000 AXNT20 KNHC 291744 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT SAT SEP 29 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 1645 UTC. ...SPECIAL FEATURES... HURRICANE NADINE IS LOCATED NEAR 33.3N 36.2W AT 29/1500 UTC. THIS POSITION IS LOCATED ABOUT 530 NM WSW OF THE AZORES ISLANDS. NADINE IS MOVING NNW NEAR 12 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 988 MB. MAXIMUM SUSTAINED WIND SPEED IS 65 KT WITH GUST TO 80 KT. PLEASE SEE LATEST NHC FORECAST/ ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT4/WTNT24 KNHC FOR MORE DETAILS. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 32N-36N BETWEEN 34W-39W. ...TROPICAL WAVES... TROPICAL WAVE IS NEARING THE CAPE VERDE ISLANDS ALONG 17N18W TO 10N25W. THIS WAVE IS CURRENTLY MOVING SLOWLY AT ABOUT 5-10 KT. IT WILL CONTINUE TO MOVE SLOWLY FOR LIKELY THE NEXT 24 HOURS BEFORE GAINING A FASTER WESTWARD MOTION. THE WAVE IS EMBEDDED WITHIN A BROAD AREA OF MOISTURE COVERING THE EASTERN TROPICAL ATLC. MAXIMUM MOISTURE VALUES ARE NOTED NEAR THE WAVE AXIS. AN ASCAT SCATTEROMETER PASS FROM EARLIER THIS MORNING INDICATES THAT LOW LEVEL CYCLONIC FLOW IS AROUND THE NE PORTION OF THE WAVE. DUE TO THE BROAD NATURE OF THE WAVE...ISOLATED MODERATE CONVECTION RANGES FROM THE COAST OF AFRICA TO 30W WITH SCATTERED MODERATE/ISOLATED STRONG CONVECTION JUST WEST OF THE AXIS FROM 13N-15N BETWEEN 21W-24W. TROPICAL WAVE IS ALONG 17N36W TO 10N41W MOVING W NEAR 10 KT. IT LIES ON THE WEST SIDE OF A SURGE OF DEEP LAYER MOISTURE PRESENT IN TOTAL PRECIPITABLE WATER IMAGERY. SCATTERED MODERATE/STRONG CONVECTION IS NEAR THE ITCZ AXIS FROM 5N-9N BETWEEN 38W-42W. SCATTERED MODERATE CONVECTION IS E OF THE WAVE AXIS FROM 14N-18N BETWEEN 32W-35W. TROPICAL WAVE IS IN THE WESTERN CARIBBEAN ALONG 21N83W TO 15N84W MOVING W 5-10 KT. THE WAVE LIES ON THE WESTERN EDGE OF AN AREA OF ENHANCED MOISTURE PRESENT ACROSS THE WESTERN AND CENTRAL CARIBBEAN. THE WAVE ALSO LIES UNDERNEATH THE AXIS OF A NARROW UPPER LEVEL TROUGH. THIS UPPER TROUGH IS MAKING IT DIFFICULT TO DISTINGUISH EXACTLY WHERE THE WAVE AXIS IS. CONVECTION TO THE EAST OF THE WAVE IS LIKELY MORE ATTRIBUTED TO THE UPPER TROUGH THAN THE WAVE. THE WAVE IS NOW MOVING TOWARD THE WESTERN AND DRY SIDE OF THE UPPER TROUGH WHICH IS INHIBITING CONVECTION NEAR THE WAVE AXIS. CONVECTION ASSOCIATED WITH THE UPPER TROUGH IS DESCRIBED IN THE CARIBBEAN SEA SECTION. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS ACROSS WEST AFRICA TO THE COAST OF GUINEA-BISSAU AT 11N16W CONTINUING OVER ATLC WATERS ALONG 9N21W 9N34W. THE ITCZ BEGINS FROM 9N34W ALONG 9N40W 8N50W 9N57W. CONVECTION ACROSS THE EASTERN AND CENTRAL TROPICAL ATLC ARE ASSOCIATED WITH TROPICAL WAVES. SEE TROPICAL WAVE SECTION ABOVE. A SURFACE TROUGH IS ANALYZED NORTH OF THE ITCZ ALONG 14N52W TO 10N53W. THIS TROUGH MORE OUTLINES AN AREA OF WIND SPEED CONVERGENCE WITH STRONGER WINDS TO THE EAST AND WEAKER WINDS TO THE WEST. THE TROUGH IS BEING ENHANCED BY AN UPPER LEVEL TROUGH PRESENT ACROSS THE CENTRAL ATLC THAT EXTENDS SOUTHWARD ALONG 52W. THIS COMBINATION IS HELPING PRODUCE SCATTERED MODERATE/STRONG CONVECTION FROM 9N-12N BETWEEN 50W-55W. ...DISCUSSION... GULF OF MEXICO... WEAK SURFACE RIDGING IS ACROSS THE GULF OF MEXICO EXTENDING FROM A 1016 MB HIGH CENTER OVER THE NE GULF NEAR 29N87W. THE RIDGE ALONG WITH A SMALL AREA OF DRY AIR ALOFT AROUND AN UPPER LEVEL RIDGE ACROSS THE BASIN IS HELPING PRODUCE FAIR WEATHER OVER A GOOD PORTION