000 AXNT20 KNHC 171749 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT FRI OCT 17 2008 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 1715 UTC. ...SPECIAL FEATURES... OMAR WAS DOWNGRADED TO A TROPICAL STORM AT 17/0300 UTC. TWELVE HOURS LATER...AT 17/1500 UTC THE CENTER OF TROPICAL STORM OMAR IS NEAR 28.9N 55.1W OR ABOUT 545 NM...1000 KM...EAST-SOUTHEAST OF BERMUDA MOVING NE OR 035 DEG AT 30 KT. THE SYSTEM IS EXPECTED TO CONTINUE MOVING IN THIS GENERAL DIRECTION WITH A DECREASE IN FORWARD SPEED DURING THE NEXT 48 HOURS. ESTIMATED MINIMUM CENTRAL PRESSURE IS 987 MB. MAXIMUM SUSTAINED WIND SPEED IS 60 KT WITH GUSTS TO 75 KT. SOME SMALL FLUCTUATIONS IN INTENSITY ARE POSSIBLE IN THE NEXT 24 HOURS WITH GRADUAL WEAKENING OCCURRING ON SATURDAY. PLEASE SEE LATEST NHC PUBLIC ADVISORY UNDER AWIPS/WMO HEADERS MIATCPAT5/ WTNT35 KNHC AND THE FULL FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT5/WTNT25 KNHC FOR MORE DETAILS. THE CYCLONE HAS DEVELOPED A STRONG CURVED BAND THIS MORNING...AND HAS A SHORT WINDOW OF OPPORTUNITY TO BECOME A MINIMAL HURRICANE TODAY BEFORE REACHING COOLER WATERS AND UNDER MUCH STRONGER SHEAR IN ABOUT 24 HOURS. LATEST SATELLITE IMAGERY INDICATES THAT CONVECTION IS ALREADY DIMINISHING NEAR THE OMAR'S CENTER. ...TROPICAL WAVES... A TROPICAL WAVE IS ALONG 30W/31W S OF 16N MOVING W 10-15 KT. THIS WAVE SHOWS UP VERY WELL ON THE TPW PRODUCT FROM CIMSS WHERE A NORTH-SOUTH MOISTURE MAXIMUM IS SEEN. WELL-DEFINED CYCLONIC CURVATURE IS EVIDENT ON SATELLITE IMAGERY WITH A VERY LARGE AREA OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION FROM 5N-15N BETWEEN 22W-35W. FURTHER DEVELOPMENT OF THIS SYSTEM IS NOT EXPECTED DURING THE NEXT 48 HOURS OR SO DUE TO THE PRESENCE OF AN UPPER-LEVEL LOW AHEAD OF THE WAVE AXIS. A TROPICAL WAVE IS ALONG 51W/52W S OF 15N MOVING W 10-15 KT. THE WAVE IS OBSERVED ON THE SSMI-TPW PRODUCT FROM CIMSS AND REMAINS EMBEDDED WITHIN THE ITCZ. SCATTERED MODERATE CONVECTION IS FROM 7N-11N BETWEEN 50W-55W. THERE ARE NO SIGNS OF ORGANIZATION AND DEVELOPMENT...IF ANY...WILL BE SLOW TO OCCUR. ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 8N13W 9N27W 7N40W 9N50W 8N60W. IN ADDITION TO CONVECTION ASSOCIATED WITH THE TROPICAL WAVES...A CLUSTER OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS NEAR 9N16W. SIMILAR CONVECTION IS 12N40W AND FROM 7N-10N BETWEEN 56W-58W. ...DISCUSSION... GULF OF MEXICO... A COLD FRONT EXTENDS ACROSS SE LOUISIANA TO 28N94W...THEN CONTINUES AS A STATIONARY FRONT ACROSS THE WESTERN GULF ENTERING MEXICO JUST SOUTH OF TAMPICO. A BAND OF MULTILAYERED CLOUDS WITH EMBEDDED SHOWERS IS ASSOCIATED WITH THE FRONT OVER THE NW CORNER OF THE GULF WHILE A BAND OF MAINLY LOW CLOUDS DEFINES THE FRONT OVER MEXICO. A SHORT-WAVE TROUGH EXTENDING OVER THE DEEP SOUTH TEXAS AND NE MEXICO