000 AXNT20 KNHC 041738 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 PM 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1715 UTC. ...TROPICAL WAVES... TROPICAL WAVE IS ALONG 39W S OF 16N MOVING W 15 KT. LOW AMPLITUDE WAVE MOSTLY EMBEDDED WITHIN THE ITCZ AND EMBEDDED WITHIN A DEEP LAYER MOISTURE MAXIMUM AS OBSERVED IN TOTAL PRECIPITABLE WATER IMAGERY. BROAD MID LEVEL CYCLONIC TURNING CAN BE OBSERVED IN THE VISIBLE SATELLITE IMAGERY. ASSOCIATED CONVECTION IS BEING ENHANCED BY A BROAD E/W UPPER RIDGE THAT EXTENDS ACROSS THE TROPICAL ATLC. SCATTERED MODERATE WITH EMBEDDED CLUSTERS OF ISOLATED STRONG CONVECTION COVER A LARGE AREA FROM 7N16N BETWEEN 34W-46W. TROPICAL WAVE IS ALONG 53W S OF 15N MOVING W NEAR 15 KT. WELL DEFINED LOW AMPLITUDE WAVE WITH A LOW LEVEL CYCLONIC CURVATURE ALONG THE WAVE AXIS. WAVE ALSO COINCIDES WITH A DEEP LAYER MOISTURE MAXIMUM AS INDICATED IN TOTAL PRECIPITABLE WATER IMAGERY. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 8N-13N BETWEEN 52W-57W. TROPICAL WAVE IS ALONG 77W S OF 18N MOVING W 15 KT. WAVE HAS BECOME BETTER DEFINED OVER THE PAST 24 HOURS AS IT MOVES BENEATH AN UPPER TROUGH. WAVE REMAINS EMBEDDED WITHIN AN AREA OF SLIGHT MOISTURE AS INDICATED IN TOTAL PRECIPITABLE WATER IMAGERY. SCATTERED SHOWERS/THUNDERSTORMS ARE FROM 15N-19N BETWEEN 74W-78W. ...ITCZ... THE ITCZ AXIS IS CENTERED ALONG 9N12W 7N23W 11N40W 10N46W 12N52W 9N62W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 150 NM S OF THE ITCZ FROM 32W-35W. ...DISCUSSION... GULF OF MEXICO... A COLD FRONT EXTENDS INTO THE W ATLC AND ACROSS N FLORIDA BECOMING STATIONARY NEAR CEDAR KEY CONTINUING W TO INLAND OVER SE LOUISIANA NEAR NEW ORLEANS. A BROAD UPPER RIDGE ANCHORED OVER CENTRAL MEXICO EXTENDS ACROSS THE ENTIRE GULF NEAR TUXPAN TO S FLORIDA PROVIDING DIFFLUENCE ALOFT TO ENHANCE SCATTERED SHOWERS/ ISOLATED THUNDERSTORMS MOVING OFF TEXAS AND LOUISIANA N OF 27N W OF 90W. ISOLATED SHOWERS ARE ACROSS THE REMAINDER OF THE N GULF N OF 27N BETWEEN FLORIDA AND TEXAS. DUE TO AN UPPER TROUGH OVER THE W ATLC AND THE BROAD UPPER RIDGE IS GIVING THE E GULF STRONG UPPER LEVEL WINDS. THE S GULF IS ENJOYING RATHER TRANQUIL WEATHER THIS AFTERNOON WITH RELATIVELY CLEAR SKIES. CARIBBEAN SEA... BROAD UPPER RIDGE THAT COVERS THE GULF EXTENDS OVER THE W CARIBBEAN WITH A SECOND UPPER RIDGE COVERING THE E CARIBBEAN ANCHORED OVER NW VENZUELA. THIS SCENARIO IS CREATING A SHARP INVERTED TROUGH FROM PANAMA TO SW HAITI. THE UPPER RIDGE OVER W CARIBBEAN IS USHERING IN DRY STABLE AIR W OF 80W GIVING THE AREA MOSTLY CLEAR SKIES. THE INVERTED UPPER TROUGH IS GENERATING CLUSTERS OF SCATTERED SHOWERS/ISOLATED THUNDERSTORMS S OF 12N TO INLAND OVER COLOMBIA TO COSTA RICA W OF 75W AND ENHANCING THE ACTIVITY ASSOCIATED WITH THE TROPICAL WAVE ALONG 77W. A SURFACE TROUGH IS JUST E OF THE LEEWARD ISLANDS GENERATING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS OVER THE LEEWARD ISLANDS BETWEEN MARTINIQUE AND ANGUILLA. ATLANTIC OCEAN... THE BROAD UPPER RIDGE THAT COVERS THE GULF OF MEXICO EXTENDS OVER THE FAR W ATLC W OF 77W WITH A NARROW UPPER TROUGH ENTERING THE AREA JUST TO THE E ALONG 32N70W TO THE TURKS AND CAICOS NEAR 22N73W SUPPORTING A COLD FRONT THAT ENTERS THE REGION NEAR 32N77W CROSSING FLORIDA JUST S OF ST. AUGUSTINE AND INTO THE GULF OF MEXICO. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE TO THE E OF THE UPPER TROUGH WITHIN 90 NM OF LINE FROM 23N70W TO BEYOND 32N66W. AN UPPER LOW IS IN THE CENTRAL ATLC NEAR 29N53W WITH AN UPPER TROUGH EXTENDING SW TO 25N57W. A WEAK SURFACE TROUGH IS TO THE E OF THE UPPER LOW EXTENDING FROM 30N44W 27N49W TO 26N55W GENERATING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS WITHIN 90/120 NM OF LINE FROM 28N40W TO 25N50W WITH SCATTERED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS FROM 27N-29N BETWEEN 48W-54W. A REMNANT SURFACE TROUGH REMAINS IN THE E ATLC EXTENDING OVER THE MADEIRA ISLANDS ALONG 28N22W TO 26N35W GENERATING SCATTERED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS WITHIN 200 NM W OF THE TROUGH AXIS. THE TYPICAL E/W UPPER RIDGE DOMINATES MUCH OF THE TROPICS WITH THE AXIS EXTENDING ALONG 15N TO 50W ANCHORED OVER THE CAPE VERDE ISLANDS AND ENHANCING THE CONVECTION ASSOCIATED WITH THE TROPICAL WAVES. WEAK SURFACE RIDGE CUTS A SWATH ACROSS THE REGION BETWEEN 20N-30N WITH A 1020 MB HIGH NEAR 23N43W. $$ WALLACE