000 AXNT20 KNHC 021807 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT WED AUG 02 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 1735 UTC. ...SPECIAL FEATURE... TROPICAL STORM CHRIS CONTINUES TO SKIRT THE NORTHERNMOST LEEWARD ISLANDS. THE CENTER OF T.S. CHRIS IS LOCATED NEAR 19.5 NORTH 64.0 WEST OR ABOUT 85 NM...EAST-NORTHEAST OF ST. THOMAS AT 02/1500 UTC. CHRIS IS MOVING TOWARD THE WEST-NORTHWEST NEAR 9 KT. ON THIS TRACK...THE CENTER OF CHRIS WILL REMAIN NORTH OF THE VIRGIN ISLANDS AND PUERTO RICO THIS AFTERNOON AND EVENING. HOWEVER...SOME OF THE STRONG RAIN BANDS ON THE SOUTH SIDE OF CHRIS MAY AFFECT PUERTO RICO AND THE VIRGIN ISLANDS LATER TONIGHT AND EARLY THURSDAY MORNING. THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 1007 MB. THE MAXIMUM SUSTAINED WINDS REMAIN 55 KT WITH HIGHER GUSTS. CHRIS IS EXPECTED TO PRODUCE TOTAL RAINFALL ACCUMULATIONS OF 2 TO 4 INCHES OVER THE NORTHERN LEEWARD ISLANDS...THE U.S. VIRGIN ISLANDS...AND PORTIONS OF PUERTO RICO...WITH ISOLATED MAXIMUM AMOUNTS OF 8 INCHES POSSIBLE OVER HIGHER TERRAIN THROUGH THURSDAY. 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. RECENT AIRCRAFT DATA FOUND THAT CHRIS HAS NOT STRENGTHENED YET. MODERATE CONVECTION/HEAVY SHOWERS AND TSTMS ASSOCIATED WITH CHRIS ARE NOTED FROM 19N TO 22N BETWEEN 61W AND 66W. UW-CIMMS SHEAR ANALYSIS STILL SHOWS ABOUT 10KTS OF SHEAR OVER CHRIS...AND THE CYCLONE IS EXPECTED TO MOVE WEST INTO AN UPPER COL REGION DURING THE NEXT FEW DAYS WHICH IS A REASONABLY FAVORABLE ENVIRONMENT FOR STRENGTHENING. ...TROPICAL WAVES... A TROPICAL WAVE IN THE EASTERN ATLANTIC ALONG 36W/37W S OF 18N MOVING WEST 15-20 KT. THIS WAVE REMAINS SUPERIMPOSED UPON A QUASI STATIONARY MONSOONAL TROUGH WITH SURFACE SW FLOW NOTED BACK TO THE NE COAST OF BRAZIL ON THE SOUTH SIDE OF THE ITCZ. BROAD CYCLONIC CURVATURE WITH A VAGUE INVERTED V PATTERN ASSOCIATED WITH THIS WAVE IS STILL NOTED IN VISIBLE IMAGERY THIS AFTERNOON. WIDELY SCATTERED SHOWERS AND TSTMS EXISTS NORTH OF THE ITCZ FROM 10N TO 15N BETWEEN 31W AND 43W...WITH A PATCH OF MODERATE CONVECTION JUST EAST OF THE AXIS NEAR 14N34W. WIDESPREAD SHOWERS AND TSTMS EXIST JUST SOUTH OF THE ITCZ/MONSOON TROUGH FROM 5N TO 10N BETWEEN 31W AND 44W. THE TROPICAL WAVE THAT WAS MOVING THROUGH THE SE CARIBBEAN SEA AND VENEZUELA YESTERDAY WAS RECENTLY REMOVED FROM THE ANALYSIS DUE TO A LACK OF CLEAR EVIDENCE. TODAYS SATELLITE AND SURFACE