000 AXNT20 KNHC 161050 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 AM EDT WED AUG 16 2006 TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHEASTERN 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...WEATHER OBSERVATIONS...RADAR... AND METEOROLOGICAL ANALYSIS. BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1045 UTC. ...SPECIAL FEATURE... A WEAK AREA OF SURFACE LOW PRESSURE IS LOCATED A COUPLE OF HUNDRED MILES SOUTHEAST OF THE NORTH CAROLINA COAST. SHOWER ACTIVITY REMAINS MINIMAL WITH THIS SYSTEM...AND UPPER-LEVEL WINDS WILL GRADUALLY BECOME LESS FAVORABLE FOR DEVELOPMENT OVER THE NEXT COUPLE OF DAYS. HOWEVER...SOME POTENTIAL FOR DEVELOPMENT STILL EXISTS TODAY AND AN AIR FORCE RESERVE RECONNAISSANCE AIRCRAFT WILL BE AVAILABLE TO INVESTIGATE THE SYSTEM THIS AFTERNOON...IF NECESSARY. ...TROPICAL WAVES... AN ATLANTIC OCEAN 1012 MB SURFACE LOW IS LOCATED SW OF THE CAPE VERDE ISLANDS NEAR 13N28W MOVING W 10 TO 15 KT. THIS LOW APPEARS TO BE TRANSITIONING INTO AN OPEN WAVE BASED ON THE FIRST FEW FRAMES OF VISIBLE IMAGERY THIS MORNING. DEEP CONVECTION REMAINS AT A MINIMUM WITH THIS WAVE. AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 40W/41W SOUTH OF 21N MOVING WEST NEAR 10 TO 15 KT. THIS WAVE CONTINUES TO EXHIBIT A CLASSIC INVERTED V PATTERN BUT CONVECTION REMAINS LIMITED N OF THE ITCZ AXIS AND 9N. SCATTERED MODERATE CONVECTION IS NOTED SOUTH OF THE ITCZ FROM 4N-9N BETWEEN 37W AND 44W. A CARIBBEAN SEA TROPICAL WAVE EXTENDING S THROUGH HISPANIOLA IS ALONG 71W SOUTH OF 20N MOVING WEST 10 TO 15 KT. CYCLONIC CURVATURE IS STILL EVIDENT ABOUT THE WAVE AXIS THOUGH THIS WAVE IS NOT AS DEFINED AS IT USED TO BE. THE SCATTERED MODERATE CONVECTION THAT WAS AFFECTING ERN HISPANIOLA AND THE ADJACENT WATERS LAST NIGHT HAS DIMINISHED. ONLY ISOLATED SHOWERS/TSTMS ARE NOTED OVER MUCH OF THE CARIBBEAN WITHIN 200NM OF EITHER SIDE OF THE AXIS. HOWEVER...A CLUSTER OF NUMEROUS MODERATE/ISOLATED STRONG CONVECTION HAS FLARED UP OVER NW COLOMBIA AND IS BEGINNING TO SPREAD W INTO THE ADJACENT CARIBBEAN WATERS. ...THE ITCZ... ITCZ IS CENTERED ALONG 17N16W 13N26W 12N31W 10N39W 9N42W AND TO THE SOUTH AMERICA NEAR 7N59W. VERY LITTLE SHOWER/TSTM ACTIVITY IS NOW NOTED NEAR THE ITCZ OFF THE COAST OF AFRICA TO 25W. CLUSTERS OF SCATTERED MODERATE CONVECTION LIE FROM 4N TO 10N BETWEEN 30W AND 50W. ...DISCUSSION... THE GULF OF MEXICO... SHORTWAVE IR IMAGERY SHOWS A COUPLE LOW TO MID LEVEL CYCLONIC CIRCULATIONS IN THE CENTRAL GULF...WITH THE MOST OBVIOUS NEAR 25N87W. BUOY OBS ALSO