Quantitative Precipitation Forecast
Issued by NWS

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FOUS11 KWBC 120920
QPFHSD

PROBABILISTIC HEAVY SNOW AND ICING DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
420 AM EST FRI FEB 12 2016

VALID 12Z FRI FEB 12 2016 - 12Z MON FEB 15 2016

...PACIFIC NORTHWEST/NORTHERN ROCKIES...

AN UPPER THROUGH MOVING INLAND OVER THE NORTHWEST...COMBINED WITH
A SURGE OF PACIFIC MOISTURE...WILL FOSTER WIDESPREAD PRECIPITATION
ACROSS THE PACIFIC NORTHWEST AND NORTHERN ROCKIES FRIDAY INTO
SATURDAY.  ANOMALOUSLY WARM CONDITIONS IN PLACE WILL INITIALLY
KEEP SNOW CONFINED TO THE HIGHEST PEAKS...BUT AS TEMPERATURES AND
SNOW LEVEL DROP BEHIND THE ASSOCIATED COLD FRONT...SNOW WILL BEGIN
TO ACCUMULATE ALONG THE OLYMPICS...WASHINGTON CASCADES...AND
NORTHERN ROCKIES.  ONCE THE UPPER TROUGH PROGRESSES DOWNSTREAM
LATE SATURDAY...PERSISTENT ONSHORE FLOW INTO THE TERRAIN SHOULD
SUPPORT MODERATE TO HEAVY SNOW OVER THE FAVORED SLOPES OF THE
TERRAIN THROUGH THE WEEKEND.  MODELS WERE IN REASONABLE AGREEMENT
ACROSS THE REGION...SO MINIMAL ADJUSTMENTS WERE MADE TO
CONTINUITY.


...NORTHERN PLAINS/UPPER TO MIDDLE MISSISSIPPI VALLEY TO THE
OHIO/TENNESSEE VALLEYS AND CENTRAL APPALACHIANS...

A WIDE SWATH OF LIGHT TO MODERATE ACCUMULATING SNOW WILL BE
POSSIBLE OVER PORTIONS OF THE NORTHERN PLAINS AND UPPER
MISSISSIPPI VALLEY...SOUTHEASTWARD ACROSS THE OHIO VALLEY...AND
INTO THE CENTRAL APPALACHIANS AS AN UPPER TROUGH EJECTS OUT OF THE
NORTHERN ROCKIES ON SATURDAY AND PROGRESSES TOWARDS THE GREAT
LAKES ON SUNDAY.  ON SATURDAY...AN AXIS OF LOW LEVEL WAA AND
MOISTURE ADVECTION WILL FOCUS THE HEAVIEST SNOW OVER THE EASTERN
DAKOTAS AND INTO WESTERN MINNESOTA.  BY SUNDAY INTO
MONDAY...SHORTWAVE ENERGY DIGGING INTO THE SOUTHERN PLAINS AND A
SURFACE LOW SPINNING UP OVER TEXAS COULD SHIFT THE FOCUS FOR THE
HEAVIEST SNOW TO THE LOWER OHIO VALLEY AND CENTRAL APPALACHIANS.
FREEZING RAIN WILL ALSO BE POSSIBILITY FOR PORTIONS OF THE MIDDLE
MISSISSIPPI AND TENNESSEE VALLEYS AS RETURN FLOW FROM THE GULF
OVERRUNS AN ARCTIC AIRMASS IN PLACE.  HOWEVER...DETERMINISTIC
GUIDANCE CONTINUES TO SHOW LARGE FLUCTUATIONS WITH EACH RUN...SO
THIS REMAINS A LOW CONFIDENCE FORECAST.


...GREAT LAKES...

BROAD CYCLONIC FLOW WILL CONTINUE TO SUPPORT WIDESPREAD LAKE
EFFECT SNOWS FRIDAY INTO SATURDAY.  ACTIVITY SHOULD BEGIN TO WIND
DOWN SATURDAY EVENING AS A STRONG SURFACE HIGH SLIDES INTO THE
REGION.  MODELS WERE IN GOOD AGREEMENT...SO MINIMAL ADJUSTMENTS
WERE MADE TO CONTINUITY.


...EASTERN NORTH CAROLINA AND SOUTHEAST VIRGINIA...

WEAK MID-LEVEL ENERGY ROUNDING THE BASE OF A BROAD TROUGH IN THE
EAST WILL HAVE THE POTENTIAL TO PRODUCE A QUICK BURST OF SNOW AND
WINTRY MIX ON FRIDAY AS THE SHORTWAVE AND EVENTUAL SURFACE LOW
STREAKS OFFSHORE FRIDAY EVENING.  LATEST THERMAL PROFILES WOULD
SUPPORT AN AXIS OF SNOW/SLEET...AND MAYBE EVEN FREEZING
RAIN...ACROSS EASTERN NORTH CAROLINA.


...MAINE...

AN INVERTED SURFACE TROUGH EXTENDING BACK FROM A LOW LIFTING INTO
THE CANADIAN MARITIMES IS EXPECTED TO FOCUS AN AREA OF MODERATE TO
HEAVY SNOW ACROSS PORTIONS OF MAINE ON SATURDAY INTO SATURDAY
NIGHT.  THERE IS STILL A LOT OF UNCERTAINTY WITH EXACTLY WHERE
THIS AXIS SETS UP.  MINIMAL ADJUSTMENTS WERE MADE TO CONTINUITY
SINCE IT APPEARED IN THE MIDDLE OF THE LATEST MODEL SPREAD.



THE PROBABILITY OF SIGNIFICANT ICING IS LESS THAN 10 PERCENT.

GERHARDT

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