Quantitative Precipitation Forecast
Issued by NWS

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FOUS11 KWBC 262038
QPFHSD

PROBABILISTIC HEAVY SNOW AND ICING DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
338 PM EST THU FEB 26 2015

VALID 00Z FRI FEB 27 2015 - 00Z MON MAR 02 2015

DAYS 1 TO 3...

...PACIFIC NORTHWEST/CALIFORNIA/GREAT BASIN/CENTRAL TO SOUTHERN
ROCKIES/...

AN INITIAL SHORTWAVE/JET SYSTEM WILL DIVE SOUTHEASTWARD ACROSS THE
GREAT BASIN ON FRIDAY AND THEN DAMP OUT AS IT SHEARS WITHIN THE
DEEP BROAD TROUGH COVERING THE EASTERN TWO THIRDS OF THE COUNTRY
BY SATURDAY. THIS SYSTEM WILL STILL BRING PACIFIC MOISTURE QUITE
FAR INLAND AND SPREAD SIGNIFICANT SNOW ACROSS THE CENTRAL AND
SOUTHERN ROCKIES AND INTO PORTIONS OF THE SOUTHERN PLAINS ON DAY
1...AS UPSLOPE FLOW AROUND THE WESTERN PERIPHERY OF A LARGE/COLD
ANTICYCLONE OVER THE PLAINS/MISSISSIPPI VALLEY AIDS IN THE
DEVELOPMENT OF SNOWFALL EAST OF THE ROCKIES INTO THE RED RIVER
VALLEY OF TEXAS/OKLAHOMA.  WHILE THERE IS ONLY RELATIVELY LOW
PROBABILITIES THAT ACCUMULATIONS WILL EXCEED 4 INCHES IN THE TEXAS
PANHANDLE...THE HEAVIEST SNOW IS LIKELY ALONG THE SANGRE DE CRISTO
RANGE IN SOUTHERN COLORADO INTO NORTH CENTRAL NEW MEXICO WHERE
THERE IS A MODERATE TO HIGH PROBABILITY OF 4 TO 8 INCHES OF SNOW
WITH SOME AREAS POSSIBLY RECEIVING AS MUCH AS A FOOT OF SNOW.

THIS WILL BE THE BEGINNING OF A SIGNIFICANT SNOWY PERIOD
ESPECIALLY ACROSS THE CENTRAL AND SOUTHERN ROCKIES THROUGH THE
FORECAST PERIOD. ONCE THIS FIRST SYSTEM PASSES...A SECOND AND MORE
WIDESPREAD SYSTEM WILL PROGRESS SOUTHEASTWARD FROM THE PACIFIC
NORTHWEST AND AMPLIFY OVER THE SOUTHWESTERN US WITH A BROAD UPPER
SOUTHWESTERLY FLOW DEVELOPING FROM SOUTHERN CALIFORNIA EASTWARD
ACROSS THE SOUTHWEST ACROSS THE SOUTHERN ROCKIES INTO THE SOUTHERN
AND CENTRAL PLAINS ON DAYS 2 INTO 3/FRIDAY EVENING THROUGH SUNDAY
EVENING.  AS THE SYSTEM MOVES SOUTHEASTWARD ON DAY 1...SIGNIFICANT
SNOW WILL OCCUR IN THE WASHINGTON AND OREGON CASCADES...AND
SPREADING SOUTH AND EASTWARD INTO THE MOUNTAINS OF NORTHERN
CALIFORNIA AND PORTIONS OF THE GREAT BASIN...ESPECIALLY EASTERN
OREGON AND NORTHERN NEVADA.

