000 AXNT20 KNHC 291758 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT WED OCT 29 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 1715 UTC. ...TROPICAL WAVES... TROPICAL WAVE IS ALONG 52W S OF 16N MOVING W 10-15 KT. CIMSS WAVETRAK PRODUCT SHOWS THAT LOW LEVEL CYCLONIC CIRCULATION IS MAXIMIZED ALONG WAVE AXIS. WAVE IS AT THE LEADING EDGE OF A WESTWARD-MOVING SURGE IN DEEP LAYER MOISTURE BASED ON TOTAL PRECIPITABLE WATER PRODUCT FROM CIMSS. ISOLATED MODERATE CONVECTION IS FROM 10N-16N BETWEEN 48W-53W. TROPICAL WAVE IS ALONG 64W/65W FROM 10N-19N MOVING W 10-15 KT. VISIBLE SATELLITE IMAGERY DEPICTS A WELL-DEFINED INVERTED-V SIGNATURE IN CLOUD PATTERN COINCIDING WITH THE WAVE AXIS... WHICH ALSO COINCIDES WITH A MAXIMUM IN DEEP LAYER MOISTURE. ISOLATED SHOWERS ARE WITHIN 60 NM EITHER SIDE OF WAVE AXIS N OF 12N. ...THE ITCZ... ITCZ AXIS IS ANALYZED ALONG 12N15W 9N28W 9N37W 9N49W 8N61W. A SURFACE TROUGH IS EMBEDDED WITHIN THE ITCZ...AND THIS TROUGH EXTENDS FROM 14N40W...TO A 1012 MB SURFACE LOW NEAR 11N40W...TO 8N40W. LOW LEVEL CONVERGENCE NEAR THESE FEATURES IS RESULTING IN SCATTERED MODERATE CONVECTION FROM 10N-13N BETWEEN 37W-39W. ADDITIONALLY...ISOLATED MODERATE CONVECTION IS WITHIN 210 NM EITHER SIDE OF ITCZ AXIS BETWEEN 17W-32W. ISOLATED MODERATE CONVECTION IS WITHIN 90 NM N OF ITCZ AXIS BETWEEN 45W-49W. SIMILAR CONVECTION IS WITHIN 60 NM EITHER SIDE OF ITCZ AXIS BETWEEN 57W-60W. ...DISCUSSION... GULF OF MEXICO... GENERALLY FAIR WEATHER AND DRY CONDITIONS PREVAIL ACROSS THE GULF REGION...AS A MODIFIED CONTINENTAL POLAR AIRMASS PERSISTS...WITH TEMPERATURES BELOW SEASONAL AVERAGES ACROSS THE N GULF COAST. THIS RELATIVELY COOL AND DRY AIRMASS IS BEING SUPPORTED BY A 1031 MB SURFACE HIGH IN THE SE CONUS. WEAK LOW-LEVEL INSTABILITY RESULTING FROM THE COOLER AIR PERSISTING OVER THE RELATIVELY WARMER GULF WATERS IS MAINTAINING THE PRESENCE OF STRATOCUMULUS CLOUDS OVER MUCH OF THE GULF. ALSO... STRONG SOUTHWESTERLY FLOW ALOFT IS BRINGING UPPER LEVEL MOISTURE AND HIGH CLOUDS FROM THE E PACIFIC REGION INTO THE W GULF. ADDITIONALLY...STRONG NE SURFACE WINDS ARE BLOWING THROUGH THE ISTHMUS OF TEHUANTEPEC RESULTING IN GALE FORCE WINDS IN THE E PACIFIC REGION. CARIBBEAN SEA... A COLD FRONT EXTENDS FROM W HAITI NEAR 20N72W TO 16N78W TO E HONDURAS NEAR 15N85W. THIS FRONT IS INTERACTING WITH