000 FXUS61 KOKX 040739 AFDOKX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEW YORK NY 339 AM EDT SAT JUL 4 2009 .SYNOPSIS... A CLIPPER SYSTEM WILL PASS NORTH OF THE REGION ON SATURDAY WITH ANOTHER LOW PASSING TO THE SOUTH OF THE AREA SUNDAY INTO SUNDAY NIGHT. AN UPPER TROUGH WILL APPROACH ON MONDAY AND AFFECT THE REGION THROUGH MIDWEEK. RIDGING MAY BUILD IN FOR THE END OF THE WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... A STRONG SHORTWAVE AND CLIPPER LOW OVER CENTRAL ONTARIO THIS MORNING DIVES INTO CENTRAL/NORTHERN NEW ENGLAND TODAY. DEEP NW FLOW AND BEST COLD POOL INSTABILITY TO THE NORTH WILL KEEP THE REGION DRY...WITH JUST SOME AFTERNOON CU DEVELOPMENT WITH ASSOCIATED COLD FRONT PASSAGE THIS AFTERNOON. STRONG OFFSHORE FLOW SHOULD INHIBIT SEABREEZE DEVELOPMENT. MOSTLY SUNNY SKIES AND DOWNSLOPE FLOW WILL HAVE HIGHS IN THE UPPER 70S TO LOWER 80S AREAWIDE...WARMEST NY/NJ METRO AND COAST. && .SHORT TERM /6 PM THIS EVENING THROUGH MONDAY/... GENERALLY ZONAL FLOW TONIGHT IN WAKE OF CLIPPER TYPE SYSTEM...WITH WEAK HIGH PRESSURE BUILDING OVER THE REGION. THIS WILL HAVE MOSTLY CLEAR SKIES...WITH JUST SOME HIGH AND MID CLOUDS ACROSS SOUTHERN ZONES LATE FROM DEVELOPING LOW PRES OVER THE TN VALLEY. CANADIAN AIRMASS ADVECTS IN THE WAKE OF THE CLOD FRONT THIS EVENING. THEN WITH GOOD RADIATIONAL COOLING CONDS OVERNIGHT...TEMPS WILL RUN SEVERAL DEGREES BELOW NORMAL ACROSS OUTLYING AREAS...FALLING INTO THE 50S. PERHAPS SOME UPPER 40S IN THE PINE BARRENS AND NORTHERN VALLEYS. NEXT PIECE OF NORTHERN STREAM ENERGY WILL HAVE AN UPPER LOW DEVELOPING OVER ONTARIO ON SUNDAY AND DIGGING TOWARDS THE EASTERN GREAT LAKES SUN NIGHT. AT THE SAME TIME A WEAK SOUTHERN STREAM SHORTWAVE WILL TRACK E ACROSS THE TENNESSEE VALLEY AND THEN OFFSHORE SUN NIGHT. MODELS ARE NOT INDICATING ANY PHASING OF THESE TWO IMPULSES...BUT WILL BE A CLOSE CALL. WITHOUT PHASING...WEAK LOW PRESSURE TRACKING THROUGH THE TENNESSEE VALLEY ON SUN WILL PASS WELL SOUTH OF NYC/LONG ISLAND LATE SUN/SUN NIGHT. IF THE NORTHERN AND SOUTHERN STREAM ENERGY WERE TO PHASE THIS WOULD DIG THE NORTHERN STREAM TROUGH FURTHER SOUTH...BRINGING THE LOW FURTHER NORTH WITH MORE WIDESPREAD SHOWER ACTIVITY SUN NIGHT. BUT CONFIDENCE IS NOT HIGH ON THAT OCCURRING. WILL CONTINUE WITH SLIGHT CHANCE POPS FOR SOUTHERN PORTIONS OF THE CWA FOR SUN EVE/SUN NIGHT BASED ON THIS UNCERTAINTY AND CLOSEST APPROACH. OTHERWISE...SHOULD BE MAINLY DRY DAY ON SUN WITH PARTY CLOUDY CONDITIONS WITH MAINLY HIGH AND MID DECK CLOUDS. BACKING FLOW ON SUN WILL ALLOW FOR AFTERNOON SEA BREEZE DEVELOPMENT. HIGHS IN THE LOWER 80S INTERIOR...MID TO UPPER 70S ALONG THE COAST. UPPER LOW CONTINUES TO DIG TOWARDS THE NORTHEAST ON MON. UNCERTAINTY ON HOW FAR S AND E THIS FEATURE DIGS...WHICH WILL DETERMINE AMOUNT OF INSTABILITY SHRA/TSRA DEVELOPMENT. WILL CONTINUE AFTERNOON SLIGHT CHANCE POPS FOR NW 1/2 OF CWA. TEMPS RUNNING NEAR SEASONABLE. