000 AXNT20 KNHC 230555 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 AM EDT FRI OCT 23 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0515 UTC. ...TROPICAL WAVES... TROPICAL WAVE IS TILTED FROM 12N38W TO 19N34W MOVING NW NEAR 10 KT. THE WAVE IS EMBEDDED WITHIN A MAXIMUM IN DEEP LAYER MOISTURE AS DEPICTED BY TOTAL PRECIPITABLE WATER IMAGERY N OF 10N BETWEEN 27W-40W. CIMSS WAVETRAK MODEL GUIDANCE ALSO INDICATES AN AREA OF 850 MB RELATIVE VORTICITY IN THE VICINITY OF THE WAVE AXIS N OF 10N. SCATTERED MODERATE CONVECTION IS OCCURRING FROM 12N-22N BETWEEN 26W-37W PRIMARILY EAST OF THE WAVE AXIS. THIS ACTIVITY IS BEING ENHANCED BY AN AREA OF UPPER LEVEL DIFFLUENCE LOCATED E OF AN UPPER LEVEL SHORTWAVE TROUGH WITH AXIS DIPPING SOUTH TO 18N ALONG 35W. ...ITCZ... THE ITCZ AXIS IS CENTERED ALONG 9N13W 8N33W 6N57W. CLUSTERS OF SCATTERED MODERATE CONVECTION ARE FROM 3N-11N BETWEEN 20W-38W. ...DISCUSSION... GULF OF MEXICO... AS OF 0300 UTC...A COLD FRONT ENTERS THE GULF NEAR ATCHAFALAYA BAY AND EXTENDS SW ALONG 25N94W INTO EASTERN MEXICO NEAR 23N98W TURNING STATIONARY ALONG THE EASTERN SLOPES OF THE SIERRA MADRE ORIENTAL MOUNTAINS. A PRE-FRONTAL SURFACE TROUGH EXTENDS FROM 26N92W TO 22N94W. LOW-LEVEL CONVERGENCE NEAR BOTH OF THESE SURFACE BOUNDARIES IS GENERATING NUMEROUS SHOWERS AND SCATTERED TSTMS WITHIN 120 NM OF A LINE FROM 23N93W TO INLAND OVER SOUTHERN ALABAMA NEAR MOBILE BAY. THE FRONT IS SUPPORTED BY A BROAD UPPER TROUGH ACROSS THE CENTRAL CONUS WITH THE UPPER LOW CENTERED OVER WESTERN IOWA. A DRY AND STABLE AIRMASS FOLLOWS BEHIND THE FRONT WITH NW WINDS UP TO 20 KT. AN UPPER LEVEL RIDGE ANCHORED OVER THE BAY OF CAMPECHE NEAR 19N93W EXTENDS A RIDGE AXIS NE OVER THE NE GULF AND FLORIDA PANHANDLE THUS ENHANCING THE CONVECTION ASSOCIATED WITH THE COLD FRONT. CARIBBEAN SEA... A 1007 MB LOW REMAINS IN THE SW CARIBBEAN OFF THE COAST OF NICARAGUA NEAR 13N82W. MOSTLY SCATTERED SHOWERS ACCOMPANY THIS LOW ACROSS THE SW CARIBBEAN S OF 15N W OF 78W AS MOST CONVECTION IS BEING INHIBITED BY HIGH SHEAR VALUES NEAR THE BASE OF A HIGHLY AMPLIFIED UPPER LEVEL TROUGH THAT EXTENDS FROM THE SW NORTH ATLC ACROSS EASTERN CUBA TO NICARAGUA AND HONDURAS. THIS TROUGH IS LOCATED BETWEEN A BROAD UPPER LEVEL RIDGE OVER THE GULF OF MEXICO AND A SECOND UPPER LEVEL RIDGE ANCHORED OVER VENEZUELA THAT EXTENDS A RIDGE AXIS ACROSS THE EASTERN CARIBBEAN ALONG 67W. THIS UPPER LEVEL PATTERN IS PROVIDING THE NW AND FAR EASTERN CARIBBEAN WITH STRONG SUBSIDENCE AND A DRY AIRMASS IN PLACE WITH ONLY A FEW ISOLATED SHOWERS OBSERVED ON SATELLITE IMAGERY MOVING ACROSS THE LEEWARD ISLANDS AND PUERTO RICO. A SWATH OF MOISTURE IS ACROSS THE CENTRAL CARIBBEAN WITH SCATTERED SHOWERS FROM 10N-20N BETWEEN 71W-78W. AN AREA OF SCATTERED TSTMS IS OCCURRING NORTH OF THE GUAJIRA PENINSULA FROM 11N-13N BETWEEN 72W-75W. THE ITCZ AXIS EXTENDS FROM NW COLOMBIA ACROSS THE SW CARIBBEAN ALONG 10N AND INTO THE E PACIFIC REGION GENERATING SCATTERED SHOWERS S OF 11N W OF 79W. ATLANTIC OCEAN... A NARROW AMPLIFIED UPPER LEVEL TROUGH AXIS EXTENDS SW FROM 30N70W THROUGH THE CENTRAL BAHAMAS AND EASTERN CUBA DIPPING S INTO THE WESTERN CARIBBEAN SEA. THIS UPPER LEVEL TROUGH IS PROVIDING STRONG SUBSIDENCE AND DRY STABLE AIR W OF 76W AND ALSO SUPPORTS A SURFACE TROUGH ANALYZED FROM 27N71W TO THE WINDWARD PASSAGE NEAR 20N74W. LOW-LEVEL CONVERGENCE NEAR THE SURFACE TROUGH COUPLED WITH UPPER LEVEL DIFFLUENCE E OF THE UPPER LEVEL TROUGH AXIS IS GENERATING SCATTERED SHOWERS FROM 20N-27N BETWEEN 66W-76W. A BROAD UPPER LEVEL TROUGH IS OVER THE CENTRAL ATLC N OF 28N AND SUPPORTS A COLD FRONT N OF THE REGION TO NEAR 31N42W. LINGERING WEAK LOW-LEVEL CONVERGENCE TRAILS TO THE WEST ALONG 26N BETWEEN 52W-65W AND CONTINUES TO PRODUCE ISOLATED LOW-LEVEL SHOWERS FROM 23N-27N BETWEEN 53W-65W. EAST OF THE COLD FRONT ACROSS THE CENTRAL ATLC...A PRE-FRONTAL SURFACE TROUGH IS ANALYZED FROM 24N46W TO BEYOND 32N36W WITH SCATTERED SHOWERS AND ISOLATED TSTMS OCCURRING WITHIN 200 NM E OF THE SURFACE TROUGH. EAST OF THE SURFACE TROUGH ACROSS THE EASTERN ATLC...A SURFACE RIDGE IS PRESENT ANCHORED BY A 1022 MB HIGH CENTERED OVER THE MADEIRA ISLANDS. IN THE TROPICAL ATLC...A 1011 MB LOW IS N OF THE ITCZ AXIS WITH ISOLATED SHOWERS WITHIN 200 NM RADIUS OF THE LOW CENTER. $$ HUFFMAN