000 AXNT20 KNHC 031803 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT THU AUG 03 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1715 UTC. ...SPECIAL FEATURE... TROPICAL STORM CHRIS IS EXPECTED TO WEAKEN TO A DEPRESSION LATER TODAY...WITH LOW TO MID LEVEL DRY AIR AND SHEAR HAVEN TAKEN ITS TOLL. THE CENTER OF TROPICAL STORM CHRIS WAS LOCATED NEAR 20.7 NORTH 67.7 WEST OR ABOUT 225 NM EAST-SOUTHEAST OF GRAND TURK ISLAND AT 03/1800 UTC. CHRIS IS MOVING TOWARD THE WEST-NORTHWEST NEAR 10 KT. THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 1012 MB. THE MAXIMUM SUSTAINED WINDS REMAIN 35 KT WITH HIGHER GUSTS. PLEASE REFER TO THE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT3/ WTNT23 KNHC AND THE PUBLIC ADVISORY MIATCPAT3/WTNT33 KNHC FOR MORE DETAILS. CHRIS IS EXPECTED TO PRODUCE TOTAL RAINFALL AMOUNTS OF 1 TO 3 INCHES WITH ISOLATED TOTALS OF UP TO 5 INCHES OVER THE HIGHER TERRAIN OF PUERTO RICO...THE U.S. AND BRITISH VIRGIN ISLANDS...AND THE DOMINICAN REPUBLIC. RAINFALL AMOUNTS OF 1 TO 2 INCHES ARE POSSIBLE OVER THE SOUTHEAST BAHAMAS...THE TURKS AND CAICOS ISLANDS...AND NORTHERN HAITI THROUGH FRIDAY. THE CLOUD TOPS ASSOCIATED WITH CHRIS REMAIN MUCH WARMER THAN THEY WERE YESTERDAY AND EVEN LAST NIGHT. DISPLACED...SCATTERED SHOWER AND THUNDERSTORM ACTIVITY IS GENERALLY CONFINED TO THE REGION S AND SE OF THE CENTER FROM 17.5N N TO 19.5N BETWEEN 65.3W AND 67.8W. HE UW-CIMMS SHEAR ANALYSIS DEPICTS 20 TO 30 KTS OF NORTHERLY SHEAR AFFECTING THESE SHOWERS AND THUNDERSTORMS...ASSOCIATED WITH AN UPPER LEVEL LOW TO THE NE OF CHRIS CENTERED NEAR 24N55W AND ITS INTERACTION WITH AN UPPER RIDGE WHOSE AXIS EXTENDS EAST THROUGH HISPANIOLA. ...TROPICAL WAVES... AN ATLANTIC OCEAN TROPICAL WAVE ALONG 43W/44W S OF 17N...OR ABOUT 1000NM E OF THE LESSER ANTILLES...IS MOVING WEST 15-20 KT. VISIBILE IMAGERY THIS AFTERNOON DEPICTS SOME BROAD CYCLONIC CURVATURE BUT THE SIGNAL IS A BIT NOISY DUE TO ITCZ ACTIVITY ALONG WITH BROAD UPPER EASTERLY FLOW OVER THE AREA. MOST OF THE SHOWER AND TSTM ACTIVITY IN THE VICINITY LIES EAST OF THE WAVE...MORE ASSOCIATED WITH THE ITCZ/MONSOON TROUGH. ONLY ISOLATED SHOWERS AND TSTMS ARE NOTED WITHIN 250NM OF EITHER SIDE OF THE WAVE AXIS. A TROPICAL WAVE IS MOVING W NEAR 15 KT THROUGH THE SW CARIBBEAN SEA ALONG 79W S OF 13N. SHIP AND SURFACE OBSERVATIONS SHOW A CLEAR CYCLONIC CURVATURE ABOUT THE WAVE AXIS...THOUGH THERE IS VERY LITTLE SIGNIFICANT CONVECTION NEAR THE WAVE. THE CARIBBEAN PORTION OF THE WAVE IS DOMINATED BY DRY AIR AND FAIR WEATHER...WITH JUST A SMALL PATCH OF MODERATE CONVECTION NOTED IN THE GULF OF PANAMA NEAR 4N81W. ...ITCZ... ITCZ AXIS IS CENTERED ALONG 9N12W 9N40W 7N46W AND INLAND THROUGH SOUTH AMERICAN TO NEAR 8N77W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION LIES FROM 3N TO 14N BETWEEN 10W AND 25W WHICH COVERS A PORTION OF THE W AFRICAN COAST. ANOTHER AREA OF SCATTERED SHOWERS AND THUNDERSTORMS WITH EMBEDDED ISOLATED MODERATE CONVECTION LIES FROM 5N TO 13N BETWEEN 27W AND 41W. ...DISCUSSION... THE GULF OF MEXICO... THE MOST ACTIVE WEATHER IN THE GULF THIS AFTERNOON LIES IN THE WESTERN BAY OF CAMPECHE...WHERE A CLUSTER OF MODERATE CONVECTION LIES FROM 18N TO 24N BETWEEN 92W AND 98W. THIS IS