Area Forecast Discussion
Issued by NWS Buffalo, NY

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000 FXUS61 KBUF 230335 AFDBUF AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BUFFALO NY 1135 PM EDT FRI AUG 22 2014 .SYNOPSIS... AN UPPER LEVEL TROUGH WILL ONCE AGAIN SUPPORT A FEW SHOWERS AND THUNDERSTORMS ON SATURDAY. A BROAD AREA OF HIGH PRESSURE WILL THEN BUILD ACROSS THE LOWER GREAT LAKES DURING THE SECOND HALF OF THE WEEKEND...BRINGING FAIR CONDITIONS AND LATE SUMMER WARMTH INTO NEXT WEEK. && .NEAR TERM /THROUGH SATURDAY/... WHILE AN UPPER LEVEL TROUGH SUPPORTED CONVECTION DURING THIS PAST DAY...THE ACTIVITY WAS LARGELY DRIVEN BY DIURNALLY BASED INSTABILITY AND THE PASSAGE OF A SUBTLE SHORTWAVE. NOW THAT THE SHORTWAVE HAS EXITED THE REGION AND THAT THE AIRMASS HAS STABILIZED SOMEWHAT... THE OVERNIGHT PERIOD SHOULD BE LARGELY DRY. ONLY A SHOWER OR TWO IS POSSIBLE THROUGH DAYBREAK FOR SITES EAST OF THE GENESEE VALLEY. THE MAIN PROBLEM OVERNIGHT WILL BE DETERMINING WHERE AND WHEN LOW CLOUDS AND AREAS OF FOG DEVELOP. THIS LOW LEVEL MOISTURE...LIFTED BY A NORTHERLY UPSLOPE FLOW...WILL BE SLOW TO DISSIPATE SATURDAY MORNING. THE LOW CLOUDS AND FOG WILL DISSIPATE BY LATE MORNING ACROSS MOST OF THE AREA. THE UPPER LEVEL LOW WILL NOW BE IN THE NORTH ATLANTIC. HOWEVER...ONE LAST RIPPLE FROM THIS WILL DROP ACROSS THE REGION SATURDAY. THIS SUBTLE FEATURE SHOULD BE JUST ENOUGH FOR SOME SCATTERED SHOWERS...AND PERHAPS AN ISOLATED THUNDERSTORM...WITH THESE GENERALLY BEING ACROSS THE SOUTHERN TIER AND FINGER LAKES REGION. && .SHORT TERM /SATURDAY NIGHT THROUGH MONDAY NIGHT/... SATURDAY NIGHT...THE UPPER LEVEL LOW WHICH HAS BEEN A PERSISTENT FEATURE ON OUR WEATHER MAP WILL NOW BE MOVING THROUGH THE NORTH ATLANTIC. HOWEVER...ONE LAST SPOKE OF ENERGY ASSOCIATED WITH THE UPPER LOW WILL BE EXITING OUT OF NEW YORK STATE OVERNIGHT SATURDAY NIGHT. THIS MAY SUSTAIN JUST A FEW SHOWERS ACROSS THE SOUTHERN TIER THROUGH THE EARLY OVERNIGHT HOURS. CLOUD COVER SHOULD LESSEN AS THE NIGHT GOES ON WITH LOWS MAINLY IN THE UPPER 50S TO LOWER 60S. SUNDAY THROUGH MONDAY NIGHT...UPPER LEVEL RIDGING WILL BUILD INTO THE REGION ALONG WITH SURFACE HIGH PRESSURE AND LAST INTO EARLY NEXT WEEK. THIS WILL RESULT IN DRY AND WEATHER THROUGH MONDAY NIGHT...WITH A FAIR AMOUNT OF SUNSHINE SUNDAY AND MONDAY. TEMPERATURES WILL BE SLIGHTLY ABOVE NORMAL...WITH HIGHS ON SUNDAY IN THE UPPER 70S TO AROUND 80...AND LOWS AGAIN SUNDAY NIGHT GENERALLY IN THE UPPER 50S TO LOWER 60S. AS THE SURFACE HIGH PRESSURE MOVES JUST EAST OF THE REGION...A SOUTHERLY RETURN FLOW ON THE BACK SIDE OF THE HIGH WILL HELP RAISE HIGH TEMPERATURES ON MONDAY UP ANOTHER DEGREE OR TWO WITH HIGHS RANGING FROM AROUND 80 IN MOST LOCATIONS TO THE LOWERS 80S IN A FEW OF THE TYPICALLY WARMER SPOTS. && .LONG TERM /TUESDAY THROUGH FRIDAY/... TUESDAY THROUGH WEDNESDAY...EXPANSIVE RIDGING ALOFT COMBINED WITH SURFACE HIGH PRESSURE SLOWLY CONTINUING TO SHIFT OFF THE NEW ENGLAND COAST WILL MAINTAIN THE NICE STRETCH OF WARM AND DRY WEATHER ACROSS THE REGION. THE GFS MAINTAINS A MORE AMPLIFIED RIDGE ALOFT WHILE THE ECMWF FLATTENS THE RIDGE OUT ACROSS SOUTHERN QUEBEC BY LATE WEDNESDAY. EITHER WAY IT LOOKS LIKE DRY CONDITIONS SHOULD PREVAIL THROUGH THIS PERIOD. THAT SAID...500MB HEIGHTS AND 850MB TEMPS ARE IN PRETTY CLOSE AGREEMENT. THE ECMWF IS STILL A BIT COOLER THAN THE GFS...WHICH IS MAINLY DUE TO THE ECMWF