000 AXNT20 KNHC 191805 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT WED SEP 19 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1715 UTC. ...SPECIAL FEATURE... A WEAK 1010 MB SURFACE LOW PRESSURE AREA ALONG THE COAST OF FLORIDA NEAR 27N80W AND AN UPPER LEVEL LOW IN THE EASTERN GULF NEAR 26N83W ARE PRODUCING A LARGE AREA OF DISTURBED WEATHER OVER THE WESTERN ATLANTIC...THE CENTRAL AND NORTHWESTERN BAHAMAS...PORTIONS OF THE FLORIDA PENINSULA...AND THE EASTERN GULF MEXICO. THIS SYSTEM WILL LIKELY BRING SHOWERS...SQUALLS...AND LOCALLY HEAVY RAINS OVER PORTIONS OF FLORIDA DURING THE NEXT DAY OR TWO. THE SURFACE LOW IS NOT WELL DEFINED AT THE MOMENT...BUT IS EXPECTED TO MOVE INTO OR REDEVELOP OVER THE EASTERN GULF OF MEXICO DURING THE NEXT DAY OR SO...WHERE A SUBTROPICAL OR TROPICAL CYCLONE COULD FORM. THE SURFACE WINDS IN THE IMMEDIATE VICINITY OF THE LOW ARE NOT VERY STRONG...MOSTLY 15 KT OR LESS. STRONGER WINDS ARE DISPLACED FURTHER N OF THE LOW WHERE THE INTERACTION BETWEEN THE LOW ITSELF...STRONG CONTINENTAL HIGH PRESSURE CENTERED OVER NEW ENGLAND...AND A SLOW MOVING COASTAL WARM FRONT ARE PRODUCING 20-25 KT NE TO E WINDS OFF THE CAROLINAS THROUGH NORTH FLORIDA. ...TROPICAL WAVES... A LOW AMPLITUDE TROPICAL WAVE IS OVER THE E ATLC ALONG 29W/30W S OF 15N MOVING W 10-15 KT. THIS WAVE STILL SHOWS UP WELL IN LOW LEVEL SATELLITE DERIVED WINDS AND VORTICITY...AND THE UW CIMSS TPW PRODUCTS. HOWEVER...THE WAVE REMAINS DISORGANIZED WITH LIMITED SHOWER ACTIVITY...WHICH IS GENERALLY ISOLATED WITHIN 210 NM OF THE AXIS. TROPICAL WAVE IS ALONG 54W/55W S OF 20N MOVING W NEAR 15 KT. THIS WAVE ALSO IS NOT VERY WELL ORGANIZED. SOME OF THE ENERGY/MOISTURE ASSOCIATED WITH THE NRN PORTION OF THE WAVE APPEARS TO BE ROUNDING THE E ATLC RIDGE AND MOVING TOWARDS THE FRONTAL TROUGH IN THE CENTRAL ATLC. SCATTERED SHOWERS ARE WITHIN 180NM E/60NM W OF THE AXIS N OF 16N WITH WLY SHEAR OVER THE AREA. MINIMAL SHOWER ACTIVITY IS NOTED FURTHER S. TROPICAL WAVE IS ALONG 86W S OF 21W MOVING W 10-15 KT. SHOWER ACTIVITY REMAINS LIMITED IN ASSOCIATION WITH THIS WAVE. STRONG UPPER WLY FLOW IS OVER THIS PORTION OF THE CARIBBEAN BETWEEN THE STRONG UPPER LOW IN THE ERN GULF AND RIDGING OVER CENTRAL AMERICA. ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 13N16W 11N26W 6N35W 8N52W 7N62W. SCATTERED MODERATE CONVECTION IS NEAR THE COAST OF W AFRICA MOVING W WITHIN 240 NM S/180 NM N OF THE AXIS. THIS ACTIVITY MAY BE ASSOCIATED WITH THE NEXT TROPICAL WAVE BASED ON RECENT SOUNDING DATA UPSTREAM. SCATTERED MODERATE CONVECTION IS FROM 3N-9N BETWEEN 32W-39W. SIMILAR ACTIVITY IS WITHIN 250NM N OF THE AXIS BETWEEN 46W-52W. DISCUSSION... GULF OF MEXICO... A WELL DEFINED UPPER-LEVEL LOW IS OVER THE ERN GULF NEAR 26N83W. A SWATH OF VERY DRY MID TO UPPER AIR CONTINUES TO WRAP AROUND THE PERIPHERY OF THIS FEATURE THROUGH THE MIDDLE GULF THEN SE TO WRN CUBA AND NE INTO S FLORIDA. HOWEVER...SCATTERED SHOWERS AND ISOLATED TSTMS ASSOCIATED WITH THE SYSTEM ARE NOW AFFECTING THE ERN