310  
FXUS61 KBGM 201137  
AFDBGM  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE BINGHAMTON NY  
637 AM EST MON NOV 20 2017  
   
SYNOPSIS
 
 
ACCUMULATING LAKE EFFECT SNOW WILL CONTINUE IN NORTH CENTRAL  
NEW YORK THIS MORNING, SHIFTING MAINLY NORTH OF THE NEW YORK  
THRUWAY BY MID MORNING. HOWEVER, AT LEAST SCATTERED SNOW  
SHOWERS AND FLURRIES CAN BE EXPECTED ACROSS THE REST OF CENTRAL  
NEW YORK TODAY AND EVEN NORTHEAST PENNSYLVANIA THIS MORNING.  
MILDER TEMPERATURES AND DRY WEATHER ARE EXPECTED INTO TUESDAY.  
 

 
   
NEAR TERM /THROUGH TONIGHT/
 
 
315 AM UPDATE...  
EVOLUTION AND EVENTUAL END OF ONGOING LAKE EFFECT SNOW WILL BE  
THE MAIN FORECAST ISSUE IN THE NEAR TERM.  
 
LAKE HURON TO LAKE ONTARIO CONNECTION BECAME ESTABLISHED OVER  
THE LAST SEVERAL HOURS, WHICH ON RADAR HAS STRETCHED A 20-35  
DBZ BAND OF SNOW ACROSS ONONDAGA AND MADISON COUNTIES, REACHING  
IN PIECES TO THE COOPERSTOWN AREA. UNDER THE HEAVIEST PART OF  
THE BAND, 1 TO 2 INCH-PER-HOUR SNOWFALL RATES ARE LIKELY  
OCCURRING. VISIBILITY HAS BEEN ABOUT A HALF MILE AT TIMES AT  
SYRACUSE AND ROME OVERNIGHT. AS THE LAKE-TO-LAKE CONNECTION  
BAND BECAME DOMINANT, THE EARLIER ONE IN ONEIDA COUNTY  
DISSIPATED. HOWEVER, UPSTREAM THE BOUNDARY LAYER FLOW IS ALREADY  
BEGINNING TO BACK WESTERLY AS EVIDENCED BY THE SHIFTING BAND IN  
WESTERN LAKE ONTARIO. AS FLOW CONTINUES TO BACK ACROSS OUR  
REGION, THERE WILL BE A LIFTING OF THE PRIMARY LAKE BAND  
NORTHWARD ALONG AND THEN NORTH OF THE NY THRUWAY THIS MORNING,  
WHICH WILL GET ONEIDA COUNTY BACK INTO THE SNOW. ALL TOLD,  
AN ADDITIONAL 2 TO 5 INCHES OF SNOW IS EXPECTED FROM 4 AM  
THROUGH EARLY AFTERNOON IN THE LAKE EFFECT SNOW WARNING AREA,  
WITH LOCALLY HIGHER AMOUNTS IN FAR NORTHERN ONONDAGA-MADISON  
COUNTIES. THE WARNING GOES THROUGH 1 PM, BUT ONONDAGA-MADISON-  
SOUTHERN ONEIDA COUNTIES WILL PROBABLY BE ABLE TO BE DROPPED  
WELL AHEAD OF THAT TIME AS THE BAND LIFTS.  
 
LAKE ONTARIO HAS NOT PRODUCED THE ONLY ACTION, HOWEVER. LAKE  
ERIE HAS ALSO CAUSED BAND EXTENSIONS TO REACH INTO THE TWIN  
TIERS AND EVEN THE GREATER WILKES-BARRE/SCRANTON METRO AND THE  
POCONOS AT TIMES. THE RESULTING DUSTING OF SNOW, AND  
TEMPERATURES FALLING BELOW FREEZING CAUSING ICE WITHIN  
PREVIOUSLY WET ROADWAYS, WILL MEAN SLICK SPOTS STILL POSSIBLE ON  
UNTREATED ROADS. SCATTERED SNOW SHOWERS AND FLURRIES WILL STILL  
OCCUR AT TIMES THIS MORNING FOR NORTHEAST PA-SOUTHERN TIER NY,  
AND INTO THE AFTERNOON FOR THE REST OF CENTRAL NY. THIS WILL BE  
COURTESY OF LAKE ERIE MOISTURE AS FLOW CONTINUES TO BACK  
WESTERLY TO WEST-SOUTHWEST WITH TIME. THAT BEING SAID, WARM AIR  
ADVECTION ALOFT WILL CAUSE COMPRESSION OF THE CLOUD LAYER TO  
SIGNIFICANTLY LIMIT SNOWFALL RATES.  
 
