415  
FXUS61 KBUF 270240  
AFDBUF  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE BUFFALO NY  
1040 PM EDT MON SEP 26 2016  
   
SYNOPSIS
 
 
A COLD FRONT WILL EXIT EAST OF OUR REGION OVERNIGHT AND THE  
COLDER AIR IN ITS WAKE WILL GENERATE SOME LAKE EFFECT RAIN SHOWERS  
NORTHEAST OF THE LAKES ON TUESDAY MORNING. A SLOW MOVING STORM  
SYSTEM TO OUR SOUTH COULD THEN KEEP SOMEWHAT UNSETTLED WEATHER  
OVER OUR REGION THROUGH MUCH OF THE REST OF THE WEEK.  
 

 
   
NEAR TERM /THROUGH TUESDAY/
 
 
A COLD FRONT WHICH IS ACROSS WESTERN NEW YORK LATE THIS EVENING  
WILL CONTINUE TO PUSH TO THE EAST OVERNIGHT. AT 10 PM, SHOWERS  
ASSOCIATED WITH THIS BOUNDARY MOVING INTO THE EASTERN LAKE ONTARIO  
REGION, WITH SCATTERED SHOWERS JUST BEHIND THIS MAIN AREA ALONG  
THE FRONTAL BOUNDARY ITSELF. ALL OF THIS SHOULD SLIDE EAST OF THE  
CWA AROUND OR SHORTLY AFTER MIDNIGHT. OTHERWISE, IR SATELLITE  
SHOWS DRIER AIR JUST BEHIND THE FRONT WHICH SHOULD PROVIDE A  
PERIOD OF PARTLY TO MOSTLY CLEAR SKIES FOR A PERIOD OVERNIGHT.  
 
LAKE EFFECT RAIN SHOWERS WILL DEVELOP LATE TONIGHT AS 850MB  
TEMPS DROP TO AROUND 5C. THIS WILL RESULT IN MODERATELY UNSTABLE  
CONDITIONS OVER THE LAKES. THIS WILL BE ACCOMPANIED BY A WEAKLY  
CAPPED, LOW SHEARED ENVIRONMENT THAT WILL STILL HAVE SOME SYNOPTIC  
MOISTURE TO FURTHER SUPPORT THE HEAT AND MOISTURE TRANSFERS OFF  
THE WARM LAKE WATERS. WE OFTEN SEE A DRY ENVIRONMENT THAT CAN NOT  
BE MOISTENED ENOUGH BY LAKE PROCESSES, BUT THIS CASE WILL NOT BE  
ONE OF THEM.  
 
THE MOST PRONOUNCED LAKE RESPONSE WILL BE NORTHEAST OF LAKE ERIE  
WHERE A NEAR MAXIMUM FETCH WILL ENCOURAGE THE DEVELOPMENT OF A BAND  
OF LAKE EFFECT RAIN THAT WILL EXTEND ACROSS THE BUFFALO METRO AREA  
AFTER 09Z. THIS BAND SHOULD DRIFT NORTH TO THE NORTHTOWNS AND  
TOWARDS THE FALLS BY DAYBREAK. THE PLACEMENT OF THIS BAND IS A  
LITTLE FURTHER NORTH THAN MOST OF THE MESOSCALE GUIDANCE PACKAGES,  
TAKING INTO ACCOUNT THE THERMALLY INDUCED LOW LEVEL BACKING OF THE  
FLOW WHICH IS OFTEN DISCOUNTED BY GUIDANCE. OFF LAKE ONTARIO...THE  
240 DEGREE FLOW WILL RESULT IN A SHORTER FETCH AND LESS IMPRESSIVE  
ORGANIZATION. THE ASSOCIATED SHOWERS WILL BE DIRECTED ACROSS  
NORTHERN JEFFERSON COUNTY TO THE THOUSAND ISLANDS REGION.  
 
TEMPERATURES TONIGHT WILL DROP BACK THROUGH THE 50S, WITH SOME 40S  
ANTICIPATED FOR THE SOUTHERN TIER.  
 

 
   
SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY NIGHT/
 
 
TUESDAY NIGHT INTO WEDNESDAY MORNING IS SHAPING UP TO BE A  
RELATIVELY QUIET AND MAINLY DRY PERIOD FOR WESTERN AND NORTH-  
CENTRAL NEW YORK. A LARGE UPPER LEVEL LOW WILL BE CONTINUING ITS  
GRADUAL DESCENT ACROSS THE CENTRAL GREAT LAKES, WHILE DRIER AIR  
WRAPPING ACROSS THE SOUTHEASTERN FLANK OF THIS LOW WILL CONTINUE  
TO REMAIN OVERHEAD MUCH OF THE LOWER GREAT LAKES. THIS, ALONG WITH  
A SYNOPTICALLY UNFAVORABLE POSITION IN THE LEFT ENTRANCE REGION OF  
AN EXITING UPPER-LEVEL JET STREAK WILL KEEP THINGS DRY TUESDAY  
NIGHT. THE COOL AND RELATIVELY DRY AIR ALOFT SHOULD ALSO ALLOW  
TEMPERATURES TO FALL INTO THE 40S TUESDAY NIGHT.  
 
