000 AXNT20 KNHC 170555 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 205 AM EDT MON OCT 17 2011 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...WEATHER OBSERVATIONS...RADAR...AND METEOROLOGICAL ANALYSIS. BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0515 UTC. ...SPECIAL FEATURES... A BROAD AREA OF LOW PRESSURE COVERS THE NW CARIBBEAN...SE GULF OF MEXICO AND THE YUCATAN PENINSULA WITH A 1004 MB SURFACE LOW CENTERED ALONG THE COAST OF THE YUCATAN PENINSULA NEAR 20N86W AT 17/0300 UTC. SCATTERED/NUMEROUS STRONG CONVECTION IS WITHIN A 75 NM RADIUS OF 22.5N85.5W WITH SCATTERED TO HEAVY RAINS COVERING THE AREA FROM 20N-24N BETWEEN 80W-88W AND FROM 24N-27N BETWEEN 80W-84W. THIS SYSTEM IS GRADUALLY BECOMING BETTER DEFINED. UPPER-LEVEL WINDS ARE EXPECTED TO BE MARGINALLY CONDUCIVE FOR DEVELOPMENT DURING THE NEXT DAY OR SO BEFORE BECOMING UNFAVORABLE AFTER THAT. ALTHOUGH THIS LARGE DISTURBANCE IS INTERACTING WITH THE YUCATAN PENINSULA...SOME GRADUAL DEVELOPMENT IS STILL POSSIBLE AS THE LOW MOVES TOWARD THE N OR NW AT 4-9 KT. THIS SYSTEM HAS A HIGH CHANCE OF BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS. REGARDLESS OF DEVELOPMENT...LOCALLY HEAVY RAINFALL AND GUSTY WINDS ARE EXPECTED OVER THE YUCATAN PENINSULA...WESTERN CUBA...THE FLORIDA KEYS...AND SOUTH FLORIDA DURING THE NEXT COUPLE OF DAYS. AN AIR FORCE RESERVE RECONNAISSANCE AIRCRAFT IS SCHEDULED TO INVESTIGATE THE LOW THIS AFTERNOON...IF NECESSARY. ...TROPICAL WAVES... TROPICAL WAVE IS ANALYZED OFF THE COAST OF W AFRICA FROM 17N18W TO 10N20W MOVING W AT 10-15 KT. WAVE IS WELL DEFINED IN THE UPPER LEVEL SATELLITE WINDS AND IS EMBEDDED WITHIN A SLIGHT MOISTURE SURGE AS DEPICTED ON THE TOTAL PRECIPITABLE WATER IMAGERY. CLUSTERS OF SCATTERED MODERATE/STRONG CONVECTION ARE FROM 10N-15N BETWEEN 18W-26W. TROPICAL WAVE IS ANALYZED IN THE CENTRAL TROPICAL ATLC FROM 16N38W TO 7N42W MOVING W NEAR 15 KT. WAVE IS WELL DEFINED IN THE UPPER LEVEL SATELLITE WINDS AND IS EMBEDDED WITHIN A BROAD AREA OF MOISTURE AS DEPICTED ON THE TOTAL PRECIPITABLE WATER IMAGERY. SCATTERED MODERATE/STRONG CONVECTION IS FROM 7N-13N BETWEEN 36W-40W. TROPICAL WAVE IS ANALYZED OVER THE LESSER ANTILLES FROM 17N60W TO 10N62W MOVING 10-15 KT. WAVE IS DEFINED IN THE UPPER LEVEL SATELLITE WINDS AND IS EMBEDDED WITHIN A SLIGHT MOISTURE SURGE AS DEPICTED ON THE TOTAL PRECIPITABLE WATER IMAGERY. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 9N-12N 57W-64W. ...THE ITCZ/THE MONSOON TROUGH... THE MONSOON TROUGH EXTENDS ACROSS AFRICA TO THE COAST NEAR 16N17W THEN RESUMES NEAR 10N21W 10N27W TO 8N32W. THE ITCZ IS ANALYZED FROM 8N32W TO 10N39W THEN RESUMES NEAR 4N39W TO SOUTH AMERICA NEAR 2N51W. CLUSTERS OF SCATTERED MODERATE/STRONG CONVECTION ARE FROM 10N-14N BETWEEN 30W-35W. SMALL CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION DOT THE AREA FROM 4N-9N E OF 38W TO THE COAST OF AFRICA. ...DISCUSSION... GULF OF MEXICO... AN UPPER TROUGH OVER THE NW ATLC CONTINUES TO SUPPORT A QUASI- STATIONARY FRONT THAT ENTERS THE GULF ACROSS EXTREME S FLORIDA TO 25N86W FURTHER ENHANCING THE ACTIVITY ASSOCIATED WITH THE