MOISTURE IN DIFFLUENT SW FLOW ALOFT TO RESULT IN ENHANCED CLOUD BANDS AND ISOLATED SHOWERS WITHIN 60 NM EITHER SIDE OF THE COLD FRONT. DEEP MOISTURE PRESENT OVER THE SW CARIBBEAN COMBINED WITH UPPER LEVEL DIFFLUENCE IS RESULTING IN SCATTERED MODERATE CONVECTION FROM 8N-12N BETWEEN 77W-82W...AFFECTING PORTIONS OF PANAMA AND COSTA RICA. FARTHER TO THE E...AN UPPER RIDGE AXIS EXTENDS FROM AN UPPER HIGH IN THE SW ATLC NEAR 23N62W TO THE NE CARIBBEAN NEAR 17N69W. DEEP LAYER DRY AIR EMBEDDED WITHIN THIS RIDGE IS RESULTING IN MAINLY FAIR WEATHER ACROSS THE E CARIBBEAN. ATLANTIC OCEAN... A DEEP LAYER TROUGH IS OVER THE W ATLC...WITH MUCH OF THE ENERGY ASSOCIATED WITH THE TROUGH NOW N OF THE DISCUSSION AREA. THIS TROUGH CONTINUES TO SUPPORT A COLD FRONT THAT EXTENDS FROM 32N61W TO 25N66W TO W HAITI NEAR 20N72W. DEEP LAYER DRY AIR EMBEDDED WITHIN THE TROUGH IS RESULTING IN GENERALLY FAIR WEATHER IN THE WAKE OF THE FRONT...WHERE A RELATIVE DRY AND COOL MODIFIED CONTINENTAL POLAR AIRMASS IS IN PLACE. HOWEVER... ATMOSPHERIC LIFT IN MOIST SOUTHWESTERLY FLOW ALOFT IS SUPPORTING ISOLATED SHOWERS WITHIN 60 NM EITHER SIDE OF THE COLD FRONT. FARTHER TO THE E...AN UPPER LEVEL RIDGE AXIS EXTENDS FROM THE SW ATLC NEAR 19N66W TO AN UPPER HIGH ALSO OVER THE SW ATLC NEAR 23N62W TO 32N54W. A WEAK SURFACE TROUGH E OF THE UPPER RIDGE AXIS EXTENDS FROM 31N52W TO 27N54W TO 24N57W...WITH ISOLATED SHOWERS WITHIN 60 NM EITHER SIDE OF THE SURFACE TROUGH S OF 29N. FARTHER TO THE E...A DEEP LAYER TROUGH IS N OF 23N E OF 30W. DRY AIR EMBEDDED WITHIN THE TROUGH IS INHIBITING DEEP CONVECTIVE DEVELOPMENT NEAR THIS FEATURE. ADDITIONALLY...THIS TROUGH IS SUPPORTING A COLD FRONT MIDWAY BETWEEN THE CANARY ISLANDS AND THE CAPE VERDE ISLANDS. THIS FRONT EXTENDS FROM THE W COAST OF AFRICA NEAR 24N16W TO 24N27W TO 30N36W...AND A BAND OF INCREASED CLOUDINESS IS WITHIN 30 NM EITHER SIDE OF THE COLD FRONT. OVER THE TROPICAL ATLC...AN EAST-TO-WEST UPPER RIDGE IS ALONG 12N BETWEEN THE AFRICAN COAST AND 44W...AND A SURFACE TROUGH IS EMBEDDED WITHIN THE ITCZ. THIS TROUGH EXTENDS FROM 14N40W...TO A 1012 MB SURFACE LOW NEAR 11N40W...TO 8N40W. LOW LEVEL CONVERGENCE NEAR THESE FEATURES IS RESULTING IN SCATTERED MODERATE CONVECTION FROM 10N-13N BETWEEN 37W-39W...WHICH IS BEING ENHANCED BY UPPER LEVEL DIVERGENCE NEAR THE UPPER RIDGE AXIS. $$ COHEN