TEMPERATURES WILL REBOUND INTO THE 70S ALONG THE LAKE PLAINS ON  
WEDNESDAY, AIDED BY STRENGTHENING DOWNSLOPING SOUTHEASTERLY FLOW,  
WITH 60S ACROSS THE HIGHER ELEVATIONS. WHILE THIS SOUTHEASTERLY FLOW  
SHOULD INITIALLY KEEP THINGS DRY FOR MUCH OF THE DAY ON WEDNESDAY,  
THE MAIN UPPER LEVEL LOW IS CURRENTLY PROGGED TO DROP SOUTH TOWARDS  
THE OHIO VALLEY, WHILE A SECONDARY LOW OFF THE MID-ATLANTIC IS  
SHUNTED OFF TO THE NORTHEAST. THIS WILL OPEN UP MUCH OF PENNSYLVANIA  
AND WESTERN NEW YORK TO A LONG SOUTHEASTERLY FETCH OF ATLANTIC  
MOISTURE THAT WILL ISENTROPICALLY LIFTED ALONG THE NORTHEASTERN  
FLANK OF THE MAIN LOW OVER OHIO, IN TURN GENERATING AN INCREASING  
NUMBER OF SHOWERS ACROSS MUCH OF THE FORECAST AREA AS WE MOVE FROM  
WEDNESDAY EVENING INTO THURSDAY. AS A SIDE NOTE, THE STRENGTHENING  
EAST-NORTHEAST FLOW IN THE LOWER LEVELS ON THE NORTHERN EDGE OF THE  
SURFACE FLOW WILL LIKELY PRODUCE A CONSIDERABLE SWATH OF LAKE-  
ENHANCED RAINS JUST TO OUR NORTH ACROSS THE GREATER TORONTO AREA  
WEDNESDAY NIGHT INTO THURSDAY MORNING.  
 
THE INCREASING CLOUD COVER AND INFLUX OF MARITIME AIR INTO THE  
REGION WILL PRODUCE MORE MILD TEMPERATURES WEDNESDAY NIGHT, WITH  
LOWS IN THE UPPER 40S TO LOWER 50S, WHILE THE WIDESPREAD CLOUDS WILL  
KEEP READINGS IN THE LOW TO MID 60S THURSDAY. SHOWERS WILL LIKELY  
PERSIST THROUGH THE END OF THE WEEK AS THE UPPER LOW STALLS OUT OVER  
THE REGION. THE PERSISTENT MILD AIR WILL KEEP LOWS IN THE 50S  
THURSDAY NIGHT.  
 

 
   
LONG TERM /FRIDAY THROUGH MONDAY/
 
 
THIS PERIOD WILL BE DOMINATED BY A LARGE CUT-OFF LOW WHICH IS  
GENERALLY FORECAST BY MEDIUM-RANGE GLOBAL MODELS TO MEANDER FROM THE  
OHIO VALLEY NORTH AND EAST ACROSS THE EASTERN GREAT LAKES THEN  
SHIFTING OFF THE COAST OF NEW ENGLAND AS AN OPEN TROUGH BY EARLY  
NEXT WEEK. AMONG THE 12Z RUNS THE ECMWF REMAINS THE SLOWER OF THE  
MODEL SOLUTIONS. THE CUT-OFF LOW WILL DRAW A BROAD SLUG OF ATLANTIC  
MOISTURE WESTWARD ACROSS THE TRI-STATE REGION TO THE EASTERN GREAT  
LAKES AND UPPER OHIO VALLEY WHERE IT WILL INTERACT WITH MULTIPLE  
VORTICITY MAXES CIRCULATING AROUND THE LOW. EACH OF THESE VORT MAXES  
SHOULD FORCE A SWATH OF RAIN SHOWERS SHIFTING FROM EAST TO WEST  
ACROSS THE REGION. 12Z NAEFS STANDARD ANOMALIES OF PWAT FOR THE  
FRIDAY INTO THE WEEKEND TIMEFRAME ARE RUNNING BETWEEN 1.5 AND 2  
DEVIATIONS ABOVE NORMAL WHICH MEANS MOISTURE WILL BE PLENTIFUL FOR  
NUMEROUS PERIODS OF RAIN SHOWERS. WPC 48-HOUR QPF GUIDANCE FOR 00Z  
FRIDAY INTO 00Z IS SHOWING A LARGE SWATH OF 1-2+ INCHES OF RAINFALL.  
 
