000 AXNT20 KNHC 161802 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT TUE SEP 16 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1745 UTC. ...SPECIAL FEATURES... NONE. ...TROPICAL WAVES... AN ATLANTIC OCEAN LOW AMPLITUDE TROPICAL WAVE IS ALONG 36W SOUTH OF 13N MOVING WEST NEAR 10 KT. SCATTERED SHOWERS ARE NEAR THE INTERSECTION OF THE WAVE AXIS AND THE ITCZ. A CARIBBEAN SEA TROPICAL WAVE IS ALONG 61W SOUTH OF 20N MOVING WEST 15 KT. THE MIMIC TOTAL PRECIPITABLE WATER PRODUCT FROM CIMMS DEPICTS ENHANCED DEEP LAYER MOISTURE JUST EAST OF THE WAVE AXIS...WITH ISOLATED MODERATE CONVECTION WITHIN AN AREA 150 NM EAST OF THE WAVE AXIS. A CARIBBEAN SEA TROPICAL WAVE IS ALONG 77W/78W SOUTH OF 20N MOVING WEST 10-15 KT. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS NEAR AND SOUTH OF THE INTERSECTION OF THE WAVE AXIS AND THE ITCZ...PARTICULARLY WITHIN AN AREA 100 NM WEST OF THE WAVE AXIS. A TROPICAL WAVE IS ALONG 88W FROM THE YUCATAN PENINSULA SOUTH OF 20N INTO THE EASTERN PACIFIC OCEAN MOVING WEST NEAR 10 KT. VISIBLE SATELLITE IMAGERY DEPICTS LOW LEVEL TURNING AND AN INVERTED-V STRUCTURE IN THE CLOUD ELEMENTS ASSOCIATED WITH THIS WAVE. ISOLATED MODERATE CONVECTION IS MAINLY SOUTH OF 17N WITHIN AN AREA 100 NM EITHER SIDE OF THE WAVE AXIS. ...THE ITCZ... ITCZ AXIS IS ANALYZED ALONG 10N15W 8N35W 9N55W 11N70W 9N81W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 7N-14N BETWEEN 14W-27W NEAR THE WEST AFRICAN COAST. SCATTERED MODERATE CONVECTION IS FROM 8N-21N BETWEEN 49W-60W. CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE FROM 4N-12N BETWEEN 79W-85W. ...DISCUSSION... GULF OF MEXICO... A WEAKENING COLD FRONT EXTENDS FROM THE WEST COAST OF FLORIDA NEAR 29N84W WESTWARD TO THE CENTRAL GULF...AND THEN CURVES SOUTHWARD TOWARD THE NORTHWESTERN BAY OF CAMPECHE. NORTH TO NORTHEASTERLY SURFACE WINDS...WITH SPEEDS UP TO 25 KTS PER A RECENT QUIKSCAT PASS WEST OF 95W...ARE OCCURRING BEHIND THE COLD FRONT...WITH MORE EASTERLY WINDS AHEAD OF THE FRONT. SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS CONTINUE TO DEVELOP IN THE VICINITY OF THE FRONT...ESPECIALLY OFF THE EAST COAST OF MEXICO AND OVER THE NORTHWESTERN GULF. THIS CONVECTIVE ACTIVITY IS IN RESPONSE TO WEAK UPPER LEVEL DIFFLUENCE TO THE EAST OF AN UPPER LEVEL ANTICYCLONE OVER CENTRAL MEXICO. ACROSS THE CENTRAL AND EASTERN GULF...A WEAK SURFACE PRESSURE GRADIENT AHEAD OF THE COLD FRONT WAS SUPPORTING LIGHT EASTERLY WINDS GENERALLY UNDER 10 KT FROM A RECENT QUIKSCAT PASS. OTHERWISE...MOSTLY FAIR CONDITIONS WERE IMPACTING THE CENTRAL AND EASTERN GULF...THOUGH SOME MOISTURE TO THE EAST OF AN UPPER LEVEL TROUGH OVER THE CENTRAL GULF WAS ENHANCING SOME CLOUDINESS OVER THE SOUTHEASTERN GULF. THE AFOREMENTIONED FRONT WILL CONTINUE TO WEAKEN AND BECOME STATIONARY OVER THE NEXT 24 HOURS...THOUGH IT COULD SURGE SOUTHWARD TOWARD THE BAY OF CAMPECHE OVER THE WESTERN GULF. SCATTERED SHOWERS WILL REMAIN POSSIBLE NEAR THE FRONT...ESPECIALLY NEAR THE EASTERN MEXICAN COAST. CARIBBEAN SEA... ONE TROPICAL WAVE IS ALONG 61W SOUTH OF 20N MOVING WEST 15 KT. ISOLATED MODERATE CONVECTION WITHIN AN AREA 150 NM EAST OF THE WAVE AXIS. A SECOND TROPICAL WAVE IS ALONG 77W/78W SOUTH OF 20N MOVING WEST 10-15 KT. