVEL DIFFLUENCE IN THE VICINITY OF AN UPPER RIDGE PRESENT OVER THE W CARIBBEAN...WITH THE AXIS OF THIS UPPER RIDGE EXTENDING FROM N COLOMBIA NEAR 12N72W TO 15N79W TO THE NW CARIBBEAN NEAR 20N84W. OVER THE E AND CENTRAL CARIBBEAN...UPPER LEVEL DIFFLUENCE IS SUPPORTING SCATTERED SHOWERS AND THUNDERSTORMS S OF 15N BETWEEN 68W-76W. THIS ACTIVITY IS BEING ENHANCED BY LOW LEVEL CONVERGENCE ASSOCIATED WITH THE TROPICAL WAVE ALONG 75W. ATLANTIC OCEAN... OVER THE W ATLC...A RELATIVELY COOL AND DRY AIRMASS IS IN PLACE...WITH TEMPERATURES BELOW SEASONAL AVERAGES ACROSS FLORIDA. THIS AIRMASS IS BEING SUPPORTED BY A 1030 MB SURFACE HIGH OVER SOUTH CAROLINA NEAR 33N82W. FARTHER E...AN UPPER TROUGH TILTED FROM NW TO SE OVER THE CENTRAL ATLC CONTINUES TO DIG SOUTHWARD AS A 120 KT CYCLONICALLY-CURVED UPPER LEVEL JET BEGINS TO ROUND THE BASE OF THIS TROUGH. DEEP AND STRONG ASCENT ORIGINATING FROM STRONG UPPER LEVEL DIVERGENCE IN THE NE QUADRANT OF THIS JET IS APPROACHING A SURFACE STATIONARY FRONT. THIS FRONT CURRENTLY EXTENDS FROM 21N71W TO 27N57W TO 32N53W TO N OF THE DISCUSSION AREA...AND IS WEAKENING W OF 63W. AS THE DEEP ASCENT CONTINUES TO APPROACH THE STATIONARY FRONT... A 1003 MB SURFACE LOW IS FORECAST TO FORM IN THE VICINITY OF THE FRONT NEAR 31N50W BY 25/0600 UTC. THE CORRESPONDING TIGHTENING OF THE SURFACE PRESSURE GRADIENT WILL RESULT IN GALE FORCE SURFACE WINDS WITHIN 240 NM OF THE SW QUADRANT OF THE DEVELOPING SURFACE LOW. ALSO...AS THIS LOW DEVELOPS ALONG THE STATIONARY FRONT... RELATIVELY COOLER AIR TO THE W WILL BEGIN TO WRAP CYCLONICALLY AROUND THE LOW...FORCING THE STATIONARY FRONT TO MOVE EASTWARD AS A COLD FRONT S OF THE LOW. AT PRESENT... INCREASING LOW LEVEL CONVERGENCE IN THE VICINITY OF THIS DEVELOPING SURFACE LOW IS STRENGTHENING THE FRONT...WITH THE RESULTING ASCENT SUPPORTING SCATTERED SHOWERS AND THUNDERSTORMS N OF 27N BETWEEN 51W-56W. FARTHER TO THE S...A SURFACE TROUGH EXTENDS FROM 14N59W TO A 1011 MB SURFACE LOW NEAR 14N55W TO 13N51W. ISOLATED SHOWERS ARE OCCURRING WITHIN 60 NM OF THIS SURFACE LOW AND SURFACE TROUGH. OVER THE E ATLC...AN UPPER TROUGH IS N OF 23N BETWEEN 29W-42W WITH AN UPPER LOW NEAR 31N35W. AN ASSOCIATED SURFACE TROUGH EXTENDS FROM 28N29W TO A 1012 MB SURFACE LOW NEAR 25N32W TO A 1013 MB SURFACE LOW NEAR 22N35W TO 21N36W. THE 1012 MB LOW IS NEW ON THE 24/0600 UTC SURFACE ANALYSIS...WHILE THE 1013 MB LOW CONTINUES TO WEAKEN...AS THE STRONGEST UPPER LEVEL DIFFLUENCE ASSOCIATED WITH THE UPPER TROUGH TRANSLATES NORTHEASTWARD. THE COMBINATION OF LOW LEVEL CONVERGENCE WITH THE SURFACE LOWS AND SURFACE TROUGH AND UPPER LEVEL DIFFLUENCE IS SUPPORTING SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS FROM 24N-29N BETWEEN 24W-27W. ALSO...UPPER LEVEL DIVERGENCE IN THE VICINITY OF A MID/UPPER-LEVEL WIND SPEED MAXIMUM OVER THE E ATLC IS SUPPORTING SCATTERED SHOWERS FROM 14N-19N BETWEEN 16W-27W. $$ COHEN/MT