000 AXNT20 KNHC 222357 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT THU OCT 22 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 WWWW UTC. ...TROPICAL WAVES... TROPICAL WAVE IS TILTED FROM 19N32W TO 11N38W MOVING NW NEAR 10 KT. WAVE IS AT THE LEADING EDGE OF A MAXIMUM IN TOTAL PRECIPITABLE WATER. DENSE OVERCAST MULTILAYERED CLOUDS COVER A BROAD AREA MASKING THE LOW LEVEL SIGNATURE. SCATTERED MODERATE WITH CLUSTERS OF SCATTERED STRONG CONVECTION COVERS THE AREA FROM 12N-20N BETWEEN 27W-30W BEING ENHANCED BY AN UPPER LEVEL RIDGE OVER THE TROPICAL EASTERN ATLC. ...ITCZ... THE ITCZ AXIS IS CENTERED ALONG 10N12W 8N23W 10N35W 12N45W 8N52W 9N62W. CLUSTERS OF SCATTERED MODERATE/STRONG CONVECTION ARE FROM 4N-8N BETWEEN 27W-30W. ...DISCUSSION... GULF OF MEXICO... A COLD FRONT THAT HAS MOVED INTO THE W GULF IS MOVING RAPIDLY EASTWARD AND AT 2100 UTC ENTERS THE GULF OVER LAKE CHARLES LOUISIANA ALONG 26N94W THEN W INTO MEXICO NEAR 24N97W TO ALONG THE E SLOPES OF THE SIERRA MADRE MOUNTAINS. SCATTERED/HEAVY SHOWERS WITH SCATTERED/NUMEROUS THUNDERSTORMS ARE WITHIN 60/75 NM OF LINE FROM 25N93W TO INLAND OVER E LOUISIANA/MISSISSIPPI NEAR 30N90W. THIS FRONT IS BEING SUPPORTED BY A BROAD UPPER TROUGH WITH THE UPPER LOW OVER THE MIDWEST STATES AND DRY STABLE AIRMASS BEHIND THE FRONT. AN UPPER RIDGE ANCHORED OVER THE BAY OF CAMPECHE NEAR 19N95W EXTENDING AN AXIS NE ACROSS THE FLORIDA PANHANDLE AND ALONG THE COAST OF GEORGIA TO NORTH CAROLINA THUS ENHANCING THE ACTIVITY ASSOCIATED WITH THE FRONT. FRONT IS EXPECTED TO MOVE ACROSS THE GULF BEFORE WEAKENING OVER THE E GULF DURING THE WEEKEND. CARIBBEAN SEA... A 1008 MB LOW REMAINS IN THE SW CARIBBEAN OFF THE COAST OF NICARAGUA/COSTA RICA NEAR 11N82W. HIGHLY AMPLIFIED UPPER TROUGH EXTENDS FROM THE W ATLC ACROSS E/CENTRAL CUBA TO OVER NICARAGUA/HONDURAS BETWEEN THE BROAD UPPER RIDGE OVER THE GULF OF MEXICO AND A SECOND UPPER RIDGE ANCHORED OVER VENEZUELA ACROSS THE E CARIBBEAN AND PUERTO RICO INTO THE W/CENTRAL ATLC. THIS SCENARIO IS GIVING THE NW AND FAR E CARIBBEAN STRONG SUBSIDENCE AND A DRIER AIRMASS. A SWATH OF MOISTURE IS ACROSS THE CENTRAL CARIBBEAN WITH SCATTERED SHOWERS/ISOLATED THUNDERSTORMS FROM 11N-15N BETWEEN 74W-83W. THE ITCZ AXIS EXTENDS FROM COLOMBIA ACROSS THE SW CARIBBEAN INTO THE E PACIFIC REGION OVER PANAMA/COSTA RICA GENERATING SCATTERED SHOWERS/ ISOLATED THUNDERSTORMS S OF 10N W OF 81W WITH ISOLATED SHOWERS WITHIN 150 NM OF LINE FROM 15N77W ACROSS HAITI AND E CUBA NEAR THE WINDWARD PASSAGE LEAVING THE REMAINDER OF THE CARIBBEAN UNDER MOSTLY CLEAR SKIES THIS EVENING. ATLANTIC OCEAN... AN UPPER LEVEL TROUGH COVERS THE W AND CENTRAL ATLC N OF 30N WITH A NARROW AMPLIFIED TROUGH AXIS EXTENDING S THROUGH THE W ATLC ALONG 30N67W 26N75W ACROSS CENTRAL CUBA AND INTO THE W CARIBBEAN. THIS AMPLIFIED UPPER LEVEL TROUGH IS PROVIDING STRONG SUBSIDENCE AND DRY STABLE AIR MAINLY W OF 75W AND SUPPORTING A SURFACE TROUGH JUST TO THE E ALONG 26N72W TO 21N74W. LOW-LEVEL CONVERGENCE NEAR THE SURFACE TROUGH COUPLED WITH UPPER LEVEL DIFFLUENCE IS GENERATING SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS FROM 21N-28N BETWEEN 60W-74W AND S OF 21N OVER HAITI AND E CUBA BETWEEN 71W-76W. THE BROAD UPPER LEVEL TROUGH OVER THE CENTRAL ATLC N OF 30N IS SUPPORTING A COLD FRONT N OF THE REGION AND A SURFACE TROUGH ANALYZED FROM 29N41W ALONG 23N54W TO 21N68W. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE WITHIN 90/120 NM OF LINE FROM 25N43W TO BEYOND 32N35W. WEST OF THE SURFACE TROUGH...A SURFACE RIDGE ANCHORED BY A 1021 MB HIGH WNW OF BERMUDA WITH A SURFACE RIDGE E OF THE SURFACE TROUGH ANCHORED BY A 1020 MB HIGH OVER THE MADEIRA ISLANDS. IN THE TROPICAL ATLC...A 1009 MB LOW IS N OF THE ITCZ AND W OF THE TROPICAL WAVE NEAR 14N43W WITH ISOLATED SHOWERS WITHIN 150 NM RADIUS OF THE LOW. $$ WALLACE