OBSERVATIONS SUGGEST THE WAVE HAS REEMERGED...AND IS THUS REPLACED ON THE 12Z MAP ALONG 71W/72W S OF 13N. ANALYSIS OF THE HOVMOLLER DIAGRAMS ON THE TAFB WEBSITE SHOW THAT THE REGION HAD VERY LITTLE CONVECTIVE ACTIVITY YESTERDAY...BUT REDEVELOPED LAST NIGHT AND THIS MORNING. A CLUSTER OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS LOCATED IN THE SW CARIBBEAN THAT EXTENDS S THROUGH PANAMA AND INTO THE GULF OF PANAMA...SOME OF THIS MAY BE ASSOCIATED WITH THE WAVE BUT IS ALSO LIKELY BEING ENHANCED BY THE ITCZ AND THE COLOMBIAN LOW. A SMALLER CLUSTER OF MODERATE CONVECTION IS NOTED EAST OF THE AXIS NOW MOVING THROUGH NW VENEZUELA. A TROPICAL WAVE IS MOVING THROUGH THE BAY OF CAMPECHE AND SOUTHERN MEXICO ALONG 95W S OF 22N MOVING W NEAR 15 KT. WEAK CURVATURE ASSOCIATED WITH THIS WAVE IS MAINLY NOTED IN THE EAST PACIFIC WATERS TO THE SOUTH. GFS INITIALIZED A WEAK REGION OF 700 MB POSITIVE VORTICITY ADVECTION IN THE SOUTHERN BAY OF CAMPECHE..WHICH IS VERY CLOSE TO WHERE THE PATCH OF MODERATE CONVECTION DEVELOPED THIS MORNING NEAR 19N95W. THIS HAS BEEN DIMINISHING IN BOTH STRENGTH AND COVERAGE OVER THE PAST FEW HOURS THOUGH. ANOTHER PATCH OF MODERATE CONVECTION IS NOTED BETWEEN COASTAL VERACRUZ AND TAMPICO MEXICO...WHICH SEEMS TO BE MORE ASSOCIATED WITH UPPER DIFFLUENCE ALONG WITH UPSLOPE FLOW. ...ITCZ... ITCZ AXIS IS CENTERED ALONG 12N16W 10N35W 9N40W TO THE SOUTH AMERICAN COAST NEAR 6N53W. A PATCH OF MODERATE CONVECTION LIES EAST OF THE WEST AFRICAN COAST/SOUTH OF THE ITCZ AXIS FROM 6N TO 7N BETWEEN 16W AND 19W. ISOLATED SPOTS OF MODERATE TO STRONG CONVECTION HAVE DEVELOPED ALONG OR JUST WEST OF THE AFRICAN COAST FROM 7N TO 14N MAINLY AFTER 1500 UTC. THIS CONVECTION MAY BE IN ASSOCIATION WITH A DEVELOPING TROPICAL WAVE...WITH THE DAKAR SOUNDING SHOWING SIGNS OF THIS AS WELL WITH LOW LEVEL NORTHERLY FLOW. SCATTERED SHOWERS AND TSTMS ARE FOUND SOUTH OF THE ITCZ WITHIN THE SOUTHWESTERLY MONSOONAL FLOW IN A BOX FROM 4N TO 11N BETWEEN 20W AND 48W. A CLUSTER OF MODERATE CONVECTION IS ALSO NOTED IN THE EXTREME SW CARIBBEAN SEA JUST NORTH OF THE PANAMA COAST. ...DISCUSSION... THE GULF OF MEXICO... UPPER LEVEL E/SE FLOW AND DRY AIR/FAIR WEATHER DOMINATES MUCH OF THE EAST AND CENTRAL GULF OF MEXICO ON THE SOUTH SIDE OF AN UPPER HIGH CENTERED NEAR KNOXVILLE TENNESSEE. AN UPPER LEVEL LOW IS SEEN SPINNING ON WATER VAPOR OVER ERN MEXICO AND SRN TEXAS. DIFFLUENCE BETWEEN THIS FEATURE