000 AXNT20 KNHC 020608 AAA TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 AM 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0515 UTC. ...SPECIAL FEATURE... TROPICAL STORM CHRIS CONTINUED TO STRENGTHEN THIS EVENING AS IT NEARS THE NORTHERNMOST LEEWARD ISLANDS. THE CENTER OF T.S. CHRIS IS LOCATED NEAR 18.5 NORTH 62.2 WEST OR ABOUT 55 NM...EAST-NORTHEAST OF ST. MAARTEN AT 02/0600 UTC. CHRIS IS MOVING TOWARD THE WEST-NORTHWEST NEAR 9 KT. ON THE FORECAST TRACK...CHRIS IS EXPECTED TO MOVE NEAR OR OVER THE NORTHERNMOST LEEWARD ISLANDS LATER THIS MORNING...AND POSSIBLY AFFECT THE VIRGIN ISLANDS THIS AFTERNOON OR EVENING. THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 1002 MB. THE MAXIMUM SUSTAINED WINDS HAS INCREASED TO 50 KT WITH GUSTS TO 60 KT. CHRIS IS EXPECTED TO PRODUCE TOTAL RAINFALL AMOUNTS OF 3 TO 5 INCHES OVER THE NORTHERN LEEWARD ISLANDS...THE U.S. VIRGIN ISLANDS...AND PORTIONS OF PUERTO RICO...WITH POSSIBLE ISOLATED MAXIMUM AMOUNTS OF 8 INCHES THROUGH WEDNESDAY. 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. CONVECTION IS MORE CONSOLIDATED THIS EVENING WITH A CENTRAL DENSE OVERCAST BEGINNING TO FORM. THUNDERSTORM ACTIVITY IS CURRENTLY CONFINED WITHIN A RADIUS OF ABOUT 100 NMI FROM THE CENTER. WHILE NORTHWESTERLY VERTICAL WIND SHEAR HAS WEAKENED TO ABOUT 5 TO 10 KT ACCORDING TO THE CIMSS ANALYSES...OUTFLOW IS CONFINED PRIMARILY TO THE SOUTHERN SEMICIRCLE. DRY MID TO LOW LEVEL AIR...ASSOCIATED WITH A SAHARAN AIR LAYER...IS TO THE NORTH AND WEST OF TROPICAL STORM CHRIS...THOUGH THIS MAY BE TOO FAR FROM THE STORM'S CENTER TO INHIBIT INTENSIFICATION. ...TROPICAL WAVES... A TROPICAL WAVE IN THE EASTERN ATLANTIC ALONG 35W MOVING WEST 15-20 KT. THIS WAVE IS SUPERIMPOSED UPON A STRONG WEST AFRICAN MONSOONAL FLOW ON THE SOUTH SIDE OF THE ITCZ...WITH SURFACE SOUTHWESTERLIES EXTENDING ALL THE WAY TO 42W. ONLY ISOLATED SHOWERS AND TSTMS EXIST FROM 11-15N BETWEEN 30W-40S. MORE EXTENSIVE SHOWERS AND TSTMS ARE EMBEDDED IN THE MONSOONAL FLOW EQUATORWARD OF 10N...WHICH IS DISCUSSED IN THE ITCZ SECTION. A TROPICAL WAVE IS INLAND OVER THE YUCATAN PENINSULA ALONG 90W S OF 20N MOVING W NEAR 10-15 KT. THIS WEAK WAVE WILL LIKELY MOVE W THROUGH THE BAY OF CAMPECHE ON WEDNESDAY. WHILE THE WAVE HAS ONLY A WEAK 700 MB VORTICITY SIGNATURE...THE COMBINATION OF THE WAVE AND A DIVERGENT FLOW ALOFT HAS INITIATED NUMEROUS SHOWERS AND TSTMS OVER THE YUCATAN OF MEXICO...SOUTHEAST MEXICO...AND GUATEMALA. ...ITCZ... ITCZ AXIS IS CENTERED ALONG 8N13W 13N26W 8N40W TO THE SOUTH AMERICAN COAST NEAR 6N 56W. A LINE OF MODERATE CONVECTION IS ALONG THE COAST OF WEST AFRICA FROM 6-15N...WHICH MAY BE IN ASSOCIATION WITH A DEVELOPING TROPICAL WAVE. ADDITIONAL ISOLATED CLUSTERS OF SHOWERS AND TSTMS ARE FOUND SOUTH OF THE ITCZ WITHIN