240  
FXUS61 KALY 192321  
AFDALY  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE ALBANY NY  
621 PM EST WED FEB 19 2020  
   
SYNOPSIS
 
 
LAKE EFFECT SNOW TONIGHT INTO TOMORROW MORNING SHOULD BRING  
ACCUMULATIONS TO THE MOHAWK AND SCHOHARIE VALLEY WHICH MAY LEAD  
TO A SLIPPERY MORNING COMMUTE. THEN COLDER AND DRY AIR SETTLES  
OVER THE REGION THROUGH TOMORROW NIGHT BEFORE TEMPERATURE RISE  
ABOVE NORMAL THIS WEEKEND.  
 

 
   
NEAR TERM /THROUGH THURSDAY/
 
 
WINTER WEATHER ADVISORY ISSUED FOR SOUTHERN HERKIMER COUNTY  
FROM 7PM TONIGHT TO 1PM THURSDAY...  
 
LAKE EFFECT CLOUDS AND SNOW SHOWERS EXTENDING INTO THE  
SCHOHARIE VALLEY AND EASTERN CATSKILLS BUT VERY SCATTERED. BASED  
ON TRENDS AND LATEST MESOSCALE MODEL DATA, LAKE EFFECT SNOW  
BAND SHOULD BECOME MORE ORGANIZED THROUGH THE EVENING AND NIGHT  
AND BRUSH SOUTHERN HERKIMER COUNTY. AS LOW LEVEL FLOW  
FLUCTUATES, THE NORTHERN EDGE OF THE SNOW SHOWERS COULD BRUSH  
THROUGH THE CAPITAL REGION AND BERKSHIRES. JUST MINOR  
ADJUSTMENTS TO TEMPERATURES AND SKY COVER THROUGH TONIGHT.  
PREVIOUS AFD HAS A FEW MORE DETAILS AND IS BELOW...  
 
HIGH PRESSURE ANALYZED NEAR ~1050HPA OVER THE NORTHERN PLAINS  
CONTINUES TO BUILD EASTWARD RESULTING IN A TIGHT PRESSURE  
GRADIENT AND THUS BREEZY WINDS OVER EASTERN NY/WESTERN NEW  
ENGLAND. INCREASED MIXING DEPTHS HAVE ALLOWED WINDS TO PEAK NEAR  
35-40MPH AS PER NYS MESONET AND ASOS STATIONS AND WINDS SHOULD  
GRADUALLY WEAKEN AS WE APPROACH SUNSET. OTHERWISE, TEMPERATURES  
HAVE BENEFITED FROM THE INCREASED MIXING HEIGHTS WITH MOST  
PLACES HITTING HIGHS IN THE MID TO UPPER 30S UP THE HUDSON  
VALLEY WITH EVEN LOW 40S FROM KINGSTON SOUTHWARD. AREAS WEST OF  
THE HUDSON ARE COOLER IN THE UPPER 20S TO LOW 30S DUE TO MORE  
CLOUD COVERAGE/LOWER MIXING DEPTHS.  
 
WITH SKIES MAINLY CLEAR THIS EVENING ALONG WITH LOW DEW POINTS  
IN THE SINGLE DIGITS AND LOW TEENS, AREAS SHOULD RADIATE  
ALTHOUGH THE CONTINUED BREEZE MAY IMPEDE TEMPERATURES FROM  
RAPIDLY DROPPING. HOWEVER, WE STILL EXPECT TEMPERATURES TO FALL  
INTO THE TEENS AND WHERE THERE IS A DEEP SNOW PACK OF 12 TO 24  
INCHES ACROSS THE ADIRONDACKS, UPPER HUDSON VALLEY AND SOUTHERN  
VT, TEMPERATURES SHOULD DROP INTO THE SINGLE DIGITS BY MIDNIGHT.  
 
A POSITIVELY TILTED SHORTWAVE TROUGH WILL PROGRESS THROUGH  
THE GREAT LAKES TONIGHT WITH A REINFORCING SHOT OF COLD AIR OUT  
AHEAD OF IT EXPECTED TO MOVE ACROSS LAKE ONTARIO. THE 925-850MB  
WIND TRAJECTORIES SHOW WESTERLY FLOW OVER LAKE ONTARIO EXTENDING  
INTO WESTERN/CENTRAL NY WITH UPSTREAM FLOW OVER LAKE HURON AND  
THE GEORGIAN BAY VEERING TO THE NORTHWEST. THE WESTERLY FLOW  
OVER LAKE ONTARIO WILL CONTINUE TO ADVECT IN A COLDER AIR MASS  
CHARACTERIZED BY 850MB ISOTHERMS BETWEEN -16C TO -19C. THE GREAT  
LAKES ENVIRONMENTAL RESEARCH LABORATORY (GLERC) SHOWS THE  
AVERAGE LAKE ONTARIO WATER TEMPERATURE TO BE A MILD +4C.  
NEEDLESS TO SAY, WE WILL SURPASS THE CRITICAL 13C DELTA-T  
NEEDED TO GENERATE LAKE EFFECT SNOW TONIGHT.  
 
