000 AXNT20 KNHC 060045 CCA TWDAT TROPICAL WEATHER DISCUSSION...COR NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT MON OCT 05 2009 CORRECTION IN ORDER TO INCLUDE INFORMATION ABOUT TROPICAL STORM GRACE 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 2315 UTC. ...SPECIAL FEATURES... THE CENTER OF TROPICAL STORM GRACE AT 05/2100 UTC WAS NEAR 47.7N 14.8W...OR ABOUT 400 MILES/645 KM TO THE SOUTHWEST OF CORK IRELAND...AND ABOUT 480 MILES/775 KM TO THE WEST OF BREST FRANCE. GRACE IS MOVING TOWARD THE NORTH-NORTHEAST 26 KT. THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 990 MB. THE MAXIMUM SUSTAINED WIND SPEEDS ARE 50 KT WITH GUSTS TO 60 KT. PLEASE READ THE NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT4/ WTNT24 KNHC AND THE PUBLIC ADVISORY UNDER MIATCPAT4/WTNT34 KNHC FOR MORE DETAILS. GRACE IS FORECAST TO BE ABSORBED BY A COLD FRONT ON TUESDAY MORNING. TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO 70 MILES/110 KM FROM THE CENTER. CLOUD TOP TEMPERATURES HAVE BEEN WARMING DURING THE LAST FEW HOURS AS GRACE IS MOVING THROUGH WATERS WHOSE TEMPERATURES ARE NEAR 17C AND 18C. AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 46W/47W TO THE SOUTH OF 19N MOVING WEST 15 KT. SCATTERED MODERATE SHOWERS TO ISOLATED STRONG THUNDERSTORMS COVER THE AREA FROM 12N TO 16N BETWEEN 45W AND 48W. THE CHANCE THAT THIS FEATURE MAY DEVELOP INTO A TROPICAL CYCLONE DURING THE NEXT 48 HOURS IS MEDIUM... FROM 30 PERCENT TO 50 PERCENT. ...TROPICAL WAVES... AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 58W/59W TO THE SOUTH OF 14N MOVING WESTWARD 15 KT. A WEAKENING UPPER LEVEL TROUGH EXTENDS FROM A CYCLONIC CENTER THAT IS ABOUT 250 NM TO THE NORTHEAST OF PUERTO RICO TO 12N60W. A SECOND UPPER LEVEL TROUGH EXTENDS FROM A CYCLONIC CIRCULATION CENTER NEAR 29N47W TO 21N55W TO 16N60W. ISOLATED MODERATE SHOWERS AND SOME CELLS WITH WARMING CLOUD TOP TEMPERATURES COVER THE AREA FROM 8N TO 14N BETWEEN 55W AND 61W. A CARIBBEAN SEA TROPICAL WAVE IS ALONG THE HONDURAS/NICARAGUA COAST ALONG 83W/84W TO THE SOUTH OF 17N MOVING WESTWARD 15 KT. THIS WAVE IS MOVING THROUGH THE AREA OF AN UPPER LEVEL TROUGH. NEARBY SHOWERS MAY BE MORE RELATED TO THE UPPER LEVEL TROUGH THAN TO THE WAVE. ...THE ITCZ... 10N14W 6N31W 13N45W 10N55W 11N58W. STRONG INDIVIDUAL THUNDERSTORM CELLS WITHIN A 30 NM RADIUS OF 6N12W. WARMING CLOUD TOP TEMPERATURES AND DISSIPATING PRECIPITATION WITHIN A 30 NM RADIUS OF 10N17W. ISOLATED MODERATE SHOWERS AND POSSIBLE THUNDERSTORMS FROM 4N TO 8N BETWEEN 30W