Flash Flood Warning 12, NWS Salt Lake City, UT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
345 PM MDT FRI JUN 5 2015

.SYNOPSIS...THE LOW PRESSURE SYSTEM OVER SOUTHERN CALIFORNIA WILL
MOVE NORTHEAST INTO AND THEN THROUGH THE GREAT BASIN THIS
WEEKEND. SHOWERS AND THUNDERSTORMS WILL COVER MUCH OF THE AREA
THROUGH SATURDAY NIGHT...THEN GRADUALLY DECREASE IN AREAL COVERAGE
LATE IN THE WEEKEND.

&&

.SHORT TERM (THROUGH 12Z TUESDAY)...THE UPPER LOW OVER SOUTHERN
CALIFORNIA IS BEGINNING SHOW THE ANTICIPATED NORTHEAST DRIFT LATE
THIS AFTERNOON. THE SLOW NORTHEAST MIGRATION OF THIS FEATURE WILL
OFFER UP WIDESPREAD SHOWERS/STORMS THROUGH SATURDAY...THEN
CONFINED MUCH OF THE CONVECTION TO AREAS NORTH AND EAST OF THE
UPPER LOW LATE IN THE WEEKEND.

THE VERY MOIST AIR MASS AHEAD OF THE ADVANCING LOW...PWAT VALUES
BETWEEN .75 AND 1.00 INCHES ACROSS MUCH OF THE FORECAST AREA...
HAS FUELED SEVERAL SHOWERS AND THUNDERSTORMS THIS AFTERNOON. THE
STRONGEST STORMS ARE SUPPORTED BY THE VORTICITY LOBE ROTATING
NORTH AHEAD OF THE MAIN LOW AND UNDERNEATH THE LEFT EXIT REGION OF
THE UPPER JET OVER SOUTHEAST UTAH. VERTICAL SHEAR IN THE 45 TO 55
KT RANGE THIS AFTERNOON HAS HELPED SUPPORT SEVERE/NEAR SEVERE
CONVECTION THROUGH SOUTH-CENTRAL AND CENTRAL UTAH. THE FAVORABLE
MOISTURE AND SHEAR PROFILE WILL PERSIST INTO THE EVENING AS THE
BEST FORCING CONTINUES NORTH INTO CENTRAL AND PORTIONS OF NORTHERN
UTAH.

THE BROAD AREA OF SYNOPTIC-SCALE LIFT GENERATED FROM THE ADVANCING
UPPER LOW WILL BRING WIDESPREAD PRECIP TO THE NORTHERN AND
EASTERN FLANKS OF THE LOW SATURDAY/SATURDAY NIGHT. SIGNIFICANTLY
DRIER AIR ENTRAINED INTO SOUTHWEST UTAH BY THE UPPER LOW WILL
LIMIT ANY ADDITIONAL CONVECTION ACROSS SOUTHWEST AND SOUTH-CENTRAL
UTAH SATURDAY.

A GRADUALLY WEAKENING OF THE UPPER LOW ON SUNDAY WILL RESULT IN AN
ELONGATED TROUGH EXTENDING FROM SOUTHERN WYOMING THROUGH CENTRAL
CALIFORNIA AND THEN INTO THE EASTERN PACIFIC. LOOKING AT
CONVECTION REMAINING FOCUSED NEAR THE TROUGH SUNDAY AFTERNOON AND
EVENING. THE POTENTIAL FOR HEAVY RAINFALL IS FAIRLY HIGH IN THIS
SITUATION AS THE PWAT VALUES REMAIN HIGH AND THE FLOW ALOFT WEAK
THROUGH MONDAY EVENING.

.LONG TERM (AFTER 12Z TUESDAY)...H7 TEMPS WILL CONTINUE TO CLIMB
TUESDAY...REACHING +12 TO +13 AT KSLC BY 00Z WED. CONTINUE TO
FORECAST THIS AS THE WARMEST DAY OF THE WEEK AS THE RIDGE OVERHEAD
WILL ALREADY BE BREAKING DOWN BY WEDNESDAY.

