Flash Flooding and Damaging Wind in Utah, July 26 to 27, 2011

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
307 PM MDT TUE JUL 26 2011

.SYNOPSIS...MONSOONAL MOISTURE WILL REMAIN IN PLACE OVER CENTRAL
AND SOUTHERN UTAH THROUGH THIS EVENING. SOMEWHAT DRIER AIR WILL
SPREAD ACROSS THE AREA FOR THE LATTER HALF OF THE WEEK...BEFORE A
VERY MOIST AIRMASS SPREADS BACK INTO UTAH DURING THE UPCOMING
WEEKEND AND EARLY NEXT WEEK.

&&

.DISCUSSION...A BROAD UPPER TROUGH IS MAKING ITS WAY ACROSS THE
GREAT BASIN THIS AFTERNOON...TURNING THE FLOW ALOFT A BIT MORE
WESTERLY OVER THE FORECAST AREA. THIS IS ALLOWING DRIER AIR TO
BEGIN TO FILTER INTO NORTHWEST UTAH...THOUGH SOME WELL DEFINED
THUNDERSTORMS HAVE DEVELOPED ALONG THE AXIS BETWEEN THE MOIST AIR
AND DRIER AIR. OVER SOUTHERN UTAH...MONSOONAL MOISTURE REMAINS IN
PLACE...AND NUMEROUS SHOWERS WITH EMBEDDED THUNDERSTORMS ARE
CONTINUING TO DEVELOP AND DRIFT SLOWLY EASTWARD. THESE SLOW MOVING
STORMS WITH HEAVY RAIN HAVE LIKELY PRODUCED SOME AREAS OF FLASH
FLOODING THIS AFTERNOON...AND THE THREAT WILL CONTINUE WELL INTO
THE EVENING. HAVE KEPT EXISTING FLASH FLOOD WARNING AS IS WITH THE
AFTERNOON PACKAGE.

DRIER AIR WILL CONTINUE TO SLOW MAKE ITS WAY INTO THE STATE
THROUGH FRIDAY...BUT PWS ARE ONLY PROGGED TO DROP TO ABOUT
0.75 IN THE GFS...WHICH WOULD STILL ALLOW FOR AFTERNOON CONVECTION
OVER THE HIGHER TERRAIN...PARTICULARLY OVER SOUTHERN AND EASTERN
PORTIONS OF THE FORECAST AREA. EARLIER RUNS OF THE ECMWF WERE A
BIT MORE AGGRESSIVE BRINGING DRIER AIR IN...BUT THE 12Z HAS COME
MOSTLY IN LINE WITH THE GFS. LITTLE CHANGE IS EXPECTED IN
TEMPERATURES OVER THE NEXT FEW DAYS...WITH MAXES EXPECTED TO REACH
VALUES NEAR SEASONAL NORMALS.

BY SATURDAY...GLOBAL MODELS INDICATE THAT THE FLOW ALOFT WILL
BECOME MORE SOUTHERLY ONCE AGAIN ON THE BACK SIDE OF AN AMPLIFYING
RIDGE. THIS WILL ALLOW DEEP MOISTURE THE SPREAD INTO THE FORECAST
AREA ONCE AGAIN...WITH PWS IN EXCESS OF 1.3 INCHES EXPECTED TO
MOVE INTO PORTIONS OF THE STATE BY SUNDAY AFTERNOON. THIS WILL
ALLOW FOR INCREASED COVERAGE OF CONVECTION...WITH THE POSSIBILITY
OF HEAVY RAIN WITH ANY CELLS THAT FORM. THE MOISTURE LOOKS TO
REMAIN IN PLACE THROUGH DAY 7.

&&

.AVIATION...SOUTHERLY WINDS WILL CONTINUE TO SLOWLY DECREASE AT THE
SLC TERMINAL THROUGH AROUND 22Z. WINDS SHOULD THEN TURN NORTHWEST.
THERE IS A 30 PERCENT CHANCE THAT THE SOUTHERLY WINDS WILL REMAIN
AND KEEP THE NORTHWEST FLOW AT BAY. ALSO ISOLATED THUNDERSTORMS
COULD BUMP THE WINDS....DIRECTION DEPENDING ON PROXIMITY TO THE
AIRFIELD. OTHERWISE...VFR CONDITIONS UNDER PARTLY TO MOSTLY CLOUDY
SKIES WILL CONTINUE.

&&

.FIRE WEATHER...SOME DRYING HAS SPREAD INTO NORTHWEST UTAH THIS
AFTERNOON WHILE DEEP MOISTURE REMAINS IN PLACE ACROSS THE REMAINDER
OF THE AREA. WETTING RAINS WILL CONTINUE ACROSS THE SOUTHWEST INTO
THIS EVENING WITH A GOOD CHANCE OF WETTING RAINS ACROSS CENTRAL AND
SOUTHEAST PORTIONS. MODEST DRYING IS FORECAST TO SPREAD ACROSS THE
DISTRICT FROM THE WEST STARTING WEDNESDAY AND CONTINUING INTO
THURSDAY. SHOWERS AND THUNDERSTORMS ARE STILL POSSIBLE WEDNESDAY AND
THURSDAY BUT THEY WILL BE LESS NUMEROUS AND THE THREAT OF WETTING
RAINS WILL BE LOWER. MOISTURE WILL START TO SPREAD BACK INTO THE
DISTRICT FRIDAY WITH A DEEPLY MOIST AIRMASS FORECAST TO BE OVER THE
ENTIRE REGION BY SUNDAY BRINGING AN INCREASED CHANCE OF WETTING
RAINS AND HIGHER HUMIDITIES.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...FLASH FLOOD WATCH UNTIL 10 PM MDT THIS EVENING FOR
     UTZ013-019>021-518.

