FXUS61 KBUF 171126 AFDBUF AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BUFFALO NY 726 AM EDT SAT JUL 17 2010 .SYNOPSIS... THE WEEKEND WILL START WITH ANOTHER WARM AND MAINLY SUNNY DAY...BUT A WEAK COLD FRONT WILL APPROACH OUR REGION LATER TODAY AND BRING A THREAT OF AFTERNOON THUNDERSTORMS...MOSTLY WELL NORTH OF THE THRUWAY. HIGH PRESSURE WILL BRING A RETURN TO SUNSHINE AND WARM TEMPERATURES ON SUNDAY BUT ANOTHER FRONT WILL BRING A BETTER CHANCE OF SHOWERS AND THUNDERSTORMS SUNDAY NIGHT INTO EARLY MONDAY. DRIER WEATHER WILL RETURN LATER MONDAY AND TUESDAY BEFORE A WARM FRONT LIFTS NORTH AND BRINGS THE THREAT FOR UNSETTLED WEATHER TO WESTERN AND CENTRAL NEW YORK DURING THE MIDWEEK PERIOD. .NEAR TERM /THROUGH TONIGHT/... 700 AM UPDATE...RATHER SUBTLE MID LEVEL BOUNDARY SET OFF SOME WIDELY SCATTERED SHOWERS/TSHWRS ALONG A LINE FROM CNTRL MICH TO NEAR TORONTO A FEW HOURS BACK..WITH EVEN AN ISOLD SHOWER OR TWO OVER MONROE AND WYOMING COS. THIS FEATURE...NOT BEING PICKED UP BY ANY MODEL...WAS BEING REFLECTED BY TCU MOVING INTO WESTERN NY ATTM. EXPECT THIS MID LEVEL BASED INSTABILITY TO WANE LATER THIS MORNING BEFORE SFC BASED HEATING SET SIF OFF THIS AFTERNOON. WILL CONTINUE WITH SLGT CHC POPS UNTIL ABOUT 14Z ACROSS THE WEST. NO OTHER CHANGES AT THIS TIME...PREV DISC FOLLOWS...OTHERWISE...WE SHOULD SEE A DECENT AMOUNT OF SUNSHINE LATER THIS MORNING AS SW WIND INCREASES. STRONGER SFC FRONT BACK OVER UPPER LAKES EARLY THIS MORNING WILL GRADUALLY SETTLE SOUTH...INCREASING THE GRADIENT. GOOD LAKE ERIE SHADOW WILL BECOME ESTABLISHED BY MIDDAY/EARLY AFTERNOON AND THIS WILL SERVE TO SUPPRESS CONVECTION E AND NE OF LK ERIE ACROSS BUF METRO AND ALSO LATER OFF LK ONTARIO OVER MUCH OF JEFF AND OSW COUNTIES. CONVERSELY...INSTABILITY AND CONVERGENCE WILL INCREASE BETWEEN THE LAKES OVER NIAG PENINSULA WITH SOME CONVECTION BREAKING OUT EARLY-MID AFTERNOON. MODEL SFC WINDS ARE QUITE STRONG THOUGH 230-240/20-25 KTS...SO ACTUAL LAKE ERIE BOUNDARY MAY ACTUALLY GET SHOVED OUT INTO LK ONTARIO. WILL CONTINUE WITH STRIP OF HIGHER POPS BUT DELAY IT A COUPLE HOURS FROM PREV FORECAST. ALSO ADDED CHC POPS WELL SOUTH AND SOUTHEAST OF LK ERIE ACROSS SRN TIER AS WELL FOR LATER IN DAY. 850 MB TEMPS RISE TO 17C AGAIN...SO TEMPS SHOULD EASILY REACH M-U 80S AWAY FROM LK INFLUENCES...CLOSER TO 80 IN DOWNWIND SHADOW. THERE WILL BE SOME CLOUDINESS FOR AWHILE THIS MORNING BUT THIS SHOULD HAVE LITTLE EFFECT ON TEMPS. SW FLOW RELAXES ENOUGH THIS EVENING TO PERHAPS ALLOW FOR SOME SHOWER THREAT DOWN INTO BUF AREA SO WILL HAVE CHC POPS FOR AWHILE. ALSO WORKED THE HIGH CHC POPS OVER TO WAYNE-OSWEGO COUNTIES THIS EVENING TOO...BEFORE EVERYTHING DISSIPATES BY MIDNIGHT AS WEAK SFC RIDGE WORKS IN. .SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... WEAK HIGH PRESSURE CENTERED OVER NEW YORK AND PA WILL BRING A FAIR AMOUNT OF SUNSHINE AND WARM TEMPERATURES ON SUNDAY. THERE WILL BE AN INCREASE IN CLOUDS LATER IN THE AFTERNOON AS LOW PRESSURE HEADS EAST ACROSS THE CENTRAL GREAT LAKES. THE GFS IS A LITTLE FASTER WITH THE EASTWARD PROGRESSION OF THE LOW...AND CONSEQUENTLY BRINGS IN THE LEADING EDGE OF THE RAIN A LITTLE FASTER THAN THE NAM. BUT...EVEN