000 AXNT20 KNHC 041040 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 AM EDT SUN OCT 04 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1015 UTC. ...TROPICAL WAVES... TROPICAL WAVE IS ALONG 37W S OF 15N MOVING W NEAR 18 KT. PARTIALLY EMBEDDED WITHIN THE ITCZ...A BROAD SWATH OF DEEP LAYER MOISTURE SURROUNDS THE WAVE FROM 5N-14N BETWEEN 33W-43W AS OBSERVED IN THE TOTAL PRECIPITABLE WATER IMAGERY. LOW-LEVEL CYCLONIC TURNING IS NOTED PRIMARILY W OF THE WAVE AXIS ON SATELLITE IMAGERY AND IS ENHANCING SCATTERED STRONG CONVECTION FROM 7N-16N BETWEEN 33W-44W. TROPICAL WAVE IS ALONG 52W S OF 16N MOVING W NEAR 15 KT. RATHER WELL DEFINED ON SATELLITE IMAGERY...THIS WAVE EXHIBITS A MAXIMUM IN 850 MB RELATIVE VORTICITY ALONG THE WAVE AXIS NEAR 10N ACCORDING TO THE LATEST CIMSS WAVETRAK MODEL GUIDANCE. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 8N-14N BETWEEN 48W-52W. TROPICAL WAVE IS ALONG 76W S OF 19N MOVING W NEAR 10 KT. WEAK CYCLONIC CURVATURE IS NOTED IN THE LOW-LEVEL CLOUD FIELD OVER THE CENTRAL CARIBBEAN. THE WAVE ALSO LIES BENEATH UPPER LEVEL TROUGHING BETWEEN 72W-80W. SCATTERED MODERATE CONVECTION IS FROM 13N-16N BETWEEN 73W-78W AND IS LIKELY ENHANCED BY THE UPPER LEVEL TROUGH. ...ITCZ... THE ITCZ AXIS IS CENTERED ALONG 7N11W 8N34W 9N39W 9N51W 9N54W 8N61W. ASIDE FROM THE CONVECTION ASSOCIATED WITH THE TROPICAL WAVES...NO OTHER SIGNIFICANT AREAS OF DEEP CONVECTION ARE NOTED ON SATELLITE IMAGERY. ...DISCUSSION... GULF OF MEXICO... A STATIONARY FRONT EXTENDS ACROSS ALONG THE NRN GULF COAST FROM TALLAHASSEE TO NEW ORLEANS AND INTO INTERIOR SRN TEXAS NEAR GALVESTON. MOSTLY SELY WINDS OF UP TO 20 KT ARE OBSERVED OVER MUCH OF THE CENTRAL AND WRN GULF. THIS MOIST LOW-LEVEL SLY RETURN FLOW ALONG WITH LOW-LEVEL CONVERGENCE NEAR THE FRONTAL BOUNDARY IS GENERATING SCATTERED SHOWERS AND ISOLATED TSTMS N OF 27N W OF 86W. THIS ACTIVITY IS BEING ENHANCED BY UPPER LEVEL ANTICYCLONIC FLOW AND DIFFLUENCE FOUND ACROSS MUCH OF THE GULF AS AN UPPER LEVEL HIGH IS CENTERED NEAR 21N97W. ELSEWHERE...THE GULF REMAINS RATHER TRANQUIL THIS MORNING AS THE NLY FLOW REGIME ALOFT KEEPS STABLE ATMOSPHERIC CONDITIONS OVER THE GULF S OF 27N. CARIBBEAN SEA... AN UPPER LEVEL TROUGH COVERS THE CENTRAL CARIBBEAN FOCUSED ON AN UPPER LOW CENTERED NEAR 13N77W. COMBINED WITH THE UPPER LEVEL RIDGE LOCATED OVER THE GULF OF MEXICO...NLY WINDS ALOFT ARE PROVIDING DRY STABLE AIR W OF 80W AND OVER A LARGE PORTION OF CENTRAL