WY...NONE.
&&

PUBLIC...TRAPHAGAN
FIRE WEATHER...WILENSKY
AVIATION...YOUNG

FOR MORE INFORMATION FROM NOAA/S NATIONAL WEATHER SERVICE VISIT...
HTTP://WEATHER.GOV/SALTLAKECITY (ALL LOWER CASE)

FOR FREQUENTLY ASKED QUESTIONS ABOUT THE AREA FORECAST DISCUSSION
VISIT...
HTTP://WEATHER.GOV/SALTLAKECITY/GENERAL/AFD_FAQS.PHP (ALL LOWER CASE)

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
347 AM MDT TUE JUL 26 2011

UTZ001>016-019>021-517-518-WYZ021-271100-
CACHE VALLEY/UTAH PORTION-NORTHERN WASATCH FRONT-
SALT LAKE AND TOOELE VALLEYS-SOUTHERN WASATCH FRONT-
GREAT SALT LAKE DESERT AND MOUNTAINS-WASATCH MOUNTAIN VALLEYS-
WASATCH MOUNTAINS I-80 NORTH-WASATCH MOUNTAINS SOUTH OF I-80-
WESTERN UINTA MOUNTAINS-WASATCH PLATEAU/BOOK CLIFFS-
WESTERN UINTA BASIN-CASTLE COUNTRY-SAN RAFAEL SWELL-
SANPETE/SEVIER VALLEYS-WEST CENTRAL UTAH-SOUTHWEST UTAH-
UTAHS DIXIE AND ZION NATIONAL PARK-SOUTH CENTRAL UTAH-
GLEN CANYON RECREATION AREA/LAKE POWELL-CENTRAL MOUNTAINS-
SOUTHERN MOUNTAINS-SOUTHWEST WYOMING-
347 AM MDT TUE JUL 26 2011

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

.DAY ONE...TODAY AND TONIGHT

A VERY MOIST AIRMASS ACROSS SOUTHERN UTAH COUPLED WITH A WEATHER
DISTURBANCE PASSING THROUGH THE AREA WILL BRING SHOWERS AND
THUNDERSTORMS CAPABLE OF PRODUCING HEAVY RAINFALL AND RESULTANT
FLASH FLOODING TO SOUTHERN PORTIONS OF THE OUTLOOK AREA THROUGH
THIS EVENING. FLASH FLOODING IS POSSIBLE ACROSS SLOT
CANYONS...SLICK ROCK AREAS AND NORMALLY DRY WASHES.

FURTHER NORTH SCATTERED SHOWERS AND THUNDERSTORMS ARE EXPECTED
ACROSS NORTHERN AND CENTRAL UTAH THIS AFTERNOON AND EVENING.
IN ADDITION TO DANGEROUS LIGHTNING...SMALL HAIL...LOCALLY HEAVY
RAINFALL AND STRONG GUSTY WINDS ARE POSSIBLE WITH THESE STORMS.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY

MOISTURE LOOKS TO LINGER ACROSS THE OUTLOOK AREA THROUGH THE
REMAINDER OF THE WEEK...WHICH WILL MAINTAIN A THREAT FOR AFTERNOON
AND EVENING SHOWERS AND THUNDERSTORMS.

DEEPER MOISTURE LOOKS TO SPREAD BACK INTO THE AREA DURING THE
UPCOMING WEEKEND. THIS WILL BRING A BETTER CHANCE FOR SHOWERS AND
THUNDERSTORMS...ALONG WITH THE POTENTIAL FOR LOCALLY HEAVY
RAINFALL.

.SPOTTER INFORMATION STATEMENT...

WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER
CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES.

FOR MORE INFORMATION FROM NOAA/S NATIONAL WEATHER SERVICE VISIT...
HTTP://WEATHER.GOV/SALTLAKECITY (ALL LOWER CASE)

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
345 PM MDT TUE JUL 26 2011

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0330 PM     FLOOD            KEARNS                  40.65N 112.01W
07/26/2011                   SALT LAKE          UT   COUNTY OFFICIAL

            STREET FLOODING...MANHOLE COVERS BLOWN OFF DUE TO
            FLOODING.

0330 PM     HAIL             KEARNS                  40.65N 112.01W
07/26/2011  E0.75 INCH       SALT LAKE          UT   COUNTY OFFICIAL

            DIME SIZED HAIL REPORTED IN KEARNS NEAR 5400S AND 5300 W.

&&

CRK