000 AXNT20 KNHC 080000 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT TUE OCT 07 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. ...SPECIAL FEATURES... TROPICAL DEPRESSION MARCO IS CENTERED NEAR 19.9N 97.1W AT 07/2100 UTC OR ABOUT 70 NM S-SE OF TUXPAN MEXICO AND ABOUT 65 NM NW OF VERACRUZ MEXICO MOVING W AT 4 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1007 MB. MAXIMUM SUSTAINED WIND SPEED IS 30 KT WITH GUSTS TO 40 KT. SEE THE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT3/WTNT23 KNHC FOR MORE DETAILS. MARCO CONTINUES TO WEAKEN AS IT MOVES INLAND OVER THE HIGHER TERRAIN OF E/CENTRAL MEXICO. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 19N-22N BETWEEN 95W-98W. ...TROPICAL WAVES... TROPICAL WAVE IS ALONG 22W S OF 12N MOVING W NEAR 10 KT. BROAD MID-LEVEL CYCLONIC CURVATURE IS OBSERVED ON SATELLITE IMAGERY WITH A LAYER OF SAHARAN DUST LOCATED NORTH OF 15N SUPPRESSING THE WAVE TO THE S. CONVECTION IS EMBEDDED WITHIN THE ITCZ WITH CLUSTERS OF SCATTERED MODERATE CONVECTION WITHIN 220 NM W OF THE WAVE AXIS N OF 3N. TROPICAL WAVE PREVIOUSLY ALONG 41W HAS BEEN RE-POSITIONED TO ALONG 50W/51W BASED ON INVERTED-V SATELLITE SIGNATURE AND CYCLONIC CURVATURE NOTED FROM RECENT BUOY/SHIP OBSERVATIONS. THE WAVE IS S OF 16N MOVING W NEAR 10 KT. SCATTERED MODERATE CONVECTION IS FROM 10N-14N BETWEEN 47W-54W. TROPICAL WAVE IS ALONG 68W/69W S OF 19N MOVING W NEAR 15 KT. WEAK INVERTED-V CURVATURE IS OBSERVED IN THE LOW/MID LEVEL CLOUD FIELD ON SATELLITE IMAGERY. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 10N-16N BETWEEN 66W-71W. TROPICAL WAVE IS ALONG 78W S OF 20N MOVING W NEAR 15 KT. THE WAVE IS LOCATED BENEATH MODERATE SUBSIDENCE/DRY AIR ASSOCIATED WITH AN UPPER HIGH ACROSS THE WRN CARIBBEAN SEA...THEREFORE ONLY SCATTERED SHOWERS ARE NOTED ACROSS JAMAICA. ...THE ITCZ... THE ITCZ AXIS IS ANALYZED ALONG 13N16W 8N21W 7N24W 9N34W 10N40W 9N49W 9N54W TO INLAND ACROSS NRN VENEZUELA. SCATTERED MODERATE/ STRONG CONVECTION IS ALONG THE W AFRICA COAST FROM 7N-12N BETWEEN 12W-16W. SCATTERED MODERATE CONVECTION IS FROM 3N-7N BETWEEN 15W-19W. SIMILAR CONVECTION IS FROM 8N-10N BETWEEN 54W-57W. ...DISCUSSION... GULF OF MEXICO... TROPICAL STORM MARCO IS LOCATED INLAND ACROSS E/CENTRAL MEXICO...SEE SPECIAL FEATURES ABOVE FOR MORE DETAILS. A BROAD UPPER RIDGE COVERS THE GULF ANCHORED IN THE SW GULF NEAR 21N92W. AN UPPER LEVEL TROUGH IS ACROSS THE CENTRAL CONUS WITH AXIS ALONG 96W EXTENDING S ACROSS ERN TEXAS TO 30N. STRONG SWLY UPPER FLOW IS BRINGING