THE SOUTHWESTERLY MONSOONAL FLOW IN A BOX FROM 4N-11N TO 24-40W. ...DISCUSSION... THE GULF OF MEXICO... THE GULF OF MEXICO IS DOMINATED BY EAST-SOUTHEASTERLY FLOW OF 10-20 KT ALONG THE SOUTH SIDE OF A SURFACE RIDGE LOCATED ALONG 30N. THE ONLY SIGNIFICANT SHOWER ACTIVITY IS ALONG A LINE FROM 22N93W TO 26N95W...WHICH IS GENERATED BY WEAK UPPER DIVERGENCE ON THE EAST SIDE OF AN UPPER LEVEL LOW OVER NRN MEXICO/SRN TEXAS NEAR 27N100W. MUCH OF THE CENTRAL AND EASTERN GULF HAS A FAIR AMOUNT OF DRY STABLE AIR ALOFT LIMITING ANY SHOWER ACTIVITY TO ISOLATED. WHILE THE TROPICAL WAVE ALONG 90W MENTIONED EARLIER MAY EXTEND INTO THE GULF...NO SIGNIFICANT CONVECTION IS BEING FORCED BY THE WAVE OVER THE GULF AT THIS TIME. SEE THE TROPICAL WAVES SECTION FOR MORE DETAILS. 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 60W-64W. FOR MORE DETAILS...REFER TO THE SPECIAL FEATURE SECTION ABOVE. BESIDES FOR T.S. CHRIS THERE IS ONE OTHER AREA OF UNSETTLED WEATHER IN THE CARIBBEAN. SCATTERED MODERATE CONVECTION LIES N OF 18N BETWEEN 77W-84W COVERING JAMAICA...THE CAYMAN ISLANDS AND CUBA...MAINLY ASSOCIATED WITH UPPER DIFFLUENT FLOW BETWEEN AN UPPER HIGH CENTERED NEAR THE CAYMAN ISLANDS AND A WELL-DEFINED UPPER LOW E OF THE BAHAMAS NEAR 25N74W. THE REMAINDER OF THE CARIBBEAN HAS A DRY/STABLE UPPER LEVEL ENVIRONMENT UNDER WEAK UPPER RIDGING WITH THE AXIS ALONG 19N/20N E OF 83W. AT THE SURFACE...10 TO 25 KT E TO SE TRADE WINDS ARE DOMINATING ON THE SW SIDE OF THE ATLANTIC HIGH. THE ATLANTIC OCEAN... A HIGH AMPLITUDE UPPER LEVEL PATTERN EXISTS OVER THE NORTH ATLANTIC WITH RIDGING OVER THE SOUTHEAST U.S. AND A STRONG SSW-NNE TILTING TROUGH NEAR 50W THAT EXTENDS TO 20N. THIS UPPER TROUGH HAS A WEAK SURFACE TROUGH EXTENDING FROM 28N52W TO 32N48W TO 39N43W AND IS ASSOCIATED WITH SCATTERED SHOWERS AND TSTMS WITHIN 100 NM OF THE TROUGH. AN UPPER LOW IS LOCATED JUST NORTH OF THE BAHAMAS. THIS UPPER LOW HAS A WEAK SURFACE REFLECTION ANALYZED AS A TROUGH FROM 24N73W TO 27N70W. ONLY ISOLATED SHOWERS ARE WITHIN 300 NM OF THE UPPER LOW. ANOTHER SURFACE TROUGH CLIPS THE AREA FROM 29N75W TO 32N68W TO 38N64W...THOUGH LITTLE SHOWER ACTIVITY IS ASSOCIATED WITH THIS SYSTEM SOUTH OF 32N. LARGE SCALE UPPER RIDGING CONTINUES TO DOMINATE MUCH OF THE CENTRAL AND EASTERN ATLC WATERS ANCHORED FROM ITS HIGH CENTER NEAR 22N36W. PLENTY OF DRY/STABLE AIR ALOFT COVERS THE E ATLC OUT TO 45W. ACCORDING TO THE 03 Z SAHARAN AIR LAYER ANALYSIS FROM UW-CIMSS THE LEADING EDGE OF DENSE DUST STRETCHES TO 42W 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 1023 MB HIGH IN THE CENTRAL ATLC NEAR 25N55W. THE OTHER SURFACE FEATURES NOTED ARE T.S CHRIS AFFECTING THE NRN LEEWARD ISLANDS AND THE BROAD TROPICAL WAVE ALONG 35W...SEE MORE INFO ON THESE FEATURES ABOVE. $$ LANDSEA