Damaging Winds in Utah, August 20, 2001

UTAH AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
250 PM MDT MON AUG 20 2001

SYNOPSIS...MOIST AND UNSTABLE AIR  WILL REMAIN OVER UTAH TONIGHT AND
TUESDAY.  BY WEDNESDAY THE AIR MASS OVER THE STATE WILL BE DRY AND
STABLE.

DISCUSSION...SHORTWAVE MOVING SLOWLY EAST ALONG UT/AZ BORDER.  IT
SHOULD KEEP QUITE A BIT OF CONVECTION GOING THROUGH THE EVENING OVER
THE SOUTHEAST.  WILL KEEP FLASH FLOOD WATCH GOING AS IS FOR THE
EVENING.  AT THE SAME TIME SOME SUPPRESSION EVIDENT OVER SOUTHWEST
UT WHERE IT SHOULD BE FAIRLY QUITE THIS EVENING.  OVER THE NORTH IT
MAY GET MORE ACTIVE AS DIVERGENCE ALOFT IS FORECAST TO INCREASE OVER
THE AREA THROUGH THIS EVENING.  FAIRLY RAPID DEVELOPMENT OF
CONVECTION JUST SOUTHWEST OF ENV MAY BE AN INDICATION OF THE
DIVERGENCE STARTING TO DEVELOP.  THIS IS ON THE FRINGE OF AN AREA
THAT WOULD NORMALLY SHOW SOME DIURNAL DEVELOPMENT ABOUT NOW BUT
TODAYS STRONGEST CELLS ARE LITTLE FARTHER NORTH AND EAST THAN WOULD
USUALLY BE EXPECTED.  18Z ETA IS EVEN A LITTLE STRONGER ON THIS
DIVERGENCE AND IF CORRECT MIGHT ALLOW SOME OF THE STORMS TO BECOME
STRONG.  WILL KEEP SCATTERED ACTIVITY OVER THE NORTH AND EAST FOR
THIS EVENING WITH ONLY A SLIGHT CHANCE PLANNED FOR THE SOUTHWEST.

BY TOMORROW THERE IS SOME DRYING BEGINNING OVER THE WEST BUT AGAIN
THE 18Z ETA ISNT AS FAST ON THE DRYING...ESPECIALLY OVER THE
SOUTHWEST.  WE ALSO HAVE A LARGER SCALE TROF MOVING ACROSS THE GREAT
BASIN AND AGAIN THERE IS CONSIDERABLE DIVERGENCE FORECAST OVER MUCH
OF UT AT MIDDAY.  THE NEW ETA ALSO PUTS -4 LIFTED INDICES AND CAPE
VALUES AROUND 1500 OVER THE WASATCH FRONT AT MIDDAY TUE.  WE WILL
ONLY GO WITH SCATTERED ACTIVITY FOR NOW BUT WE MAY HAVE TO BEEF THAT
UP IF THE LATEST MODEL TRENDS ARE RIGHT.  WE MAY ALSO HAVE A HIGHER
RISK OF SOME SEVERE WEATHER WITH THE INCREASED INSTABILITY...
RELATIVELY HIGH CAPE VALUES AND PROXIMITY OF A WEAK JET.  BUT ITS A
LITTLE TOO EARLY TO REALLY HIT THAT IDEA HARD.

BY WEDNESDAY STRONG DRYING IS EXPECTED ALTHOUGH THERE MAY STILL BE A
LITTLE MOISTURE OVER THE EASTERN PART OF THE AREA.  FOR THE REST OF
THE EXTENDED PERIOD IT WILL PROBABLY REMAIN DRY.  THERE IS A HINT IN
THE MODELS OF SOME INCREASE IN MOISTURE OVER THE EXTREME EAST OVER
THE WEEKEND BUT WE WONT ADDRESS THAT FOR NOW.  WE SHOULD SEE NEAR
SEASONAL TEMPERATURES THROUGH FRIDAY THEN WARM A FEW DEGREES OVER
THE WEEKEND.

SLC 333- CDC 233- SANDERS

.SLC...FLASH FLOOD WATCH SOUTH CENTRAL UT UNTIL 0400Z.