GULF FROM 24N-29N E OF 86W. A 1010 MB SFC LOW NEAR THE COAST OF S FLORIDA IS INTERACTING WITH THE UPPER LOW. THE SFC LOW IS EXPECTED TO MOVE INTO OR REDEVELOP OVER THE ERN GULF OVER THE NEXT DAY OR SO...SEE SPECIAL FEATURE SECTION ABOVE FOR MORE DETAILS. UPPER RIDGING DOMINATES THE FAR NW AND SW PORTIONS OF THE GULF WHILE AN UPPER LOW CONTINUES TO MOVE SLOWLY OVER MEXICO NEAR 22N101W. UPPER DIFFLUENCE BETWEEN THESE FEATURES IS HELPING SUPPORT SCATTERED SHOWERS/ISOLATED TSTMS S OF 24N W OF 95W TO THE COAST OF MEXICO. ANOTHER SIMILAR AREA OF SHOWERS IS OVER THE CENTRAL GULF WATERS FROM 23N-27N BETWEEN 88W-92W. WEAK SFC TROUGHING IS ALSO AFFECTING THESE AREAS GIVING FURTHER SUPPORT. ELSEWHERE AT THE SFC RIDGING DOMINATES N OF 26N FROM THE LARGE FALL-LIKE ANTICYCLONE CENTERED OVER NEW ENGLAND. THIS IS PRODUCING MODERATE NE TO E WINDS OVER THE N GULF...WHILE LIGHTER MORE VARIABLE WINDS PERSIST FURTHER S AROUND TROUGHING. CARIBBEAN SEA... THE MOST ACTIVE WEATHER IN THE CARIBBEAN THIS AFTERNOON IS IN THE SW PORTION OFF THE COAST OF COLOMBIA AND PANAMA. SCATTERED MODERATE CONVECTION IS GENERALLY S OF 12N. THIS IS ASSOCIATED WITH THE ITCZ AND DIFFLUENCE ALOFT. OTHERWISE...SHOWER ACTIVITY IS LIMITED AND ISOLATED AT BEST. EXTENSIVE WLY FLOW ALOFT IS OVER THE MAJORITY OF CARIBBEAN TODAY WHICH IS STRETCHING THE HIGH CLOUDS OVER THE LIMITED SHOWER ACTIVITY TO THE E. THE SFC PRES GRADIENT REMAINS FAIRLY RELAXED S OF THE PAIR OF WEAK LOWS IN THE WRN ATLC. THIS IS KEEPING TRADES MOSTLY LIGHT IN THE 5-15 KT RANGE AGAIN TODAY...EXCEPT SLIGHTLY STRONGER NEAR THE COAST OF COLOMBIA. SIMILAR CONDITIONS EXPECTED OVER THE NEXT DAY OR SO. ATLANTIC OCEAN... MESSY WEATHER CONTINUES OVER THE WRN ATLC ASSOCIATED WITH THE SPECIAL FEATURE...SEE ABOVE. THE MOST CONCENTRATED SHOWER AND TSTM ACTIVITY IS N OF 22N BETWEEN 72W-79W...WHICH IS IN A REGION OF PRONOUNCED UPPER DIFFLUENCE BETWEEN THE UPPER LOW OVER THE ERN GULF AND THE UPPER HIGH NEAR 29N69W. THE NEXT WEATHER PRODUCER IS THE REMNANTS OF INGRID...ANALYZED AS A 1012 MB LOW NEAR 22N64W. UPPER-LEVEL WINDS ARE NOT FAVORABLE FOR REDEVELOPMENT OF THIS SYSTEM. THIS ALONG WITH AN UPPER LOW NEAR 24N66W ARE PRODUCING DISORGANIZED SCATTERED SHOWERS/ISOLATED TSTMS FROM 19N-24N BETWEEN 59W-64W. A WEAK 1017 MB SFC LOW IS NEAR 31N50W THAT HAS A TRAILING TROUGH EXTENDING SW TO NEAR 25N59W. SCATTERED SHOWER ACTIVITY IS WITHIN 150 NM E OF THE TROUGH...WHICH IS ALSO BEING SUPPORTED BY ANOTHER UPPER LOW NEAR 32N52W. AN UPPER RIDGE EXTENDS N THROUGH THE CENTRAL ATLC ALONG 44W...WITH AN UPPER TROUGH ALONG 30W N OF 20N. UPPER RIDGING DOMINATES THE REMAINDER OF THE E ATLC FROM ITS ORIGIN OVER W AFRICA. THESE FEATURES CONTINUE TO PRODUCE AN ABUNDANCE OF WLY FLOW ALOFT N OF 16N E OF 55W. THE E ATLC SFC PATTERN CONTINUES TO BE DOMINATED BY RIDGING S OF A 1032 MB HIGH N OF THE AZORES NEAR 42N25W. THIS IS PRODUCING MODERATE NE TRADES E OF 35W...EXCEPT SLIGHTLY STRONG NEAR THE COAST OF NW AFRICA WHERE THE USUAL STRONGER GRADIENT EXISTS. $$ WILLIS