FORECAST-WISE THIS REQUIRES AN EXTENDED PERIOD OF CHANCE RANGE POPS  
AND CLOUDY TO MOSTLY CLOUDY SKIES RUNNING FRIDAY THROUGH SUNDAY ONLY  
TAPERING TO SLIGHT CHANCE BY MONDAY WHEN THE LOW IS FORECAST TO BE  
SHIFTING EAST OF NEW ENGLAND. HIGHEST CONFIDENCE IS ON FRIDAY ACROSS  
THE SOUTHERN TIER CLOSEST TO THE CENTER OF THE CUT-OFF LOW. AS MODEL  
AGREEMENT BECOMES BETTER ALIGNED AS THIS EVENT GETS CLOSER AND  
CONFIDENCE INCREASE EXPECT THAT POPS WILL BE INCREASED FURTHER WITH  
FINER DETAIL IN TIMING OF SWATHES OF SHOWERS. THE HIGH LEVEL OF  
ATLANTIC MOISTURE STREAMING ACROSS THE REGION SHOULD ENSURE MILD  
SEASONABLE TEMPERATURES WITH HIGHS IN THE MID TO UPPER 60S AND LOWS  
ONLY SLIPPING BACK INTO THE 50S.  
 

 
   
AVIATION /02Z TUESDAY THROUGH SATURDAY/
 
 
A COLD FRONT NEAR ROC AT 02Z WILL PUSH EAST LATE THIS EVENING.  
SHOWERS ASSOCIATED WITH THIS BOUNDARY AND MOISTURE POOLED ALONG  
THE BOUNDARY WILL RESULT IN SOME MVFR CONDITIONS IN BOTH CIGS AND  
VSBY IN HEAVIER SHOWERS. MEANWHILE CONDITIONS WILL IMPROVE RATHER  
QUICKLY BEHIND THE BOUNDARY AS DRIER AIR BUILDS IN.  
 
EXPECT MAINLY VFR CONDITIONS LATE TONIGHT AND TUESDAY, WITH THE  
EXCEPTION OF SOME LAKE EFFECT RAIN SHOWERS WILL WILL PRODUCE AREAS  
OF MVFR CONDITIONS. THESE WILL PRIMARILY IMPACT BUF/IAG TUESDAY  
MORNING, WITH THE BAND LIFTING NORTHWARD DURING THIS TIME. LAKE  
EFFECT RAIN SHOWERS WILL WEAKEN IN THE AFTERNOON. ELSEWHERE,  
EXPECT MAINLY SCATTERED CLOUDS WITH VFR CONDITIONS.  
 
OUTLOOK...  
 
TUESDAY NIGHT...VFR.  
WEDNESDAY THROUGH SATURDAY...VFR/MVFR WITH A CHANCE OF SHOWERS.  
 

 
   
MARINE
 
 
COLDER AIR WILL MOVE IN BEHIND THE COLD FRONT WHICH WILL HELP  
WINDS ALOFT MIX TO THE LAKE SURFACE. A STRONGER PRESSURE GRADIENT  
FOLLOWING THE FRONT AND THE COLDER AIR WILL PRODUCE GUSTY WINDS  
OVERNIGHT AND TUESDAY, RESULTING IN SMALL CRAFT ADVISORIES ALONG  
THE LAKE ERIE NEARSHORES, AND ALONG THE EASTERN END OF LAKE  
ONTARIO. THE LAKE ONTARIO CONDITIONS WILL IMPROVE AS WINDS BECOME  
SOUTHEASTERLY LATE TUESDAY, BUT WIND WILL REMAIN RATHER STRONG  
FROM THE SOUTH TO SOUTHWEST ALONG THE LAKE ERIE SHORES. ALTHOUGH  
CONDITIONS WILL NOT BE IDEAL, THERE IS A POTENTIAL FOR SOME  
WATERSPOUTS ALONG A CONVERGENCE BAND WHICH IS EXPECTED TO DEVELOP  
ON LAKE ERIE LATE TONIGHT AND TUESDAY.  
 

 
   
BUF WATCHES/WARNINGS/ADVISORIES
 
 
NY...NONE.  
MARINE...SMALL CRAFT ADVISORY UNTIL 5 AM EDT WEDNESDAY FOR LEZ040-041.  
SMALL CRAFT ADVISORY UNTIL 5 PM EDT TUESDAY FOR  
LOZ045.  
 

 
 

 
 
SYNOPSIS...RSH/WCH  
NEAR TERM...APFFEL/RSH/WCH  
SHORT TERM...WOOD  
LONG TERM...JJR  
AVIATION...APFFEL/WCH  
MARINE...APFFEL/WCH  
 
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