Quantitative Precipitation Forecast
Issued by NWS

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FOUS11 KWBC 200803
QPFHSD

PROBABILISTIC HEAVY SNOW AND ICING DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
302 AM EST FRI JAN 20 2017

VALID 12Z FRI JAN 20 2017 - 12Z MON JAN 23 2017


MUCH OF THE WEST...

TWO ADDITIONAL STRONG CYCLONES WILL AFFECT THE WEST COAST...AND
PARTICULARLY CALIFORNIA...OVER THE NEXT 3 DAYS WITH ANOTHER ROUND
OF EXCESSIVE HIGH ELEVATION SNOWFALL WITH WIDESPREAD SNOWFALL
EXCEEDING 4 FEET ACROSS MUCH OF THE SIERRA. THE FIRST SYSTEM IS AN
AMPLIFYING NEGATIVELY TILTED TROUGH WITH HEAVY RAIN AND MOUNTAIN
SNOW MOVING EAST SOUTHEASTWARD ACROSS CALIFORNIA ACROSS THE
SOUTHWEST AND ACROSS THE SOUTHERN INTERMOUNTAIN WEST THROUGH DAY
1/FRIDAY INTO SATURDAY MORNING. WHILE THE HEAVIEST SNOW IS
EXPECTED ACROSS THE SIERRA WITH A TO MORE THAN 2 FEET OF SNOW
LIKELY...SNOW EXCEEDING A FOOT IS ALSO LIKELY ACROSS THE HIGHEST
PEAKS ACROSS NORTHERN AND SOUTHERN CALIFORNIA...SOUTHWESTERN UTAH
AND ACROSS PARTS OF THE MOGOLLON RIM IN CENTRAL AND EASTERN
ARIZONA.

IN COMPARISON...DAY 2/SATURDAY INTO SUNDAY MORNING IS A RELATIVE
RESPITE IN THE VERY HEAVY SNOWFALL COMPARED TO SNOWFALL ON DAYS 1
AND 3...WITH SNOWFALL DIMINISHING ACROSS THE MOUNTAINOUS SOUTHWEST
INTO THE SOUTHERN ROCKIES BUT WITH CONTINUED HEAVY SNOW ACROSS THE
SIERRA WITH MODERATE TO HIGH CHANCES FOR AN ADDITIONAL FOOT OF
SNOW ESPECIALLY ACROSS THE SIERRA AND THE MOUNTAINS OF NORTHERN
CALIFORNIA.  WHILE SIGNIFICANT SNOW CONTINUES ACROSS PORTIONS OF
UTAH/COLORADO/ARIZONA AND NEW MEXICO...HEAVIEST AMOUNTS ARE MORE
LIKELY IN THE 4 TO 8 INCH RANGE WITH SOME OF THE HEAVIEST TOTALS
EXPECTED ACROSS THE SAN JUAN RANGE IN COLORADO.

THE NEXT CYCLONE IS ALSO EXPECTED TO PRODUCE A POWERFUL INFLUX OF
MOISTURE AND LIFT TO THE WEST COAST THAT WILL THEN MOVE ACROSS THE
INTERMOUNTAIN WEST AGAIN WITH A SLIGHTLY FARTHER NORTHWARD
EXPANSE. AGAIN...THERE IS A HIGH PROBABILITY THAT THE SIERRA WILL
AGAIN SEE SNOWFALL AMOUNTS OF 1 TO 2 FEET OR GREATER WITH
SIGNIFICANT SNOW ACROSS NEVADA/NORTHERN ARIZONA/UTAH/CENTRAL IDAHO
AND WESTERN COLORADO.

DAY 3...

INTERIOR NORTHEAST...

AN ACTIVE BUT UNUSUALLY MILD JANUARY WEATHER PATTERN DOMINATED BY
A STRONG UPPER LEVEL TROUGH/JET SYSTEM WILL RESULT IN A MOSTLY WET
UPPER LOW OVER THE SOUTHEAST THAT WILL BEGIN TO LIFT NORTHWARD
ALONG THE EAST COAST.  A BLOCKING UPPER LEVEL RIDGE OVER SOUTHEAST
CANADA WILL BE ASSOCIATED WITH A CELL OF COOL BUT NOT COLD HIGH
PRESSURE BUT WHOSE LOCATION WILL ALLOW SOME COOLER AIR SOUTHWARD
TOWARD THE INTERIOR NORTHEAST.  SOME SNOW/ICE COULD FALL ALONG THE
NORTHERN PERIPHERY OF THE EXPANDING PRECIPITATION AREA MOVING
NORTHWARD ALONG THE ATLANTIC COAST THAT WILL BEGIN LATE ON DAY
3/EARLY MONDAY THAT WILL LIKELY EXTEND NORTHWARD PAST DAY 3. WHILE
THE 00Z NAM IS QUITE FAST...CURRENTLY MODEL CONSENSUS SHOWS ONLY A
LOW PROBABILITY THAT SNOWFALL ACROSS INTERIOR NEW YORK AND NEW
ENGLAND WILL LIKELY REMAIN BELOW 4 INCHES BY MONDAY MORNING.


KOCIN

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