MOIST TROPICAL AIR ACROSS MUCH OF THE NRN GULF. UPPER DIFFLUENCE E OF THE UPPER TROUGH...ALONG WITH A SURFACE TROUGH EXTENDING FROM PORT ARTHUR TEXAS TO NEAR BROWNSVILLE TEXAS IS GENERATING CLUSTERS OF SCATTERED SHOWERS/ISOLATED TSTMS OVER THE NRN AND WRN GULF N OF A LINE FROM ST. PETERSBURG FLORIDA TO NEAR TUXPAN MEXICO. SIMILAR ACTIVITY DUE TO MARCO AND THE UPPER LEVEL DIFFLUENCE IS IN THE WRN BAY OF CAMPECHE W OF 95W TO INLAND ACROSS ERN MEXICO. A COLD FRONT ASSOCIATED WITH THE UPPER TROUGH ACROSS THE CENTRAL CONUS IS EXPECTED TO ENTER THE GULF THIS EVENING WITH SUBSIDENCE/DRY AIR FOLLOWING BEHIND TO THE WEST. CARIBBEAN SEA... AN UPPER LOW COVERS THE WRN CARIBBEAN CENTERED IN THE GULF OF HONDURAS NEAR 16N85W GENERATING SCATTERED SHOWERS AND TSTMS FROM 10N-17N BETWEEN 83W-85W...INCLUDING ERN NICARAGUA AND NRN COSTA RICA. THE CENTRAL AND SE CARIBBEAN IS DOMINATED BY A BROAD UPPER RIDGE ANCHORED OVER NRN VENEZUELA E OF 80W TO OVER THE LESSER ANTILLES AND S OF 17N. DIFFLUENCE ALOFT ALONG WITH THE TROPICAL WAVE ALONG 68W/69W IS GENERATING SCATTERED SHOWERS/ISOLATED TSTMS E OF 72W AND S OF 16N ACROSS THE ERN CARIBBEAN TO THE LESSER ANTILLES. ATLANTIC OCEAN... A WEAK UPPER RIDGE EXTENDS FROM THE GULF OF MEXICO INTO THE W ATLC W OF 76W. UPPER DIFFLUENCE ACROSS THE NE GULF WATERS IS SPREADING MULTILAYERED CLOUDINESS ACROSS THE FLORIDA PENINSULA AND NW BAHAMAS THIS EVENING. UPPER LEVEL TROUGHING COVERS THE REMAINDER OF THE W ATLC N OF 17N BETWEEN 57W-76W. A COLD FRONT ENTERS THE REGION NEAR 32N58W AND EXTENDS W-SW TO 29N70W AND INLAND ACROSS CENTRAL FLORIDA NEAR MELBOURNE. ISOLATED SHOWERS ARE LOCATED WITHIN 90 NM S OF THE FRONT. AN UPPER LOW IS IN THE CENTRAL ATLC CENTERED NEAR 25N58W WITH A SURFACE TROUGH EXTENDING FROM 31N59W TO 23N65W PRODUCING SCATTERED SHOWERS AND ISOLATED TSTMS FROM 23N-30N BETWEEN 52W-58W. AN UPPER RIDGE IS TO THE E CENTERED NEAR 27N39W AND EXTENDS NE TO BETWEEN THE AZORES AND MADEIRA ISLANDS. AN UPPER LOW IS ACROSS THE CENTRAL TROPICAL ATLC CENTERED NEAR 16N40W WITH AN UPPER HIGH CENTERED EAST OF THE CAPE VERDE ISLANDS. UPPER LEVEL DIFFLUENCE BETWEEN THESE TWO UPPER FEATURES ALONG WITH A PAIR OF 1011 MB SURFACE LOWS...ONE CENTERED NEAR 13N31W AND ANOTHER CENTERED NEAR 11N37W WITH A SURFACE TROUGH EXTENDING N TO NEAR 22N34W IS GENERATING A LARGE AREA OF MULTILAYERED CLOUDINESS AND POSSIBLE SCATTERED SHOWERS FROM 11N-22N BETWEEN 23W-36W. A SURFACE RIDGE COVERS THE E ATLC N OF 22N E OF 50W ANCHORED BY A 1026 MB HIGH CENTERED NEAR 33N26W. $$ HUFFMAN