AND UPPER RIDGING TO ITS SOUTH...ALONG WITH SOME LOW LEVEL UPSLOPE FLOW...IS GENERATING A PATCH OF MODERATE CONVECTION IN THE SW GULF BETWEEN COASTAL VERACRUZ AND TAMPICO MEXICO. ISOLATED SHOWERS AND THUNDERSTORMS ARE NOTED ELSEWHERE IN THE WESTERN THIRD OF THE GULF. SFC WINDS ACROSS THE GULF REMAIN FAIRLY LIGHT...5 TO 15KT FROM THE E/SE ON THE S/SW PORTION OF SFC HIGH PRESSURE. SIMILAR SFC CONDITIONS EXPECTED TO PERSIST OVER THE NEXT COUPLE OF DAYS. THE CARIBBEAN SEA... THE MAIN FEATURE IN THE REGION IS TROPICAL STORM CHRIS WHICH IS AFFECTING THE NRN LEEWARD ISLANDS. GUSTY WINDS AND SCATTERED MODERATE CONVECTION IS N OF 17N BETWEEN 61W-66W. FOR MORE DETAILS...REFER TO THE SPECIAL FEATURE SECTION ABOVE. A CLUSTER OF MODERATE CONVECTION NEAR THE ITCZ IS MOVING W THROUGH THE SW CARIBBEAN AS DESCRIBED ABOVE. THE OTHER AREA OF UNSETTLED WEATHER IN THE CARIBBEAN IS SCATTERED MODERATE CONVECTION FROM 17N TO 23N BETWEEN 78W AND 85W...MAINLY ASSOCIATED WITH UPPER DIFFLUENT FLOW BETWEEN UPPER RIDGING EXTENDING EAST THROUGH THE YUCATAN AND NW CARIBBEAN A WELL-DEFINED UPPER LOW NEAR THE BAHAMAS. THE REMAINDER OF THE CARIBBEAN HAS A DRY/STABLE UPPER LEVEL ENVIRONMENT WITH WEAK UPPER RIDGING DOMINATING. AT THE SURFACE...10 TO 25 KT E TO SE TRADE WINDS ARE DOMINATING ON THE SW SIDE OF THE ATLANTIC HIGH...WITH THE STRONGEST WINDS IN THE CENTRAL CARIBBEAN BETWEEN 70W AND 80W. THE ATLANTIC OCEAN... THE PERSISTENT UPPER LOW THAT HAS BEEN SPINNING E OF THE BAHAMAS THE LAST SEVERAL DAYS HAS SHIFTED SLOWLY WESTWARD TODAY AND IS NOW CENTERED JUST NORTH OF ELEUTHERA. LARGE SCALE UPPER RIDGING DOMINATES THE W ATLC WATERS NORTH OF THIS LOW. TO THE EAST...DISTINCT OUTFLOW IS NOTED ABOVE T.S. CHRIS. AN UPPER TROF LIES NE OF CHRIS WITH THE PORTION OF ITS AXIS S OF 30N BETWEEN 25N62W AND 30N52W. AN UPPER ANTICYCLONE CENTERED NEAR 20N34W IS AFFECTING MUCH OF THE TROPICAL ATLANTIC WATERS BETWEEN 47W AND THE AFRICAN COAST. 02/12Z UW-CIMSS SAHARAN LAYER ANALYSIS SHOWS THE LEADING EDGE OF DENSE DUST STRETCHING OUT TO 40W MAINLY N OF 15N. AT THE SURFACE...HIGH PRESSURE IS DOMINATING MUCH OF THE TROPICAL ATLANTIC WATERS ON THE SOUTH AND WEST PORTION OF ITS 1031 MB HIGH OVER THE AZORES AND A 1022 MB HIGH IN THE CENTRAL ATLC NEAR 27N62W. THE OTHER SURFACE FEATURES NOTED ARE T.S CHRIS AFFECTING THE NRN LEEWARD ISLANDS AND THE BROAD TROPICAL WAVE ALONG 36W...SEE MORE INFO ON THESE FEATURES ABOVE. $$ WILLIS