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FOUS11 KWBC 202018
QPFHSD
PROBABILISTIC HEAVY SNOW AND ICING DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
418 PM EDT FRI MAR 20 2026
VALID 00Z SAT MAR 21 2026 - 00Z TUE MAR 24 2026
..NORTHEAST
DAYS 1-3...
A CLIPPER WILL MOVE INTO THE NORTHEAST SATURDAY NIGHT BRINGING A
SWATH OF ACCUMULATING SNOWFALL TO UPSTATE NY INTO NORTHERN NEW
ENGLAND. STILL SOME UNCERTAINTY WITH THE EXACT TRACK OF THIS
SYSTEM, WHICH WILL IMPACT WHERE THE HEAVIEST SWATH OF QPF IS AND
WHERE THE RAIN/SNOW LINE SETS UP. THE HIGHER ELEVATIONS ARE MOST
FAVORED FOR HIGHER SNOWFALL TOTALS, BUT STRONG WAA SHOULD SUPPORT A
PERIOD OF MODERATE TO LOCALLY HEAVY PRECIPITATION. THIS SHOULD
ALLOW SNOW EVEN DOWN TO THE LOWER ELEVATIONS OF NORTHERN NEW
ENGLAND, ESPECIALLY SATURDAY NIGHT INTO EARLY SUNDAY. SNOW RATIOS
FROM THE NBM ARE LIKELY TOO HIGH WITH THIS SYSTEM. WHILE SNOW
SHOULD BE COMING DOWN AT A DECENT CLIP FOR A STRETCH, THE STRONGEST
LIFT APPEARS TO BE MAINLY CENTERED BELOW THE DGZ, WHICH SHOULD CAP
SNOWFALL RATIOS. THEN DURING THE DAYLIGHT HOURS THE LATE MARCH SUN
WILL PLAY A ROLE IN LOWERING RATIOS FURTHER. IN FACT, WHERE SNOW
IS FALLING AT A LIGHTER CLIP WE PROBABLY WON'T SEE MUCH
ACCUMULATION DURING THE DAYTIME, WITH ACCUMULATIONS FOCUSED IN
EITHER THE HIGHEST TERRAIN OR WHERE SNOW IS FALLING AT A HEAVY
ENOUGH CLIP TO OVERCOME THE MARGINAL TEMPERATURES AND HIGHER SUN
ANGLE.
THE LATEST WPC SNOWFALL PROBABILITIES HAVE INCREASED FOR THE
SATURDAY NIGHT TO SUNDAY TIMEFRAME. THE PROBABILITY OF EXCEEDING 4"
IN THE 24HR PERIOD ENDING 00Z MONDAY ARE GENERALLY 40-80% FROM
UPSTATE NY INTO CENTRAL TO NORTHERN VT/NH AND WESTERN ME. THE
HIGHEST PROBABILITIES ARE IN THE HIGHER TERRAIN, BUT VALUES OF
30-50% EVEN GET INTO THE LOWER ELEVATION AREAS. THE PROBABILITIES
OF 6" ARE 30-60%, WITH 8" EXCEEDANCE PROBABILITIES AS HIGH AS
30-50% IN THE WHITE MOUNTAINS OF NH. THESE PROBABILITIES SEEM
REASONABLE, WITH EXACT SNOWFALL TOTALS DEPENDENT ON THE SPECIFIC TRACK
OF THE SYSTEM. THIS IS A SCENARIO WHERE THE HIGHER TERRAIN HAS THE
HIGHEST PROBABILITIES (AND THUS CONFIDENCE) IN SEEING GREATER
SNOWFALL TOTALS, BUT THERE IS STILL A LOWER RISK OF IMPACTFUL SNOW
GETTING INTO SOME OF THE LOWER ELEVATIONS IF A SNOWFALL BAND IS
ABLE TO MOVE INTO THESE AREAS OVERNIGHT OR EARLY MORNING AND IS
HEAVY ENOUGH TO OVERCOME THE MARGINAL TEMPERATURES.
A BIT MORE UNCERTAINTY EXISTS ON MONDAY AS A COASTAL LOW TRIES TO
DEVELOP OFFSHORE NEW ENGLAND. BY THIS TIME IT WILL BE COLD ENOUGH
OVER NORTHERN NEW ENGLAND FOR SNOW, BUT IF PRECIPITATION INTENSITY
IS LIGHT THEN THE HIGH SUN ANGLE WILL LIKELY LIMIT ACCUMULATION.
HOWEVER, A BROADER AND/OR MORE INTENSE SNOW SHIELD WOULD BE
CAPABLE OF PRODUCING ADDITIONAL ACCUMULATING SNOWFALL. MODELS HAVE
BEEN FLUCTUATING REGARDING THIS LOW AND INLAND PRECIPITATION
EXTENT...ALTHOUGH MOST 12Z MODELS SHIFTED LIGHTER WITH QPF. EVEN
THE AIFS, WHICH HAS BEEN MORE CONSISTENTLY ON THE WETTER SIDE OF
THE QPF SPECTRUM, DID BACK OFF AT 12Z. THERE IS STILL TIME FOR THIS
TO CHANGE, BUT THE PROBABILITIES OF IMPACTFUL SNOWFALL MONDAY
APPEAR TO BE DECREASING, BUT STILL NEED TO CONTINUE TO MONITOR.
THE CHANCES FOR SIGNIFICANT ICING ACROSS THE CONUS IS LESS THAN 10
PERCENT.
CHENARD
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