000 AXNT20 KNHC 270553 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 AM EDT THU JUL 27 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0530 UTC. ...TROPICAL WAVES... BASED UPON SATELLITE IMAGERY AND THE AVAILABLE DATA...THE TROPICAL WAVE IN THE EASTERN ATLANTIC PREVIOUSLY ALONG 31W HAS BEEN DROPPED FROM THE SURFACE ANALYSIS. THIS FEATURE DOES NOT APPEAR TO HAVE BEEN A TROPICAL WAVE BUT RATHER SOME INSTABILITY LEFT BEHIND FROM THE BROAD HIGH AMPLITUDE WAVE 600 NM TO ITS WEST. A HIGH AMPLITUDE TROPICAL WAVE IS ALONG 44W SOUTH OF 21N MOVING WEST 15-20 KT. THIS WAVE IS VERY BROAD YET WELL DEFINED WITH CLEAR LOW-MID LEVEL TURNING EVIDENT ON SATELLITE IMAGERY. THE WAVE IS ENHANCING CONVECTION EMBEDDED WITHIN THE ITCZ FROM 5N-12N BETWEEN 35W-53W. THE NORTHERN EXTENSION OF THE WAVE HAS LIMITED SHOWER ACTIVITY AS IT IS EMBEDDED IN A DRY/STABLE ENVIRONMENT LIKELY DUE TO SAHARAN DUST. A HIGH AMPLITUDE TROPICAL WAVE IS IN THE EASTERN CARIBBEAN ALONG 65W SOUTH OF 22N MOVING WEST NEAR 20 KT. THIS WAVE HAS BEEN WELL-DEFINED OVER THE PAST SEVERAL DAYS. SHOWER AND TSTM ACTIVITY HAS INCREASED TODAY WITH PATCHES OF SCATTERED MODERATE CONVECTION MAINLY BEHIND THE WAVE AXIS ACROSS THE VIRGIN ISLANDS...LEEWARD AND WINDWARD ISLANDS FROM 12-21N BETWEEN 58W-66W. AN INCREASE IN WINDS IS EVIDENT BEHIND THE WAVE AXIS BASED ON AN EARLIER QUIKSCAT PASS AND BUOY/SHIP OBS. FURTHER DEVELOPMENT IS NOT LIKELY TO OCCUR AS UPPER LEVEL WINDS ARE UNFAVORABLE. A WESTERN CARIBBEAN SEA TROPICAL WAVE IS ALONG 82W SOUTH OF 18N MOVING WEST NEAR 15 KT. VERY LITTLE WAVE SIGNATURE IS NOTED ON SATELLITE IMAGERY. HOWEVER...THIS WAVE MAY BE AIDING IN TRIGGERING CLUSTERS OF MODERATE/STRONG CONVECTION EMBEDDED IN THE ITCZ ACROSS THE SOUTHERN CARIBBEAN FROM 5N-11N BETWEEN 73W-82W. ...ITCZ... ITCZ AXIS IS CENTERED ALONG 11N15W 10N30W 9N42W TO INLAND OVER SOUTH AMERICA NEAR 9N62W TO PANAMA NEAR 9N82W. BESIDES FOR THE CONVECTION ENHANCED BY THE TROPICAL WAVES...CLUSTERS OF SCATTERED MODERATE CONVECTION EXISTS EAST OF 30W WITHIN 240 NM EITHER SIDE OF THE AXIS. THIS ACTIVITY MAY BE ASSOCIATED WITH ANOTHER TROPICAL WAVE APPROACHING 20W. ...DISCUSSION... GULF OF MEXICO... THE MOST ACTIVE WEATHER IN THE REGION CONTINUES TO BE IN THE NW GULF. THE SURFACE LOW THAT HAS BEEN MOVING NORTHWARD ALONG THE MEXICO/TEXAS COAST OVER THE PAST FEW DAYS APPEARS TO HAVE DISSIPATED. HOWEVER...PATCHES OF MODERATE CONVECTION CONTINUES ACROSS PORTIONS OF NRN MEXICO...SOUTH TEXAS...WRN LOUISIANA AND THE COASTAL WATERS FROM 24N-30N W OF 93W...CAUSED BY LOW LEVEL CONVERGENCE AND UPPER DIFFLUENCE BETWEEN AN UPPER HIGH IN THE CENTRAL GULF AND AN UPPER LOW OVER NRN MEXICO. THE UPPER HIGH IS ADVECTING SOME OF THE MOISTURE FROM THE W GULF ACROSS THE SE U.S. AND NRN GULF...HOWEVER MUCH OF IT IS MAINLY IN THE UPPER LEVELS. MOISTURE IS SLIGHTLY DEEPER WITH EMBEDDED SCATTERED SHOWERS/TSTMS ACROSS FLORIDA AND THE SE GULF AS UPPER DIFFLUENCE IS STRONGER BETWEEN THE GULF OF MEXICO HIGH AND A TROUGH OFF THE SE U.S. AT