BY DAY 2/FRIDAY EVENING INTO SATURDAY...THE AMPLIFYING TROUGH WILL
PRODUCE SOME VERY HEAVY SNOW ESPECIALLY ACROSS THE MOUNTAINS OF
SOUTHERN UTAH AND ESPECIALLY ACROSS THE SAN JUAN MOUNTAINS AND
AGAIN ACROSS THE SANGRE DE CRISTO PEAKS OF COLORADO INTO NORTHERN
NEW MEXICO.  HEAVY SNOW IS ALSO LIKELY TO FALL IN THE HIGHER PEAKS
OF THE SIERRA/PORTIONS OF THE HIGH ELEVATIONS OF CENTRAL NEVADA
AND INTO NORTHERN ARIZONA.  SNOWFALL IN THE SAN JUANS IN
SOUTHWESTERN COLORADO IS EXPECTED TO BE IN AT LEAST THE 1 TO 2
FOOT RANGE. RESIDUAL SNOW WILL ALSO FALL ACROSS PORTIONS OF
EASTERN OREGON/CENTRAL AND SOUTHERN WYOMING/SOUTHWESTERN MONTANA
AND NORTHWESTERN WYOMING. SOME SNOW WILL ALSO AFFECT THE MOUNTAINS
OF SOUTHERN CALIFORNIA.

WHILE THE TROUGH SUBSIDES SLOWLY SOUTHWARD JUST OFF THE COAST OF
SOUTHERN CALIFORNIA ON DAY 3/SATURDAY EVENING INTO
SUNDAY...SOUTHWESTERLY FLOW CONTINUES TO FLOW NORTHEASTWARD ACROSS
THE SOUTHWEST INTO THE CENTRAL ROCKIES AND SNOW WILL CONTINUE TO
FALL FROM THE SIERRA EASTWARD ACROSS THE GREAT BASIN INTO THE
CENTRAL ROCKIES WITH THE SAN JUAN EXPECTING TO RECEIVE THE
HEAVIEST AMOUNTS AGAIN ALTHOUGH THE AMOUNTS SHOULD NOT BE AS GREAT
AS DURING DAY 2..


...DAYS 2 TO 3...

THE SOUTHERN/CENTRAL PLAINS/MID TO UPPER MISSISSIPPI VALLEY/GREAT
LAKES/NORTHEAST...

THE COMBINATION OF SHORTWAVE ENERGY EMANATING FROM THE
SOUTHWESTERN TROUGH AND A DIGGING TROUGH MOVE SOUTH AND EASTWARD
FROM SOUTH CENTRAL CANADA TOWARD THE UPPER MIDWEST WILL PRODUCE AN
EXPANDING AREA OF SNOWFALL SPREADING EASTWARD WITHIN THE SOUTHERLY
FLOW BEHIND THE RETREATING ARCTIC HIGH PRESSURE SYSTEM.  RAPIDLY
BUILDING HEIGHTS ACROSS THE SOUTHEAST US ON DAY 3 WILL HELP CREATE
AN EXPANDING BAROCLINIC ZONE ACROSS THE CENTRAL AND EASTERN US.
WHILE THERE APPEARS TO BE LITTLE INDICATION THAT A STRONG SURFACE
SYSTEM WILL DEVELOP...SIGNIFICANT QPF WILL DEVELOP WITHIN THIS
BAROCLINIC ZONE AND THE BULK OF THE HEAVIEST PRECIPITATION WILL
FALL AS SNOW WHILE RESIDUAL LOW LEVEL COLD AIR OVER THE SOUTHERN
PLAINS AND OVER THE MID MISSISSIPPI VALLEY AND LOWER OHIO VALLEY
COULD LEAD TO SOME FREEZING RAIN/SLEET. THERE IS A MODERATE TO
HIGH PROBABILITY THAT A STRIP OF 4 TO 8 INCHES OF SNOW WILL FALL
FROM NORTHERN MISSOURI ACROSS NORTHERN ILLINOIS/INDIANA AND OHIO.
IF PRECIPITATION MOVES PAST THE APPALACHIANS ON SUNDAY...FREEZING
RAIN COULD ALSO BE POSSIBLE ALONG THE EASTERN SLOPES OF THE
APPALACHIANS ALTHOUGH THE IMPACT IS QUESTIONABLE WHEN OCCURRING
DURING THE DAYLIGHT HOURS WHEN INSOLATION MAY HELP SOME ROAD
SURFACES WARM UP.


THE PROBABILITY OF 0.25 INCHES OR GREATER ICING IS LESS THAN 10
PERCENT.

KOCIN

$$





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