SPECIAL FEATURES ABOVE. SURFACE RIDGE IS BEHIND THE FRONT ANCHORED BY A 1018 MB HIGH OVER SW GEORGIA AND A 1019 MB HIGH OFF THE COAST OF SOUTH CAROLINA. A BROAD UPPER RIDGE IS ANCHORED IN THE CARIBBEAN COVERING THE SE GULF AND PRODUCING A SHEAR AXIS ACROSS THE GULF THAT EXTENDS FROM FLORIDA NEAR CEDAR KEY TO NEAR TAMPICO MEXICO. NW OF THIS SHEAR AXIS ARE STRONG SUBSIDENCE AND DRY STABLE AIR ALOFT WITH MOSTLY CLEAR SKIES. TO THE SE...MOIST TROPICAL AIR IS BEING ADVECTED OVER THE SE GULF AND THE FLORIDA PENINSULA AND THE ACTIVITY ASSOCIATED WITH THE SPECIAL FEATURES ABOVE. THE STATIONARY FRONT WILL LIFT SLOWLY N AS A WARM FRONT WHILE DISSIPATING THROUGH TUE. A STRONG COLD FRONT WILL ENTER THE NW GULF TUE AFTERNOON AND MOVE QUICKLY SE ACROSS THE GULF TUE NIGHT THROUGH WED...SHIFTING SE OF THE GULF WED EVENING. HIGH PRESSURE WILL BUILD IN BEHIND THE FRONT THROUGH FRI. CARIBBEAN SEA... A BROAD UPPER RIDGE IS ANCHORED OVER THE NW CARIBBEAN NEAR 21N85W AND COVERS THE MOST OF THE CARIBBEAN WITH A RIDGE AXIS EXTENDING NE TO OVER THE W ATLC. THIS UPPER RIDGE IS PROVIDING A DIFFLUENT ENVIRONMENT TO ENHANCE THE ACTIVITY ASSOCIATED WITH THE SPECIAL FEATURES ABOVE. EASTERLY SURFACE FLOW COMBINED WITH THE EASTERLY FLOW ALOFT OVER THE SW CARIBBEAN IS GENERATING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS S OF 12N W OF 73W WITH SCATTERED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS FROM 12N-15N W OF 77W TO INLAND OVER CENTRAL AMERICA. THE TROPICAL WAVE OVER THE LESSER ANTILLES WILL MOVE ACROSS THE E CARIBBEAN TONIGHT THROUGH TUE WHILE WEAKENING. A COLD FRONT WILL PUSH INTO THE NW CARIBBEAN WED REACHING FROM CENTRAL CUBA TO E HONDURAS BY LATE THU WHERE IT WILL STALL. ATLANTIC OCEAN... A BROAD UPPER TROUGH COVERS THE NW ATLC N OF THE DISCUSSION AREA AND SUPPORTING A QUASI-STATIONARY FRONT THAT ENTERS THE REGION JUST E OF BERMUDA EXTENDING ALONG 27N69W ACROSS THE N BAHAMA ISLANDS NEAR 25N77W THEN EXTREME S FLORIDA S OF MIAMI INTO THE GULF OF MEXICO. SCATTERED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS COVER THE W ATLC N OF THE FRONT TO 30N. AN UPPER RIDGE AXIS EXTENDS FROM THE CARIBBEAN NEAR 21N85W ACROSS CUBA ALONG 25N75W TO BEYOND 32N55W PROVIDING A DIFFLUENT ENVIRONMENT ENHANCING THE ACTIVITY ASSOCIATED WITH THE FRONT ABOVE. A NARROWING UPPER TROUGH COVERS THE CENTRAL ATLC EXTENDING FROM AN UPPER LOW 32N32W THROUGH A SECOND UPPER LOW NEAR 23N50W NARROWING FURTHER INTO THE W TROPICAL ATLC AND E CARIBBEAN ACROSS THE WINDWARD ISLANDS TO THE COAST OF VENEZUELA NEAR 10N66W WITH ISOLATED SHOWERS/THUNDERSTORMS WITHIN 90 NM OF LINE FROM 23N42W TO 18N51W. A WEAK SURFACE RIDGE COVERS THE E AND CENTRAL ATLC BETWEEN 23N-30N E OF 60W. THE STATIONARY FRONT WILL DRIFT N ACROSS WHILE GRADUALLY DISSIPATING THROUGH MON AS HIGH PRESSURE BUILDS ALONG 31N. THE HIGH WILL SHIFT NE AND WEAKEN TUE IN RESPONSE TO A COLD FRONT THAT MOVES OFF THE NE FLORIDA COAST WED. THE FRONT WILL REACH FROM NEAR 31N76W TO S FLORIDA WED EVENING THEN WILL WEAKEN AS IT EXTENDS FROM NEAR 31N70W TO CENTRAL CUBA THROUGH FRI. 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