000 AXNT20 KNHC 211801 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT FRI SEP 21 2012 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...WEATHER OBSERVATIONS...RADAR...AND METEOROLOGICAL ANALYSIS. BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1715 UTC. ...SPECIAL FEATURES... THE CENTER OF TROPICAL STORM NADINE AT 21/1800 UTC IS NEAR 33.6N 27.3W. NADINE IS ABOUT 265 NM/490 KM TO THE SOUTH OF THE AZORES. NADINE IS MOVING SOUTH-SOUTHEASTWARD 13 KNOTS. THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 981 MB. THE MAXIMUM SUSTAINED WIND SPEEDS ARE 50 KNOTS WITH GUSTS TO 60 KNOTS. TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO 270 NM/500 KM FROM THE CENTER. TROPICAL STORM OR GALE CONDITIONS ARE EXPECTED TO CONTINUE IN SECTIONS OF THE TROPICAL STORM WARNING AREA TODAY. THESE WINDS WILL BEGIN TO DECREASE TONIGHT. SWELLS THAT ARE BEING GENERATED BY NADINE WILL AFFECT THE AZORES DURING THE NEXT DAY OR SO. IT IS LIKELY THAT THESE SWELLS WILL CAUSE LIFE-THREATENING SURF AND RIP CURRENT CONDITIONS. NADINE IS EXPECTED TO PRODUCE TOTAL RAIN ACCUMULATIONS OF 1 TO 2 INCHES ACROSS THE AZORES. PLEASE CONSULT BULLETINS FROM YOUR LOCAL WEATHER OFFICE. PLEASE READ THE FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT4/WTNT24 KNHC AND THE PUBLIC ADVISORY...MIATCPAT4/WTNT34 KNHC FOR MORE DETAILS. BROKEN TO OVERCAST MULTILAYERED CLOUDS AND RAINSHOWERS AND POSSIBLE THUNDERSTORMS ARE WITHIN 90 NM ON EITHER SIDE OF 35N26W 32N25W 32N31W 34N37W 35N42W. A 1006 MB LOW PRESSURE CENTER IS NEAR 32N57W. WIDELY SCATTERED TO SCATTERED MODERATE AND ISOLATED STRONG CONVECTIVE PRECIPITATION IS TO THE NORTH OF 20N BETWEEN 46W AND 67W IN LINES OF SURFACE WIND CONFLUENCE AND BROAD SURFACE CYCLONIC WIND FLOW. GALE-FORCE WINDS ARE WITHIN 420 NM OF THE CENTER IN THE NORTHEASTERN QUADRANT AND SEA HEIGHTS RANGE FROM 10 TO 18 FT. SOME DEVELOPMENT IS POSSIBLE TODAY BEFORE THE LOW PRESSURE CENTER ENCOUNTERS COOLER WATERS ON SATURDAY. THIS SYSTEM HAS A MEDIUM CHANCE OF BECOMING A SUBTROPICAL CYCLONE DURING THE NEXT 48 HOURS...AS IT MOVES WEST-NORTHWESTWARD ABOUT 10 MPH. ADDITIONAL INFORMATION ON THIS SYSTEM CAN BE FOUND IN HIGH SEAS FORECASTS ISSUED BY THE NATIONAL WEATHER SERVICE. ...TROPICAL WAVES... AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 38W/39W TO THE SOUTH OF 17N...MOVING WESTWARD 20 KNOTS DURING THE LAST 24 HOURS. ISOLATED TO WIDELY SCATTERED MODERATE CONVECTIVE PRECIPITATION IS FROM 13N TO 16N BETWEEN 40W AND 43W. A CARIBBEAN SEA TROPICAL WAVE IS ALONG 20N63W 16N64W 13N65W... MOVING WESTWARD 15 TO 20 KNOTS DURING THE LAST 24 HOURS. THIS WAVE IS MOVING THROUGH THE AREA OF A DEEP LAYER TROUGH THAT STRETCHES FROM THE 33N58W CYCLONIC CENTER TO THE 13N61W CYCLONIC CENTER. IT IS NOT EASY TO FIND CONVECTIVE PRECIPITATION THAT JUST IS RELATED ONLY TO THIS TROPICAL WAVE. A CARIBBEAN SEA TROPICAL WAVE IS ALONG 84W/85W TO THE SOUTH OF 23N...ALONG THE WESTERN EDGE OF CUBA. SCATTERED MODERATE TO ISOLATED STRONG CONVECTIVE PRECIPITATION IS TO THE WEST OF 80W...FROM THE GULF OF HONDURAS NORTHWARD TO THE CUBA COAST AND IN THE YUCATAN CHANNEL. ...THE ITCZ/THE MONSOON TROUGH... THE MONSOON TROUGH PASSES THROUGH COASTAL GUINEA-BISSAU NEAR 12N16W TO 9N20W 7N30W AND 5N38W. THE ITCZ IS NOT PRESENT AT THIS MOMENT DUE TO THE PREVAILING WIND FLOW. CONVECTIVE PRECIPITATION...SCATTERED STRONG IN THE COASTAL PLAINS/COASTAL WATERS OF AFRICA