000 AXNT20 KNHC 210556 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 AM EDT WED OCT 21 2009 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0515 UTC. ...TROPICAL WAVES... TROPICAL WAVE IS TILTED FROM 8N29W TO 18N26W DRIFTING WESTWARD. THE WAVE AXIS COINCIDES WITH A DEEP LAYER MOISTURE MAXIMUM AS OBSERVED IN TOTAL PRECIPITABLE WATER IMAGERY AS WELL AS A MAXIMUM IN 850 MB RELATIVE VORTICITY IN THE CIMSS GLOBAL MODEL GUIDANCE FIELDS. THE LOW-LEVEL CLOUD FIELD EXHIBITS CYCLONIC TURNING IN THE VICINITY OF THE WAVE AXIS WITH ISOLATED SHOWERS AND MODERATE CONVECTION FROM 12N-18N BETWEEN 22W-30W THAT INCLUDES THE CAPE VERDE ISLANDS. ...ITCZ... THE ITCZ AXIS IS CENTERED ALONG 8N13W 6N30W 9N38W 9N61W. A 1010 MB SURFACE LOW IS LOCATED N OF THE AXIS ACROSS THE CENTRAL TROPICAL ATLC CENTERED NEAR 13N38W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 120 NM OF LINE FROM 6N36W TO 16N39W IN ASSOCIATION WITH THE LOW. ELSEWHERE...CLUSTERS OF ISOLATED MODERATE CONVECTION COVER THE AREA FROM 3N-7N BETWEEN 16W-29W. ...DISCUSSION... GULF OF MEXICO... A BROAD SURFACE RIDGE DOMINATES ACROSS FLORIDA AND THE GULF... ANCHORED OVER THE CAROLINAS BY A 1025 MB HIGH. ALOFT...THE GULF IS INFLUENCED BY W-NW ANTICYCLONIC FLOW AROUND AN UPPER LEVEL RIDGE ACROSS MUCH OF THE GULF. STRONG SUBSIDENCE AND DRY STABLE AIR IS NOTED ON WATER VAPOR IMAGERY PRIMARILY E OF 90W...WHILE UPPER LEVEL CONVECTIVE DEBRIS CLOUDINESS FROM TROPICAL STORM RICK IN THE EASTERN PACIFIC ADVECTS EASTWARD AND SPILLS OVER THE TOP OF THE UPPER LEVEL RIDGE N OF 25N W OF 92W. AT THE SURFACE HOWEVER...E TO SE SURFACE FLOW UP TO 20 KT IS FORECAST TO CONTINUE THROUGH WEDNESDAY...TURNING MORE SOUTHERLY OVER THE WESTERN GULF BY THURSDAY AHEAD OF THE NEXT COLD FRONT EXPECTED TO ENTER THE NW GULF WATERS LATE THURSDAY. CARIBBEAN SEA... A DEEP LAYERED TROUGH IS OVER THE W ATLC AND FLORIDA PENINSULA THAT DIPS DIPS S OVER THE NW CARIBBEAN AND WESTERN CUBA. A 1007 MB LOW IS CENTERED INLAND OVER SOUTHERN NICARAGUA NEAR 12N84W AND EXTENDS SURFACE TROUGHING N-NW TO A 1009 MB LOW IN THE GULF OF HONDURAS NEAR 17N87W. A NARROW UPPER LEVEL RIDGE IS LOCATED TO THE E EXTENDING FROM NORTHERN COLOMBIA NEAR 11N75W TO ACROSS EASTERN HISPANIOLA AND INTO THE W ATLC. THIS IS PROVIDING A DIFFLUENT ENVIRONMENT ALOFT TO ENHANCE A BROAD AREA OF SCATTERED SHOWERS AND ISOLATED TSTMS THAT COVERS THE WESTERN CARIBBEAN W OF A LINE FROM PANAMA NEAR 9N78W TO HAITI NEAR 18N72W. A BROAD UPPER LEVEL TROUGH COVERS THE EASTERN CARIBBEAN EXTENDING FROM AN UPPER LOW IN THE CENTRAL ATLC PROVIDING STRONG SUBSIDENCE AND DRY STABLE AIR E OF 70W. ATLANTIC OCEAN... A BROAD DEEP LAYERED UPPER LEVEL TROUGH COVERS MUCH OF THE SW NORTH ATLC...FLORIDA PENINSULA AND STRAITS OF FLORIDA WITH THE ASSOCIATED COLD FRONT ENTERING THE REGION NEAR 32N59W SW TO 24N70W WHERE IT BECOMES STATIONARY ACROSS THE SE BAHAMAS TO EASTERN CUBA NEAR 21N76W. SCATTERED SHOWERS ARE OCCURRING WITHIN 200 NM BEHIND THE FRONT WITH LOW-LEVEL CONVERGENCE E OF THE FRONT GENERATING ISOLATED SHOWERS WITHIN 150 NM E OF THE FRONT. A NARROW UPPER RIDGE EXTENDS FROM THE WESTERN CARIBBEAN THROUGH HISPANIOLA ALONG 25N62W TO 32N54W PROVIDING DIFFLUENCE ALOFT TO ENHANCE THE ACTIVITY ASSOCIATED WITH THE FRONTAL BOUNDARY. A WEAK PRE-FRONTAL SURFACE TROUGH IS TO THE E ALONG 67W FROM 22N-25N. FARTHER EAST...A BROAD UPPER LEVEL LOW IS CENTERED IN THE CENTRAL ATLC NEAR 24N49W WITH UPPER LEVEL TROUGHING EXTENDING SW TO THE LESSER ANTILLES AND EASTERN CARIBBEAN. THIS SUPPORTS A SURFACE TROUGH THAT EXTENDS FROM 21N53W TO 27N54W WITH POSSIBLE ISOLATED SHOWERS WITHIN 120 NM EITHER SIDE OF THE SURFACE TROUGH. UPPER LEVEL DIFFLUENCE E OF THE UPPER LEVEL LOW HOWEVER IS GENERATING A MUCH MORE ACTIVE AREA OF SCATTERED SHOWERS AND ISOLATED TSTMS COVERING THE AREA FROM 20N-29N BETWEEN 39W-50W. ACROSS THE REMAINDER OF THE ATLC...A BROAD UPPER RIDGE IS LOCATED OVER THE TROPICAL ATLC ANCHORED NEAR 8N42W THAT EXTENDS A RIDGE AXIS N TO 25N27W. $$ HUFFMAN