Winter Storm in Utah, January 27 to 29, 2002

UTAH AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
400 AM MST SUN JAN 27 2002

.SYNOPSIS...A COLD PACIFIC STORM SYSTEM HAS BROUGHT A SURFACE COLD
FRONT INTO NORTHWEST UTAH EARLY THIS MORNING.  THE STORM AND COLD
FRONT WILL SLOWLY WORK ACROSS THE FORECAST AREA THROUGH MONDAY.

.DISCUSSION...TROUGH OVER PACIFIC NORTHWEST WITH COLD UPPER LEVEL LOW
CENTERED JUST OFF THE COAST OF VANCOUVER ISLAND.  STRONG JET AND
BAROCLINIC ZONE ASSOCIATED WITH THE TROUGH ORIENTED FROM CENTRAL
CALIFORNIA INTO WESTERN MONTANA.  HEAVY SNOWFALL ALREADY OCCURRING IN
NORTHEAST NEVADA AND SOUTHERN IDAHO ALONG THIS BOUNDARY.  BOUNDARY
WILL SAG SLOWLY SOUTHEAST TODAY.  JET STREAKS AND VORT LOBES MAY
TRAVEL ALONG THIS BOUNDARY ENHANCING PRECIP AT TIMES TODAY.  WITH
GOOD LIFT ALONG BOUNDARY....HAVE ISSUED WINTER WEATHER ADVISORIES AND
WARNINGS.  NO DOUBT THAT PRECIP WILL BE SNOW IN THE MOUNTAINS.
BUT...VALLEYS MAY START AS RAIN TODAY DUE TO WARM NIGHT AND THEN
SWITCH TO SNOW AFTER A COUPLE HOURS OF PRECIP.  HITTING ALL NORTHERN
MOUNTAINS WITH WINTER STORM WARNING DUE TO WINDS AND POTENTIAL FOR
HEAVY PRECIP WITH SLOWLY MOVING BOUNDARY THROUGH TONIGHT.  THE
NORTHERN VALLEYS HAVE BEEN ADDRESSED WITH ADVISORIES FOR THE MOST
PART.  THE ONLY EXCEPTION WILL BE A WARNING FOR THE AREAS NEAR THE
IDAHO BORDER WEST OF THE WASATCH WHERE THE BOUNDARY WILL SET UP
FIRST.

IN THE MEANTIME...THE UPPER LEVEL LOW MOVES LITTLE TODAY.  IT TRACKS
A LITTLE FASTER SOUTH DOWN THE WEST COAST STATES STARTING TONIGHT
INTO MONDAY.  THIS IS IN RESPONSE TO RIDGING IN GULF OF ALASKA DUE TO
NEXT SYSTEM MOVING INTO ALEUTIANS.

MODELS LOOK TO CREATE A REAL STRONGLY CONVERGENT BOUNDARY TONIGHT
FROM SLC INTO THE SOUTHWESTERN VALLEYS AS LOW LEVEL COLD AIR PUSHES
INTO THE NORTHERN HALF OF THE STATE.  IN ADDITION...SUBTROPICAL JET
IN COMBINATION WITH POLAR JET PROVIDE GOOD JET COUPLET OVER UTAH.
IF THIS WERE TO SET UP...COULD SEE SIGNIFICANT AMOUNTS OF SNOW BY
MONDAY MORNING.  ONLY PROBLEM THERE WITH HEAVY SNOW WARNING IN THE
VALLEYS IS HOW WARM TODAY WILL BE AHEAD OF THIS BOUNDARY.  CENTRAL
MOUNTAINS COULD DO VERY WELL.  COLD FRONT TO TRACK THROUGH THE STATE
BY MONDAY AFTERNOON AS THE LOW/TROUGH CONTINUES MOVE SOUTHEAST.
SHORT WAVE MOVING OUT OF TROUGH WILL HELP TO ENHANCE PRECIP ACROSS
THE SOUTHERN MOUNTAINS WITH SCATTERED SHOWERS IN THE SOUTHERN
VALLEYS.  ISOLATED TO SCATTERED SHOWERS WILL REMAIN OVER THE NORTHERN
ZONES.  LOW LEVEL COLD AIR HAS NOW PUSHED THROUGH THE FORECAST AREA.

UPPER LEVEL LOW CONTINUES TO MOVE INTO CALIFORNIA BY TUESDAY
MORNING.  THE LOW IS THEN EXPECTED TO TAKE AN EASTERLY TRACK THROUGH
ARIZONA WITH THE LONG WAVE TROUGH AXIS PUSHING THROUGH THE FORECAST
AREA.  MOST NORTHERN ZONES AT THIS TIME WILL BE VOID OF PRECIP.
SOUTHERN ZONES WILL CONTINUE PRECIP AS AREA OF CONVERGENCE PRESENT
FROM CENTRAL UTAH SOUTH.

IMPROVING CONDITIONS OVERNIGHT TUESDAY INTO WEDNESDAY WITH A FEW
LINGERING MOUNTAIN SNOW SHOWERS.  COLD CONDITIONS WILL REMAIN
WEDNESDAY BEFORE RIDGE BUILDS IN BY THURSDAY.  WARMING TO TAKE
PLACE ALOFT WITH VALLEYS TRAPPED IN COLD AIR FRIDAY INTO SATURDAY.
A FAST MOVING TROUGH TO MOVE THROUGH THE WEST SATURDAY IN SPLITTING
PATTERN.  EC DIGS THE FEATURE FARTHER SOUTH THAN MRF AND WILL LEAN
TO EC FOR THIS STORM.

SLC 488 CDC 256  NELSON

.SLC...WINTER STORM WARNING MOUNTAINS NRN UT/SE ID ZONES THROUGH
       MONDAY.
    ...HEAVY SNOW WARNING NRN UT VALLEYS ALONG IDAHO BORDER AND
       MOUNTAIN VALLEYS TODAY.
    ...SNOW ADVISORY CACHE VALLEY THROUGH TONIGHT.