A BLEND OF THE TWO MODELS QPF OUTPUTS SUGGESTS THAT MOST OF THE CWA WILL REMAIN DRY. THE PRIMARY IMPACT FROM THIS SYSTEM WILL BE FELT SUNDAY NIGHT WHEN A RATHER POTENT LOW LEVEL JET IS FORECAST TO TRACK EAST ACROSS THE STATE AND INTERSECT THE WARM FRONT THAT WILL BE ASSOCIATED WITH THE APPROACHING LOW. IMPRESSIVE LOW LEVEL MOISTURE CONVERGENCE IN THE VCNTY OF THE WARM FRONT COULD RESULT IN HEAVY RAIN WITH ANY THUNDERSTORMS THAT DEVELOP ALONG THE FRONT. THE CONVECTION MAY BECOME RATHER ACTIVE AT TIMES SUNDAY NIGHT...ESPECIALLY IF THE LOW FOLLOWS THE MORE NORTHERLY TRACK INDICATED BY THE GFS. ON MONDAY...THE MAIN CENTER OF THE LOW WILL CONTINUE TO MOVE THROUGH NEW YORK STATE IN THE MORNING...THEN SETTLE INTO NEW ENGLAND DURING THE AFTERNOON. BASED ON THIS TREND...EXPECT SHOWERS AND THUNDERSTORMS TO TAPER OFF FROM WEST TO EAST DURING THE LATE MORNING AND AFTERNOON. HIGH PRESSURE FOLLOWING THE DEPARTING LOW SHOULD BRING DRY WEATHER MONDAY NIGHT. IN TERMS OF TEMPERATURES DURING THIS PERIOD...EXPECT DAYTIME HIGHS TO AVERAGE A LITTLE ABOVE THE SEASONAL AVERAGES. RATHER HUMID CONDITIONS WILL PREVAIL SUNDAY NIGHT WITH LOWS RANGING FROM THE UPPER 60S TO LOWER 70S. .LONG TERM /TUESDAY THROUGH FRIDAY/... HIGH PRESSURE BUILDS ACROSS THE SOUTHEASTERN STATES DURING THIS PERIOD BUT THE UPPER FLOW REMAINS NEARLY ZONAL ACROSS THE GREAT LAKES TO NEW ENGLAND. THE SURFACE AND 850MB THERMAL BOUNDARY LIES JUST TO THE SOUTH OF THE REGION...THUS EXPECT THE CLUSTERS OF DAILY CONVECTION TO EDGE CLOSE TO THE NY/PA STATE LINE FOR WED AND THUR. A SLOW WARMING TREND WILL START WITH HIGHS IN THE UPPER 70S TO LOW 80S ON TUES AND WED TO LOWER 80S THURSDAY AND MOSTLY MID 80S BY FRIDAY. A PACIFIC WAVE RUNNING ALONG THE NORTHERN PERIPHERY OF THE NATION WILL BRING A LOW ACROSS THE LAKES ON THURSDAY NIGHT AND INTO SOUTHERN ONTARIO TO WESTERN QUEBEC ON FRIDAY. WILL HAVE CHANCE POPS FOR THUNDERSTORMS ON FRIDAY. .MARINE... SOUTHWEST WINDS WERE ALREADY PICKING UP OVER THE LAKES THIS MORNING WITH WAVE HTS ALREADY 3 TO 4 FT ON EASTERN LK ERIE. BROUGHT UP START TIME FOR SMALL CRAFT ADVISORY TO 9 AM. EXPECT SOLID SMALL CRAFT ADVISORY CRITERIA ON LAKE ERIE DURING THE AFTERNOON WITH SOUTHWEST WINDS BEING CHANNELLED UP THE LAKE. ALSO EXPECT A PERIOD OF STRONGER WINDS ON LAKE ONTARIO DURING THE AFTERNOON AND EARLY EVENING WITH LATEST NAM POINT SOUNDINGS SUPPORTING SMALL CRAFT CONDITIONS THERE AS WELL. HOISTED A SMALL CRAFT ADVISORY FOR LAKE ONTARIO FROM SODUS BAY UP TO THE THOUSAND ISLANDS STARTING AT 2 PM. THUNDERSTORM DEVELOPMENT IS EXPECTED ALONG OR JUST SOUTH OF THE LAKE ONTARIO SHORELINE LATER THIS AFTERNOON. A RIDGE WILL MOVE IN TONIGHT AND EARLY SUNDAY BEHIND THE SURFACE FRONT...WITH A STRONGER SYSTEM MOVING THROUGH THE EASTERN GREAT LAKES REGION LATE SUNDAY AFTERNOON OR SUNDAY NIGHT WITH ADDITIONAL THUNDERSTORMS POSSIBLE. .BUF WATCHES/WARNINGS/ADVISORIES... NY...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL MIDNIGHT EDT TONIGHT FOR LEZ020-040-041. SMALL CRAFT ADVISORY FROM 2 PM THIS AFTERNOON TO 10 PM EDT THIS EVENING FOR LOZ044-045. SYNOPSIS...SFM NEAR TERM...SFM SHORT TERM...TJP LONG TERM...WCH AVIATION...SFM MARINE...SFM/TJP