Area Forecast Discussion
Issued by NWS Salt Lake City, UT

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS65 KSLC 262307
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
407 PM MST FRI DEC 26 2014

.SYNOPSIS...HIGH PRESSURE ALOFT WILL SLIDE SOUTHEAST ACROSS UTAH
LATER TONIGHT THROUGH SATURDAY. THE NEXT COLD PACIFIC STORM SYSTEM
WILL REACH THE AREA LATE IN THE WEEKEND... AND REMAIN THROUGH THE
FIRST HALF OF NEXT WEEK.


&&

.SHORT TERM (UNTIL 12Z TUESDAY)...THE UPPER LOW EXITING TO THE
EAST THROUGH THE CENTRAL/SOUTHERN ROCKIES THIS AFTERNOON SHOULD NO
LONGER IMPACT THE AREA AFTER THIS EVENING. A TRAILING VORTICITY
MAX MOVING RAPIDLY SOUTH THROUGH EASTERN NEVADA WILL GENERATE
CLOUDS AND A FEW LIGHT SNOW SHOWERS NEAR THE NEVADA/UTAH BORDER
THIS EVENING. GRADUAL CLEARING...NEAR SNOW COVER AND COLD AIR
ALOFT WILL ALL SERVE TO BRING COLD TEMPS TO MUCH OF UTAH
OVERNIGHT. MODEL GUIDANCE ALL SUGGEST THAT PLENTY OF LOW-LEVEL
MOISTURE WILL LINGER ACROSS THE WESTERN ZONES TONIGHT. THIS
MOISTURE BANKED INTO THE HIGHER TERRAIN COULD MAINTAIN POCKETS OF
LOW CLOUDS AND MAYBE SOME FLURRIES DURING THE NIGHT. FOG IS NOT
LIKELY TO BE A WIDESPREAD ISSUE LATE TONIGHT/SATURDAY MORNING AS
MANY AREAS WILL HAVE SUFFICIENTLY LARGE DEW POINT SPREADS AND
ENOUGH WIND TO STIR THE BOUNDARY LAYER AND INHIBIT FOG
DEVELOPMENT.

THE SHORTWAVE RIDGE MOVING NORTHWEST TO SOUTHEAST ACROSS UTAH
SATURDAY WILL BE FOLLOWED BY THE NEXT COLD PACIFIC STORM ARRIVING
LATE IN THE WEEKEND. THIS NEXT TROUGH WILL REACH THE PACIFIC
NORTHWEST COAST SATURDAY...THEN EXPAND INTO A BROAD NORTHEAST TO
SOUTHWEST ORIENTED TROUGH ACROSS MUCH OF THE REGION FOR LATE
SUNDAY/MONDAY.

LIGHT PRECIP SHOULD ARRIVE AHEAD OF THE TROUGH...DRIVEN BY MOIST
WARM ADVECTION OVERRUNNING COLD LOW-LEVEL AIR MASS SATURDAY
NIGHT. DYNAMIC LIFT FROM THE TROUGH AND DEEP LAYER COLD ADVECTION
SHOULD FUEL AN INCREASE IN SNOW FOR SUNDAY THROUGH SUNDAY NIGHT.
SNOW WILL GRADUALLY TAPER OFF ACROSS THE NORTH MONDAY AS THE MAIN
BAROCLINIC ZONE ORIENTS WEST TO EAST ACROSS CENTRAL THEN SOUTHERN
UTAH LATE MONDAY/MONDAY NIGHT.

