Heavy Snow in Utah, February 27, 2001

UTAH AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
1020 AM MST MON FEB 26 2001

SYNOPSIS...RELATIVELY DRY NORTHERLY FLOW WILL BE OVER NORTHERN UTAH
TODAY WITH A MOIST AIRMASS TO THE SOUTH.  THE MOISTURE WILL SPREAD
BACK INTO NORTHERN UTAH TONIGHT.

DISCUSSION...NO BIG SURPRISES ON THE SYNOPTIC SCALE WITH A CLOSED
LOW REMAINING OFF SOUTHERN CA AND A NEW SHORTWAVE DROPING SOUTHWEST
INTO THE WESTERN GREAT BASIN.  THIS HAS BEEN WELL ADVERTISED BY THE
MODELS FOR THE LAST SEVERAL RUNS AND THE PLAN FOR THE NEXT 48 HOURS
HASNT CHANGED MUCH.  THE SHORTWAVE WILL EVOLVE INTO A NEW LOW CENTER
AND EJECT THE OLD LOW OUT AS A WEAKENING SHORTWAVE.  THE EJECTING
WAVE WILL MOVE OVER MOSTLY THE SOUTHERN PART OF UTAH LATE TONIGHT
AND EARLY WEDNESDAY.  THE ONLY SIGNIFICANT CHANGE IN THE NEW MODELS
IS THAT THE EJECTING SHORTWAVE MOVES A LITTLE FARTHER NORTH OVER
WESTERN UT AND WILL PUT A LITTLE BETTER CHANCE OF SOME SNOW SHOWERS
IN AT LEAST THE SOUTHERN HALF OF THE WASATCH FRONT LATE TONIGHT AND
WED.  AGREE WITH THE PREVIOUS IDEA THAT WE MAY NEED A SNOW ADVISORY
TONIGHT AND WEDNESDAY MORNING FOR THE SOUTHERN MOUNTAINS AS THE
SHORTWAVE MOVES PAST.

IN THE SHORT TERM CONDITIONS ARE IMPROVING THIS MORNING IN MOST
AREAS AS THE DEFORMATION ZONE THAT HAS BEEN OVER CENTRAL UT IS BEING
SQUEEZED OUT OF EXISTANCE.  THE EVOLVING LOW FROM THE NEW SHORTWAVE
WILL TURN THE FLOW SOUTHERLY THROUGHOUT THE FORECAST AREA DURING THE
DAY WITH THE DEFORMATION TOTALLY DISAPPEARING.  WILL BE UPDATING TO
IMPROVE CONDITIONS OVER MUCH OF THE AREA FOR THIS AFTERNOON. THIS IS
ESPECIALLY TRUE ALONG THE ARIZONA BORDER.  HOWEVER THE AIRMASS IN
THAT AREA IS SOMEWHAT UNSTABLE AT THE LOW LEVELS AND CUMULUS ALREADY
EVIDENT ON VISIBLE IMAGERY SO THERE COULD EASILY BE SCATTERED LIGHT
SHOWER ACTIVITY DEVELOP DURING THE AFTERNOON.

WE HAVE ALSO HAD AN INTERESTING MICROSCALE SITUATION ALONG THE
WASATCH FRONT THIS MORNING.  A SMALL SCALE LOW LEVEL CYCLONIC
CIRCULATION DEVELOPED ABOUT SUNRISE AND PRODUCED ENOUGH LIFT FOR
RAPID LOW LEVEL CLOUD DEVELOPMENT AND EVEN SOME LIGHT SNOW SHOWER
ACTIVITY.  THIS CIRCULATION SHOULD DISINTEGRATE AGAIN BY MIDDAY AS
THE PREVAILING NORTHERLY SURFACE GRADIENT TAKES OVER.  SO WILL ALSO
UPDATE THE WASATCH FRONT ZONES AGAIN (THIRD TIME THIS MORNING) TO
DROP THE SNOW FLURRIES AND BACK OFF ON THE CLOUDINESS FOR THIS
AFTERNOON.

SLC -33 CDC 577  SANDERS

SLC...NONE.