000 AXNT20 KNHC 020002 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT WED OCT 01 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2315 UTC. ...TROPICAL WAVES... TROPICAL WAVE IS ALONG 38W/39W S OF 19N MOVING W 10-15 KT. SATELLITE IMAGERY AND COMPUTER MODEL GUIDANCE SHOWS WAVE COINCIDING WITH A MAXIMUM IN LOW LEVEL CIRCULATION. WAVE IS EMBEDDED WITHIN A MAXIMUM IN DEEP LAYER MOISTURE BASED ON THE TOTAL PRECIPITABLE WATER PRODUCT FROM CIMSS. ISOLATED MODERATE CONVECTION IS WITHIN 180 NM OF THE WAVE AXIS N OF 11N. TROPICAL WAVE IS ALONG 49W/50W FROM 12N-21N MOVING W NEAR 10 KT. THIS WAVE IS EMBEDDED WITHIN A MAXIMUM OF DEEP LAYER MOISTURE...AND SATELLITE IMAGERY DEPICTS INVERTED-V CLOUD PATTERN NEAR WAVE AXIS. SURFACE OBSERVATIONS SHOW WIND VEERING TO SE DIRECTION UPON WAVE PASSAGE. ISOLATED MODERATE WITH EMBEDDED STRONG CONVECTION IS FROM 13N-17N BETWEEN 42W-47W. TROPICAL WAVE IS ALONG 66W/67W S OF 16N MOVING W NEAR 15 KT. A WEAK MAXIMUM IN DEEP LAYER MOISTURE IS PRESENT NEAR WAVE... THOUGH WAVE IS ILL-DEFINED BASED ON SATELLITE IMAGERY AND SURFACE WIND OBSERVATIONS. SCATTERED MODERATE CONVECTION IS WITHIN 120 NM OF WAVE AXIS S OF 11N...AFFECTING N VENEZUELA. ...THE ITCZ... THE ITCZ AXIS IS ANALYZED ALONG 11N13W 10N20W 10N36W 9N49W 9N60W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 4N-13N BETWEEN 22W-30W. SCATTERED MODERATE CONVECTION IS FROM 5N-11N BETWEEN 37W-43W. ISOLATED MODERATE CONVECTION IS FROM 7N-12N BETWEEN 50W-56W. ...DISCUSSION... GULF OF MEXICO... DEEP UPPER TROUGH OVER THE E CONUS EXTENDS INTO THE GULF. ALSO...A COLD FRONT IS DRAPED ACROSS THE N AND CENTRAL GULF...EXTENDING FROM THE FLORIDA BIG BEND NEAR 29N83W WESTWARD TO 27N88W AND 26N95W. SUBSIDENCE AND DRY AND STABLE AIR W OF THE UPPER TROUGH AXIS ARE AFFECTING MUCH OF THE GULF...WITH ONLY A 30 NM BAND OF SCATTERED LOW CLOUDS ALONG THE COLD FRONT. OTHERWISE...FAIR WEATHER DOMINATES MUCH OF THE GULF. OVER THE FAR SE GULF...CLOUDINESS AND POSSIBLE SHOWERS ARE MOVING TO THE NE IN RESPONSE TO ATMOSPHERIC LIFT ORIGINATING IN THE W CARIBBEAN AND SW ATLC. CARIBBEAN SEA... AN UPPER RIDGE EXTENDS FROM E CUBA TO COSTA RICA. TO THE W OF THIS RIDGE...UPPER SUPPORT IN MOIST SW FLOW ALOFT IS GENERATING SCATTERED MODERATE/ISOLATED STRONG CONVECTION OVER THE W CARIBBEAN. THIS CONVECTION IS AFFECTING AREAS FROM 15N-23N BETWEEN 79W-88W...INCLUDING W CUBA...NICARAGUA...AND COSTA RICA. THIS CONVECTION IS BEING ENHANCED BY A 1011 MB LOW OVER THE W CARIBBEAN NEAR 20N86W AND A SURFACE TROUGH THAT EXTENDS TO THE NE OF THIS LOW TO W CUBA NEAR 23N82W. FURTHER TO THE E...A WEAK UPPER TROUGH EXTENDS TO THE N FROM N COLOMBIA TO W HAITI... COVERING THE CENTRAL CARIBBEAN. DRY AIR EMBEDDED WITHIN THIS TROUGH IS GENERALLY LIMITING DEEP CONVECTION OVER THE CENTRAL CARIBBEAN. AN UPPER RIDGE COVERS THE NE CARIBBEAN...ANCHORED BY AN UPPER HIGH OVER THE SW ATLC NEAR 25N64W. DRY AND STABLE AIR IN THE RIDGE IS RESULTING IN FAIR WEATHER N OF 15N AND E OF 66W IN THE NE CARIBBEAN. THE ITCZ AXIS EXTENDS ALONG 10N IN THE SW CARIBBEAN AND ACROSS COSTA RICA AND PANAMA INTO THE E PACIFIC... ENHANCING THE CONVECTION OVER CENTRAL AMERICA. ALSO...SCATTERED MODERATE CONVECTION THAT FORMED OVER NE COLOMBIA AND NW VENEZUELA NEAR THE ITCZ AXIS IS PROPAGATING TO THE N INTO THE ADJACENT S CARIBBEAN. ATLANTIC OCEAN... DEEP TROUGH OVER THE E CONUS COVERS THE W ATLC W OF 73W...WITH MOIST SW FLOW ALOFT AFFECTING THE W ATLC. THIS TROUGH IS SUPPORTING A COLD FRONT THAT EXTENDS FROM 32N69W TO 28N74W TO A 1012 MB LOW SE OF FLORIDA NEAR 26N80W. A SURFACE TROUGH EXTENDS FROM THE LOW TO W CUBA NEAR 23N81W. THE COMBINATION OF THESE FEATURES IS RESULTING IN SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS WITHIN 150 NM TO THE SE OF THE SURFACE LOW...COLD FRONT...AND SURFACE TROUGH. FURTHER TO THE E...AN UPPER HIGH IS LOCATED NEAR 25N64W AND ANCHORS A RIDGE THAT COVERS THE CENTRAL ATLANTIC. THIS RIDGE IS BECOMING TILTED FROM THE NE TO SW WITH THE APPROACH OF THE UPPER TROUGH TO THE W. DRY AIR AND SUBSIDENCE AROUND THE UPPER HIGH IS RESULTING IN FAIR WEATHER OVER MUCH OF THE CENTRAL ATLC. FURTHER TO THE E...A SHARP UPPER TROUGH EXTENDS FROM 32N42W TO 22N46W TO 13N56W. MOISTURE AND WEAK INSTABILITY TO THE E OF THIS TROUGH ARE RESULTING IN CLOUDINESS AND POSSIBLE SHOWERS FROM 25N-32N BETWEEN 34W-43W. TO THE E OF THIS UPPER TROUGH IS A BROAD UPPER RIDGE THAT EXTENDS TO THE E OF 41W TO THE AFRICAN COAST. THE CORRESPONDING SURFACE RIDGE EXTENDS FROM A 1029 MB HIGH NEAR 42N24W S TO 20N AND COVERS THE E ATLC. THE TYPICAL E/W UPPER RIDGE THAT DOMINATES THE TROPICAL ATLC EXTENDS ALONG 15N TO 44W AND IS ANCHORED BY AN UPPER HIGH CENTERED NEAR 15N28W. MINIMUM IN TOTAL PRECIPITABLE WATER SHOWS AFRICAN DUST COVERING THE E ATLC FROM 12N-20N E OF 30W. $$ COHEN