Quantitative Precipitation Forecast
Issued by NWS

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FOUS11 KWBC 242052
QPFHSD

PROBABILISTIC HEAVY SNOW AND ICING DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
351 PM EST TUE JAN 24 2017

VALID 00Z WED JAN 25 2017 - 00Z SAT JAN 28 2017

DAYS 1...

...NORTHEAST...

A STRONG AND NEGATIVELY TILTING UPPER TROUGH CROSSING THE
NORTHEAST WILL CONTINUE TO FOSTER SOME HEAVY SNOWFALL
POTENTIAL...AS SURFACE LOW PRESSURE ADVANCES NORTH FROM OFFSHORE
SOUTHERN NEW ENGLAND UP ACROSS THE GULF OF MAINE BY WEDNESDAY
MORNING. THE MAIN FOCUS FOR HEAVY SNOW WILL BE ACROSS NORTHERN NEW
ENGLAND AND BACK INTO THE FAR NORTHERN APPALACHIANS WHERE A
WELL-DEFINED MID LEVEL DEFORMATION ZONE WILL CROSS THE REGION.
SOMEWHAT MARGINAL THERMAL PROFILES THROUGH THIS EVENING WILL
RESULT SOME MIXED PRECIPITATION TYPES CONTINUING...WITH A MIXTURE
OF SLEET/FREEZING AND SOME SNOW. THERMAL PROFILES HOWEVER WILL
GRADUALLY COOL OVERNIGHT AND ESPECIALLY EARLY WEDNESDAY WHICH WILL
ALLOW FOR MOST AREAS OF INTERIOR MAINE AND NORTHERN VERMONT/NEW
HAMPSHIRE TO CHANGE OVER TO ALL SNOW. SOME ADDITIONAL LIGHT ICING
WILL BE EXPECTED...BUT THE DOMINANT HAZARD WILL BE HEAVY SNOW OVER
NORTHWEST MAINE WHERE THE STRONGEST FORCING AND ATLANTIC MOISTURE
TRANSPORT IS EXPECTED. EXPECT ADDITIONAL SNOWFALL AMOUNTS HERE OF
6 TO 10 INCHES LOCALLY...WITH LESSER AMOUNTS OF UP TO A FEW INCHES
OVER NORTHERN VERMONT AND NORTHERN NEW HAMPSHIRE. SNOW WITH THIS
SYSTEM WILL TAPER DOWN BY WEDNESDAY EVENING.

...NORTHERN/CENTRAL PLAINS TO THE UPPER MIDWEST/GREAT LAKES...

A WELL-DEFINED SHORTWAVE TROUGH AND ASSOCIATED SURFACE LOW
EJECTING OUT ACROSS KANSAS THIS AFTERNOON WILL LIFT NORTHEAST
ACROSS NORTHERN MISSOURI AND SOUTHEAST IOWA TONIGHT AND THEN TO
LOWER MICHIGAN BY WEDNESDAY EVENING. STRONG ISENTROPIC LIFT AND AN
AXIS OF ENHANCED FRONTOGENETICAL FORCING TO NORTH OF THE LOW TRACK
IS EXPECTED TO RESULT IN AN AXIS OF MODERATE TO HEAVY SNOW FROM
SOUTHERN SOUTH DAKOTA AND NORTHERN NEBRASKA EAST ACROSS ESPECIALLY
THE NORTHERN THIRD OF IOWA AND INTO SOUTHERN MINNESOTA THROUGH
TONIGHT BEFORE THEN MOVING INTO CENTRAL AND SOUTHWEST WISCONSIN
THROUGH WEDNESDAY. THE MODELS ALSO SHOW A CORRIDOR OF ENHANCED MID
LEVEL LAPSE RATES SETTING UP OVER NORTHERN IOWA AND INTO SOUTHWEST
WISCONSIN TONIGHT THROUGH EARLY WEDNESDAY...AND THIS IS LIKELY TO
RESULT IN SOME THUNDERSTORM ACTIVITY WITH CONVECTIVE SNOWFALL
RESULTING IN ENHANCED SNOWFALL RATES THAT MAY EXCEED 2 INCHES/HR
LOCALLY. THERMAL PROFILES BECOME VERY MARGINAL AHEAD OF THE LOW
CENTER ACROSS SOUTHERN/EASTERN IOWA...NORTHERN ILLINOIS AND FAR
SOUTHERN WISCONSIN OVERNIGHT AND INTO WEDNESDAY GIVEN WARMER
BOUNDARY LAYER TEMPERATURES AND STRENGTHENING WARM ADVECTION.
THUS...EXPECTING MORE IN THE WAY OF RAIN FOR THESE AREAS.
CONSEQUENTLY...A VERY TIGHT SNOWFALL GRADIENT IS EXPECTED TO SET
UP ACROSS THE UPPER MIDWEST. SNOWFALL ACCUMULATIONS OF 6 TO 12
INCHES ARE EXPECTED WITH SOME ISOLATED TOTALS EXCEEDING A
FOOT...ESPECIALLY OVER NORTHERN IOWA AND FAR SOUTHERN MINNESOTA.

