651  
FXUS61 KALY 261125  
AFDALY  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE ALBANY NY  
625 AM EST TUE JAN 26 2021  
   
SYNOPSIS
 
 
ACCUMULATING SNOWFALL WILL IMPACT THE REGION TODAY INTO  
WEDNESDAY. THE HEAVIER SNOWFALL IS EXPECTED THIS AFTERNOON AND  
EVENING WITH LIGHTER SNOWFALL RATES OVERNIGHT INTO WEDNESDAY.  
THEN AN ARCTIC BOUNDARY WILL SLIDE THROUGH LATER THURSDAY WITH  
AN UNSEASONABLY COLD WEATHER IN THE FORECAST FRIDAY AND INTO  
THE START OF THE WEEKEND.  
 

 
   
NEAR TERM /THROUGH TONIGHT/
 
 
WINTER WEATHER ADVISORIES TO CONTINUE ACROSS ALL OF EASTERN NY  
AND WESTERN NEW ENGLAND.  
 
AS OF 600 AM EST...MAIN UPDATE WAS TO DELAY THE ONSET OF SNOW A  
COUPLE OF HOURS PER UPSTREAM TRENDS AND FORECAST HRRR SOUNDINGS  
THIS MORNING. SKIES REMAIN MOSTLY CLEAR ACROSS THE DACKS WITH  
MOSTLY CLOUDY CONDITIONS ALONG AND SOUTH OF I90 AND SOME  
STRATUS INTO NORTHERN WASHINGTON COUNTY. OTHERWISE, 06Z NCEP  
SUITE LOOKS CONSISTENT WITH FORECAST EXPECTATIONS.  
 
