THE WEATHER PREDICTION CENTER

COLLEGE PARK, MD


PROBABILISTIC HEAVY SNOW AND ICE DISCUSSION




PROBABILISTIC HEAVY SNOW AND ICING DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
350 AM EST SAT FEB 28 2015

VALID 12Z SAT FEB 28 2015 - 12Z TUE MAR 03 2015


DAYS 1-3...

...SIERRA/GREAT BASIN/SOUTHWEST/CENTRAL AND SOUTHERN ROCKIES...

A LONG DURATION PRECIPITATION EVENT...AFFORDED BY A SLOW MOVING
UPPER TROUGH/RETROGRADING LOW CENTERED OVER CA...IS EXPECTED TO
CONTINUE THROUGH THE PERIOD.  WHILE WIDESPREAD SNOWS ARE EXPECTED
ACROSS THE REGION...THE HEAVIEST ACCUMULATIONS OF THE PERIOD ARE
EXPECTED TO FOCUS ALONG THE SAN JUANS OVER SOUTHWESTERN CO INTO
NORTH CENTRAL NM...WHERE AT LEAST A SLIGHT RISK FOR A FOOT OR MORE
IS INDICATED ON ALL THREE DAYS.  HEAVY TOTALS EXCEEDING A FOOT OR
MORE ARE ALSO POSSIBLE ALONG THE MOGOLLON RIM OF NORTHERN
AZ...NORTHWARD INTO THE SOUTHERN WASATCH ON DAYS 1-2.  BY DAY 3
THE HEAVY SNOW THREAT...WITH A FOOT OR POSSIBLE...IS EXPECTED TO
EXTEND NORTH THROUGH THE ROCKIES INTO NORTHWESTERN CO...AS A
SHORTWAVE EJECTING OUT OF THE TROUGH REORIENTS THE BETTER
MOISTURE/DYNAMICS FURTHER TO THE NORTHWEST. WPC AMOUNTS UTILIZED
WPC QPF AND THERMAL PROFILES FROM THE NCEP GUIDANCE AND THE ECMWF.

...CENTRAL AND SOUTHERN PLAINS TO THE NORTHEAST...

INITIATED BY ISENTROPIC LIFT AND WEAK MID LEVEL ENERGY EJECTING
OUT THE WESTERN TROUGH AND THEN SUSTAINED BY NORTHERN STREAM
HEIGHT FALLS DROPPING OUT CANADA...LIGHT TO MODERATE SNOWS ARE
EXPECTED FROM THE CENTRAL PLAINS NORTHEASTWARD THROUGH THE MID MS
VALLEY ON DAY 1...WITH A MODERATE RISK OF 4-INCHES EXTENDING FROM
EASTERN KS TO CENTRAL IL.  AS THE NORTHERN STREAM TROUGH SWINGS
ACROSS THE UPPER MIDWEST/GREAT LAKES ON DAY 2...IT WILL SUPPORT
LIGHT TO MODERATE SNOWS FROM THE OH VALLEY THROUGH THE NORTHEAST. 
SOUTH OF THE HEAVY SNOW THREAT...A WINTRY MIX IS EXPECTED.  WHILE
WIDESPREAD ICE ACCUMULATIONS EXCEEDING A QUARTER-INCH ARE NOT
EXPECTED DURING THE DAY 1 PERIOD...A SLIGHT RISK EXISTS ON DAY 2
ACROSS PORTIONS OF THE NORTHERN MID ATLANTIC INTO SOUTHERN NY ON
DAY 2.  WPC AMOUNTS UTILIZED WPC QPF AND THERMAL PROFILES FROM THE
NCEP GUIDANCE AND THE ECMWF ON BOTH DAYS.

PEREIRA





Last Updated: 350 AM EST SAT FEB 28 2015