TEMPERATURES TODAY WILL QUIETLY SNEAK UP IN THE MID 30S-NEAR 40  
FOR HIGHS, WHICH ALONG WITH DRY AIR AND WEST WINDS GUSTING 15-25  
MPH, AS WELL AS GROUND TEMPERATURES STILL WELL ABOVE FREEZING; WILL  
TEND TO MELT OR SUBLIMATE THE FLUFFY LAKE SNOW. HIGHER TERRAIN  
OF CENTRAL NY HOWEVER WILL STRUGGLE TO GET ABOVE THE LOWER 30S.  
 
SOUTHWEST TO SOUTH FLOW, AND WARM AIR ADVECTION ALOFT, WILL LEAD  
TO A CLEARING SKY INTO TONIGHT. TEMPERATURES WILL SETTLE INTO  
THE UPPER 20S-LOWER 30S THIS EVENING, THEN HOLD FAIRLY STEADY  
OVERNIGHT.  
 

 
   
SHORT TERM /TUESDAY THROUGH THURSDAY/
 
 
MILD SW FLOW CONTINUES TUESDAY AS A LOW PRESSURE SYSTEM AND  
ASSOCIATED UPPER LEVEL TROUGH MOVE ACROSS NORTHERN ONTARIO.  
EXPECT PLENTY OF SUNSHINE WITH HIGHS MAINLY IN THE LOW 50S TO  
EVEN SOME MID 50S ACROSS THE WARMER SPOTS SUCH AS THE WYOMING  
VALLEY AND WESTERN SOUTHERN TIER INTO THE LAKE PLAIN. THE COLD  
FRONT ASSOCIATED WITH THIS LOW WILL MOVE ACROSS THE AREA AFTER  
MIDNIGHT TUESDAY NIGHT BRINGING WITH IT A SWATH OF RAIN SHOWERS  
WHICH WILL CHANGE OVER TO SNOW SHOWERS IN THE COOLER AIR BEHIND  
THE FRONT. NOT EXPECTING THIS WILL AMOUNT TO MUCH  
ACCUMULATION....AT MOST A COATING TO HALF INCH, IF THAT BY  
WEDNESDAY MORNING WITH ANY ACCUMULATION BEING MAINLY LIMITED TO  
HIGHER TERRAIN AREAS OF CENTRAL NY. THE OTHER COMPLICATING  
FACTOR WITH THIS PART OF THE FORECAST WILL BE THAT SOME OF THE  
MODELS (GEM AND ECMWF) HOOK THIS FRONT UP WITH SOME MOISTURE  
COMING UP FROM THE SOUTH WHICH COULD ENHANCE PRECIP A BIT OVER  
EASTERN ZONES THROUGH THE CATSKILLS. THIS WILL HAVE TO BE  
MONITORED FOR FUTURE UPDATES. LOWS BY WEDNESDAY MORNING WILL BE  
GENERALLY IN THE LOW TO MID 30S.  
 
FOR WEDNESDAY, SOME LINGERING PRECIP WILL CONTINUE TO BE  
POSSIBLE INTO THE MORNING WITH OTHERWISE A MAINLY DRY AND  
COOLER DAY BEHIND THE FRONT. THE ONE EXCEPTION WILL BE ACROSS  
NORTHERN COUNTIES WHERE SOME WEAK LAKE EFFECT SNOW WILL BE  
POSSIBLE AROUND THE I-90 CORRIDOR IN THE COLD NW FLOW OFF THE  
LAKES HOWEVER THIS DOESN'T LOOK TO AMOUNT TO MUCH. HIGHS WILL  
GENERALLY RANGE FROM THE MID 30S TO LOW 40S, MILDEST OVER NE PA  
AND SULLIVAN COUNTY.  
 
HIGH PRESSURE BUILDS IN FOR WEDNESDAY NIGHT SETTING THE STAGE  
FOR A COLD NIGHT UNDER MAINLY CLEAR TO PARTLY CLOUDY SKIES WITH  
LIGHT WINDS. LOWS WILL BE MAINLY IN THE LOW TO MID 20S WITH  
SOME TEENS POSSIBLE ACROSS THE COLDER SPOTS IN STEUBEN COUNTY AS  
WELL AS THE CATSKILLS.  
 
