Area Forecast Discussion
Issued by NWS Buffalo, NY

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000 FXUS61 KBUF 012347 AFDBUF AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BUFFALO NY 747 PM EDT SAT AUG 1 2015 .SYNOPSIS... A FEW WIDELY SCATTERED SHOWERS AND THUNDERSTORMS WILL END LATER THIS EVENING. HIGH PRESSURE WILL THEN BRING DRY AND WARM CONDITIONS ON SUNDAY TO WRAP UP THE WEEKEND. A COLD FRONT WILL CROSS THE AREA SUNDAY NIGHT AND MONDAY WITH A BETTER CHANCE OF MORE WIDESPREAD SHOWERS AND THUNDERSTORMS. THIS COLD FRONT WILL USHER IN MUCH COOLER AIR THAT WILL LAST FOR ALL OF NEXT WEEK. && .NEAR TERM /THROUGH SUNDAY/... RADAR IMAGERY NEAR 8PM THIS EVENING IS SHOWING ISOLATED SHOWERS AND THUNDERSTORMS ACROSS WESTERN NEW YORK WITH A BAND OF MORE INTENSE THUNDERSTORMS APPROACHING THE SAINT LAWRENCE RIVER AND NORTH COUNTY FROM ACROSS THE CANADIAN BORDER. LINGERING CAPE TO 1000 J/KG AND BULK SHEAR OF 20-40 KTS HAS SUPPORTED A FEW STRONGER CELLS WITH SMALL HAIL AND GUSTY WINDS. ALL OF THIS CONVECTION IS SUPPORTED BY THE DIURNAL CYCLE IN THE PRESENCE OF BROAD MID-LEVEL TROUGH ALOFT...AND WILL QUICKLY END BY MID EVENING WITH THE LOSS OF DAYTIME HEATING. OVERNIGHT EXPECT MAINLY CLEAR TO PARTLY CLOUDY SKIES WITH JUST A FEW PATCHES OF STRATUS DRIFTING ACROSS THE AREA. THERE WILL BE A WIDE RANGE IN LOWS TONIGHT WITH MID 60S ON THE LAKE PLAINS WHERE A BREEZE WILL STAY UP THROUGH THE NIGHT. THE SOUTHERN TIER VALLEYS AND TUG HILL REGION WILL DECOUPLE MORE...WITH LOWS IN THE LOWER TO MID 50S IN THE COOLEST LOCATIONS. ON SUNDAY HIGH PRESSURE WILL REMAIN IN PLACE FROM THE OHIO VALLEY TO THE MID ATLANTIC. THIS HIGH WILL BE CLOSE ENOUGH TO PROVIDE SUBSIDENCE AND DRYING...WHICH WILL LIKELY PREVENT ANY DIURNAL CONVECTION DESPITE THE WARM TEMPERATURES. EXPECT NOTHING MORE THAN SCT DIURNAL CUMULUS TO DEVELOP ALONG AND INLAND FROM THE LAKE BREEZE BOUNDARIES AND ALSO SOME MODEST INCREASE IN CIRRUS LEVEL CLOUDINESS DURING THE AFTERNOON. WARM ADVECTION AHEAD OF THE NEXT SYSTEM WILL BOOST 850MB TEMPS TO AROUND +16...WHICH WILL SUPPORT HIGHS IN THE MID 80S ACROSS LOWER ELEVATIONS AND AROUND 80 ON THE HILLS. && .SHORT TERM /SUNDAY NIGHT THROUGH MONDAY NIGHT/... SUNDAY NIGHT A SHORTWAVE TROUGH OF LOW PRESSURE WILL DIG TOWARDS THE BASE OF AN UPPER LEVEL LOW THAT IS SPINNING OVER ONTARIO PROVINCE CANADA. AT THE SURFACE AN AREA OF LOW PRESSURE NEAR THE SOUTHERN TIP OF JAMES BAY WILL BE DRAGGING A COLD FRONT ACROSS THE CENTRAL GREAT LAKES. FOR OUR REGION A WARM AND SOMEWHAT HUMID NIGHT IS ON TAP AS A STRONG LOW LEVEL JET OF 45 TO 60 KNOTS WITHIN THE 850 - 700 HPA LAYER STRENGTHENS THE WARM AIR ADVECTION. THIS JET WILL ALSO BE DRAWING MOISTURE NORTHWARD AS PWATS CLIMB TO NEAR 1.5 INCHES ACROSS WESTERN AND CENTRAL NEW YORK THROUGH THE NIGHT. THE COLD FRONT WILL BE SLICING ACROSS THE CENTRAL GREAT LAKES REGION SUNDAY NIGHT...TO BE KNOCKING ON OUR WESTERN DOORSTEPS MONDAY MORNING. THROUGH THE OVERNIGHT A FEW SHOWERS ARE POSSIBLE AS CONVERGENCE AHEAD OF THE LOW LEVEL JET PRODUCES ENOUGH LIFT TO FORM ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS. GREATEST COVERAGE AREA WILL BE NEAR THE LAKES...WHICH WILL BE HOLDING ONTO INSTABILITY THROUGH THE OVERNIGHT. LATER IN THE NIGHT SHOWERS WILL BEGIN TO INCREASE IN NUMBER ACROSS FAR WESTERN NEW YORK AND THE SAINT LAWRENCE VALLEY AS THE COLD FRONT DRAWS NEAR. ON MONDAY THE UPPER LEVEL SHORTWAVE WILL BE PUSHING A FAIRLY STRONG COLD FRONT ACROSS THE REGION. AHEAD OF THE COLD FRONT A PREFRONTAL TROUGH IS EXPECTED TO FORM WITH A LINE OF SHOWERS AND THUNDERSTORMS ADVANCING EASTWARD ACROSS THE BUFFALO CWA. CURRENT MODEL/THINKING FOR THE TIMING OF THIS INITIAL LINE OF STORMS IS TO BE ACROSS WNY MONDAY MORNING...REACHING CENTRAL NEW YORK MIDDAY. THOUGH THIS IS AN EARLY IN THE DAY TIMING TO THE BAND OF THUNDERSTORMS (AND NOT DURING THE TIME OF PEAK HEATING AND INSTABILITY)...THERE WILL STILL BE A DECENT AMOUNT OF INSTABILITY AROUND COUPLED WITH STEEPING LAPSE RATES TO NEAR 7 TO 8 C/KM AND 0-6KM BULK SHEAR VALUES UP TO 40 KNOTS TO ALLOW A FEW OF THESE THUNDERSTORMS TO BECOME STRONG TO POSSIBLY SEVERE. WILL MENTION THIS PROSPECT IN THE HWO. FOLLOWING THE INITIAL LINE OF SHOWERS AND THUNDERSTORMS THERE WILL BE A BRIEF BREAK IN PRECIPITATION. IN FACT THE SUN MIGHT EVEN APPEAR BRIEFLY DURING THE MIDDAY AND EARLY AFTERNOON HOURS. WITHIN THIS SUNSHINE SOUTHWEST WINDS COULD BECOME GUSTY AS MIXING HEIGHTS RISE. GUSTS UP TO 20 TO 25 MPH...AND NEAR 30 MPH DOWNWIND OF THE EASTERN GREAT LAKES WILL BE POSSIBLE AHEAD OF THE COLD FRONT. CLOUDS WILL THICKEN AGAIN IN THE AFTERNOON AND SHOWER CHANCES SHALL INCREASE WITH THE LATE DAY PASSAGE OF THE SURFACE COLD FRONT. MUCH OF THE INSTABILITY WILL LIKELY BE USED TO FUEL THE INITIAL LINE OF STORMS...SUCH THAT THE SECOND LINE WILL TEND TO BE MORE OF A BROKEN LINE OF SHOWERS WITH ISOLATED THUNDER CHANCES. FOLLOWING THE PASSAGE OF THIS COLD FRONT OUR 850 HPA TEMPERATURES WILL DROP FROM THE HIGH TEENS DOWN TO NEAR 10C BY TUESDAY MORNING. SHOWER CHANCES WILL DIMINISH THROUGH THE NIGHT MONDAY NIGHT WITH SOME PATCHY AREAS OF FOG FORMING OVER A WET GROUND. TUESDAY WILL HAVE MORE OF A FALLISH FEEL TO THE DAY AS A POOL OF COLD AIR ALOFT PASSES OVER THE EASTERN GREAT LAKES. TEMPERATURES AT 850 HPA IN THE HIGH SINGLE DIGITS WILL GENERATE STEEP LAPSE RATES THAT COULD GENERATE A FEW SHOWERS. IN ADDITION TO THE INSTABILITY SHOWERS A WESTERLY FLOW OVER THE WARM GREAT LAKES COULD BRING SOME LAKE ENHANCED SHOWERS ACROSS SW NYS AS WELL AS SE AND EAST OF LAKE ONTARIO. EXPECT SHOWER COVERAGE TO DIMINISH THROUGH THE NIGHT TUESDAY NIGHT AS LAPSE RATES WEAKEN WITH THE SETTING SUN. TEMPERATURES SUNDAY NIGHT WILL REMAIN MILD OVERNIGHT WITH LOWS REMAINING IN THE LOWER 70S FOR MOST LOCATIONS NEAR THE GREAT LAKES...WHILE INLAND AREAS AND THE NORTH COUNTRY DROP BACK INTO THE MID TO UPPER 60S. ON MONDAY THESE SEASONABLY WARM TEMPERATURES WILL FALL BACK INTO THE UPPER 50S AND LOWER 60S MONDAY NIGHT. WITH THE COOL POOL OVER THE REGION TUESDAY EXPECT HIGHS TO BE WELL BELOW EARLY AUGUST NORMALS...WITH HIGHS ONLY IN THE LOWER 70S. && .LONG TERM /TUESDAY THROUGH