Quantitative Precipitation Forecast
Issued by NWS

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
000
FOUS11 KWBC 220738
QPFHSD

PROBABILISTIC HEAVY SNOW AND ICING DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
337 AM EDT FRI SEP 22 2017

VALID 12Z FRI SEP 22 2017 - 12Z MON SEP 25 2017


DAYS 1-3...

NORTHERN INTER-MOUNTAIN WEST

AN AMPLIFIED UPPER-LEVEL TROUGH WILL DRIFT SLOWLY EAST ACROSS THE
GREAT BASIN AND ROCKIES THROUGH THE WEEKEND. 2 EMBEDDED
CIRCULATIONS ARE FORECAST TO PRODUCE PERIODS OF SNOW. THE FIRST
CIRCULATION IS FORECAST TO BE NEAR 700 MB AS IT MEANDER AROUND
SOUTHERN ID ON DAY 1.
AN UPPER-LEVEL JET STREAK IN THE BASE OF THE 500MB TROUGH OVER
CA/NV AND LIFT NORTH AND EAST TOWARD THE NRN INTER-MOUNTAIN REGION
TO FEATURE FAVORABLE UPPER LEVEL JET DYNAMICS ALONG WITH 700-850MB
FRONTOGENESIS. AREAS OF UPPER DIVERGENCE/LOWER CONVERGENCE SPUR
ASCENT...AIDED BY TOPOGRAPHY ACROSS SOUTHERN ID AND SOUTHWEST MT.
SEVERAL INCHES OF SNOW ARE EXPECTED IN THESE AREAS.

THE MID TO UPPER CLOSED LOW NEAR ID/WY/MT WILL BREAK DOWN ON SAT.
SNOWS SHOULD TAPER IN ID AND MT. THE MODELS SHOW A SECOND
CIRCULATION DEVELOPING NEAR THE AZ/NV/UT BORDER AND MOVE SLOWLY
NORTHEAST ACROSS UT. LIGHT SNOWS ARE FORECAST TO DEVELOP IN THE
FRONTAL CIRCULATION NEAR THE UT UINTAS AND ALSO WIND
RIVER...ABSAROKA...AND BIGHORN RANGES IN WY.

ON SUN, THE MODELS FCST THE 700-500MB CIRCULATION TO DRIFT
NORTHEAST FROM UT INTO SOUTHWEST WY WHILE GRADUALLY WEAKENING.
LOW-MID LEVEL CONVERGENCE NEAR THE CIRCULATION FOCUSES SNOW
POTENTIAL IN TERRAIN FROM NORTHEAST UT INTO SOUTHERN WY AND
NORTHERN CO...WHERE PRE-FRONTAL CONVERGENCE DEVELOPS.  THERE IS
BETTER THAN NORMAL CLUSTERING IN THE MODEL MASS FIELDS SO EACH
SOLUTION WAS WEIGHTED EQUALLY FOR QPF AND TEMPERATURE PROFILES.

THE PROBABILITY OF SIGNIFICANT ICING IS LESS THAN 10 PERCENT.

PETERSEN

$$





USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.