SUPPORTS THIS FRONTAL SYSTEM WHILE A DEEP LAYERED TROUGH IS OVER THE CENTRAL CONUS. MOIST SWLY FLOW IS OVER THE NW QUADRANT OF THE GULF AHEAD OF THIS TROUGH. AN UPPER LEVEL RIDGE ANCHORED IN THE CENTRAL GULF NEAR 24N89W COVERS THE E-CENTRAL GULF AND THE FLORIDA PENINSULA PRODUCING A DRY AND STABLE ATMOSPHERE DUE TO THE SUBSIDENCE. AT THE SURFACE...A WEAK 1021 MB HIGH PRESSURE CENTERED OVER THE NE GULF AND NORTHERN FLORIDA CONTROLS THE EASTERN HALF OF THE GULF...INCLUDING THE FLORIDA PENINSULA AND STRAITS OF FLORIDA. AS A RESULT...WINDS HAVE DIMINISHED ACROSS THE AREA COMPARED WITH THE PREVIOUS DAYS. CARIBBEAN SEA... A BROAD AND ELONGATED AREA OF LOW PRES COVERS THE CENTRAL AND WESTERN CARIBBEAN WITH TWO CENTERS. ONE IS A 1011 MB LOW LOCATED NEAR 16N75W AND THE SECOND ONE IS SPINNING OVER THE GULF OF HONDURAS. A SFC TROUGH THAT EXTENDS WWD FROM THE NORTHERN LEEWARD ISLANDS ACROSS THE CARIBBEAN ALONG ROUGHLY 16N CONNECTS THE ABOVE MENTIONED LOW CENTERS. ISOLATED TO SCATTERED MODERATE CONVECTION IS ASSOCIATED WITH THE TROUGH OVER THE NE CARIBBEAN AND WITH THE LOW CENTERS. THE FIRST LOW IS FORECAST TO DISSIPATE BY SAT...WHILE THE LOW OVER THE GULF OF HONDURAS WILL REMAIN NEARLY STATIONARY DURING THE UPCOMING WEEKEND THEN WILL SLOWLY MOVE NWD THROUGH WED. ON THE OTHER HAND...THE REMNANT CIRCULATION OF FORMER TROPICAL DEPRESSION SIXTEEN IS CENTERED INLAND NEAR EL SALVADOR/GUATEMALA BORDER. THIS SYSTEM CONTINUES TO PRODUCE LOCALLY HEAVY RAINS FROM NICARAGUA TO SOUTHEASTERN MEXICO. THESE RAINS COULD CAUSE FLASH FLOODS AND MUD SLIDES. THIS LOW IS EXPECTED TO MOVE INTO THE EPAC PRETTY SOON. STRONG SUBSIDENCE/DRY AIR IS ACROSS HISPANIOLA...JAMAICA...CUBA AND THE NRN YUCATAN PENINSULA THANKS TO THE UPPER-LEVEL RIDGE CENTERED OVER THE CENTRAL GULF OF MEXICO NEAR 24N89W. AN UPPER-LEVEL LOW REMAINS N OF THE EASTERN TIP OF DOMINICAN REPUBLIC WHILE AN UPPER LEVEL RIDGE AXIS EXTENDS FROM THE CENTRAL ATLC ACROSS THE WINDWARD ISLANDS TO NE VENEZUELA AND IS PROVIDING UPPER DIFFLUENCE TO AID IN SUPPORTING THE PRECIPITATION ALONG THE AFOREMENTIONED SURFACE TROUGH. ATLANTIC OCEAN... THE UPPER-LEVEL RIDGE ACROSS THE GULF OF MEXICO AND THE FLORIDA STATE EXTENDS INTO THE W ATLC AND THE BAHAMAS. STRONG SUBSIDENCE IS ASSOCIATED WITH THIS UPPER RIDGE BRINGING DRY AIR ALSO ACROSS THE BAHAMAS AND CUBA. HIGH PRES ALSO DOMINATES THE AREA AT THE SURFACE. FURTHER EAST IS T.S. OMAR MOVING RAPIDLY TO THE NE. THE REMAINDER OF THE ATLANTIC FORECAST AREA IS UNDER THE INFLUENCE OF A SFC RIDGE ANCHORED ON A 1028 MB HIGH NEAR 35N31W. ALOFT...A RIDGE/TROUGH/RIDGE PATTERN IS OBSERVED OVER THE CENTRAL AND E ATLC WITH RIDGES CENTERED NEAR 28N45W AND INLAND OVER W AFRICA. IN BETWEEN...THERE IS AN UPPER-LEVEL LOW NEAR 17N38W. BOTH RIDGES ARE SUPPORTING CONVECTION ALONG THE ITCZ AXIS. $$ GR