12Z GLOBAL MODELS SHOWING A BIT LESS SPREAD IN REGARDS TO THE
INITIAL EVOLUTION OF THE NEXT TROUGH TO IMPACT THE EASTERN GREAT
BASIN MID TO LATE WEEK. THE REMNANT LOW OFF THE CALIFORNIA COAST
WILL PHASE INTO A MORE PROGRESSIVE FLOW AHEAD THE NORTHERN BRANCH
WAVE MOVING INTO THE PACNW REGION WEDNESDAY...THEN PROGRESS
THROUGH THE AREA LATE DAY THROUGH THURSDAY. MAINTAINED ISOLATED TO
SCATTERED CONVECTION FOR NOW BUT IF MODEL TRENDS CONTINUE THESE
POPS WOULD BE TOO LOW.

SPREAD INCREASES THURSDAY NIGHT AND FRIDAY...WITH BOTH EC AND THE
GFS REMAINING CONSISTENT IN THEIR SOLUTIONS RUN TO RUN. THE GFS
KEEPS THE NORTHERN BRANCH WAVE NORTH OF THE AREA ALLOWING A MORE
PROGRESSIVE TRACK...NET DRYING AND BUILDING HEIGHTS FROM WEST TO
EAST THE OUTCOME HERE. THE EC DIGS THE NORTHERN BRANCH A BIT MORE
SOUTH AND WEST MAINTAINING BETTER STRUCTURE TO THE MEAN LONG WAVE
TROUGH OVER THE WEST...COOLER AND MORE UNSETTLED CONDITIONS WOULD BE
THE OUTCOME. WITH MODELS BEING SOMEWHAT OUT OF PHASE LATE NEXT WEEK
CONFIDENCE IS RELATIVELY LOW...BUT HAVE TRENDED GRIDS TOWARDS THE EC
SOLUTION AND THAT OF THE PERSISTENTLY WET PATTERN OF LATE.

&&

.AVIATION...SHOWERS AND THUNDERSTORMS ADVANCING NORTH OUT OF
CENTRAL UTAH WILL LIKELY DISSIPATE OR WEAKEN CONSIDERABLY AS THEY
APPROACH THE TERMINAL EARLY THIS EVENING. OUTFLOW WINDS FROM THE
SOUTH WILL HAVE AROUND A 30 PERCENT CHANCE OF PRODUCING GUSTY
SOUTH WINDS AT THE TERMINAL AFTER 02Z. THE CHANCES OF SHOWERS AND
THUNDERSTORMS REACHING THE TERMINAL WILL INCREASE AFTER AROUND
05Z. THIS CONVECTION WILL LIKELY IMPACT THE TERMINAL WITH GUSTY
SURFACE WINDS AND BRIEF RAIN SHOWERS THROUGH EARLY SATURDAY
MORNING.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...NONE.
WY...NONE.
&&

SHORT TERM/AVIATION...CONGER
LONG TERM...MERRILL

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
445 AM MDT FRI JUN 5 2015

UTZ001>016-019>021-517-518-WYZ021-061045-
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-
445 AM MDT FRI JUN 5 2015

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

.DAY ONE...TODAY AND TONIGHT

NUMEROUS SHOWERS AND THUNDERSTORMS CAN BE EXPECTED ACROSS UTAH
TODAY AND TONIGHT AS AN APPROACHING LOW PRESSURE SYSTEM INTERACTS
WITH DEEP MOISTURE. THE GREATEST COVERAGE AND MOST INTENSE
ACTIVITY CAN BE EXPECTED OVER EASTERN AND SOUTHERN UTAH...WHERE
THERE IS A POTENTIAL FOR AN ISOLATED SEVERE THUNDERSTORM OR TWO
THIS AFTERNOON AND EVENING...WITH DAMAGING WIND BEING THE MOST
LIKELY HAZARD. THERE IS ALSO SOME POTENTIAL FOR LOCALLY RAIN AND
FLASH FLOODING.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY

WITH THE LOW PRESSURE SYSTEM AND DEEP MOISTURE IN PLACE OVER THE
FORECAST AREA...NUMEROUS SHOWERS AND THUNDERSTORMS CAN BE
EXPECTED ON SATURDAY...WITH SOME ACTIVITY LINGERING INTO SATURDAY
NIGHT. THERE WILL ONCE AGAIN BE A POTENTIAL FOR LOCALLY HEAVY RAIN
AND FLASH FLOODING...PRIMARILY OVER SOUTHERN AND EASTERN UTAH.