PREV DISC...RATHER ZONAL FLOW ACROSS THE NORTHEAST WHICH  
EXPLAINS THE MID LEVEL CLOUD DECK NOT MOVING TOO MUCH OVERNIGHT  
(ALONG I 90). HOWEVER, THAT WILL BE CHANGING THROUGH SUNRISE AS  
RATHER ELONGATED UPPER TROUGH EXTENDING ACROSS THE NORTH-  
CENTRAL CONUS AND INTO THE CENTER OF THE GREAT LAKES WILL SLOWLY  
TRACK EASTWARD. AT THE SURFACE, A BROAD SURFACE LOW ACROSS THE  
OHIO VALLEY WITH A FEW INVERTED SURFACE TROUGHS THROUGH THE MID-  
UPR MISSISSIPPI RIVER VALLEY AND EASTERN GREAT LAKES WILL ALSO  
BEGIN ITS APPROACH. THESE FEATURES, WHILE COMPLEX, ARE FORECAST  
TO TIGHTEN THE THERMAL GRADIENT AND ADVECT NORTHWARD THIS  
MORNING. MEANWHILE, SURFACE HIGH ACROSS NEW ENGLAND AND NORTH OF  
THE ST LAWRENCE WILL SLOWLY RETREAT TO THE NORTH. THIS HIGH  
WILL AID IN KEEPING THE COLDER AND DRIER IN PLACE A LITTLE  
LONGER, HENCE THE DELAY IN THE ONSET OF SNOW IN THE NEW  
FORECAST. ONCE THE BAROCLINIC/F-GEN H800-H700 ZONE MOVES IN FROM  
THE SOUTH- SOUTHWEST, EXPECTATIONS ARE FOR BANDS OF MODERATE  
SNOWFALL TO IMPACT THE CWA THIS AFTERNOON. CROSS SECTIONS DEPICT  
INCREASING OMEGA ALONG THIS F-GEN ZONE WHICH CROSSES THE  
DENDRITIC ZONE FOR UP TO THREE HOURS THIS AFTERNOON. GIVEN  
SPECIFIC HUMIDITIES VALUES OF 2-3 G/KG IN THE LAYER AND  
RAIN:SNOW RATIOS NEAR 15:1, WOULD NOT BE SURPRISED TO SEE 1"/HR  
RATES THIS AFTERNOON ACROSS THE NORTHERN 2/3RDS OF THE CWA (THIS  
IS ALSO SUGGESTED IN THE HREF 1"/HR PROBABILITIES AROUND THE  
EVENING RUSH-HOUR) . FURTHERMORE, LOCAL RESEARCH ALSO  
SUGGESTIONS PORTIONS OF THE MOHAWK VALLEY LEADING INTO THE DACKS  
MAY SEEN ADDITIONAL ENHANCEMENT TO THE SNOWFALL WITH 180-270  
H925 WIND AND MAGNITUDES BETWEEN 20-39KTS. PLUMES FROM GEFS/SREF  
HAVE COME A UP A LITTLE BIT WITH RESPECT TO SNOWFALL/QPF WHICH  
WAS ALSO COORDINATED WITH WPC AND SURROUNDING OFFICES. SO WE DID  
INCREASE SNOWFALL FORECAST FOR MOST AREAS, ESPECIALLY FOR THOSE  
AFOREMENTIONED AREAS WEST AND NORTHWEST OF ALBANY. BUT AS THIS  
WILL BE FAST MOVING MODERATE SNOWFALL, BRIEFLY HEAVY, WE DID NOT  
UPGRADE THOSE AREAS TO A WARNING AT THIS TIME. AS THIS WILL BE  
A DRAWN OUT EVENT, EXPECTATIONS ARE FOR THE INITIAL BURST OF  
SNOW TO FALL SHORT OF WARNING CRITERIA (7"/12HRS). AS THIS  
LIFT/F-GEN TRANSLATE NORTHWARD BY 00Z/WED, PERSISTENT LIFT IS  
EXPECTED AS SURFACE LOW APPROACHES BUT BELOW THE DENDRITIC ZONE  
TONIGHT WITH LIGHTER SNOWFALL RATES AND SNOW DENSITY. WE WILL  
CONTINUE TO WATCH FOR MESOSCALE FORCING INTO THE MOHAWK VALLEY  
AND SOUTHERN DACKS WHERE MESOSCALE MODELS SUGGEST A BAND OR TWO  
OF SNOW COULD DEVELOP AND MOVE INTO SCHENECTADY COUNTY  
OVERNIGHT. LASTLY, A CLOSER LOOK AT ANY WINTRY MIXTURE WITH DRY  
SLOT MOVING IN ALOFT, SOME MIX MAY OCCUR NEAR I84. HOWEVER, HREF  
PTYPE PROBABILITIES ARE QUITE LOW SO WE PRECLUDED THE MENTION  
IN THE FORECAST AT THE MOMENT.  
 
HIGH TEMPERATURES GENERALLY INTO THE 20S WITH OVERNIGHT LOWS NOT  
CHANGING TOO MUCH WITH UPPER TEENS FOR THE DACKS AND 20S  
ELSEWHERE.  
 

 
   
SHORT TERM /WEDNESDAY THROUGH THURSDAY/
 
 
A WEAKENING SURFACE LOW AND TROUGH ALOFT TRANSLATES EAST LEAVING  
BEHIND AMPLE MID-LOWER LEVEL MOISTURE AND CONTINUOUS BROAD LIFT.  
THIS WILL SURE TO KEEP OCCASIONAL LIGHT SNOW/FLURRIES IN THE  
FORECAST THROUGH WEDNESDAY. 00Z MODEL SUITE SUGGEST A PERIOD OF  
ENHANCED SNOW TO DEVELOP DURING THE MID-LATE AFTERNOON HOURS AS  
A WEAK SHORT WAVE DIVES IN FROM THE NORTHWEST AND UPSLOPE  
ENHANCEMENT INTO THE TACONICS AND WESTERN NEW ENGLAND  
COMMENCES. IN FACT, THIS COULD ALSO BE NEAR A WEAK INVERTED  
SURFACE TROUGH AXIS JUST TO THE EAST OF THE HUDSON RIVER AS  
SUGGESTED BY THE NAM3KM/HREF. AS THERMAL PROFILE HAS MODERATED A  
FEW DEGREES, THIS SHOULD HAVE A LITTLE POSITIVE IMPACT TO  
FORECAST HIGH TEMPERATURES WITH LOWER HALF OF THE 30S FOR THE  
HUDSON RIVER VALLEY LOCATIONS AND MID-UPR 20S ACROSS THE  
TERRAIN.  
 