...NORTHERN/CENTRAL ROCKIES...

A BROAD UPPER TROUGH WITH EMBEDDED VORT CENTERS WILL WORK IN
TANDEM WITH MID LEVEL MOISTURE AND LOCALIZED UPSLOPE FLOW TO
GENERATE NUMEROUS SNOW SHOWERS OVER THE HIGHER TERRAIN OF THE
NORTHERN/CENTRAL ROCKIES THROUGH WEDNESDAY. EXPECTING A FEW INCHES
OF NEW SNOW FROM THE BITTERROOTS SOUTHEAST DOWN INTO THE
TETONS/WASATCH AND ULTIMATELY THE COLORADO HIGH COUNTRY.


DAYS 2 AND 3...

...GREAT LAKES INTO THE CENTRAL APPALACHIANS/NORTHEAST...

THE UPPER TROUGH AND ASSOCIATED SURFACE WAVE CROSSING THE MIDWEST
ON WEDNESDAY WILL LIFT THROUGH THE GREAT LAKES REGION WEDNESDAY
NIGHT AND THEN ACROSS THE INTERIOR OF THE NORTHEAST ON THURSDAY. A
SWATH OF SEVERAL INCHES OF ACCUMULATING SNOW IS EXPECTED ACROSS
NORTHERN LOWER MICHIGAN AND DOWNSTREAM ACROSS NORTHERN NEW YORK TO
THE NORTH OF THE LOW TRACK. THE THERMAL PROFILES ACTUALLY ARE
CONDUCIVE FOR SOME FREEZING RAIN LOCALLY ACROSS THE INTERIOR OF
THE NORTHEAST AND MAINLY ACROSS EASTERN NEW YORK WHERE A NOSE OF
WARMER AIR ALOFT WILL ARRIVE WITH THE WARM ADVECTION PATTERN AHEAD
OF THE LOW CENTER. BY THURSDAY NIGHT AND FRIDAY...THE
TROUGH/SURFACE WAVE WITH THIS SYSTEM WILL BEGIN TO LIFT OUT...BUT
IN ITS WAKE WILL BE A STRONG COLD AIR ADVECTION PATTERN THAT WILL
FOSTER A WIDESPREAD AREA OF LAKE EFFECT SNOW SHOWERS AND SOME
SQUALLS ACROSS THE UPPER AND LOWER GREAT LAKES AND INTO THE
CENTRAL/NORTHERN APPALACHIANS. SEVERAL INCHES OF NEW SNOW WILL BE
EXPECTED LOCALLY.

...NORTHERN/CENTRAL ROCKIES...

SOME LINGERING TROUGHING AND MOISTURE OVER THE HIGHER TERRAIN OF
THE NORTHERN/CENTRAL ROCKIES WILL FOSTER A FEW MORE SNOW SHOWERS
AND POSSIBLY UPWARDS OF A COUPLE OF INCHES OF NEW SNOW. THIS
SHOULD TAPER DOWN THOUGH GRADUALLY BY FRIDAY.

ORRISON

$$




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