Flash Flood in Utah, July 20, 2005

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
940 AM MDT WED JUL 20 2005

.SYNOPSIS...A STRONG UPPER LEVEL RIDGE OF HIGH PRESSURE WILL REMAIN
OVER THE AREA. INCREASING MOISTURE WILL LEAD TO MORE CLOUDS AND
SHOWERS LATER IN THE WEEK.

&&

.DISCUSSION...PRECIPITABLE WATER AS SEEN IN GOES
IMAGERY...RAOB...AND GPS INSTRUMENT AT THE WFO ALL SHOW INCREASES
OVER THE PAST 24 HOURS. MOST SURFACE DEWPOINTS AT 15Z ARE 5-10
DEGREES F HIGHER THAN SAME TIME YESTERDAY.  NO DOUBT ABOUT IT THE
LONG AWAITED INCREASE IN MOISTURE IS UNDERWAY.  SLC SOUNDING STILL
HAS A SUBSTANTIAL SUBSIDENCE INVERSION NEAR 450 MB SO IT MAY BE
TOUGH FOR CONVECTION TO GET GOING IN THE NORTH TODAY. BUT EXPECT
UINTAS...CENTRAL WASATCH PLATEAU...AND THE MOUNTAINS SOUTH OF I-70
TO ALL SEE SOME ISOLATED TO WIDELY SCATTERED THUNDERSTORMS THIS
AFTERNOON AND EVENING.

UPPER LEVEL TROUGH NEAR 135W/35N BEGINS TO EJECT NE TOMORROW AND
THIS WILL SHIFT THE RIDGE AXIS EASTWARD. FLOW BECOMES MORE SOUTHERLY
AND THIS SHOULD ENHANCE MOISTURE TRANSPORT NORTHWARD INTO UT. MODELS
ALL SHOW A GOOD SURGE NORTHWARD OF MOISTURE OVER THE NEXT FEW DAYS
IN RESPONSE TO THE EJECTION OF THE AFOREMENTIONED SHORT WAVE.  SO WE
SHOULD SEE INCREASING CONVECTIVE ACTIVITY EACH OF THE NEXT FEW DAYS.

ONCE THE MOISTURE IS IN PLACE...DIURNAL CONVECTION LIKELY TO
CONTINUE EVEN HAS UPPER PATTERN RETURNS TO LESS FAVORABLE RIDGE
LOCATION.

&&

.FIRE WEATHER...SIGNIFICANT INCREASE IN MOISTURE HAS BEGUN AND WILL
CONTINUE NEXT FEW DAYS. THIS WILL BRING CLOUD COVER AND EVENTUALLY
LOCALLY HEAVY SHOWERS WITH MUCH HIGHER HUMIDITY. SOME ACTIVITY IN
THE SOUTH TODAY...INCREASING AND BECOMING MORE WIDESPREAD THURSDAY
AND AGAIN FRIDAY.

&&

.AVIATION...NONE. SEE SLCTAFSLC.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...HEAT ADVISORY FOR LOWER ELEVATIONS OF WASHINGTON
     COUNTY THROUGH FRIDAY...SEE SLCNPWSLC.
WY...NONE.

&&

DUNN

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
500 AM MDT WED JUL 20 2005

UTZ001>021-WYZ021-211300-
CACHE VALLEY/UTAH PORTION-CASTLE COUNTRY-
CENTRAL AND SOUTHWEST MOUNTAINS-
GLEN CANYON RECREATION AREA/LAKE POWELL-
GREAT SALT LAKE DESERT AND MOUNTAINS-HENRY MOUNTAINS-
NORTHERN WASATCH FRONT-SALT LAKE AND TOOELE VALLEYS-SAN RAFAEL SWELL-
SANPETE/SEVIER VALLEYS-SOUTH CENTRAL UTAH-SOUTHERN WASATCH FRONT-
SOUTHWEST UTAH-SOUTHWEST WYOMING-UTAHS DIXIE AND ZION NATIONAL PARK-
WASATCH MOUNTAIN VALLEYS-WASATCH MOUNTAINS I-80 NORTH-
WASATCH MOUNTAINS SOUTH OF I-80-WASATCH PLATEAU/BOOK CLIFFS-
WEST CENTRAL UTAH-WESTERN UINTA BASIN-WESTERN UINTA MOUNTAINS-
500 AM MDT WED JUL 20 2005

THIS HAZARDOUS WEATHER OUTLOOK IS FOR MOST OF THE WESTERN TWO-THIRDS
OF UTAH AND EXTREME SOUTHWEST WYOMING.

.DAY ONE...TODAY

A STRONG UPPER LEVEL RIDGE OF HIGH PRESSURE WILL DOMINATE
THROUGH FRIDAY AND BRING HOT TEMPERATURES TO THE REGION. NORTHERN
VALLEYS WILL HAVE TEMPERATURES BACK NEAR 100 DEGREES TODAY. EXCESSIVE
HEAT WILL CONTINUE ACROSS SOUTHERN UTAH...WITH HIGH TEMPERATURES IN
THE LOWER ELEVATIONS OF WASHINGTON COUNTY AROUND ST GEORGE EXCEEDING
110 DEGREES. A HEAT ADVISORY REMAINS IN EFFECT FOR THE LOWER
ELEVATIONS OF WASHINGTON COUNTY.

.DAYS TWO THROUGH SEVEN... THURSDAY THROUGH TUESDAY

UPPER LEVEL RIDGE OF HIGH PRESSURE WILL REMAIN ACROSS THE REGION
THROUGH FRIDAY...WITH TEMPERATURES APPROACHING OR EXCEEDING
RECORD LEVELS. THUNDERSTORMS WILL INCREASE IN COVERAGE FROM
THURSDAY INTO THE WEEKEND. INITIALLY MOST STORMS WILL HAVE
LITTLE RAINFALL. THUNDERSTORMS COULD PRODUCE LOCALLY HEAVY RAIN FROM
FRIDAY THROUGH THE WEEKEND.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME.

AOT