Flash Flooding and Debris Flow in Utah, June 10 to 13, 2015

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
537 PM MDT WED JUN 10 2015

.UPDATE...UPDATED AVIATION SECTION.

&&

.SYNOPSIS...A PACIFIC LOW PRESSURE SYSTEM WILL CROSS THE GREAT
BASIN TONIGHT THROUGH THURSDAY...AND INTERACT WITH TROPICAL
MOISTURE ALREADY IN PLACE. MOISTURE WILL LINGER INTO THE DAY
FRIDAY...BEFORE HIGH PRESSURE DEVELOPS THIS WEEKEND.

&&

.DISCUSSION...A POSITIVELY TILTED MID LEVEL TROUGH EXTENDS ACROSS
THE GREAT BASIN THIS AFTERNOON...AND WILL CONTINUE TO GRADUALLY
TRANSLATE EASTWARD OVERNIGHT INTO THE DAY THURSDAY. A VERY MOIST
BOUNDARY LAYER REMAINS IN PLACE ACROSS THE FORECAST AREA...IN
PARTICULAR ACROSS THE SOUTHEAST WHERE DEW POINTS REMAIN IN THE MID
TO UPPER 50S AND PW VALUES NEAR 1 INCH. THIS AREA HAS BEEN SLOW TO
RECOVER IN THE WAKE OF A MID LEVEL WAVE WHICH PASSED OVERNIGHT
INTO THE MORNING HOURS...AND BROUGHT FAIRLY WIDESPREAD
PRECIPITATION. HOWEVER THE CONVECTION WHICH HAS FORMED HAS
PRODUCED LOCALLY VERY HEAVY RAINFALL...AND THIS WILL CONTINUE INTO
THE EARLY EVENING.

MEANWHILE ALTHOUGH THE NORTH AND WEST REMAIN A BIT DRIER...DEW
POINTS REMAIN IN THE MID TO UPPER 40S AND PW VALUES NEAR 0.75
INCHES THIS AFTERNOON. VERY LIGHT FLOW ALOFT HAS RESULTED IN STORM
MOTIONS BEING NEARLY STATIONARY AND LOCALLY VERY HEAVY RAINFALL
RATES.

AS THE UPPER TROUGH SLOWLY CROSSES THE FORECAST AREA THURSDAY
ANTICIPATE BETTER THUNDERSTORM COVERAGE AREAWIDE OWING TO STRONGER
UPPER FORCING WORKING ON THE VERY MOIST BOUNDARY LAYER. NAM BUFR
SOUNDINGS SUGGEST A FAVORABLE ENVIRONMENT FOR WARM RAIN
PROCESSES THURSDAY...INCLUDING A DEEP WARM CLOUD LAYER...NARROW
CAPE PROFILE WITH SMALL NCAPE...AND VERY LITTLE VERTICAL
SHEAR...WHICH MAY LOCALLY ENHANCE RAINFALL. ADDITIONALLY ACROSS
THE SOUTH...NORTHERLY FLOW DEVELOPING DURING THE AFTERNOON WILL
RESULT IN STORM MOTIONS GENERALLY DOWNBASIN WHICH WILL ENHANCE THE
FLASH FLOOD RISK. AS SUCH HAVE EXTENDED THE GOING FLASH FLOOD
WATCH THROUGH THURSDAY EVENING.

THE UPPER TROUGH IS FORECAST TO PULL EAST OF THE REGION FRIDAY
LEAVING THE FORECAST AREA WITHIN A NORTHWESTERLY FLOW ALOFT.
LINGERING MOISTURE SHOULD REMAIN SUPPORTIVE OF SCATTERED
CONVECTION DURING THE AFTERNOON HOURS. WITH HEIGHTS RISING IN THE
WAKE OF THE DEPARTING WAVE SHOULD ALSO SEE MAX TEMPS RECOVER
SEVERAL DEGREES FROM THURSDAYS HIGHS.

MID LEVEL RIDGING IS FORECAST TO BRIEFLY BUILD OVERTOP OF THE
AREA SATURDAY CONTINUING THE DRYING TREND...WITH ANY CONVECTION
REMAINING ISOLATED AND LIKELY TIED TO THE TERRAIN. SOUTHWESTERLY
FLOW ALOFT IS EXPECTED TO FOLLOW FOR NEXT WEEK ACROSS THE GREAT
BASIN AS AN UPPER TROUGH DEVELOPS ALONG THE PACIFIC NORTHWEST
COAST. THIS WILL KEEP TEMPERATURES NEAR TO SLIGHTLY ABOVE NORMAL
INTO EARLY NEXT WEEK.

&&

.AVIATION...SOUTH WINDS WILL PREVAIL AT KSLC THROUGH THE EVENING.
WINDS COULD SHIFT TO NORTHWEST DURING THE NIGHT AFTER ABOUT 05-07Z
BUT MORE LIKELY WILL BECOME LIGHT AND VARIABLE AT TIMES AFTER 07Z.
THERE IS A 40 PERCENT CHANCE WINDS WILL NOT SHIFT AND REMAIN
SOUTHERLY UNTIL 14-15Z THURSDAY. SHOWERS AT OR NEAR THE TERMINAL
SHOULD HOLD OFF UNTIL AFTER 06-08Z BUT THERE IS AN INCREASING
CHANCE OF SHOWERS THROUGH THE MORNING THURSDAY. CIGS AOB 6000 FEET
ARE POSSIBLE AFTER THE SHOWERS DEVELOP.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...FLASH FLOOD WATCH THROUGH THURSDAY EVENING FOR UTZ010-012-013-
     019>021-517-518.

WY...NONE.
&&

SEAMAN/WILENSKY

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
525 AM MDT WED JUN 10 2015

UTZ001>016-019>021-517-518-WYZ021-111300-
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-
525 AM MDT WED JUN 10 2015

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

.DAY ONE...TODAY AND TONIGHT

SHOWERS AND THUNDERSTORMS WILL CONTINUE TO DEVELOP THROUGH THE DAY
AND INTO THE NIGHTTIME HOURS. DUE TO THE TROPICAL MOISTURE THAT HAS
SPREAD INTO THE AREA...HEAVY RAIN CAN BE EXPECTED WITH SOME OF THE
STORMS.

PRECIPITATION WILL BE HEAVIEST AND MOST WIDESPREAD ACROSS
SOUTHERN AND EASTERN PORTIONS OF THE OUTLOOK AREA THROUGH THIS
AFTERNOON. FOR THE OVERNIGHT HOURS...EXPECT SHOWERS TO INCREASE
FROM WEST-CENTRAL THROUGH NORTHEAST UTAH.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY

THE WET WEATHER WILL CONTINUE ON THURSDAY AS THE TROPICAL
MOISTURE INTERACTS WITH THE NEXT STORM SYSTEM. SCATTERED TO
NUMEROUS SHOWERS AND THUNDERSTORMS WITH LOCALLY HEAVY RAIN CAN BE
EXPECTED.

LINGERING MOISTURE WILL CONTINUE TO PRODUCE ISOLATED TO SCATTERED
SHOWERS AND THUNDERSTORMS THROUGH THE WEEKEND...ALTHOUGH THEY WILL
BECOME INCREASINGLY CONFINED TO THE SOUTHERN AND EASTERN PORTIONS
OF THE OUTLOOK AREA AS DRIER AIR GRADUALLY SPREADS INTO NORTHWEST
UTAH.

.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)

FOR INFORMATION ON POTENTIAL ROAD TRAVEL IMPACTS VISIT...
HTTP://WWW.UDOTTRAFFIC.UTAH.GOV/ROADWEATHERFORECAST.ASPX