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... UPPER LOW SLOWLY MOVES THROUGH THE NORTHEAST...BRINGING US LOWER-END POPS THROUGH WEDNESDAY. HIGHEST OVERALL CHANCES OF CONVECTIVE ACTIVITY LOOK TO BE DIURNAL ON TUESDAY AND WEDNESDAY. RIDGING ALOFT AND AT THE SURFACE MOVES IN BEHIND THE UPPER LOW. DRY WEATHER THEREFORE FOR THE REST OF THE LONG TERM. HIGH TEMPERATURES AT OR SLIGHTLY BELOW NORMAL TO START...THEN WARMING ABOVE NORMAL LATE IN THE PERIOD WITH THE RIDGING ALOFT. && .AVIATION /07Z SATURDAY THROUGH WEDNESDAY/... VFR. INCREASING NW ALOFT SHOULD INHIBIT ANY FOG FORMATION...BUT THOSE WINDS IN COMBINATION WITH LIGHTER SFC WINDS COULD PRODUCE SOME LOW LEVEL WIND SHEAR UNTIL ONSET OF DAYTIME HEATING/MIXING (ABOUT 12Z) AT AREA TERMINALS OTHER THAN KJFK/KLGA/KEWR...TOO MARGINAL A SITUATION TO INCLUDE IN TAF. WITH NW FLOW GUSTING TO 20-25 KT AT TIMES THIS AFTERNOON...DO NOT EXPECT A TRUE AFTERNOON SEA BREEZE...THOUGH CANNOT TOTALLY RULE OUT WINDS AT COASTAL TERMINALS BACKING SLIGHTLY MORE W IN THE AFTERNOON...ESPECIALLY AT KGON WHICH WILL LIE TO THE EAST OF A DEVELOPING LEE SFC TROUGH IN RESPONSE TO A STRONG UPPER DISTURBANCE MOVING ACROSS. OUTLOOK FOR 06Z SUNDAY THROUGH WEDNESDAY... LOOK FOR A SLIGHT CHANCE OF BRIEF SUB-VFR CONDITIONS ON MON...THEN A SOMEWHAT BETTER CHANCE TUE-WED...VIA DIURNAL AFTERNOON/EARLY EVENING CONVECTION...AS YET ANOTHER UPPER LOW AND ASSOCIATED SFC TROUGH APPROACH. && .MARINE... FRONT PUSHES E OF THE AREA TODAY WITH GUSTY W-NW FLOW TAKING HOLD THIS AFTERNOON AND EARLY EVENING IN ITS WAKE...15-20 KT WITH AN OCCASIONAL GUST UP TO 25 KT POSSIBLE JUST DOWNWIND OF BETTER VERTICAL MIXING OVER THE NYC URBAN HEAT ISLAND. GIVEN NUMBER OF RECREATIONAL BOATERS WHO WILL BE OUT ON THE WATERS THIS INDEPENDENCE DAY HOLIDAY...ISSUING SCA FOR THIS WOULD BE OVERKILL BUT WILL STILL ISSUE MARINE WX STATEMENT TO HIGHLIGHT THE SITUATION. QUIET CONDITIONS WILL OTHERWISE BE THE RULE THROUGH THE REST OF THE FORECAST PERIOD...WITH A LACK OF SIGNIFICANT SURFACE FEATURES IN THE REGION. && .HYDROLOGY... GENERALLY DRY CONDITIONS THROUGH THE WEEKEND. MORE CONVECTIVE PRECIP POSSIBLE EARLY NEXT WEEK. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. NJ...NONE. MARINE...NONE. && $$ SYNOPSIS...NV NEAR TERM...NV SHORT TERM...NV LONG TERM... AVIATION...BG MARINE...BG HYDROLOGY...NV