000 AXNT20 KNHC 201038 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 AM EDT THU SEP 20 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1015 UTC. ...SPECIAL FEATURE... AS OF 0900 UTC...A 1007 MB SURFACE LOW PRESSURE AREA NEAR 29N82W AND AN UPPER-LEVEL LOW IN THE EASTERN GULF OF MEXICO ARE PRODUCING A LARGE AREA OF DISTURBED WEATHER OVER THE WESTERN ATLC...THE NW BAHAMAS...THE FLORIDA PENINSULA AND THE EASTERN GULF MEXICO. SURFACE OBSERVATIONS INDICATE THAT THIS WEAK LOW PRESSURE SYSTEM IS MOVING WESTWARD NEAR 10 MPH ACROSS CENTRAL FLORIDA. SATELLITE IMAGES AND RADAR OBSERVATIONS INDICATE THAT THE ASSOCIATED SHOWER ACTIVITY IS LIMITED AND DISORGANIZED AT THIS TIME. HOWEVER...THE ENVIRONMENT IS GRADUALLY BECOMING FAVORABLE FOR A SUBTROPICAL OR A TROPICAL CYCLONE TO FORM AS THE SYSTEM MOVES WESTWARD INTO THE EASTERN GULF OF MEXICO LATER TODAY. LOCALLY HEAVY RAINFALL IS POSSIBLE OVER PORTIONS OF THE SOUTHEASTERN U.S. DURING THE NEXT DAY OR TWO. AN AIR FORCE HURRICANE HUNTER AIRCRAFT IS SCHEDULED TO INVESTIGATE THE SYSTEM LATER TODAY. ALL INTERESTS ALONG THE NORTHERN GULF OF MEXICO COAST SHOULD MONITOR THE PROGRESS OF THIS WEATHER DISTURBANCE. ...TROPICAL WAVES... A NEW TROPICAL WAVE IS ADDED TO THE 0600 UTC ANALYSIS/SFC MAP ALONG 2OW/21W BASED ON SATELLITE IMAGERY AND THE VERTICAL SOUNDING FROM DAKAR SENEGAL THAT SHOWED THE PASSAGE OF THE WAVE YESTERDAY. THE 20/00Z SOUNDING FROM SAL CAPE VERDE ISLANDS IS SHOWING NE WINDS OF 15 TO 20 KT AT LOW LEVEL INDICATING THE PROXIMITY OF THE WAVE. IN ADDITION...850 MB AND 700 MB MODEL GUIDANCE INDICATE THE WIND SHIFT ASSOCIATED WITH THE WAVE. ALSO...THE CIMSS VORTICITY PRODUCT PROVIDES SOME SUPPORT FOR THE WAVE POSITION INDICATED. A QUIKSCAT PASS FROM AROUND 0730 UTC ALSO REVEALS THE PRESENCE OF THIS FEATURE. WAVE HAS A CLASSIC V-STRUCTURE ON EARLIER VIS SATELLITE IMAGERY. SCATTERED MODERATE CONVECTION IS FROM 11N-16N BETWEEN 18W-23W. A LOW AMPLITUDE TROPICAL WAVE IS OVER THE ATLC ALONG 33W 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. SCATTERED MODERATE CONVECTION IS SEEN NEAR THE INTERSECTION OF THE WAVE AND THE ITCZ FROM 7N-9N BETWEEN 31W-35W. TROPICAL WAVE IS SLIGHTLY ADJUSTED AHEAD ALONG 59W WHERE SATELLITE IMAGERY SHOWS A WEAK INVERTED-V PATTERN. THIS WAVE IS NOT VERY WELL ORGANIZED WITH ONLY ISOLATED SHOWERS NEAR THE WAVE AXIS. TROPICAL WAVE IS OVER THE YUCATAN PENINSULA AND GUATEMALA ALONG 90W S OF 21W MOVING W 10-15 KT. SHOWER ACTIVITY REMAINS LIMITED IN ASSOCIATION WITH THIS WAVE. THE WAVE...COUPLED WITH STRONG UPPER WLY FLOW IS GENERATING SCATTERED SHOWERS AND ISOLATED TSTMS OVER THE AREA. ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 10N16W 9N26W 8N36W 6N45W 5N54W. OUTSIDE OF THE CONVECTION ASSOCIATED WITH THE TROPICAL WAVES... CLUSTERS OF SCATTERED MODERATE TO ISOLATED STRONG CONVECTION ARE FROM 5N-10N BETWEEN 35W-44W. DISCUSSION... GULF OF MEXICO... ATTENTION REMAINS FOCUSED ON A LARGE AREA OF DISTURBED WEATHER MOVING SLOWLY WESTWARD ACROSS CENTRAL FLORIDA. THIS ACTIVITY IS ASSOCIATED WITH A WEAK SURFACE LOW PRES AREA AND A WELL DEFINED UPPER-LEVEL LOW LOCATED OVER THE ERN GULF NEAR 27N83W. SEE SPECIAL FEATURE. A SWATH OF VERY DRY MID TO UPPER AIR CONTINUES TO WRAP AROUND THE PERIPHERY OF THE UPPER-LEVEL LOW THROUGH THE MIDDLE AND WESTERN GULF...INCLUDING ALSO THE NORTHERN YUCATAN PENINSULA THEN SE TO WRN CUBA AND NE ACROSS THE EASTERN FLORIDA COAST. SHOWER AND TSTM ACTIVITY HAS SLIGHTLY INCREASED OVER THE E GULF AFFECTING FROM 25N-28N E OF 86W. SURFACE OBSERVATIONS INDICATE THAT ANOTHER WEAK SURFACE LOW IS NEAR 25.5N84W. IN GENERAL A BROAD AREA OF LOW PRES DOMINATES THE FLORIDA PENINSULA AND THE EASTERN GULF. UPPER RIDGING DOMINATES THE FAR NW AND SW PORTIONS OF THE GULF WHILE ANOTHER UPPER LOW CONTINUES TO MOVE SLOWLY WWD ACROSS MEXICO. WIDELY SCATTERED SHOWERS ARE OBSERVED OVER THE WESTERN HALF OF THE GULF. ELSEWHERE AT THE SURFACE RIDGING DOMINATES THE SE US AND THE NW GULF. PRES GRADIENT BETWEEN THE SFC RIDGE AND LOWER PRES OVER FLORIDA IS GENERATING MODERATE NE TO E WINDS OVER THE N GULF. MODERATE SW WINDS ARE BLOWING OVER THE SE GULF AND THE FLORIDA KEYS. CARIBBEAN SEA... AS THE NIGHT WORE ON...CONVECTION DIED OUT OVER NORTHERN COLOMBIA WHILE SOME SHOWER/TSTM ACTIVITY REMAINS OVER CENTRAL VENEZUELA. SCATTERED MODERATE CONVECTION IS ALSO SEEN OVER THE SW CARIBBEAN AND ALONG THE COAST OF WESTERN PANAMA/COSTA RICA. THIS ACTIVITY IS BEING ENHANCED BY A DIFFLUENT PATTERN ALOFT. THE SURFACE PRES GRADIENT REMAINS FAIRLY RELAXED ACROSS THE AREA. THIS IS KEEPING THE TRADE WINDS MOSTLY LIGHT...EXCEPT SLIGHTLY STRONGER NEAR THE COAST OF COLOMBIA. EXTENSIVE WLY FLOW ALOFT IS OVER THE MAJORITY OF THE BASIN...WITH RIDGING OVER NORTHERN SOUTH AMERICA AND CENTRAL AMERICA. ATLANTIC OCEAN... SHOWERS AND THUNDERSTORM ACTIVITY CONTINUES OVER THE WRN ATLC AND THE NW BAHAMAS ASSOCIATED WITH A LARGE AREA OF DISTURBED WEATHER. SEE SPECIAL FEATURE ABOVE. SCATTERED MODERATE TO ISOLATED STRONG CONVECTION ARE FOUND OVER THE CENTRAL ATLC FROM 16N-30N BETWEEN 42W-53W...WHICH IS IN A REGION OF PRONOUNCED UPPER DIFFLUENCE BETWEEN AN UPPER LOW NEAR 32N50W AND AN UPPER HIGH LOCATED EAST OF THE LESSER ANTILLES NEAR 15N54W. AN UPPER RIDGE EXTENDS FROM THIS HIGH N THROUGH THE CENTRAL ATLC ALONG 42W/43W. THE NEXT WEATHER PRODUCER IS THE REMNANTS OF INGRID... ANALYZED AS A 1012 MB LOW NEAR 23N65W WITH A WEAK SURFACE TROUGH. THIS FEATURE IS INTERACTING WITH AN UPPER-LEVEL LOW NEAR 22N66W. UPPER-LEVEL WINDS ARE NOT FAVORABLE FOR SIGNIFICANT DEVELOPMENT OF THIS SYSTEM. SCATTERED SHOWERS AND ISOLATED TSTMS ARE ASSOCIATED WITH THIS FEATURE. A WEAK 1015 MB SURFACE LOW IS NEAR 30N50W THAT HAS A TRAILING TROUGH EXTENDING SW TO NEAR 20N55W WHERE SATELLITE IMAGERY DEPICTS A SMALL CLUSTER OF MODERATE CONVECTION. ANOTHER UPPER LOW IS OVER THE E ATLC NEAR 30N25W. AN UPPER TROUGH EXTENDS FROM THIS LOW TO NEAR 17N37W. RIDGING DOMINATES THE TROPICAL ATLC. THE E ATLC SURFACE PATTERN CONTINUES TO BE DOMINATED BY RIDGING S OF A 1027 MB HIGH LOCATED N OF THE AZORES. THIS IS PRODUCING MODERATE NE TRADES E OF 35W. $$ GR