Quantitative Precipitation Forecast
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FOUS11 KWBC 040742
QPFHSD

PROBABILISTIC HEAVY SNOW AND ICING DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
242 AM EST THU FEB 04 2016

VALID 12Z THU FEB 04 2016 - 12Z SUN FEB 07 2016


DAYS 1 TO 2...

...COASTAL NORTHEAST/MIDDLE ATLANTIC...

IN GENERAL...THERE HAS BEEN A SLIGHT WESTWARD TREND IN THE MODELS
WITH THE FAST MOVING SYSTEM DEVELOPING ALONG THE OLD FRONTAL
BOUNDARY OFF THE EAST COAST.  A SHARPENING BUT PROGRESSIVE UPPER
LEVEL TROUGH WILL INITIATE A FRONTAL WAVE ALONG THE FRONT
OFFSHORE. IT WILL MOVE RAPIDLY NORTHEASTWARD AND THE WESTERN EDGE
OF A BROAD SHIELD OF QPF WILL OVERSPREAD THE COASTAL AREAS OF THE
MIDDLE ATLANTIC COAST AND EASTERN NEW ENGLAND AS COLDER AIR MOVES
IN FROM THE WEST.  RAIN IS LIKELY TO CHANGE TO SNOW FROM EASTERN
VIRGINIA INTO NEW JERSEY WHERE MARGINAL TEMPERATURES MAY LIMIT
ACCUMULATIONS TO NO MORE THAN AN INCH OR TWO WHILE MORE
SIGNIFICANT SNOW IS LIKELY TO DEVELOP OR BEGIN AS RAIN...THEN
CHANGE TO SNOW ACROSS LONG ISLAND INTO EASTERN NEW ENGLAND.  MUCH
OF THE SNOW WILL END BY FRIDAY AFTERNOON AND EVENING IN DOWNEAST
MAINE.  THERE IS A MODERATE CHANCE OF GREATER THAN 4 INCHES OF
SNOW FROM EASTERN LONG ISLAND TO BOSTON WITH A LOW TO MODERATE
PROBABILITY OF GREATER THAN 8 INCHES OF SNOW IN SOUTHEASTERN
MASSACHUSETTS. GIVEN THAT THERE IS A VERY SHARP GRADIENT ALONG THE
WESTERN EDGE OF THE QPF AND HIGHER AMOUNTS AND THE EXACT TIMING OF
THE CHANGEOVER FROM RAIN TO SNOW...THERE IS STILL ONLY AVERAGE
CONFIDENCE WITH THE FORECAST GIVEN THE SMALL BUT SIGNIFICANT
DIFFERENCES BETWEEN THE HIGH RESOLUTION MODELS AND THE OPERATIONAL
ENSEMBLE SUITE.

DAYS 1 THROUGH 3...

...PACIFIC NORTHWEST/INTER-MOUNTAIN WEST TO UPPER MIDWEST...

AN INITIAL SHORTWAVE TROUGH WILL PASS THROUGH THE MEAN RIDGE
POSITION OVER THE WEST COAST AND HEAD DOWNSTREAM ACROSS THE WEST
BEFORE REACHING THE PLAINS STATES BY FRIDAY MORNING.  ANOTHER
UPPER TROUGH WILL PASS ACROSS THE US CANADIAN BORDER OVER THE
NORTHWEST BY SATURDAY MORNING BEFORE DIVING SOUTH AND EASTWARD
TOWARD THE NORTHERN PLAINS STATES BY SUNDAY MORNING.

THE FIRST SYSTEM IS NOT PARTICULARLY MOIST BUT WILL STILL PRODUCE
SNOWS ACROSS THE CASCADES/BITTERROOTS AND THE MOUNTAINS OF WESTERN
MONTANA/EASTERN IDAHO AND NORTHWESTERN WYOMING...AS WELL AS SOME
MOSTLY LIGHT SNOW ACROSS THE COLORADO ROCKIES NORTHWARD INTO
SOUTHEAST WYOMING. THERE ARE ONLY MOSTLY LOW TO MODERATE CHANCES
OF GREATER THAN 4 INCHES OF SNOW SCATTERED THROUGHOUT THIS REGION
WITH THE GREATEST CHANCES OVER THE BITTERROOTS SEPARATING IDAHO
AND MONTANA.

ON DAY 2/FRIDAY INTO SATURDAY MORNING...THE APPROACH OF THE NEXT
TROUGH TO THE PACIFIC NORTHWEST WILL RESULT IN MORE SNOW FOR THE
OLYMPICS/CASCADES/BLUE MOUNTAINS AND THE BITTERROOTS.  THE
HEAVIEST SNOW IS EXPECTED IN THE WASHINGTON CASCADES WHERE THERE
IS A MODERATE TO HIGH PROBABILITY OF GREATER THAN 8 INCHES WITH
SOME AREAS PICKING UP MORE THAN A FOOT OF SNOW.

ON DAY 3/SATURDAY INTO SUNDAY MORNING...THE TROUGH CONTINUES
DIGGING SOUTH AND EASTWARD AND SOME MOUNTAIN SNOW IS LIKELY TO
FALL ACROSS THE BITTERROOTS INTO THE MOUNTAINS OF NORTHWESTERN
WYOMING...WHERE SOME OF THE HIGHER TOTALS WILL LIKELY BE IN THE 4
TO 8 INCH RANGE.  MOSTLY LIGHT SNOW IS EXPECTED TO DEVELOP OVER
THE UPPER MIDWEST/NORTHERN PLAINS AS THE SURFACE LOW ASSOCIATED
WITH THE TROUGH MOVES TOWARD NORTHERN MINNESOTA.

THE PROBABILITY OF SIGNIFICANT ICING IS LESS THAN 10 PERCENT.

KOCIN


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