AMERICA. THE UPPER LEVEL TROUGHING COUPLED WITH THE TROPICAL WAVE ALONG 76W IS GENERATING CLUSTERS OF SCATTERED SHOWERS AND ISOLATED TSTMS S OF 17N BETWEEN 70W-79W. E OF THE UPPER LEVEL TROUGH...A LARGE AREA OF MOIST SWLY FLOW AND UPPER LEVEL DIFFLUENCE ARE NOTED ON WATER VAPOR IMAGERY WHICH IS GENERATING ISOLATED SHOWERS BETWEEN 63W-74W. A SURFACE TROUGH IS ALSO ANALYZED TO THE E OF THE LESSER ANTILLES FROM 21N58W TO 15N59W. LOW-LEVEL CONVERGENCE NEAR THE SURFACE TROUGH IS GENERATING SCATTERED SHOWERS AND TSTMS WITHIN 170 NM W OF THE BOUNDARY WHICH IS IMPACTING THE LEEWARD ISLANDS. ATLANTIC OCEAN... AN UPPER LEVEL TROUGH EXTENDS OVER THE W ATLC WATERS WITH AXIS ALONG 73W. THIS TROUGHING EXTENDS SWD INTO THE CENTRAL CARIBBEAN TROUGH ACROSS ERN CUBA...THE WINDWARD PASSAGE AND HISPANIOLA AND SUPPORTS A COLD FRONT THAT IS POSITIONED ALONG THE ERN U.S. SEABOARD TO SAVANNAH GEORGIA. VERY LITTLE PRECIPITATION IS OBSERVED WITH THIS FRONT...HOWEVER SURFACE DEWPOINTS ARE NOTICEABLY LOWER ON THE BACK SIDE OF THE BOUNDARY. E OF THE UPPER LEVEL TROUGH AXIS...A LARGE AREA OF UPPER DIFFLUENCE IS NOTED ON WATER VAPOR IMAGERY N OF 22N BETWEEN 63W-73W. ISOLATED SHOWERS ARE FOUND OVER THIS AREA...WITH SCATTERED SHOWERS FOUND MAINLY N OF 28N BETWEEN 67W-73W WHERE THE UPPER LEVEL FORCING IS STRONGEST. FARTHER TO THE E...A WEAKNESS IN THE CENTRAL ATLC SUBTROPICAL RIDGE IS NOTED BY A SURFACE TROUGH THAT EXTENDS FROM 28N45W TO 25N54W. SUPPORTED ALOFT BY A SHORTWAVE UPPER LEVEL TROUGH...MOST OF THE SCATTERED SHOWERS AND ISOLATED TSTMS BEING GENERATING ARE FROM 26N-30N BETWEEN 42W-48W. THE UPPER LEVEL TROUGH EXTENDS SW FROM 24N50W TO E OF THE LESSER ANTILLES AND SUPPORTS ANOTHER SURFACE TROUGH EXTENDING FROM 21N58W TO 15N59W. SCATTERED SHOWERS AND TSTMS ARE OCCURRING FROM 15N-21N BETWEEN 58W-62W...INCLUDING PORTIONS OF THE LEEWARD ISLANDS. ELSEWHERE OVER THE REMAINDER OF THE ERN ATLC...UPPER LEVEL ZONAL FLOW DOMINATES N OF 24N E OF 45W. EMBEDDED WITH THIS FLOW ALOFT IS A SURFACE TROUGH ANALYZED FROM 32N30W TO 27N36W. CLUSTERS OF SCATTERED SHOWERS AND ISOLATED TSTMS ARE OCCURRING WITHIN 120 NM EITHER SIDE OF THE SURFACE TROUGH. THE TYPICAL E/W UPPER RIDGE DOMINATES MUCH OF THE TROPICS EXTENDING TO 50W...WITH THE ANTICYCLONIC CIRCULATION ANCHORED OVER THE CAPE VERDE ISLANDS. THIS UPPER LEVEL FEATURES CONTINUES TO ENHANCE THE CONVECTION ASSOCIATED WITH THE TROPICAL WAVES ACROSS THE TROPICAL CENTRAL ATLC. $$ HUFFMAN