Quantitative Precipitation Forecast
Issued by NWS

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000
FOUS11 KWBC 232056
QPFHSD

PROBABILISTIC HEAVY SNOW AND ICING DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
356 PM EST TUE JAN 23 2018

VALID 00Z WED JAN 24 2018 - 00Z SAT JAN 27 2018

...CENTRAL APPALACHIANS...EASTERN GREAT LAKES AND NORTHERN NEW
ENGLAND...

LOW PRESSURE LIFTS NORTHEAST ACROSS NORTHERN NEW ENGLAND TONIGHT.
WRAP AROUND SNOW WILL GRAZE THE NORTHERN NEW ENGLAND BORDER WITH A
COUPLE INCHES. DEEP CYCLONIC FLOW ON THE BACKSIDE OF THE SYSTEM
WILL ALSO LEAD TO A BRIEF PERIOD OF LAKE EFFECT SNOW DOWNWIND OF
LAKE ONTARIO AND LAKE ERIE...AS WELL AS THE WESTERN SIDE OF THE
SOUTHERN SECTION OF THE ALLEGHENY PLATEAU IN WV/PA/MD. SNOW WILL
TAPER OFF ACROSS THIS REGION WEDNESDAY NIGHT AS SURFACE HIGH
PRESSURE BUILDS IN.

...PACIFIC NORTHWEST AND CALIFORNIA INTO THE INTER-MOUNTAIN WEST...

A DEEP UPPER LOW WILL APPROACH THE SOUTHERN BC COAST TUESDAY NIGHT
BEFORE SHIFTING UP THE COAST WEDNESDAY. AN AMPLIFIED UPPER TROUGH
EXTENDING SOUTH FROM THE LOW WILL CROSS THE PAC NW LATE WEDNESDAY
NIGHT WITH A LEADING SHORTWAVE CROSSING THE OLYMPIC PENINSULA
WEDNESDAY EVENING.

PRECIPITATION WITH HIGH SNOW ELEVATIONS FROM FAR NORTHERN CA TO WA
THEN EAST TO THE ID/MT BORDER WILL SLOWLY SHIFT INLAND/SOUTH WITH
LITTLE SNOW ELEVATION CHANGE UNTIL THE UPPER TROUGH AXIS CROSSES
LATE WEDNESDAY NIGHT. PW OF 0.75 INCHES LEADS TO PARTICULARLY
HEAVY PRECIP TONIGHT...THOUGH DEEP WARM AIR WILL KEEP HEAVY SNOW
LIMITED TO HIGH ELEVATIONS OF THE COAST RANGES AND CASCADES.

DAY 2 (00Z THU-00Z FRI) AND DAY 3 (00Z FRI-00Z SAT) WILL FEATURE
LOWERING SNOW ELEVATIONS AS COLD AIR ADVECTION FILLS IN BEHIND THE
COLD FRONT...DESPITE AMPLE PACIFIC MOISTURE STREAMING INLAND. SNOW
IS EXPECTED OVER THE NORTHERN AND CENTRAL PORTIONS OF THE SIERRA
NEVADA AS THE COLD FRONT WEAKENS SOUTH OF THE BAY AREA. A GREATLY
WEAKENED COLD FRONT IS EXPECTED TO REACH THE CENTRAL ROCKIES WITH
MAINLY LIGHT SNOW BY 00Z SATURDAY.

THE PROBABILITY OF SIGNIFICANT ICING IS LESS THAN 10 PERCENT.

JACKSON




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