PROJECTING MORE CLOUD COVER ACROSS THE LOWER GREAT LAKES REGION...ESPECIALLY ON WEDNESDAY. A CONSENSUS SUPPORTS HIGH TEMPERATURES GENERALLY IN THE UPPER 70S TO LOWER 80S TUESDAY AND WEDNESDAY...WITH LOW TEMPERATURES TUESDAY NIGHT RANGING FROM THE UPPER 50S TO LOWER 60S. WEDNESDAY NIGHT THROUGH FRIDAY...GFS/ECMWF CONTINUE TO BE IN FAIRLY GOOD AGREEMENT THAT THE UPPER LEVEL RIDGE WILL BEGIN TO BREAK DOWN MID WEEK AS AN UPPER LEVEL TROUGH PUSHES EAST INTO THE EASTERN GREAT LAKES FOR THE LATTER HALF OF THE WORK WEEK. GFS/ECMWF BEGIN TO DIVERGE WEDNESDAY NIGHT IN TERMS OF THE STRENGTH AND AMPLITUDE OF THE APPROACHING UPPER LOW AND ASSOCIATED UPPER TROUGH. THE GFS SHOWS A MUCH MORE AMPLIFIED SLOWER MOVING UPPER TROUGH HANGING AROUND THROUGH THE END OF WEEK...WHILE THE ECMWF SHOWS A MUCH FASTER LESS AMPLIFIED PROGRESSIVE UPPER TROUGH CROSSING THE REGION THURSDAY AND MOVING OFF THE NEW ENGLAND COAST BY FRIDAY WITH MORE OF A ZONAL FLOW SETTING UP IN ITS WAKE. THUS THE GFS SURFACE REFLECTION SHOWS A STRONGER SLOWER MOVING COLD FRONT CROSSING THE REGION THURSDAY THROUGH THURSDAY NIGHT WITH SOME RESIDUAL SHOWERS LEFT BEHIND FOR THE END OF THE WEEK WITH THE UPPER TROUGH STILL LINGERING OVERHEAD. THE ECMWF HAS A WEAK SURFACE LOW CROSSING THE REGION THURSDAY AND THURSDAY NIGHT...WITH SURFACE HIGH PRESSURE MOVING IN FOR THE END OF THE WEEK WITH DRIER WEATHER. HIGH TEMPERATURES WILL BEGIN TO FALL A BIT BELOW AVERAGE ON THURSDAY INTO THE LOWER TO MID 70S DUE TO THE CLOUD COVER AND POTENTIAL RAIN SHOWERS...WITH HIGHS BY FRIDAY FALLING BACK EVEN MORE INTO THE UPPER 60S TO LOWER 70S BEHIND THE COLD FRONT AS A COOLER AIR MASS PUSHES IN. LOW TEMPERATURES WILL REMAIN ON THE WARM SIDE WEDNESDAY NIGHT OUT AHEAD OF THE APPROACHING COLD FRONT WITH LOWS GENERALLY IN THE 60S...AND A BIT COOLER THURSDAY NIGHT BEHIND THE FRONT WITH LOWS GENERALLY RANGING FROM THE UPPER 50S TO AROUND 60. && .AVIATION /04Z SATURDAY THROUGH WEDNESDAY/... VFR CONDITIONS ACROSS THE REGION THIS EVENING WILL DETERIORATE OVERNIGHT AS A WEALTH OF LOW LEVEL MOISTURE IS EXPECTED TO PROMOTE THE DEVELOPMENT OF MVFR STRATO-CU ACROSS THE BULK OF THE REGION... WITH SOME IFR STRATUS OR FOG DEVELOPING ACROSS THE SRN TIER OR IN AREAS THAT RECEIVED SIGNIFICANT RAINFALL DURING THE PAST 18 HOURS. SITES MOST LIKELY TO EXPERIENCE IFR CONDITIONS WILL BE KJHW AND KELZ. ON SATURDAY...IFR/MVFR CONDITIONS WILL SLOWLY IMPROVE BY MID TO LATE MORNING ACROSS ALL TERMINALS AS FOG AND LOW CLOUDS WILL THIN/BURN OFF. MEANWHILE...SCATTERED SHOWERS WILL BE POSSIBLE ACROSS THE SOUTHERN TIER TO THE FINGER LAKES REGION...WITH AN ISOLATED AFTERNOON THUNDERSTORM NOT OUT OF THE QUESTION. EXPECT MAINLY VFR FLIGHT CONDITIONS THROUGH THE AFTERNOON...WITH MVFR POSSIBLE BRIEFLY IN ANY HEAVIER SHOWERS. OUTLOOK... SATURDAY NIGHT THROUGH WEDNESDAY...NO SIGNIFICANT WEATHER EXPECTED. && .MARINE... HIGH PRESSURE WILL BUILD SOUTHWARD ACROSS THE EASTERN LAKES THROUGH THE WEEKEND WITH IMPROVING WEATHER CONDITIONS. AN EASTERLY FLOW ON THE LAKES SATURDAY WILL BRING PEAK WINDS OF 10-15 KNOTS OVER THE WESTERN END OF LAKE ONTARIO. THE HIGH WILL SETTLE OVER THE LAKES EARLY NEXT WEEK WITH LIGHT WINDS. && .BUF WATCHES/WARNINGS/ADVISORIES... NY...NONE. MARINE...NONE. && $$ SYNOPSIS...JM/RSH NEAR TERM...FRANKLIN/JM/RSH SHORT TERM...JM LONG TERM...JM AVIATION...RSH MARINE...FRANKLIN

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