THE RIDGE OF HIGH PRESSURE MOVES OFF TO THE S/E THANKSGIVING DAY  
BUT CONDITIONS STAY MAINLY DRY WITH SUNSHINE GIVING WAY TO SOME  
INCREASING LATE DAY CLOUDS AHEAD OF THE NEXT FRONT APPROACHING  
FROM THE NORTH. A DEVELOPING W/SW FLOW COULD SPARK A FEW LAKE  
EFFECT FLURRIES LATE DAY NORTH OF I-90 BUT THIS SHOULD NOT BE OF  
ANY CONSEQUENCE.  
 

 
   
LONG TERM /THURSDAY NIGHT THROUGH SUNDAY/
 
 
320 PM UPDATE...  
UPPER LOW MOVES FROM THE HUDSON BAY INTO QUEBEC THURSDAY NIGHT  
INTO FRIDAY, BRINGING A COLD FRONT INTO THE UPSTATE. WE MAY SEE  
A LITTLE BIT OF LIGHT SNOW OVER (MAINLY) THE NORTHERN TIER OF  
COUNTIES FRIDAY IN ASSOCIATION WITH THE FRONT. BY FRIDAY  
EVENING, THOUGH, THE BOUNDARY LAYER FLOW IS EXPECTED TO BECOME  
SOUTHWESTERLY AND SET UP A LOW-LEVEL WARM ADVECTION PATTERN OVER  
THE REGION AS THE FRONT MOVES BACK NORTH AS A WARM FRONT.  
 
FORECAST CONFIDENCE WANES FROM THERE. PLENTY OF DISCREPANCIES ARE  
EVIDENT WITH REGARD TO TIMING, EVOLUTION, AND IMPACTS FROM THE NEXT  
SYSTEM. IN GENERAL, EXPECT PRECIPITATION PROBABILITIES TO INCREASE  
HEADING INTO NEXT WEEKEND AS THE UPPER-LEVEL STORM SYSTEM PUSHES A  
SURFACE LOW FROM ONTARIO INTO QUEBEC. DEPENDING ON THE UPPER  
TROUGH'S AMPLITUDE, THIS COULD PUSH THE ASSOCIATED COLD FRONTS  
THROUGH THE REGION SOMETIME BETWEEN SATURDAY NIGHT AND SUNDAY NIGHT.  
I'VE STAYED FAIRLY CLOSE TO THE MODEL BLEND DURING THIS PERIOD GIVEN  
EVOLUTIONARY UNCERTAINTY.  
 

 
   
AVIATION /12Z MONDAY THROUGH FRIDAY/
 
 
LAKE EFFECT SNOW WILL BE WINDING DOWN TODAY, BUT THE MAIN LAKE  
ONTARIO SNOWBAND WILL STILL IMPACT KSYR AND KRME THROUGH 14Z  
AND 17Z RESPECTIVELY WITH BELOW ALTERNATE MINIMUM VISIBILITY AT  
TIMES. SCATTERED FLURRIES WILL BE FOUND ELSEWHERE, COURTESY OF  
LAKE ERIE MOISTURE DRIFTING BY THE AREA, BUT WITH FEW IF ANY  
ASSOCIATED RESTRICTIONS. VFR WILL BECOME PREDOMINANT ACROSS THE  
REGION, WITH 4-6 KFT AGL CEILINGS LIFTING AND SCATTERING OUT  
WITH TIME. WNW WINDS OF 9-12 KNOTS, WITH GUSTS OF 16-20 KNOTS,  
WILL SLACKEN WHILE BACKING SOUTHWEST LATE AFTERNOON THROUGH  
EVENING. THOUGH THE SKY WILL CLEAR OUT INTO TONIGHT, THERE WILL  
ALSO BE AN INCREASING SOUTHWESTERLY LOW LEVEL JET OF 35-40  
KNOTS WHICH WILL CAUSE DEVELOPMENT OF LOW LEVEL WIND SHEAR FOR  
AT LEAST THE NY TERMINALS; IT WILL BE BORDERLINE FOR KAVP.  
 
OUTLOOK...  
 
TUESDAY...VFR.  
 
TUESDAY NIGHT THROUGH WEDNESDAY...RESTRICTIONS POSSIBLE IN  
SCATTERED RAIN/SNOW SHOWERS.  
 
WEDNESDAY NIGHT THROUGH FRIDAY...MAINLY VFR.  
 

 
   
BGM WATCHES/WARNINGS/ADVISORIES
 
 
PA...NONE.  
NY...LAKE EFFECT SNOW WARNING UNTIL 1 PM EST THIS AFTERNOON FOR  
NYZ009-018-036-037.  
 

 
 

 
SYNOPSIS...MDP  
NEAR TERM...MDP  
SHORT TERM...PCF  
LONG TERM...DAB  
AVIATION...MDP  
 
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