CONVECTIVE ACTIVITY ON SUNDAY SHOULD BE WEAKER IN NATURE AND
GENERALLY CONFINED TO NORTHERN AND CENTRAL 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

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
132 PM MDT FRI JUN 5 2015

UTZ020-021-052015-
SOUTH CENTRAL UTAH UT-GLEN CANYON RECREATION AREA/LAKE POWELL UT-
132 PM MDT FRI JUN 5 2015

...SIGNIFICANT WEATHER ADVISORY FOR SOUTHWESTERN SAN JUAN AND EASTERN
KANE COUNTIES UNTIL 215 PM MDT...

AT 131 PM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
STRONG THUNDERSTORM 8 MILES NORTHEAST OF WAHWEEP...OR 11 MILES NORTH
OF ANTELOPE CANYON NEAR SR 98...MOVING NORTHEAST AT 30 MPH.

PENNY TO NICKEL SIZE HAIL AND WINDS OF 40 TO 55 MPH WILL BE POSSIBLE.

THIS STORM WILL REMAIN OVER MAINLY RURAL AREAS OF SOUTHWESTERN SAN
JUAN AND EASTERN KANE COUNTIES.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

IF THREATENING WEATHER APPROACHES...TAKE SHELTER IN A STURDY
BUILDING.

IF ON OR NEAR LAKE POWELL...GET OUT OF THE WATER AND MOVE INDOORS OR
INSIDE A VEHICLE. REMEMBER...LIGHTNING CAN STRIKE OUT TO 15 MILES
FROM THE PARENT THUNDERSTORM. IF YOU CAN HEAR THUNDER...YOU ARE
CLOSE ENOUGH TO BE STRUCK BY LIGHTNING. MOVE TO SAFE SHELTER NOW. DO
NOT BE CAUGHT ON THE WATER IN A THUNDERSTORM. ROUGH CONDITIONS ARE
EXPECTED ON LAKE POWELL WITH THIS STORM.

&&

LAT...LON 3706 11150 3748 11114 3731 11088 3700 11127
      3700 11141
TIME...MOT...LOC 1931Z 218DEG 27KT 3706 11136

CRK

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
212 PM MDT FRI JUN 5 2015

UTZ020-021-052100-
SOUTH CENTRAL UTAH UT-GLEN CANYON RECREATION AREA/LAKE POWELL UT-
212 PM MDT FRI JUN 5 2015

...SIGNIFICANT WEATHER ADVISORY FOR SOUTH CENTRAL SAN JUAN AND
EASTERN KANE COUNTIES UNTIL 300 PM MDT...

AT 211 PM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
STRONG THUNDERSTORM 25 MILES SOUTHWEST OF HALLS CROSSING...OR 30
MILES NORTHEAST OF ANTELOPE CANYON NEAR SR 98...MOVING NORTHEAST AT
25 MPH.

WINDS OF 40 TO 55 MPH WILL BE POSSIBLE.

LOCATIONS IMPACTED INCLUDE...
BULLFROG...HALLS CROSSING AND DANGLING ROPE MARINA.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

IF THREATENING WEATHER APPROACHES...TAKE SHELTER IN A STURDY
BUILDING.

TORRENTIAL RAINFALL IS ALSO OCCURRING WITH THIS STORM...AND MAY LEAD
TO LOCALIZED FLOODING. DO NOT DRIVE YOUR VEHICLE THROUGH FLOODED
ROADWAYS.

IF ON OR NEAR LAKE POWELL...GET OUT OF THE WATER AND MOVE INDOORS OR
INSIDE A VEHICLE. REMEMBER...LIGHTNING CAN STRIKE OUT TO 15 MILES
FROM THE PARENT THUNDERSTORM. IF YOU CAN HEAR THUNDER...YOU ARE
CLOSE ENOUGH TO BE STRUCK BY LIGHTNING. MOVE TO SAFE SHELTER NOW. DO
NOT BE CAUGHT ON THE WATER IN A THUNDERSTORM.

&&

LAT...LON 3726 11127 3754 11073 3740 11063 3738 11069
      3730 11069 3730 11065 3726 11064 3727 11055
      3721 11054 3713 11056 3720 11062 3716 11066
      3708 11068 3707 11081 3700 11099 3700 11116
TIME...MOT...LOC 2011Z 234DEG 24KT 3722 11103

CRK