HIGH-RES GUIDANCE, INCLUDING THE RGEM WHICH TENDS TO PERFORM  
WELL IN LAKE EFFECT SITUATIONS, POINTS TO A SINGLE LAKE EFFECT  
BAND EXTENDING INLAND OFF LAKE ONTARIO AFTER 03Z AND PENETRATING  
INTO SOUTHERN HERKIMER COUNTY BY 06Z. BUFKIT PROFILES SHOW THE  
BOUNDARY LAYER DEEPENING AT UTICA ABOVE 750MB LEADING TO  
MODERATE TO SEVERE INSTABILITY. GIVEN THAT THE WIND  
TRAJECTORIES FAVOR A MULTI-LAKE CONNECTION, OUR LOCAL INLAND  
LAKE EFFECT EXTENT RESEARCH SHOWS THAT IF A SINGLE LAKE EFFECT  
BAND DEVELOPS, IT HAS POTENTIAL TO EXTEND UP TO ~130MILES  
DOWNSTREAM OF LAKE ONTARIO OR INTO WESTERN SCHENECTADY COUNTY OR  
EVEN THE HELDERBERGS. QPF AMOUNTS OVER SOUTHERN HERKIMER LOOK TO  
RANGE 0.10 - 0.20 INCHES AND WITH SLRS EXPECTED TO BE 20-25:1,  
THIS SHOULD EQUATE TO 2 TO 4 INCHES WITH LOCALLY UP TO 5 INCHES  
NEAR UTICA. THIS IS WHY WE ISSUED A WINTER WEATHER ADVISORY FOR  
THIS AREA. WITH INCREASING CONFIDENCE THAT THE BAND EXTENDS  
INTO THE MOHAWK AND SCHOHARIE VALLEY, WE SHOW AMOUNTS OF 1 TO 3  
INCHES WITH EVEN COATINGS TO 0.5" NEARING THE CAPITAL REGION  
THROUGH 12Z. THE WESTERLY FLOW MAY LEAD TO UPSLOPE SNOW  
ENHANCEMENTS ALONG THE WESTERN FACING SLOPES OF THE TACONICS,  
SOUTHERN GREENS BERKSHIRES WHICH IS WHY WE SHOW COATING TO 0.5"  
HERE AS WELL. DESPITE THE COLD AIR ADVECTION, THE SLIGHT BREEZE  
TONIGHT SHOULD HINDER LOW TEMPERATURES FROM FALLING MUCH BELOW  
CLIMATOLOGY, FALLING INTO THE TEENS FOR MOST SPOTS WITH SINGLE  
DIGITS IN THE ADIRONDACKS AND SOUTHERN GREENS.  
 
BY TOMORROW MORNING, THE AFOREMENTIONED SHORTWAVE TROUGH SHOULD  
PUSH INTO WESTERN NY WITH THE WIND FIELD VEERING TO THE WEST-  
NORTHWEST. AS A RESULT, ANY SINGLE LAKE EFFECT BAND THAT  
DEVELOPS SHOULD SHIFT SOUTHWARD WITH POTENTIAL FOR SNOW TO SHIFT  
SOUTH OF THE CAPITAL REGION INTO THE EASTERN CATSKILLS AND  
POSSIBLY THE CENTRAL TACONICS. AFTER 15Z, THE WIND FIELD SHOULD  
VEER ENOUGH TO THE NORTHWEST THAT LAKE EFFECT TRANSITIONS INTO  
MORE MULTI-BANDS BEFORE DIMINISHING.  
 
WITH THE UPPER LEVEL TROUGH AXIS OVERHEAD BY THURSDAY AFTERNOON  
AND A COLD POOL ALOFT, THE BOUNDARY LAYER SHOULD REMAIN DEEP AND  
PROMOTE MIXING WITH GUSTY WINDS UP TO 25-35MPH STILL POSSIBLE.  
TEMPERATURES SHOULD BE CHILLY AS WELL WITH HIGHS ONLY IN THE  
20S AND THE BREEZY WINDS WILL ONLY MAKE IT FEEL COLDER.  
 