SATURDAY/... AN UPPER LEVEL TROUGH WILL START THIS TIME PERIOD OVER EASTERN CANADA...WITH BELOW NORMAL TEMPERATURES FOUND UNDER THIS FEATURE. THIS TROUGH WILL WEAKEN SOME THROUGH THE TIME PERIOD BUT WILL REMAIN GENERALLY IN PLACE AND NOT ALLOW FOR AN UPPER LEVEL RIDGE FOUND OVER THE DESERT SOUTHWEST...AND PLAIN STATES TO PUSH EASTWARD TO THE ATLANTIC COASTLINE. MOISTURE WILL BE LIMITED THE FIRST PART OF THE EXTENDED TIME FRAME WITH PARTLY SUNNY SKIES PREDOMINATE. THERE WILL BE SMALL CHANCES FOR SHOWERS...WITH CONFIDENCE FOR CHANCE POPS ONLY EAST OF LAKE ONTARIO WHICH WILL BE CLOSER TO BOTH THE UPPER LEVEL TROUGH AND DEEPER MOISTURE. IN ADDITION ON WEDNESDAY A COOL POOL ALOFT MAY BRING ENOUGH INSTABILITY OVER LAKE ONTARIO TO BRING SOME LAKE ENHANCED RAIN SHOWERS SE AND E OF THE LAKE. TOWARDS THE END OF THE EXTENDED PERIOD DEEPER MOISTURE WILL ADVECT NORTHWARD AND ADDITIONAL SHORTWAVES ROUNDING THE UPPER LEVEL TROUGH WILL BRING INCREASED CHANCES FOR SHOWERS AND THUNDERSTORMS TO CLOSE OUT THE EXTENDED. TEMPERATURES WILL REMAIN SLIGHTLY COOLER THAN NORMAL THIS PERIOD. && .AVIATION /00Z SUNDAY THROUGH THURSDAY/... RADAR SHOWING THAT ISOLATED SHOWERS AND THUNDERSTORMS ARE WEAKENING WITH THE LOSS OF DAYTIME HEATING. A FEW SHOWERS/TSRA MAY PASS NEAR KROC AND KART WITH A SHRA NEAR KJHW BUT EXPECT THIS ACTIVITY WILL END BY MID EVENING. THIS WILL LEAVE VFR TO PREVAIL OVERNIGHT WITH JUST A FEW PATCHES OF VFR LEVEL STRATUS. THERE SHOULD BE ENOUGH WIND TO PREVENT ANY RIVER VALLEY FOG LATE TONIGHT. ON SUNDAY HIGH PRESSURE WILL REMAIN IN CONTROL FROM THE OHIO VALLEY TO THE MID ATLANTIC. THIS SHOULD PROVIDE ENOUGH SUBSIDENCE TO PREVENT ANY CONVECTION UNTIL A SYSTEM BEGINS TO APPROACH FROM THE WEST SUNDAY EVENING. VFR WILL PREVAIL THROUGH THE DAY WITH JUST SCT DIURNAL CUMULUS AND SOME MODEST INCREASE IN CIRRUS LEVEL CLOUDINESS. OUTLOOK... SUNDAY NIGHT...MAINLY VFR WITH SCATTERED SHOWERS AND THUNDERSTORMS AND ASSOCIATED BRIEF/LOCAL MVFR/IFR CONDITIONS. MONDAY...VFR TO OCCASIONALLY MVFR WITH SHOWERS AND STORMS LIKELY. TUESDAY...MAINLY VFR WITH A CHANCE OF A FEW LIGHT SHOWERS. WEDNESDAY AND THURSDAY...MAINLY VFR. && .MARINE... MODERATE WESTERLIES WILL CONTINUE TO PRODUCE MARGINAL SMALL CRAFT ADVISORY CONDITIONS ON LAKES ERIE AND ONTARIO THROUGH MID EVENING. WINDS WILL DIMINISH OVERNIGHT AS THE PRESSURE GRADIENT RELAXES. WINDS WILL INCREASE TO AROUND 15 KNOTS AGAIN ON SUNDAY... BUT CONDITIONS ARE EXPECTED TO REMAIN JUST BELOW SMALL CRAFT ADVISORY CRITERIA. A STRONGER COLD FRONT WILL CROSS THE AREA SUNDAY NIGHT AND MONDAY AND LIKELY BRING ANOTHER ROUND OF SMALL CRAFT ADVISORY CONDITIONS TO LAKES ERIE AND ONTARIO. && .BUF WATCHES/WARNINGS/ADVISORIES... NY...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 11 PM EDT THIS EVENING FOR LEZ040- 041. SMALL CRAFT ADVISORY UNTIL 11 PM EDT THIS EVENING FOR LOZ043>045. && $$ SYNOPSIS...HITCHCOCK NEAR TERM...HITCHCOCK/SMITH SHORT TERM...THOMAS LONG TERM...THOMAS AVIATION...HITCHCOCK/SMITH MARINE...HITCHCOCK/SMITH

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