THE SURFACE...RIDGING HAS BUILT ACROSS THE REGION FROM THE BERMUDA-AZORES HIGH TO A 1018 MB HIGH CENTER OVER THE FL/GA BORDER. SFC FLOW IS LIGHT ACROSS FLORIDA AND THE E GULF...STRONGER W OF 87W WHERE SE WINDS OF 15-20 KT ARE COMMON. THE MOISTURE IN THE W GULF WILL CONTINUE TO DRIFT NWD AND SLOWLY WEAKEN. LITTLE CHANGE IN THE SURFACE PATTERN IS EXPECTED OVER THE NEXT FEW DAYS AS SFC RIDGING IS LIKELY TO REMAIN ESTABLISHED. CARIBBEAN SEA... TWO TROPICAL WAVES ARE IN THE CARIBBEAN SEA THIS EARLY MORNING. THE WESTERN-MOST WAVE IS ALONG 82W ENHANCING CONVECTIVE ACTIVITY IN THE ITCZ ACROSS THE SOUTHERN CARIBBEAN. SEE THE TROPICAL WAVES SECTION FOR MORE DETAILS. THE OTHER WAVE...ALONG 65W...IS MORE IMPRESSIVE INTERACTING WITH AN UPPER LEVEL LOW IN THE ATLC TO PRODUCE A RATHER WIDE AREA OF SHOWERS AND TSTMS ACROSS THE LESSER ANTILLES NOW MOVING OVER PUERTO RICO FROM 12N-21N BETWEEN 58W-67W. PUERTO RICO DOPPLER RADAR SHOWS NARROW BANDS OF SHOWERS AND TSTMS MOVING WWD ACROSS THE ISLAND WITH A MUCH LARGER SHIELD OF MODERATE TO HEAVY RAIN OVER THE VIRGIN ISLANDS. THIS WAVE WILL CONTINUE TO MOVE QUICKLY TO THE WEST...STEERED BY THE STRONG SFC HIGH...SPREADING MOISTURE ACROSS THE CENTRAL CARIBBEAN LATER TODAY. AN UPPER LOW IS MOVING TO THE WSW IN THE WRN CARIBBEAN CENTERED NEAR 19N85W. WEAK UPPER DIFFLUENCE BETWEEN THIS UPPER LOW AND THE GULF OF MEXICO UPPER HIGH IS TRIGGERING SCATTERED SHOWERS/ISOLATED TSTMS OVER SOUTH CUBA AND THE CAYMAN ISLANDS FROM 20N-22N BETWEEN 78W-84W. TRADE WINDS ARE GENERALLY IN THE 15-20 KT RANGE WITH SOME SLIGHTER STRONGER WINDS OFF THE COAST OF COLOMBIA AND POSSIBLY IN THE CONVECTION ACROSS THE LESSER ANTILLES. THE ATLANTIC OCEAN... A BERMUDA-AZORES SURFACE RIDGE RUNS FROM A 1027 MB HIGH PRESSURE CENTER OVER THE AZORES TO A 1029 MB HIGH IN THE CENTRAL ATLC NEAR 36N49W ACROSS BERMUDA INTO THE CENTRAL GULF OF MEXICO. A WEAK RATHER BENIGN 1020 MB SURFACE LOW PRESSURE CENTER IS CONTAMINATING THE RIDGE NEAR 32N30W. IN THE UPPER LEVELS...A TROUGH OFF THE SE U.S. INTERACTING WITH AN UPPER HIGH IN THE GULF IS PRODUCING A CONSIDERABLE AMOUNT OF UPPER LEVEL MOISTURE W OF 72W N OF 24N. ONLY SCATTERED SHOWERS AND ISOLATED TSTMS ARE EMBEDDED IN THIS MOISTURE PLUME. A WELL-DEFINED UPPER LOW IS CENTERED NEAR 26N65W. THIS UPPER LOW IS INTERACTING WITH THE EASTERN CARIBBEAN TROPICAL WAVE TO PRODUCE SCATTERED MODERATE CONVECTION. SEE THE CARIBBEAN SECTION FOR MORE DETAILS. A VERY WEAK DRY UPPER LOW IS MOVING NWD OUT OF THE DISCUSSION AREA NEAR 31N55W. A BROAD UPPER RIDGE COVERS A LARGE PORTION OF THE ATLC N OF 10N BETWEEN 18W AND 54W. MIDDLE TO UPPER LEVEL DRY/STABLE AIR IS NORTH OF 14N BETWEEN 25W AND 55W. AN UPPER TROUGH CLIPS THE AREA E OF 18W N OF 27N. A WIDESPREAD AREA OF DENSE SAHARAN DUST EXTENDS OUT TO ABOUT 65W...BEHIND THE E CARIBBEAN TROPICAL WAVE. THE COMBINATION OF THE DRY/STABLE ATMOSPHERE FROM THE SAHARAN DUST AND SUBSIDENCE FROM UPPER RIDGING IS SUPPRESSING ANY SIGNIFICANT CONVECTION IN THE ATLC N OF THE ITCZ. $$ CANGIALOSI