High Wind in Utah, December 30 to 31, 2011

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
420 PM MST FRI DEC 30 2011

.SYNOPSIS...A PACIFIC COLD FRONT WILL ENTER NORTHWEST UTAH THIS
EVENING...THEN SWEEP ACROSS THE REMAINDER OF THE STATE BY SATURDAY
AFTERNOON. PRECIPITATION WILL BE CONFINED TO THE NORTHERN UTAH...
WITH COLDER TEMPERATURES SPREADING ACROSS THE ENTIRE REGION. HIGH
PRESSURE ALOFT WILL RETURN BY LATE IN THE WEEKEND.

&&

.DISCUSSION...THE UPPER TROUGH OVER THE PACIFIC NORTHWEST LATE
THIS AFTERNOON WILL CONTINUE EAST THROUGH THE NORTHERN ROCKIES/NORTHERN
GREAT BASIN TONIGHT THROUGH EARLY SATURDAY. THE ASSOCIATED SURFACE COLD
FRONT WILL REACH NORTHWEST UTAH THIS EVENING...THEN SWEEP SOUTHEAST
ACROSS THE FORECAST AREA BY SATURDAY AFTERNOON. THE LATEST 18Z
MODEL GUIDANCE STILL INDICATED STRONG LOW-LEVEL COLD ADVECTION
BEHIND THE FRONT...WITH A BIT OF A NEW WRINKLE IN THAT MORE OF THE
MID-LEVEL COLD AIR WORKS SOUTH INTO THE FAR NORTHERN MOUNTAINS
OVERNIGHT. GREATER INSTABILITY NEAR THE IDAHO BORDER SHOULD RESULT
IN GREATER OROGRAPHICALLY ENHANCED SNOWFALL TONIGHT. THIS SNOW
ALONG WITH VERY STRONG WINDS NEAR AND ABOVE 700MB SHOULD CREATE
HAZARDOUS MOUNTAIN CONDITIONS IN SNOW AND BLOWING SNOW THROUGH
EARLY SATURDAY. HAVE ADDED A SNOW/BLOWING SNOW ADVISORY TO THE
NORTHERN WASATCH MOUNTAINS /UTZ007/ THROUGH EARLY SATURDAY...WITH
THE EMPHASIS ON THE HIGHER TERRAIN. HAVE DECIDED TO KEEP THE
HIGHLIGHTS OUT OF THE REMAINING NORTHERN MOUNTAINS AS SIGNIFICANT
SNOWS LOOK QUESTIONABLE...EVEN THOUGH WINDS ALONG THE RIDGES WILL
BE QUITE STRONG INTO SATURDAY MORNING.

HAVE LEFT ALL OF THE POST-FRONTAL WIND HIGHLIGHTS IN PLACE WITH
THE AFTERNOON PACKAGE. THE SUPPORTING STRONG SURFACE GRADIENT
COMBINED WITH STRONG WINDS ALOFT AND A STABLE AIR MASS SHOULD
BRING STRONG WINDS IN THE WESTERN UINTA BASIN...SOUTHWEST WYOMING
AND IN THE DOWNSLOPE REGIONS OF WESTERN EMERY/CARBON COUNTIES.
ALSO LOOKING AT A LESSER STRONG WIND EVENT OUT OVER THE SALT FLATS
TONIGHT...THOUGH WITH THE GRADIENT WEAKEN LATE TONIGHT...DOUBT
THIS EVENT WILL EXTEND MUCH INTO SATURDAY.

