000 AXNT20 KNHC 062350 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT SAT OCT 06 2007 TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHERN SECTIONS OF SOUTH AMERICA...AND THE 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 FEATURE... AN AREA OF LOW PRESSURE CENTERED ABOUT 520 NM EAST OF THE LESSER ANTILLES HAS BECOME LESS ORGANIZED THIS AFTERNOON. A 1009 MB SFC LOW WAS ANALYZED NEAR 15N52W ON THE 1800 UTC SURFACE MAP. THE LOW IS EMBEDDED IN A TROPICAL WAVE WITH THE AXIS ALONG 52W. UPPER-LEVEL WINDS ARE NOT FAVORABLE FOR SIGNIFICANT DEVELOPMENT...AND THE CHANCES FOR THIS SYSTEM TO BECOME A TROPICAL DEPRESSION ARE DIMINISHING DUE TO THE PRESENCE OF STRONG SLY UPPER-LEVEL WINDS. THE EXPOSED LOW LEVEL CENTER IS WELL DEFINED BY CU LINES ON LATEST VIS SAT IMAGERY. SCATTERED MODERATE CONVECTION IS JUST E OF THE TROPICAL WAVE AXIS/LOW FROM 13N-20N BETWEEN 46W-52W. THIS LOW IS EXPECTED TO MOVE SLOWLY NORTHWESTWARD DURING THE NEXT DAY OR SO. ...TROPICAL WAVES... THERE IS ONLY ONE TROPICAL WAVE BETWEEN AFRICA AND THE LESSER ANTILLES. THE WAVE IS ALONG 52W S OF 21N MOVING W 10 KT. A 1009 MB LOW IS ALONG THE WAVE AXIS NEAR 15N. SEE SPECIAL FEATURE. ...THE ITCZ... AXIS IS CENTERED ALONG 10N14W 7N30W 11N48W 13N54W 11N62W. BESIDES THE CONVECTION ASSOCIATED WITH THE TROPICAL WAVE...WIDELY SCATTERED MODERATE CONVECTION IS WITHIN 100 NM EITHER SIDE OF AXIS BETWEEN 25W-45W. SCATTERED MODERATE CONVECTION IS NEAR 5N22W...AND NEAR 5N19W. A CLUSTER OF MODERATE TO ISOLATED STRONG CONVECTION IS MOVING OUT OF THE AFRICAN COAST JUST N OF THE ITCZ AXIS. DISCUSSION... THE GULF OF MEXICO... A SURFACE RIDGE AXIS DOMINATES THE SE U.S. AND THE NORTHERN GULF WATERS N OF 25N. PRESSURE GRADIENT BETWEEN THIS RIDGE AND A SFC LOW OVER THE NW CARIBBEAN IS PRODUCING ELY WINDS OF 15 TO 25 KT OVER FLORIDA AND THE EASTERN GULF. WIDELY SCATTERED SHOWERS ARE MOVING FROM THE W ATLC THROUGH FLORIDA INTO THE EASTERN GULF UNDER THE INFLUENCE OF THESE WINDS. LIGHTNING DATA ALSO DEPICTS ISOLATED TO SCATTERED TSTMS MAINLY OVER THE FLORIDA PANHANDLE AND NEAR 27N89W. THE REMAINDER OF THE GULF HAS LIGHT 5-10 KT WINDS WITH MOSTLY FAIR WEATHER OVER THE WESTERN GULF...WHERE A MID/TO UPPER DRY AIR MASS PREVAILS. ALOFT...AN UPPER-LEVEL RIDGE ANCHORED ON A HIGH OVER THE SE U.S. DOMINATES THE GULF MOST OF THE GULF WHILE AN UPPER LOW IS OVER NE MEXICO GENERATING SOME SHOWER/TSTM ACTIVITY. THE RIDGE OVER THE NORTHERN GULF WILL PERSIST THE REST OF THE WEEKEND AND WILL WEAKEN MONDAY. THE CARIBBEAN SEA... THE MAIN WEATHER FEATURE ACROSS THE REGION IS A BROAD AREA OF LOW PRESSURE CENTERED BETWEEN HONDURAS AND THE CAYMAN ISLANDS. SURFACE PRESSURES ARE FALLING IN THE AREA WITH BUOYS REPORTING NEAR 1005 