OF THE CENTRAL..EASTERN...AND SOUTHERN GULF INCLUDING FLORIDA AND THE YUCATAN PENINSULA. THE NW GULF IS A DIFFERENT STORY WHERE NUMEROUS SHOWERS/SCATTERED THUNDERSTORMS ARE PRESENT ACROSS TEXAS AND SOUTHERN LOUISIANA AND EXTEND OFFSHORE N OF 27N W OF 88W. THE ACTIVITY IS ASSOCIATED WITH AN UPPER LEVEL TROUGH EXTENDING DOWN WESTERN TEXAS INTO CENTRAL MEXICO PLACING THE NW GULF UNDERNEATH THE UPPER TROUGHS DIFFLUENT SIDE. WIND SPEED CONVERGENCE ALONG THE COASTLINE IS ALSO CONTRIBUTING TO THE ACTIVITY AS STRONGER RETURN FLOW HITS LIGHTER WINDS ALONG THE COAST. THIS UPPER TROUGH WILL SUPPORT A LOW PRESSURE SYSTEM AND ASSOCIATED COLD FRONT THAT IS FORECAST TO ENTER GULF WATERS EARLY SUNDAY MORNING. SHOWERS/THUNDERSTORMS AND GUSTY WINDS ARE LIKELY ALONG THE FRONT AXIS. CARIBBEAN SEA... A TROPICAL WAVE IS MOVING THROUGH THE WESTERN CARIBBEAN ALONG 84W...BUT IS NOT CAUSING MUCH ACTIVE WEATHER. HOWEVER...A NARROW UPPER LEVEL TROUGH...NEARLY CUTOFF LOW...IS PRODUCING A LARGE AREA OF SHOWERS/THUNDERSTORMS EAST OF THE TROPICAL WAVE. NUMEROUS SHOWERS/SCATTERED THUNDERSTORMS ARE BETWEEN JAMAICA AND HISPANIOLA FROM 15N-19N BETWEEN 74W-77W. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE SOUTH OF CENTRAL CUBA FROM 18N-21N BETWEEN 79W-82W. SIMILAR ACTIVITY IS OFF THE COASTS OF NICARAGUA AND COSTA RICA FROM 10N-16N BETWEEN 80W-83W. THE REMAINDER OF THE CENTRAL AND EASTERN CARIBBEAN ARE EXPERIENCING FAIR CONDITIONS AND MOSTLY CLEAR SKIES DUE TO DRY AIR ALOFT AROUND AN UPPER LEVEL RIDGE ALONG 73W COVERING THE REMAINDER OF THE BASIN. TRADEWIND FLOW OF 15-20 KT IS PRESENT ACROSS THE MAJORITY OF THE AREA WITH STRONGER WINDS TO 25 KT N OF WESTERN VENEZUELA. EXPECT LITTLE CHANGE OVER THE NEXT 24 HOURS WITH CONTINUED SHOWER/THUNDERSTORM ACTIVITY IN THE WESTERN CARIBBEAN AS THE UPPER TROUGH REMAINS SOMEWHAT STATIONARY. ATLANTIC OCEAN... AN UPPER LEVEL TROUGH IS IMPACTING THE WESTERN ATLC WITH AXIS ALONG 75W. DIFFLUENCE ALOFT AROUND THE EAST SIDE OF THE TROUGH IS SUPPORTING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ACROSS THE BAHAMAS FROM N OF CUBA TO 25N BETWEEN 72W-78W WITH A FEW ISOLATED SHOWERS THROUGH THE FLORIDA STRAITS. THE UPPER TROUGH ALSO SUPPORTS A WEAK SURFACE TROUGH ALONG 30N72W TO 27N75W...WHICH IS PRODUCING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS N OF 26N BETWEEN 68W-72W. DESPITE THE PRESENCE OF AN UPPER LEVEL RIDGE OVER THE REMAINDER OF THE WEST ATLC...A PAIR OF SURFACE TROUGHS ALONG 25N67W TO 22N69W AND 24N63W TO 21N65W ARE SUPPORTING AN AREA OF SHOWERS/THUNDERSTORMS FROM 22N-24N BETWEEN 64W-67W. THE UPPER RIDGE SUPPORTS A WEAK SURFACE RIDGE ACROSS THE CENTRAL ATLC AROUND A 1023 MB HIGH NEAR 32N53W. HOWEVER...A BROAD UPPER TROUGH 51W IS SUPPORTING AN AREA OF SHOWERS/POSSIBLE THUNDERSTORMS FROM 19N-30N BETWEEN 51W-58W. THIS UPPER TROUGH IS ALSO RESPONSIBLE FOR AN AREA OF ACTIVITY NEAR A SURFACE TROUGH N OF THE ITCZ REGION. THIS SURFACE TROUGH IS DESCRIBED IN THE ITCZ SECTION ABOVE. ANOTHER UPPER LEVEL RIDGE ALONG 30W SUPPORTS A WEAK 1022 MB HIGH NEAR 25N37W...WHICH IS PROVIDING FAIR CONDITIONS ACROSS THE REMAINDER OF THE EASTERN ATLC. HURRICANE NADINE IS CENTERED N OF THE HIGH CENTER NEAR THE BOUNDARY OF THE DISCUSSION AREA. SEE SPECIAL FEATURES FOR MORE DETAILS. A BROAD UPPER TROUGH COVERS THE REMAINDER OF THE BASIN...BUT IS NOT CAUSING ANY ACTIVE WEATHER IN THE DISCUSSION AREA. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ WALTON/DELGADO