AND 40W. ...DISCUSSION... THE GULF OF MEXICO... AN UPPER LEVEL RIDGE EXTENDS FROM WEST CENTRAL MEXICO...INTO THE CENTRAL GULF OF MEXICO...BEYOND CENTRAL FLORIDA...BEYOND BERMUDA IN THE WESTERN ATLANTIC OCEAN. DRY AIR IN SUBSIDENCE COVERS THE AREA TO THE WEST OF 90W. UPPER LEVEL MOISTURE AND RAINSHOWERS IN A DIFFLUENT FLOW PATTERN COVER THE AREA TO THE EAST OF 90W. THE SURFACE PRESSURE GRADIENT IS WEAK. A SHALLOW FRONTAL BOUNDARY PASSES THROUGH SOUTHEASTERN LOUISIANA...BARELY INTO THE NORTHWESTERN GULF WATERS...TO THE UPPER TEXAS COAST AND BEYOND AS IT CONTINUES ACROSS CENTRAL TEXAS. ISOLATED MODERATE SHOWERS ARE IN THE COASTAL WATERS OF LOUISIANA TO THE EAST OF 92W. THE CARIBBEAN SEA... UPPER LEVEL ANTICYCLONIC FLOW FROM THE GULF OF MEXICO AND THE WESTERN ATLANTIC OCEAN STILL SPILLS INTO THE CARIBBEAN SEA... ACROSS CUBA TOWARD NICARAGUA AND ALL POINTS TO THE NORTHWEST OF NICARAGUA. AN UPPER LEVEL TROUGH PASSES THROUGH THE WINDWARD PASSAGE FROM THE ATLANTIC OCEAN...TO JUST EAST OF JAMAICA... TO A CYCLONIC CIRCULATION CENTER NEAR 15N79W...BEYOND CENTRAL COSTA RICA INTO THE EASTERN PACIFIC OCEAN. ISOLATED MODERATE SHOWERS ARE BETWEEN 76W AND 86W. A WEAKENING UPPER LEVEL TROUGH EXTENDS FROM A CYCLONIC CENTER THAT IS ABOUT 250 NM TO THE NORTHEAST OF PUERTO RICO TOWARD 12N60W. A SURFACE TROUGH CURVES THROUGH THE MONA PASSAGE FROM 16N TO 20N ALONG 66W/67W. THE COMPARATIVELY STRONGEST PRECIPITATION IS IN MONA PASSAGE. ISOLATED SHOWERS ARE ELSEWHERE FROM 15N TO 20N BETWEEN 66W AND 71W. THE ATLANTIC OCEAN... AN UPPER LEVEL TROUGH IS ALONG 31N81W BEYOND 32N76W. DEEP LAYER MOISTURE AND SHOWERS ARE IN AN UPPER LEVEL DIFFLUENT FLOW PATTERN THAT IS TO THE SOUTHEAST AND SOUTH OF THE TROUGH. THE MOISTURE AND SHOWERS ARE AT LEAST 420 NM TO THE SOUTHEAST OF THE TROUGH. A SURFACE TROUGH PASSES THROUGH 32N63W TO 29N67W TO 28N71W. A CENTRAL ATLANTIC OCEAN UPPER LEVEL TROUGH PASSES THROUGH 32N55W TO AN UPPER LEVEL CYCLONIC CENTER THAT IS NEAR 27N58W TO 24N61W TO 22N70W BEYOND THE WINDWARD PASSAGE INTO THE CARIBBEAN SEA. NO DEEP CONVECTIVE PRECIPITATION ACCOMPANIES THIS TROUGH. A SECOND UPPER LEVEL TROUGH EXTENDS FROM A CYCLONIC CIRCULATION CENTER THAT IS NEAR 29N47W TO 21N55W TO 16N60W. PRETTY MUCH ALL OF THE EARLIER PRECIPITATION WITH THIS TROUGH HAS BEEN DISSIPATING DURING THE LAST SIX HOURS. BROAD UPPER LEVEL CYCLONIC FLOW COVERS THE AREA TO THE NORTH OF 26N BETWEEN 10W AND 40W. AN UPPER LEVEL TROUGH PASSES THROUGH 32N24W TO 26N25W. NO DEEP LAYER PRECIPITATION ACCOMPANIES THIS TROUGH. $$ MT