000 AXNT20 KNHC 102315 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT SAT OCT 10 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2215 UTC. ...TROPICAL WAVES... TROPICAL WAVE EXTENDS FROM 20N36W TO 9N39W MOVING NW NEAR 15 KT. SATELLITE IMAGERY ALONG WITH SATELLITE DERIVED WINDS INDICATE LOW-LEVEL CYCLONIC FLOW IN THE VICINITY OF THE WAVE AXIS. THE WAVE ALSO LEAD A DEEP LAYER MOISTURE MAXIMUM OBSERVED IN TOTAL PRECIPITABLE WATER IMAGERY. ISOLATED MODERATE/STRONG CONVECTION IS FROM 9N-14N BETWEEN 34W-42W. TROPICAL WAVE IS ALONG 71W S OF 17N MOVING W 15-20 KT. THE LAST VISIBLE SATELLITE IMAGES OF THE DAY INDICATE CYCLONIC FLOW IN THE LOW-LEVEL CLOUD PATTERN IN THE VICINITY OF THE WAVE AXIS. THE WAVE ALSO COINCIDES WITH A NARROW DEEP LAYER MOISTURE MAXIMUM OBSERVED IN TOTAL PRECIPITABLE WATER IMAGERY...SURROUNDED BY DRY AIR ON BOTH SIDES AND SIGNIFICANTLY DRY AIR ALOFT. SCATTERED MODERATE CONVECTION IS CONFINED TO INLAND OVER VENEZUELA FROM 9N-12N BETWEEN 70W-73W. TROPICAL WAVE IS ALONG 91W S OF 16N MOVING W NEAR 15 KT. WHILE THE MAJORITY OF THE WAVE AXIS IS OVER THE E PACIFIC REGION...SCATTERED MODERATE CONVECTION IS AFFECTING THE YUCATAN PENINSULA FROM 18N-21N BETWEEN 87W-91W. THIS ACTIVITY MAY BE MORE ASSOCIATED WITH UPPER LEVEL DIFFLUENCE. SEE MIATWDEP FOR MORE DETAILS ON THIS WAVE. ...ITCZ... THE ITCZ AXIS IS CENTERED ALONG 8N10W 8N20W 12N35W 10N45W 7N63W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS APPROACHING THE AFRICA COAST FROM 6N-12N BETWEEN 9W-16W. SIMILAR CONVECTION IS FROM 9N-12N BETWEEN 22W-29W. ...DISCUSSION... GULF OF MEXICO... A COLD FRONT EXTENDING ACROSS THE ERN SEABOARD BECOMES STATIONARY AT THE FLORIDA PANHANDLE NEAR 31N84W ENTERING THE GULF OF MEXICO NEAR PANAMA CITY CONTINUING ALONG 28N91W 25N95W TO 20N97W N OF VERACRUZ MEXICO THEN ALONG THE E SLOPES OF THE SIERRA MADRE MOUNTAINS. A WEAK SURFACE TROUGH IS AHEAD OF THE FRONT IN THE BAY OF CAMPECHE FROM 22N94W TO 17N93W. SCATTERED SHOWERS/THUNDERSTORMS ARE FROM 22N-25N BETWEEN 95W-97W. BASED ON RADAR AND SATELLITE IMAGERY...ISOLATED SHOWERS/POSSIBLE THUNDERSTORMS ARE WITHIN 150 NM AHEAD...AND 100 NM BEHIND THE FRONT. THE FRONT IS SUPPORTED BY AN UPPER LEVEL TROUGH OVER THE ERN CONUS WITH A SHORTWAVE TROUGH EXTENDING INTO THE GULF TO NEAR 23N88W. THE SHORTWAVE UPPER TROUGH EXTENDS BETWEEN TWO UPPER LEVEL RIDGES...ONE OVER THE WRN GULF CENTERED OVER MEXICO...AND THE SECOND ACROSS THE FAR ERN GULF AND FLORIDA CENTERED OVER THE WRN ATLC NEAR 28N67W. EXPECT THE FRONT TO SLOWLY SHIFT N AS A WARM FRONT ON SUN AND N OF THE AREA BY MON. CARIBBEAN SEA... AN UPPER LEVEL TROUGH IS OVER THE YUCATAN PENINSULA SUPPORTING CONVECTION NEAR A TROPICAL WAVE ALONG 91W. SEE ABOVE. DIFFLUENT FLOW ALOFT BETWEEN THE UPPER TROUGH AND AN UPPER LEVEL RIDGE OVER THE WRN CARIBBEAN BETWEEN 75W-88W IS SUPPORTING ISOLATED SHOWERS/THUNDERSTORMS ACROSS CENTRAL AMERICA W OF 84W S OF 22N...AND W OF 80W S OF 14N. ISOLATED SHOWERS ARE ALSO N OF 18N BETWEEN 68W-78W. THE REMAINDER OF THE CARIBBEAN IS EXPERIENCING GENERALLY FAIR WEATHER DESPITE THE PRESENCE OF A TROPICAL WAVE ALONG 71W. SEE ABOVE. THE FAIR WEATHER IS INFLUENCED BY DRY AIR AND SUBSIDENCE ALOFT SUPPORTED BY AN UPPER LEVEL RIDGE OVER THE ERN CARIBBEAN CENTERED IN THE WRN ATLC NEAR 28N67W. MODERATE TO FRESH TRADEWINDS ARE ACROSS MUCH OF THE BASIN. EXPECT THE TROPICAL WAVE ALONG 71W TO CONTINUE WWD. ATLANTIC OCEAN... A BROAD UPPER LEVEL RIDGE DOMINATES THE WRN ATLC CENTERED NEAR 28N67W SUPPORTING A 1019 MB SURFACE HIGH NEAR 31N69W. A 1013 MB SURFACE LOW...REMNANTS OF HENRI...IS N OF HISPANIOLA NEAR 20N68W. SURFACE CONVERGENCE NEAR THE LOW IS SUPPORTING SCATTERED SHOWERS/THUNDERSTORMS FROM 20N-21N BETWEEN 70W-72W. A COLD FRONT ENTERS THE DISCUSSION AREA NEAR 30N37W EXTENDING ALONG 25N42W 22N52W CONTINUING AS A SURFACE TROUGH TO 23N65W. SCATTERED SHOWERS/POSSIBLE THUNDERSTORMS ARE WITHIN 450 NM E OF THE FRONT N OF 24N...AND WITHIN 250 NM AHEAD OF THE FRONT N OF 22N. ISOLATED SHOWERS/POSSIBLE THUNDERSTORMS ARE WITHIN 150 NM AHEAD OF THE REMAINDER OF THE FRONT AND TROUGH. THIS SYSTEM IS SUPPORTED BY A NARROW UPPER LEVEL TROUGH WITH AXIS ALONG 40N40W TO 19N37W. A SURFACE RIDGE IS E OF THE SYSTEM ANCHORED BY A 1026 MB HIGH N OF THE AREA NEAR 40N17W. A SHORTWAVE UPPER TROUGH IS E OF THE MAIN UPPER TROUGH EXTENDING ALONG 30N24W TO 22N19W SUPPORTING ISOLATED SHOWERS FROM 24N-30N BETWEEN 18W-22W. $$ WALTON