ASSOCIATED WITH UPPER DIFFLUENCE BETWEEN AN UPPER LOW CENTERED NEAR DEL RIO TEXAS AND UPPER RIDGING TO ITS SOUTH. JUST EAST OF THIS REGION LIES A SWATH OF DRY AIR FROM 21N TO 30N BETWEEN 88W AND 94W. ISOLATED SHOWER AND THUNDERSTORM ACTIVITY IS DOTTING THE AREA BETWEEN THE YUCATAN CHANNEL AND THE CENTRAL GULF COAST...IN A REGION OF WEAK UPPER DIFFLUENCE BETWEEN AN UPPER TROF AXIS EXTENDING WSW FROM ITS CENTER OVER THE BAHAMAS AND UPPER RIDGING OVER MUCH OF THE SE/MID ATLANTIC STATES. THE SURFACE PATTERN IN THE GULF REMAINS FAIRLY BENIGN WITH A 1019MB SURFACE HIGH PRESSURE CENTER ANALYZED JUST SOUTH OF PENSACOLA...AND WINDS GENERALLY BELOW 15KT/SEAS BELOW 4 FT. SIMILAR CONDITIONS EXPECTED THROUGH THE NEXT 48 HOURS. THE CARIBBEAN SEA... DESPITE THERE BEING A TROPICAL STORM JUST NORTH OF PUERTO RICO...THE MOST ACTIVE CONVECTION IN THE CARIBBEAN THIS AFTERNOON LIES IN THE NW PORTION BETWEEN THE YUCATAN PENINSULA AND WRN CUBA...WHERE SCATTERED MODERATE CONVECTION LIES FROM 18N TO 23N BETWEEN 80W AND 87W. THIS IS ASSOCIATED WITH UPPER DIFFLUENT FLOW BETWEEN UPPER RIDGING EXTENDING EAST THROUGH THE YUCATAN/BELIZE/NW CARIBBEAN AND THE WELL-DEFINED UPPER LOW CENTERED OVER THE NW BAHAMAS. MUCH OF THE REMAINDER OF THE CARIBBEAN SEA IS DOMINATED BY ANTICYCLONIC TURNING...DRY AIR...AND FAIR WEATHER. THE EXCEPTION IS THE MOISTURE AND SHEARED SHOWERS/THUNDERSTORMS FROM TS CHRIS SPREADING N TO S INTO THE NE CARIBBEAN WATERS S OF PUERTO RICO AND THE NORTHERN LEEWARD ISLANDS. AT THE SURFACE 10 TO 25 KT E TO SE TRADE WINDS ARE DOMINATING ON THE SW SIDE OF THE ATLANTIC HIGH. THE STRONGEST SWATH OF TRADE WINDS ARE NOTED IN THE CENTRAL CARIBBEAN BETWEEN 70W AND 80W...AS THE HIGH INTERACTS WITH THE COLOMBIAN LOW. THE ATLANTIC OCEAN... A RATHER LARGE UPPER LEVEL LOW CONTINUES TO DRIFT WESTWARD NOW CENTERED OVER THE WRN BAHAMAS NEAR 26N78W. THIS LOW IS AIDING IN THE DEVELOPMENT OF A FEW SHOWERS OVER THE BAHAMAS AND SOUTH FLORIDA. A BROAD FLAT UPPER RIDGE LIES TO THE N OF THE UPPER LOW EXTENDING FROM THE MID-ATLANTIC U.S. TO BERMUDA. A MID-UPPER LEVEL TROUGH DIGS INTO THE CENTRAL ATLC BEYOND 32N44W TO ANOTHER UPPER LOW LOCATED TO THE NE OF TROPICAL STORM CHRIS CENTERED NEAR 24N55W. THIS IS THE FEATURE THAT IS PROVIDING NORTHERLY VERTICAL WIND SHEAR ACROSS CHRIS'S CICRULATION SHEARING MUCH OF IT'S PREVIOUS DEEP CONVECTION...REMOVING IT WELL S OF THE EXPOSED LOW LEVEL CENTER. SEE THE SPECIAL FEATURE SECTION FOR MORE DETAILS. THE REMAINDER OF THE ATLC IS DOMINATED BY A LARGE SCALE UPPER RIDGE ANCHORED BY A HIGH CENTER NEAR 21N36W. PLENTY OF DRY/STABLE UPPER LEVEL AIR EXISTS IN THE ATLC UNDER THE INFLUNECE OF THIS RIDGING E OF 55W. AN AREA OF UPPER DIFFFLUENCE ON THE W PERIPHERY OF THE LARGE SCALE RIDGE IS PRODUCING SCATTERED SHOWERS AND TSTRMS FROM THE NRN LEEWARD ISLANDS TO 36N BETWEEN 53W-63W. AT THE SURFACE...BESIDES FOR THE TROPICAL STORM AND THE TROPICAL WAVE...HIGH PRES RIDGING IS THE THEME SUPPORTED BY A 1026 MB HIGH ABOUT 200 NM ENE OF THE AZORES. A WEAKENING COLD FRONT AND SFC TROUGH ASSOCIATED WITH THE MID-UPPER TROUGH IN THE CENTRAL ATLC ARE JUST N OF THE DISCUSSION AREA. OVERALL...NO BIG SURFACE PATTERN CHANGES ARE EXPECTED OVER THE NEXT DAY OR TWO. $$ WILLIS/CANGIALOSI