DEEP MOISTURE AND UPPER SUPPORT SLIDE SOUTHEAST OF THE REGION  
WEDNESDAY NIGHT WITH SOME RESIDUAL UPSLOPE INTO THE EASTERN HALF  
OF THE CWA WHERE WE WILL RETAIN CHANCE-SCATTERED POPS IN THE  
FORECAST. THIS WILL PRECEDE THE APPROACH ARCTIC BOUNDARY  
FORECAST ON THURSDAY.  
 
THIS ARCTIC BOUNDARY, WITH A REDUCED MOISTURE PROFILES, MAY BE  
ACCOMPANIED BY SOME SNOW SHOWERS. GIVEN THE SHALLOW NATURE OF  
THE MOISTURE (PERHAPS SOME CONTRIBUTIONS FROM LAKE ONTARIO),  
MAINLY HIGHER TERRAIN WILL HAVE THE BETTER CHANCE FOR SNOW  
SHOWERS. HIGH TEMPERATURES WILL LIKELY BE ACHIEVED EARLIER IN  
THE DAY BEFORE THE STRONG COLD ADVECTION TAKES PLACE DURING THE  
AFTERNOON. WIND MAGNITUDES WILL INCREASE AS WELL WITH MOMENTUM  
TRANSFER MAGNITUDES OF 20-30KTS ARE EXPECTED. THE WINDS  
INCREASING WITH FALLING TEMPERATURES WILL RESULT IN WIND CHILL  
READINGS FALLING AT OR BELOW ZERO BY SUNSET.  
 

 
   
LONG TERM /THURSDAY NIGHT THROUGH MONDAY/
 
 
ARCTIC COLD AND THE THREAT OF WINTER PRECIPITATION ARE THE HEADLINES  
FOR THE LONG TERM FORECAST.  
 
ARCTIC AIR WILL BE IN PLACE THROUGH THE BEGINNING OF THE EXTENDED  
PERIOD. TEMPERATURES WILL RUN 10-20 DEGREES BELOW NORMAL (AND WE ARE  
IN THE CLIMATOLOGICAL COLDEST STRETCH OF THE WINTER NOW)FOR THURSDAY  
NIGHT THROUGH SATURDAY NIGHT. TEMPERATURES MODERATE SOMEWHAT SUNDAY  
AND MONDAY. FRIGID TEMPERATURES COMBINED WITH BRISK WINDS THURSDAY  
NIGHT INTO FRIDAY AND POSSIBLY FRIDAY NIGHT INTO SATURDAY WILL ALLOW  
FOR WIND CHILL READINGS TO GET DOWN TO ADVISORY LEVELS IN THE  
ADIRONDACKS AND SOUTHERN GREEN MOUNTAINS(MINUS 20F TO MINUS 25F),  
AND POSSIBLY THE CATSKILLS AND BERKSHIRES (MINUS 15 TO MINUS 20F).  
WIND CHILLS IN VALLEY LOCATIONS WILL BE MINUS 10 TO ZERO.  
 
THE NEXT CONCERN IS THE EVOLUTION OF AN UPPER LEVEL TROUGH COMING  
ASHORE IN CALIFORNIA ON FRIDAY, THEN TRANSITING ACROSS THE CONUS.  
MODELS DIFFER IN THE HANDLING OF LOW PRESSURE TAKING SHAPE OVER THE  
OHIO VALLEY ON SUNDAY. THE GFS BRINGS THE POTENTIAL FOR SOME SNOW TO  
THE REGION SUNDAY INTO SUNDAY NIGHT. MEANWHILE THE ECMWF AND  
CANADIAN KEEP THE SYSTEM, FOR THE MOST PART, SOUTH AND EAST OF OUR  
AREA THROUGH THE EXTENDED. WE WILL KEEP AN EYE ON IT.  
 