STRONG RIDGING ACROSS THE WESTERN CONUS BEGINNING LATE IN THE
WEEKEND WILL REMAIN THE DOMINANT FEATURE ACROSS THE INTERIOR WEST
THROUGH MUCH OF THE COMING WEEK. ANY SHORTWAVE ENERGY TRYING TO
PUSH THROUGH THIS RIDGE WILL LIKELY WEAKEN CONSIDERABLY AND GENERATE
LITTLE MORE THAN MID/HIGH CLOUD COVER AS THEY PASS THROUGH UTAH.
THE NEXT BEST THREAT FOR PRECIP LIKELY TO HOLD UNTIL DAY 7 WHEN
BOTH THE GFS AND ECMWF BRING ANOTHER TROUGH INTO THE GREAT BASIN.
THE LATEST GFS CONTINUES TO SUGGEST THAT THIS FEATURE WILL SPLIT
AS IT ENTERS THE REGION...WHICH WOULD FOLLOW IN THE TREND SEEN
SO FAR THIS WINTER SEASON.

&&

.AVIATION...SOUTH WINDS AHEAD OF A COLD FRONT ARRIVING TONIGHT
HAVE LIKELY PEAKED LATE THIS AFTERNOON. CURRENT TIMING FOR FRONTAL
PASSAGE STILL LOOKS TO BE BETWEEN 05 TO 07Z. GUSTY NORTHWEST WINDS
WILL EXIST FOR A FEW HOURS BEHIND THE FRONT...WITH LIGHT NORTHERLY
WINDS LATE TONIGHT. ANY PRECIPITATION FORMING ALONG THE FRONT WILL
INITIAL BE RAIN...THEN TURNING OVER TO SNOW BY AROUND 08Z. CEILING
WILL LOWER TO AROUND 5-6KFT AFTER 06Z...WITH BRIEF PERIODS OF MVFR
CEILINGS/VISIBILITIES IN SNOW AFTER 08Z. PRECIPITATION WILL LIKELY
MOVE EAST OF THE AREA AFTER 13Z...WITH CEILINGS REMAINING NEAR 4-5
KFT THROUGH THE MID-MORNING HOURS.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...HIGH WIND WARNING FROM 4 AM TO 4 PM MST SATURDAY FOR UTZ012.

     WIND ADVISORY FROM MIDNIGHT TONIGHT TO 11 AM MST SATURDAY FOR
     UTZ011.

     WINTER WEATHER ADVISORY FROM 9 PM THIS EVENING TO 8 AM MST
     SATURDAY FOR UTZ007.

     WIND ADVISORY UNTIL 11 AM MST SATURDAY FOR UTZ005.

WY...HIGH WIND WARNING FROM 10 PM THIS EVENING TO 11 AM MST SATURDAY
     FOR WYZ021.

&&

PUBLIC...CONGER
AVIATION...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
307 AM MST FRI DEC 30 2011

UTZ001>016-019>021-517-518-WYZ021-311300-
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-
307 AM MST FRI DEC 30 2011

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

.DAY ONE...TODAY AND TONIGHT

A FAST MOVING STORM WILL ARRIVE TONIGHT AND LAST INTO SATURDAY.
LITTLE RAIN AND SNOW IS EXPECTED FOR NORTHERN AND CENTRAL UTAH
VALLEYS. THE MOUNTAINS OF NORTHERN UTAH WILL SEE ANOTHER ROUND OF
LIGHT SNOW AND STRONG HIGH ELEVATION WINDS. WINDS WILL ALSO LIKELY
BE STRONG ACROSS SOUTHWEST WYOMING AND CASTLE COUNTRY...AS WELL
AS THE WEST DESERTS AND THE UINTA BASIN.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY

GUSTY WINDS AND MOUNTAIN SNOW SHOWERS WILL SUBSIDE THROUGH THE DAY
SATURDAY.

RIDGE-TOP WARMING WILL TAKE PLACE BEGINNING SUNDAY WITH A RIDGE
OF HIGH PRESSURE PROVIDING BENIGN WEATHER NEXT WEEK. THIS WILL
ALLOW VALLEY INVERSIONS TO BUILD ONCE AGAIN STARTING SUNDAY AND
LASTING MUCH OF NEXT WEEK. AIR QUALITY WILL LIKELY START
DETERIORATING BY MID WEEK WITH THE THREAT OF URBAN HAZE AND FOG.

.SPOTTER INFORMATION STATEMENT...

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

ROGOWSKI

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

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