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS NEAR AND SOUTH OF THE INTERSECTION OF THE WAVE AXIS AND THE ITCZ...PARTICULARLY WITHIN AN AREA 100 NM WEST OF THE WAVE AXIS. A THIRD TROPICAL WAVE IS ALONG 88W FROM THE YUCATAN PENINSULA SOUTH OF 20N INTO THE EASTERN PACIFIC OCEAN MOVING WEST NEAR 10 KT. ISOLATED MODERATE CONVECTION IS MAINLY SOUTH OF 17N WITHIN AN AREA 100 NM EITHER SIDE OF THE WAVE AXIS. EASTERLY SURFACE TRADE WINDS AT 15 TO 20 KT ARE BLOWING ACROSS MUCH OF THE CARIBBEAN. ISOLATED SHOWERS ARE DEVELOPING OVER HISPANIOLA AND PUERTO RICO...AND ARE DRIFTING SOUTHWARD OVER THE NORTHERN CARIBBEAN. THESE SHOWERS ARE DEVELOPING IN RESPONSE TO UPPER LEVEL DIFFLUENCE ON THE WESTERN PERIPHERY OF AN UPPER LEVEL CYCLONE LOCATED NEAR 16N67W. UNSTABLE CONDITIONS BENEATH AN UPPER LEVEL CYCLONE EAST OF THE YUCATAN PENINSULA...NEAR 17N85W...ARE SUPPORTING SCATTERED MODERATE/ISOLATED STRONG CONVECTION OVER CENTRAL AMERICA AND THE ADJACENT CARIBBEAN WATERS. NORTHERLY FLOW ALOFT IS OCCURRING ACROSS THE CENTRAL CARIBBEAN...AND THIS FLOW IS RELATIVELY DRY AND CONFLUENT... RESULTING IN MOSTLY FAIR WEATHER ACROSS THE CENTRAL CARIBBEAN. SCATTERED CONVECTION WILL REMAIN POSSIBLE OVER THE WESTERN CARIBBEAN FOR THE NEXT DAY...ESPECIALLY NEAR CENTRAL AMERICA... WITH THE APPROACH OF THE NEXT TROPICAL WAVE. ATLANTIC OCEAN... LOW LEVEL CONVERGENCE ASSOCIATED WITH A WEAK SURFACE TROUGH WAS GENERATING SCATTERED MODERATE CONVECTION FROM 26N-31N BETWEEN 54W-61W. THIS CONVECTION IS PROPAGATING SOUTHWARD AT 20-25 KT BENEATH WEAK DIFFLUENT UPPER LEVEL SOUTHERLY FLOW. THE SURFACE TROUGH IS EXPECTED TO SLIDE NORTHWESTWARD OVER THE NEXT DAY OR SO...WITH CONVECTION REMAINING POSSIBLE PARTICULARLY EAST OF THE TROUGH. A 1018 MB SURFACE HIGH TO THE WEST OF THIS TROUGH IS RESULTING IN MOSTLY FAIR WEATHER OVER THE WESTERN ATLANTIC. ISOLATED SHOWERS AND THUNDERSTORMS ARE FORECAST TO OCCUR OVER THE EAST COAST OF FLORIDA THIS AFTERNOON AND EVENING WITH SEA BREEZE CONVERGENCE ZONES. VISIBLE SATELLITE IMAGERY DEPICTS A SMALL CYCLONIC CIRCULATION CENTER IN THE MOTION OF LOW LEVEL CLOUD ELEMENTS NEAR 18N37W...WHERE A SURFACE LOW HAS BEEN PLACED ON THE 12Z MAP. THIS LOW IS EXPECTED TO MOVE WEST-SOUTHWESTWARD DURING THE NEXT 24 HOURS. NO SUBSTANTIAL CONVECTION HAS BEEN NOTED WITH THIS LOW THUS FAR...AS THIS SURFACE LOW REMAINS EMBEDDED WITHIN A DEEP-LAYER RIDGE THAT COVERS MUCH OF THE EASTERN ATLANTIC OCEAN. THIS RIDGE EMANATES WESTWARD FROM AN UPPER LEVEL ANTICYCLONE LOCATED NEAR 11N36W. A LARGE PORTION OF THE REST OF THE CENTRAL AND EASTERN ATLANTIC IS DOMINATED BY A SURFACE RIDGE THAT EXTENDS SOUTHWESTWARD FROM A 1031 MB SURFACE HIGH NEAR 47N27W. ITCZ CONVECTION NEAR THE WEST COAST OF AFRICA IS EXPECTED TO CONTINUE MOVING WESTWARD AT 10 TO 20 KT OVER THE FAR EASTERN ATLANTIC OVER THE NEXT DAY. $$ COHEN/MT