 
   
AVIATION /12Z TUESDAY THROUGH SATURDAY/
 
 
REALLY NO CHANGE TO THINKING FROM 06Z DISCUSSION.  
 
VFR CONDITIONS WILL PREVAIL AT ALL TERMINALS THROUGH 16-18Z.  
 
THEN SNOW OVERSPREADS THE REGION.  
 
SNOW WILL ARRIVE AT THE TERMINALS THIS AFTERNOON. STARTING  
TIMES RANGE FROM 18-21Z SOUTH TO NORTH. IFR SN WILL OCCUR AT ALL  
SITES FROM ONSET THROUGH THE REMAINDER OF THE TAF PERIOD. MODEL  
GUIDANCE SHOWS BEST ISENTROPIC ASCENT/FGEN FORCING FOR KALB AND  
KGFL, LESSER SO AT THE KPOU AND KPSF. THUS EXPECTING SOMEWHAT  
HIGHER SNOWFALL RATES AT KALB AND KGFL AT ONSET. HREF 1HR  
SNOWFALL RATES > 1 INCH PROBABILITY CAP OUT IN THE 30-40% RANGE  
AT KALB AND KGFL. SO, THERE IS THE POTENTIAL FOR A PERIOD OF SAY  
1/4SM +SN, BUT CONFIDENCE REMAINS TOO LOW TO EXPLICITLY MENTION  
IN THE TAF RIGHT NOW. AFTER THE INITIAL SURGE OF SNOW, LIGHT  
SNOW WILL CONTINUE THROUGH THE REMAINDER OF THE TAF PERIOD.  
 
OUTLOOK...  
 
WEDNESDAY NIGHT: MODERATE OPERATIONAL IMPACT. CHANCE OF SHSN.  
THURSDAY: LOW OPERATIONAL IMPACT. BREEZY. SLIGHT CHANCE OF SHSN.  
THURSDAY NIGHT: LOW OPERATIONAL IMPACT. BREEZY. 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: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SN.  
 

 
   
HYDROLOGY
 
 
NO WIDESPREAD HYDROLOGICAL ISSUES ARE EXPECTED FOR THE UPCOMING  
WEEK AND WEEKEND. WHILE ACCUMULATING SNOWFALL IS EXPECTED  
INTO WEDNESDAY, THIS WILL HAVE LITTLE IMPACT ON AREA RIVERS.  
 
UNSEASONABLY COLD TEMPERATURES WILL PERSIST THROUGH MUCH OF THE WEEK  
AHEAD WITH ARCTIC AIR SET TO ARRIVE THURSDAY NIGHT AND LAST INTO  
THE START OF THE WEEKEND. THIS COLD AIR WILL CONTINUE TO  
SUPPORT RIVER AND LAKE ICE DEVELOPMENT AND THICKENING FOR THE  
REMAINDER OF THIS WEEK AND WEEKEND.  
 
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...WINTER WEATHER ADVISORY FROM NOON TODAY TO 10 AM EST WEDNESDAY  
FOR CTZ001-013.  
NY...WINTER WEATHER ADVISORY FROM 10 AM THIS MORNING TO 10 AM EST  
WEDNESDAY FOR NYZ047-051-058-063.  
WINTER WEATHER ADVISORY FROM NOON TODAY TO 10 AM EST WEDNESDAY  
FOR NYZ032-033-038>043-048>050-052>054-059>061-064>066-  
082>084.  
MA...WINTER WEATHER ADVISORY FROM NOON TODAY TO 10 AM EST WEDNESDAY  
FOR MAZ001-025.  
VT...WINTER WEATHER ADVISORY FROM NOON TODAY TO 10 AM EST WEDNESDAY  
FOR VTZ013>015.  
 

 
 

 
SYNOPSIS...BGM  
NEAR TERM...BGM  
SHORT TERM...BGM  
LONG TERM...OKEEFE  
AVIATION...OKEEFE  
HYDROLOGY...KL/BGM  
 
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