FROM 10N TO 15N...ISOLATED MODERATE TO LOCALLY STRONG WITHIN 150 NM ON EITHER SIDE OF 9N13W 7N20W 6N30W 5N40W 7N50W. ...DISCUSSION... THE GULF OF MEXICO... A MIDDLE LEVEL TO UPPER LEVEL TROUGH IS MOVING THROUGH THE CENTRAL U.S.A. AND ALONG 98W FROM TEXAS TO SOUTHERN MEXICO. THIS TROUGH HAS BEEN SUPPORTING A STATIONARY FRONT. THE STATIONARY FRONT NOW IS DISSIPATING ALONG 31N74W IN THE ATLANTIC OCEAN...TO FLORIDA NEAR 28N81W...TO 26N84W IN THE EAST CENTRAL GULF OF MEXICO. BROKEN TO OVERCAST MULTILAYERED CLOUDS AND WIDELY SCATTERED TO SCATTERED MODERATE AND ISOLATED STRONG CONVECTIVE PRECIPITATION ARE TO THE EAST OF 96W. SCATTERED TO NUMEROUS STRONG CONVECTIVE PRECIPITATION COVERS THE PARTS OF ANDROS ISLAND IN THE BAHAMAS AND THE NEARBY WATERS THAT AROUND ANDROS ISLAND FROM 24N TO 26N BETWEEN 77W AND 79W. OTHER BROKEN TO OVERCAST MULTILAYERED CLOUDS AND POSSIBLE RAINSHOWERS ARE IN THE ATLANTIC OCEAN TO THE WEST AND NORTHWEST OF 32N68W 31N74W 28N76W. A SURFACE TROUGH HAS DEVELOPED ALONG 93W/94W FROM THE ISTHMUS OF TEHUANTEPEC OF MEXICO TO 30N ALONG THE BORDER OF TEXAS AND LOUISIANA. THIS FEATURE IS APPARENT IN SURFACE OBSERVATIONS. BROAD SURFACE ANTICYCLONIC WIND FLOW COVERS THE GULF OF MEXICO... THE ATLANTIC OCEAN...AND THE U.S.A. GULF COAST STATES TO THE NORTH OF THE LINE THAT PASSES THROUGH 30N92W...TO 28N85W BEYOND 30N78W. THE CARIBBEAN SEA... A DEEP LAYER TROUGH IS IN THE CENTRAL ATLANTIC OCEAN...EXTENDING FROM A 33N58W CYCLONIC CIRCULATION CENTER...TO 25N56W TO 20N55W...CONTINUING TO 16N58W...TO A 13N61W CYCLONIC CIRCULATION CENTER. THE 13N61W CENTER IS BETWEEN BARBADOS AND SAINT VINCENT. RAINSHOWERS ARE POSSIBLE TO THE SOUTH OF 15N TO THE EAST OF 66W. RAINSHOWERS ALSO ARE POSSIBLE BETWEEN 66W AND 72W. A TROPICAL WAVE IS ALONG 84W/85W TO THE SOUTH OF 23N...ALONG THE WESTERN EDGE OF CUBA. SCATTERED MODERATE TO ISOLATED STRONG CONVECTIVE PRECIPITATION IS TO THE WEST OF 80W...FROM THE GULF OF HONDURAS NORTHWARD TO THE CUBA COAST AND IN THE YUCATAN CHANNEL. THE MONSOON TROUGH IS ALONG 9N74W IN COLOMBIA...TO 8N81W IN PANAMA...BEYOND SOUTHERN COSTA RICA. NUMEROUS STRONG CONVECTIVE PRECIPITATION IS IN THE SOUTHWESTERN CORNER OF THE AREA TO THE SOUTH OF 11.5N BETWEEN 79W AND 83W. SCATTERED MODERATE TO ISOLATED STRONG CONVECTIVE PRECIPITATION IS IN THE EASTERN PACIFIC OCEAN FROM 3N TO LAND TO THE EAST OF 86W. PLEASE READ THE HIGH SEAS FORECASTS...MIAHSFAT2...AND THE OFFSHORE FORECAST...MIAOFFNT3...FOR DETAILS ABOUT 20 TO 25 KNOT WINDS AND 8 TO 9 FOOT SEA HEIGHTS FROM 11N TO 14N BETWEEN 69W AND 77W. THE ATLANTIC OCEAN... A DEEP LAYER TROUGH IS IN THE CENTRAL ATLANTIC OCEAN... EXTENDING FROM A 33N58W CYCLONIC CIRCULATION CENTER...TO 25N56W TO 20N55W...CONTINUING TO 16N58W...TO A 13N61W CYCLONIC CIRCULATION CENTER. THE 13N61W CENTER IS BETWEEN BARBADOS AND SAINT VINCENT. THE 1006 MB LOW PRESSURE CENTER THAT IS NEAR 32N57W IS DESCRIBED IN THE SPECIAL FEATURES SECTION. ONE SURFACE RIDGE PASSES THROUGH 32N68W TO 27N71W TO THE CENTRAL BAHAMAS. A SECOND SURFACE RIDGE PASSES THROUGH 32N43W TO 25N42W AND 19N41W. PLEASE READ THE HIGH SEAS FORECASTS...MIAHSFAT2...FOR DETAILS ABOUT TROPICAL STORM NADINE. A SECOND FEATURE IS A 1006 MB LOW PRESSURE CENTER THAT IS NEAR 35N57W MOVING NORTHWESTWARD 10 KNOTS. EXPECT 20 TO 25 KNOTS AND 8 TO 9 FOOT SEA HEIGHTS TO THE NORTH OF 29N BETWEEN 54W AND 63W. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ MT