HAVE ISSUED A WINTER STORM WATCH FOR THE NORTHERN THIRD OF UTAH
LATE SATURDAY NIGHT THROUGH EARLY MONDAY. ASSUMING THAT THE
VARIOUS MODEL GUIDANCE OF /.45/ - ./60/ QPFS IS CORRECT WITH THE
EXPECTED LOW DENSITY SNOW IN THIS COLD AN AIR MASS...THE RESULT
SHOULD BE HEAVY SNOW ACROSS MANY AREAS OF NORTHERN UTAH. SNOW
TOTALS WILL LIKELY BOUNCE BETWEEN HEAVY SNOW CRITERIA AND ADVISORY
CRITERIA. THE TIPPING FACTOR HERE WILL BE THE ANTICIPATED HIGH
IMPACT DUE TO TRAVEL AT THE END OF THE HOLIDAY WEEKEND. SUSPECT
THAT A MIX OF WARNINGS AND ADVISORIES WILL BE IN PLACE BY THE TIME
THIS EVENT BEGINS LATER IN THE WEEKEND.

&&

.LONG TERM (AFTER 12Z TUESDAY)...HIGH AMPLITUDE RIDGE ALONG THE WEST
COAST OF CANADA WILL ALLOW A STORM SYSTEM TO DIG DUE SOUTH ALONG
120W BEFORE PINCHING OFF OVER NEVADA BY TUESDAY NIGHT. THIS WILL
PLACE THE H7 BAROCLINIC ZONE BETWEEN AN ARCTIC AIR MASS PUSHING IN
FROM WYOMING AND A MODERATED PACIFIC AIR MASS FROM THE SOUTHWEST.
BECAUSE THE ORIGIN OF THIS STORM IS CONTINENTAL IT IS LACKING IN
DEEP MOISTURE. THEREFORE DESPITE A PROLONGED TIME THAT THIS
BAROCLINIC ZONE WILL TREK ACROSS CENTRAL AND SOUTHERN UTAH TUESDAY
NIGHT THROUGH WEDNESDAY...PRECIPITATION AMOUNTS DO NOT LOOK TO BE
THAT GREAT.

THERE IS STILL MODERATE UNCERTAINTY WITH THIS STRENGTH OF THIS
STORM OVER THE SOUTHERN HALF OF THE CWA AS THERE IS STILL OVER 100
METERS OF DIFFERENCE IN THE 500 MB HEIGHTS BETWEEN THE GFS ENSEMBLE
MEMBERS. THE EC HAS TRENDED A LITTLE TOWARDS THE GFS WITH THE CORE
OF THE CLOSED LOW NOW NEAR RENO AT 12Z WEDNESDAY VERSES SAN
FRANCISCO. BOTTOM LINE IS HAVE GONE WITH ABOVE CLIMO POPS TUESDAY
INTO THURSDAY BUT DUE TO THE UNCERTAINTY HELD OFF FROM PUTTING
LIKELY POPS IN AS OF THIS TIME.

THE MAIN IMPACT AND HIGHEST CONFIDENCE FOR THIS STORM WILL BE THE
GUSTY EASTERLY WINDS MONDAY NIGHT THROUGH EARLY TUESDAY ACROSS THE
NORTHERN WASATCH MOUNTAINS AND WASATCH FRONT AND THE COLD
TEMPERATURES THAT WILL ACCOMPANY THE STORM ACROSS THE ENTIRE REGION.

&&

.AVIATION...AT THE SLC TERMINAL...CIGS WILL BE GENERALLY REMAIN
ABOVE 7K FT AGL THROUGH THE REMAINDER OF THE AFTERNOON AND EVENING
WITH ONLY A 20 PERCENT CHANCE OF OCCASIONALLY LOWERING BELOW 6K FT
AGL. WINDS WILL REMAIN NORTHERLY THROUGH THIS EVENING WITH A SWITCH
TO THE SOUTHEAST BETWEEN 09 AND 11Z.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...WINTER STORM WATCH FROM LATE SATURDAY NIGHT THROUGH MONDAY
     MORNING FOR UTZ006>009.

     WINTER STORM WATCH FROM LATE SATURDAY NIGHT THROUGH MONDAY
     MORNING FOR UTZ001>003.

WY...NONE.
&&

$$

SHORT TERM...CONGER
LONG TERM/AVIATION...STRUTHWOLF

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)



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.