MB OVER THE NW CARIBBEAN. AS OF 2100 UTC...A 1005 MB SFC LOW WAS ANALYZED NEAR 17N83W. FURTHER DEVELOPMENT OF THIS SYSTEM IS POSSIBLE OVER THE NEXT FEW DAYS AS IT REMAINS NEARLY STATIONARY. CLIMATOLOGICALLY...THE NW CARIBBEAN IS A FAVORABLE AREA FOR TROPICAL CYCLONE DEVELOPMENT DURING THE MONTH OF OCTOBER. A CLUSTER OF MODERATE TO ISOLATED STRONG CONVECTION IS JUST SOUTH OF THE SFC LOW. SCATTERED MODERATE CONVECTION DOTS THE CENTRAL AND WESTERN CARIBBEAN FROM THE DOMINICAN REPUBLIC TO THE GULF OF HONDURAS. AN UPPER RIDGE IS HELPING TO INDUCE THIS ACTIVITY. NUMEROUS SHOWERS AND TSTMS ARE SEEN OVER CUBA. AN UPPER-LEVEL TROUGH THAT EXTENDS WWD FROM AN UPPER LOW OVER HISPANIOLA IS ENHANCING THIS CONVECTIVE ACTIVITY. ABUNDANT MID TO UPPER LEVEL MOISTURE COVERS MOST OF THE BASIN. AN AREA OF DISTURBED WEATHER ASSOCIATED WITH A SURFACE TROUGH AND AN UPPER-LEVEL LOW IS CENTERED ABOUT 150 MILES NORTH-NORTHWEST OF PUERTO RICO. THIS SYSTEM REMAINS POORLY ORGANIZED AND ENVIRONMENTAL CONDITIONS ARE FORECAST TO BECOME LESS FAVORABLE FOR DEVELOPMENT OVER THE NEXT COUPLE OF DAYS AS IT MOVES SLOWLY NORTHWESTWARD. POCKETS OF MODERATE CONVECTION ARE OVER WESTERN VENEZUELA AND NORTHERN COLOMBIA...AS WELL AS OVER PANAMA AND COSTA RICA PRIMARILY ASSOCIATED WITH THE ITCZ. THE ATLANTIC OCEAN... A PAIR OF SFC TROUGHS ARE GENERATING SCATTERED SHOWERS AND TSTMS OVER THE WEST AND CENTRAL ATLC. THE FIRST ONE RUNS FROM 24N67W TO THE SE BAHAMAS. AN AREA OF DISTURBED WEATHER IS ASSOCIATED WITH THIS TROUGH AND AN UPPER LOW. SEE THE CARIBBEAN SEA SECTION. THE SECOND ONE EXTENDS FROM 23N55W TO 25N46W TO 28N41W. CLUSTERS OF MODERATE TO ISOLATED STRONG CONVECTION ARE WITHIN 100 NM EITHER SIDE OF TROUGH BETWEEN 50W-53W. SCATTERED SHOWERS ARE FOUND ALONG THE REMAINDER OF THE TROUGH. A 1023 MB HIGH LOCATED NEAR 35N65W EXTENDS A RIDGE OVER THE W ATLC...THE SE U.S. AND THE STATE OF FLORIDA. THE E ATLC IS ALSO DOMINATED BY A 1020 MB SFC HIGH SITUATED NEAR 27N27W. THIS FEATURE IS FORECAST TO MOVE NWD AND OUT OF AREA DURING THE NEXT 24 HOURS BUT A RIDGE WILL REMAIN IN PLACE. PRES GRADIENT WILL TIGHTEN BETWEEN THIS RIDGE AND LOWER PRES OVER WESTERN AFRICA DURING THE NEXT DAY OR SO PRODUCING MODERATE TO STRONG NELY WINDS BETWEEN THE CAPE VERDE ISLANDS AND THE AFRICAN COAST. TRADES ARE ALSO EXPECTED TO INCREASE ACROSS THE TROPICS. IN THE UPPER LEVELS...A RIDGE IS OVER THE W ATLANTIC N OF 20N AND W OF 70W. AN UPPER TROUGH EXTENDS ACROSS THE CENTRAL ATLC TO THE UPPER LOW OVER HISPANIOLA. MODERATE TO STRONG WLY UPPER LEVEL WINDS ARE OVER THE FORECAST AREA N OF 20N E OF 50W WITH A JET STREAM BRANCH OF 70-90 KT CLIPPING THE REGION E OF 36W. IN THE TROPICS AN UPPER LEVEL HIGH IS CENTERED NEAR 13N37W. $$ GR