000 AXNT20 KNHC 121719 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 PM EST THU NOV 12 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 1645 UTC. ...ITCZ... THE ITCZ AXIS IS CENTERED ALONG 8N12W 7N22W 7N31W 5N41W 6N58W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 6N-10N BETWEEN 17W-21W. A SECONDARY BOUNDARY...ANALYZED AS A SURFACE TROUGH...LIES TO THE N ALONG 15N13W 11N18W 11N25W. SCATTERED MODERATE ISOLATED STRONG CONVECTION IS WITHIN 200 NM N OF THIS BOUNDARY. SIMILAR CONVECTION IS FROM 5N-11N BETWEEN 26W-35W NEAR AN EMBEDDED SURFACE TROUGH ALONG 11N30W 7N33W. SIMILAR ACTIVITY IS ALSO FROM 4N-8N BETWEEN 36W-44W. ...DISCUSSION... GULF OF MEXICO... MAINLY NLY SURFACE FLOW PREVAILS ACROSS THE GULF OF MEXICO BEHIND THE PASSAGE OF A PAIR OF COLD FRONTS NOW IN THE WRN ATLC. STRONGEST SURFACE WINDS ARE OVER THE ERN BASIN REACHING UP TO 25 KT ACCOMPANIED BY A LARGE AREA OF STRATOCUMULUS CLOUDS EXTENDING ACROSS THE MAJORITY OF THE BASIN. ALOFT...UPPER LEVEL WLY FLOW DOMINATES S OF THE BASE OF A SHORTWAVE UPPER LEVEL TROUGH CENTERED OVER NORTH CAROLINA...ALONG WITH SIGNIFICANT DRY AIR AND SUBSIDENCE ACROSS THE GULF NOTED ON WATER VAPOR IMAGERY. EXPECT WINDS TO DIMINISH ACROSS THE BASIN AS HIGH PRESSURE BUILDS ACROSS THE AREA. SE RETURN FLOW IS EXPECTED ACROSS THE WRN GULF TOMORROW AHEAD OF A COLD FRONT FORECAST TO MOVE OFF THE TEXAS COAST MONDAY. CARIBBEAN SEA... AS OF 1500 UTC...A COLD FRONT EXTENDS ACROSS WRN CUBA TO THE YUCATAN PENINSULA ALONG 23N81W 21N84W 21N88W. A LAYER OF STRATOCUMULUS CLOUDS EXTENDS TO THE NW BEHIND THE FRONT. NO SHOWER ACTIVITY IS CURRENTLY ASSOCIATED WITH THIS FRONT. A SECOND COLD FRONT EXTENDS FROM ERN CUBA TO NE NICARAGUA ALONG 21N77W 18N79W 15N83W. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE WITHIN 90 NM EITHER SIDE OF THE FRONT WITH THE MOST CONCENTRATED SHOWER ACTIVITY S OF CUBA AND W OF JAMAICA. BOTH OF THESE FRONTS EXTEND NWD ACROSS THE W ATLC TO A 992 MB SURFACE LOW OFF THE VIRGINIA COAST...AND ARE SUPPORTED BY A SHORTWAVE UPPER TROUGH CENTERED OVER NORTH CAROLINA. SCATTERED SHOWERS/THUNDERSTORMS HAVE FORMED OVER THE SW CARIBBEAN S OF 11N BETWEEN 76W-82W DUE TO SURFACE CONVERGENCE NEAR THE E PACIFIC ITCZ. IN THE UPPER LEVELS...AN UPPER LEVEL RIDGE COVERS THE MAJORITY OF THE BASIN W OF 67W PROVIDING GENERALLY FAIR WEATHER ACROSS THE CENTRAL CARIBBEAN. AN UPPER LEVEL TROUGH E OF 67W SUPPORTS SCATTERED SHOWERS/THUNDERSTORMS ACROSS THE LEEWARD ISLANDS N OF 16N BETWEEN 62W-65W...AND ISOLATED SHOWERS/THUNDERSTORMS BETWEEN 65W-69W. ATLANTIC OCEAN... A PAIR OF COLD FRONTS EXTEND ACROSS THE WRN ATLC FROM A 992 MB LOW OFF THE COAST OF VIRGINIA NEAR 34N77W. AS OF 1500 UTC...ONE FRONT ENTERS THE DISCUSSION AREA NEAR 32N75W TO THE NE BAHAMAS NEAR 27N78W TO WRN CUBA NEAR 23N81W. NO SHOWER ACTIVITY IS ASSOCIATED WITH THIS FRONT. HOWEVER...A LARGE AREA OF STRATOCUMULUS CLOUDS TRAIL BEHIND THE FRONT. THE SECOND FRONT ENTERS THE DISCUSSION AREA NEAR 32N74W TO THE CENTRAL BAHAMAS NEAR 24N75W TO ERN CUBA NEAR 21N77W. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE E OF THE FRONT N OF 29N BETWEEN 71W-73W. ISOLATED SHOWERS/THUNDERSTORMS ARE ALSO ALONG THE FRONT AXIS ACROSS THE CENTRAL BAHAMAS. A 1005 MB LOW IS CENTERED NEAR 31N64W. ISOLATED SHOWERS/THUNDERSTORMS ARE WITHIN 200 NM OF THE CENTER IN THE NE AND SE QUADRANTS. THE LOW IS SUPPORTED BY AN UPPER LEVEL TROUGH ALONG 30N64W 19N59W 11N60W. THE UPPER LEVEL TROUGH IS ALSO SUPPORTING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS FROM 18N-24N BETWEEN 60W-64W...AND N OF 26N BETWEEN 50W-55W. A BROAD SURFACE RIDGE DOMINATES THE REMAINDER OF THE ERN ATLC ANCHORED BY A 1019 MB HIGH NEAR 33N28W. AN UPPER LEVEL TROUGH OVER THE ERN ATLC WITH AXIS FROM THE CANARY ISLANDS NEAR 29N16W TO THE CENTRAL TROPICAL ATLC NEAR 11N33W IS SHEARING MOISTURE FROM THE ITCZ TO THE NE SUPPORTING SHOWER ACTIVITY NEAR AND N OF THE ITCZ. $$ WALTON