 
   
SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY NIGHT/
 
 
THE LARGE ~1045MB HIGH PUSHES INTO THE NORTHEAST THURSDAY NIGHT  
ALLOWING THE SUBSIDENCE INVERSION TO DROP AND CLOUDS TO CLEAR.  
EXPECTING A CHILLY NIGHT THANKS TO RADIATIONAL COOLING WITH  
LOWS FALLING INTO THE SINGLE DIGITS FOR MOST OF THE REGION AND  
BETWEEN 0F AND -5F FOR THE ADIRONDACKS, UPPER HUDSON VALLEY AND  
SOUTHERN VT WHERE A DEEP SNOW EXISTS.  
 
FRIDAY SHOULD BE A PLEASANT DAY AS HIGH PRESSURE TAKES CONTROL  
OF THE NORTHEAST LEADING TO CLEAR SKIES. TEMPERATURES SHOULD BE  
A A FEW DEGREES MILDER THAN THURSDAY AS AN 850MB WARM FRONT  
PUSHES THROUGH THE AREA. HIGHS SHOULD REACH INTO THE UPPER 20S  
TO LOW 30S. FRIDAY NIGHT STAYS DRY BUT NOT AS COOL AS THURSDAY  
NIGHT THANKS TO WESTERLY FLOW ADVECTING IN MILDER AIR. LOWS  
SHOULD ONLY FALL INTO THE TEENS AND LOW 20S.  
 

 
   
LONG TERM /SATURDAY THROUGH WEDNESDAY/
 
 
THE EXTENDED FORECAST BEGINS WITH FAIR AND DRY WEATHER WITH  
MODERATING TEMPS BACK ABOVE NORMAL WITH HIGH PRESSURE IN CONTROL ON  
THE WEEKEND. A STORM SYSTEM APPROACHES FROM THE LOWER MS RIVER  
VALLEY MONDAY INTO TUESDAY WITH SOME UNSETTLED WEATHER.  
 
SATURDAY-SUNDAY...A BROAD SFC ANTICYCLONE BUILDS IN FROM THE TN  
VALLEY ON SATURDAY, AND THEN SLOWLY SHIFTS EASTWARD TO THE MID  
ATLANTIC COAST FOR SUNDAY. THE STRONG SUBSIDENCE FROM THE SFC HIGH  
WILL YIELD PARTLY/MOSTLY SUNNY CONDITIONS WITH TEMPS TRENDING FROM  
NORMAL LEVELS ON SATURDAY TO ABOVE NORMAL LEVELS BY SUNDAY WITH THE  
FLATTER MID AND UPPER LEVEL FLOW. HIGHS SATURDAY WILL BE IN THE MID  
30S TO LOWER 40S IN THE LOWER ELEVATIONS, AND UPPER 20S TO LOWER/MID  
30S OVER THE HIGHER TERRAIN. LOWS WILL COOL OFF INTO THE TEENS AND  
20S FOR SUNDAY MORNING. HIGHS ON SUNDAY WILL BE WIDESPREAD IN THE  
LOWER TO MID 40S IN THE VALLEYS, WITH SOME UPPER 40S IN THE MID  
HUDSON VALLEY AND NW CT, AND 30S OVER THE HIGHER TERRAIN.  
 
SUNDAY NIGHT INTO MONDAY...A LOW PRESSURE SYSTEM MOVES INTO THE  
LOWER OR MID MS RIVER VALLEY SUNDAY NIGHT INTO MONDAY. THERE  
CONTINUES TO BE TIMING DIFFERENCES BETWEEN THE ECMWF/GFS/CMC ON THE  
TRACK OF THE SYSTEM AND HOW MUCH IMPACT IT PROVIDES THE FORECAST  
AREA. THE MID AND UPPER LEVEL FLOW CONTINUES TO SHIFT  
SOUTHWESTERLY, AND IT DOES APPEAR A COLD FRONT WILL BEGIN TO DIP  
SOUTH FROM THE ST LAWRENCE RIVER VALLEY ON MON. MOST OF SUNDAY NIGHT  
INTO MONDAY SHOULD STAY DRY, BUT CLOUDS WILL BE ON THE INCREASE. THE  
MID AND UPPER LEVEL RIDGE AXIS SHIFTS DOWNSTREAM. SOME SHOWERS MAY  
MOVE INTO THE FORECAST AREA BASED ON A BLEND OF THE GUIDANCE MONDAY  
PM. LOWS WILL BE IN THE 20S TO AROUND 30F WITH HIGHS IN THE WARM  
ADVECTION PATTERN IN THE 40S WITH SOME MID AND UPPER 30S OVER THE  
HIGHER TERRAIN.  
 