NOW SHOW CLEAR CYCLONIC TURNING AND CONFLUENCE IN THE CENTRAL GULF WHICH HAS LEAD TO THE TROUGH PLACEMENT ON THE INTERMEDIATE 16/0900 UTC MAP. SCATTERED SHOWERS AND TSTMS ARE NOTED FROM 23N TO 29W BETWEEN 86W AND 93W. THESE SHOWERS/TSTMS ARE MOVING NE TO SW BETWEEN AN UPPER HIGH NEAR SRN ARKANSAS AND THE UPPER LOW JUST N OF TAMPA. UPPER DIFFLUENCE BETWEEN THESE FEATURES IS HELPING THE CLUSTER OF MODERATE CONVECTION SEEN S OF THE CENTRAL LOUISIANA COAST NEAR 28N91W. SHELL PLATFORM 42362 IS IN THIS VICINITY AND SHOWED THAT 30KT ENE WINDS MIXED DOWN AT 0800 UTC. DOPPLER RADAR ALSO SHOWS SCATTERED SHOWERS AND TSTMS JUST OFFSHORE FT MYERS...ASSOCIATED WITH INSTABILITY AROUND THE BASE OF THE UPPER LOW. 16/0000 UTC GFS SEEMS TO HAVE THIS HANDLED WELL...SHOWING A DISTINCT REGION OF 500MB POSITIVE VORTICITY ADVECTION IN THE REGION WHERE THE SHOWERS ARE OCCURRING OFF W FLORIDA. MUCH OF THE WRN GULF BETWEEN 93W AND 98W IS UNDER THE INFLUENCE OF DRY AIR AND FAIR WEATHER. SYNOPTIC SURFACE PATTERN IN THE GULF IS IN A VERY WEAK PRESSURE PATTERN AT THE MOMENT. THE CARIBBEAN SEA... A TROPICAL WAVE IS MOVING THROUGH HISPANIOLA AND THE CENTRAL CARIBBEAN. OVERALL THE CARIBBEAN IS FAIRLY INACTIVE ASIDE FROM THE CLUSTER OF NUMEROUS MODERATE/ISOLATED STRONG CONVECTION SPREADING W FROM NRN COLOMBIA. A MID TO UPPER LEVEL ANTICYCLONE AND DRY AIR IS AFFECTING MUCH OF THE CARIBBEAN THIS MORNING. A SMALL UPPER LOW IS SPINNING OVER CUBA...WITH A LARGER UPPER LOW IN THE WRN ATLC NEAR 19N58W AFFECTING THE NE CARIBBEAN. COLOMBIAN LOW CONTINUES TO INTERACT WITH A FAIRLY WEAK ATLC SFC RIDGE...WITH 15 TO 20KT TRADE FLOW DOMINATING MUCH OF THE CARIBBEAN...THOUGH A WEAKER GRADIENT AND LIGHTER WINDS ARE OBSERVED FAR NW PORTION. THE ATLANTIC OCEAN... A SURFACE TROUGH EXTENDS NE FROM SRN FLORIDA...THROUGH THE NW BAHAMAS...AND INTO THE ADJACENT ATLC WATERS. A CLUSTER OF MODERATE CONVECTION HAS DEVELOPED NEAR THIS TROUGH NW OF THE ABACOS. A DYING STATIONARY FRONT IS PRODUCING ISOLATED SHOWERS AND TSTMS FROM 25N TO 32N BETWEEN 56W AND 70W. UPPER RIDGING IS EXTENDING N FROM HISPANIOLA WHILE AN UPPER LOW IS ENE OF THE LEEWARD ISLANDS NEAR 19N58W. SCATTERED SHOWERS NEAR THIS UPPER LOW ARE SEEN FROM 17N-22N BETWEEN 55W-59W. BROAD UPPER RIDGING CONTINUES TO DOMINATE MUCH OF THE ERN ATLC...WITH THE RIDGE AXIS EXTENDING W FROM AFRICA ALONG 20N OUT TO 35W...WITH A COUPLE EMBEDDED HIGH CENTERS. FAIR WEATHER ALONG WITH WEAK SURFACE HIGH PRESSURE DOMINATES MUCH OF THIS AREA FROM 15N-30N BETWEEN AFRICA AND 50W. $$ WILLIS