Quantitative Precipitation Forecast
Issued by NWS

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32
000
FOUS11 KWBC 232023
QPFHSD

PROBABILISTIC HEAVY SNOW AND ICING DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
322 PM EST FRI FEB 23 2018

VALID 00Z SAT FEB 24 2018 - 00Z TUE FEB 27 2018


...CENTRAL PLAINS TO UPPER MS VALLEY/UPPER GREAT LAKES...

A WINTER STORM IS EXPECTED FROM THE CENTRAL PLAINS TO UPPER MS
VALLEY AND ADJACENT PORTIONS OF THE UP AS A 700 MB WAVE CROSSES
THE CENTRAL AND SOUTHERN ROCKIES THIS EVENING WITH LEE
CYCLOGENESIS OCCURRING ON THE PLAINS.  THE NEW LOW MOVES NORTHEAST
TOWARDS THE UP OF MI WITH MID LEVEL CONVERGENCE AND
DEFORMATION/THETA-E ADVECTION SUPPORTING SNOW DEVELOPING IN
NEBRASKA AND EXTENDING NORTHEAST ACROSS SD AND MN...NORTHWEST WI
AND WESTERN UP OF MI.  SNOWS OF 4 TO 8 INCHES FROM SOUTHEAST SD
THROUGH SOUTH/EASTERN MN INTO NWRN WI, WITH LOCALLY HIGHER AMOUNTS
FROM SOUTH/SERN MN THROUGH NWRN WI.  MORE UNCERTAINTY EXISTS
TONIGHT INTO EARLY SAT IN CO/NE AS THE MODELS DO NOT AGREE AS WELL
AS THEY NORMALLY DO ON DAY 1...WITH A FEW HIGH RES RUNS SHOWING
POTENTIAL FOR FEW BANDS OF ENHANCED SNOWFALL...BUT LACKING
OVERLAP.  THIS LEADS TO LOW CONFIDENCE AND LOW PROBABILITIES IN
CO/NE.

THE MID LEVEL WARM ADVECTION RESULTS IN A CHANGE OVER TO SLEET AND
FREEZING RAIN EAST OF THE STORM TRACK FROM CENTRAL KS AND
SOUTHEAST NE/NORTHWEST MO AND IOWA ON DAY 1 AND CENTRAL WI TO
NORTHERN LOWER MI AND THE EASTERN UP OF MI ON DAY 2. THE CONSENSUS
IS FOR AROUND A TENTH OF INCH OF ICE ACCRETION ACROSS THESE AREAS.

THE NAM SLIGHTLY FURTHER WEST LOW DEVELOPMENT RESULTS IN HEAVIER
SNOW EXTENDING FURTHER WEST IN NORTHERN MN.  MORE WEIGHTING WAS
GIVEN TO SOLUTIONS WITH A FURTHER EAST LOW TRACK.

...PACIFIC NORTHWEST/NORTHERN ROCKIES/NORTHERN GREAT BASIN...

THE DEPARTURE OF AN UPPER LEVEL RIDGE AND APPROACH AND ARRIVAL OF
AN UPPER LEVEL TROUGH LEADS TO  RAPID TRANSITION TO MODERATE TO
HEAVY VALLEY RAINS AND MOUNTAIN SNOW IN THE WAA/OR CASCADES.
FAVORABLE UPPER DIVERGENCE MAXIMA IN THE LEFT JET EXIT REGION
COMBINES WITH STRONG MID LEVEL CONVERGENCE ON THE NOSE OF A 50 KT
700 MB JET FAVORS OROGRAPHIC AID TO THE ASCENT..WITH HEAVIEST
AMOUNTS IN WINDWARD TERRAIN OF THE WA/OR CASCADES .  GOOD
MULTI-MODEL AGREEMENT AND BANDS OF 1 INCH LIQUID EQUIVALENT YIELDS
A LIKELY FOOT OF SNOW IN THE DAY 1 FORECAST FRI NIGHT-SAT.

DAY 2 LOOKS LIKE IT RHYMES WITH DAY 1...EXCEPT AN EVEN STRONGER
700 MB JET OF 70-80 KT COMING INTO THE CASCADES.
CONSEQUENTLY...THE POTENTIAL AMOUNTS ARE EVEN HIGHER WITH 18-24
INCHES POSSIBLE IN THE HIGHER ELEVATIONS OF THE WA/OR CASCADES.

AS THE UPPER TROUGH BUILDS SOUTH...TAKING THE AXIS OF THE UPPER
JET SOUTH INTO CA/NV...THEN A BREAK WILL DEVELOP IN THE PACIFIC
NORTHWEST AS THE AREAS OF SNOW SHIFT OUT OF OR INTO CA/NORTHERN
NV/WESTERN WY AS MON PROGRESSES...WHICH MATCHES THE PROGRESSION OF
PEAK 700 MB CONVERGENCE IN PROXIMITY WITH THE FRONT.

POCKETS OF 2-3 FEET ARE EXPECTED IN THE WA-OR CASCADES WITH
ISOLATED SNOW TOTALS OF 4 FEET POSSIBLE THIS WEEKEND.

...INTERIOR NEW YORK/NEW ENGLAND...

A CLUSTER OF LIGHT PRECIP MOVES INTO INTERIOR NEW ENGLAND THIS
EVENING WITH POTENTIAL FOR LIGHT ICING IN NORTHERN NH AND WESTERN
MAINE BEFORE A COLD FRONT SWEEPS ACROSS NEW ENGLAND AND PRECIP
WINDS DOWN. AMOUNTS OF FREEZING RAIN WILL MOSTLY A MEASURABLE TO A
TENTH OF AN INCH.

ON DAY 2 A MORE SIGNIFICANT EVENT IS EXPECTED AS STRONG MID LEVEL
WARM AND MOISTURE ADVECTION OCCURS OVER THE COLD COLD DOME WITH
POTENTIAL FOR A POTENTIAL FOR A QUARTER INCH OF ICING IN UPSLOPE
PORTIONS OF THE NY CATSKILL AND ADIRONDACK MOUNTAINS TO THE
BERKSHIRES OF MA/SOUTHERN GREEN MOUNTAINS OF VT.

THE EVENT WINDS DOWN LATER SUNDAY AS THE JET EXITS NEW ENGLAND AND
THE WARM/MOIST ADVECTION AND ASCENT DECLINES. A RESIDUAL
MEASURABLE ACCUMULATION IS POSSIBLE IN INTERIOR MAINE.

THE PROBABILITY OF SIGNIFICANT (GREATER THAN 0.25 INCHES) OF ICING
IS LESS THAN 10 PERCENT DAY 1 AND DAY 3.

PETERSEN


$$




USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.