MONDAY NIGHT INTO TUESDAY...THE PRIMARY LOW WEAKENS OVER THE OH  
VALLEY AND LOWER GREAT LAKES REGION. A SECONDARY WAVE TRIES TO FORM  
NEAR THE NJ COAST AND LONG ISLAND BASED ON THE 12Z ECMWF AND SOME OF  
THE ENSEMBLES. THE CHANCES FOR WIDESPREAD PCPN INCREASES. THERMAL  
PROFILES FAVOR RAIN, BUT SOME COOLING FROM ALOFT WOULD ALLOW FOR  
SOME MOUNTAINS SNOWS TUESDAY MORNING. LOWS WILL RANGE FROM THE MID  
20S TO MID 30S. HIGHS TUE STILL LOOK ABOVE NORMAL WITH MID 30S OVER  
THE SOUTHERN ADIRONDACKS TO MID AND UPPER 40S OVER THE MID HUDSON  
VALLEY AND NW CT.  
 
TUESDAY NIGHT INTO WEDNESDAY...THE SYSTEM LIFTS TO NORTH AND EAST  
OVER NORTHERN NEW ENGLAND AND THE CANADIAN MARITIMES WITH A TREND TO  
DECREASING RAIN AND SNOW SHOWERS. THE PERIOD OF TRANQUIL WEATHER  
COULD BE BRIEF, AS FULL LATITUDE TROUGH SETS UP OVER THE EASTERN TWO  
THIRDS OF THE CONUS WITH ANOTHER SHORT-WAVE EJECTING INTO THE TN  
VALLEY OR PIEDMONT REGION THAT COULD IMPACT THE FORECAST AREA WED  
NIGHT INTO THU WITH MORE RAIN OR SNOW. TEMPS TREND BACK TO LATE FEB  
NORMALS FOR THE MID-WEEK.  
 

 
   
AVIATION /23Z WEDNESDAY THROUGH MONDAY/
 
 
CLEAR TONIGHT WITH HIGH PRESSURE IN CONTROL. HOWEVER, WEST TO  
NORTHWEST LOW LEVEL FLOW WILL CAUSE SOME LAKE EFFECT CLOUDS AND  
FLURRIES TO OCCASIONALLY BE IN THE VICINITY OF KALB AND KPSF  
FROM AROUND MIDNIGHT THROUGH MID MORNING THURSDAY, SO INCLUDING  
VCSH. CEILINGS AND VISIBILITIES ARE EXPECTED TO BE VFR, EVEN IN  
ANY FLURRIES. VFR CONDITIONS CONTINUE THROUGH THE DAY THURSDAY.  
 
NORTHWEST TO WEST WINDS WILL DIMINISH TO LESS THAN 10 KT  
TONIGHT, THEN INCREASE TO NEAR 10 KT THURSDAY MORNING AND  
AFTERNOON.  
 
OUTLOOK...  
 
THURSDAY NIGHT: NO OPERATIONAL IMPACT. NO SIG WX.  
FRIDAY: NO OPERATIONAL IMPACT. NO SIG WX.  
FRIDAY NIGHT: NO OPERATIONAL IMPACT. NO SIG WX.  
SATURDAY: NO OPERATIONAL IMPACT. NO SIG WX.  
SATURDAY NIGHT: NO OPERATIONAL IMPACT. NO SIG WX.  
SUNDAY: NO OPERATIONAL IMPACT. NO SIG WX.  
SUNDAY NIGHT: NO OPERATIONAL IMPACT. NO SIG WX.  
MONDAY: MODERATE OPERATIONAL IMPACT. CHANCE OF SHRA...SHSN.  
 

 
   
HYDROLOGY
 
 
BESIDES LAKE EFFECT SNOW TONIGHT INTO TOMORROW MORNING, DRY  
WEATHER WILL PERSIST OVER THE REGION THROUGH THE WEEKEND.  
 
COLDER TEMPERATURES TONIGHT THROUGH FRIDAY SHOULD ALLOW SOME  
ICE TO DEVELOP OR THICKEN ON SOME RIVERS AND LAKES.  
 
FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES, INCLUDING OBSERVED  
AND FORECAST RIVER STAGES AND LAKE ELEVATIONS, PLEASE VISIT THE  
ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR  
WEBSITE.  
 

 
   
ALY WATCHES/WARNINGS/ADVISORIES
 
 
CT...NONE.  
NY...WINTER WEATHER ADVISORY UNTIL 1 PM EST THURSDAY FOR NYZ038.  
MA...NONE.  
VT...NONE.  
 

 
 

 
SYNOPSIS...SPECIALE  
NEAR TERM...NAS/SPECIALE  
SHORT TERM...SPECIALE  
LONG TERM...WASULA  
AVIATION...NAS  
HYDROLOGY...SPECIALE  
 
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