Winter Storm Watch 7, NWS Salt Lake City, UT

Beaver County, UT, Box Elder County, UT, Cache County, UT, Carbon County, UT, Davis County, UT, Duchesne County, UT, Emery County, UT, Garfield County, UT, Iron County, UT, Juab County, UT, Kane County, UT, Millard County, UT, Morgan County, UT, Piute County, UT, Rich County, UT, Salt Lake County, UT, Sanpete County, UT, Sevier County, UT, Summit County, UT, Utah County, UT, Wasatch County, UT, Washington County, UT, Wayne County, UT, Weber County, UT, Uinta County, WY

854 
WWUS45 KSLC 081001
WSWSLC

URGENT - WINTER WEATHER MESSAGE
National Weather Service Salt Lake City UT
301 AM MST Wed Dec 8 2021

UTZ110-112-WYZ021-090000-
/O.CON.KSLC.WS.A.0007.211209T0000Z-211210T0000Z/
Wasatch Mountains I-80 North-Western Uinta Mountains-
Southwest Wyoming-
Including the cities of Mantua, Logan Summit, 
Mirror Lake Highway, Moon Lake, Evanston, and Lyman
301 AM MST Wed Dec 8 2021

...WINTER STORM WATCH REMAINS IN EFFECT FROM THIS AFTERNOON
THROUGH THURSDAY AFTERNOON...

* WHAT...Heavy snow possible. Total snow accumulations of 4 to 10
  inches across Uinta County Wyoming to 8 to 18 inches possible 
  in the mountains. Winds could gusts as high as 35 mph in wind 
  prone areas.

* WHERE...In Wyoming, Southwest Wyoming. In Utah, Wasatch 
  Mountains I-80 North and Western Uinta Mountains.

* WHEN...From Wednesday afternoon through Thursday afternoon.

* IMPACTS...Travel could be very difficult.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Monitor the latest forecasts for updates on this situation.

&&

$$

UTZ108-111-113-090000-
/O.CON.KSLC.WS.A.0007.211209T0600Z-211211T0000Z/
Wasatch Back-Wasatch Mountains South of I-80-
Wasatch Plateau/Book Cliffs-
Including the cities of Huntsville, Park City, Heber City, Alta, 
Brighton, Scofield, and Indian Canyon
301 AM MST Wed Dec 8 2021

...WINTER STORM WATCH REMAINS IN EFFECT FROM THIS EVENING THROUGH
FRIDAY AFTERNOON...

* WHAT...Heavy snow possible. Total snow accumulations of 4 to 10
  inches in the Wasatch Back and 1 to 2 feet of snow possible in 
  the mountains. Winds could gust as high as 35 mph in wind prone 
  areas.

* WHERE...Wasatch Back, Wasatch Mountains South of I-80 and 
  Wasatch Plateau/Book Cliffs.

* WHEN...From Wednesday evening through Friday afternoon.

* IMPACTS...Travel could be very difficult.

* ADDITIONAL DETAILS...Precipitation may briefly begin as rain 
  in valley locations before switching to snow.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Monitor the latest forecasts for updates on this situation.

&&

$$

UTZ115>117-122-125-090000-
/O.CON.KSLC.WS.A.0007.211209T1200Z-211211T0000Z/
Western Millard and Juab Counties-Eastern Juab/Millard Counties-
Central Mountains-Southwest Utah-Southern Mountains-
Including the cities of Delta, Little Sahara, Nephi, Scipio, 
Fillmore, Cove Fort, Fish Lake, Joes Valley, Beaver, Cedar City, 
Milford, Brian Head, and Alton
301 AM MST Wed Dec 8 2021

...WINTER STORM WATCH REMAINS IN EFFECT FROM LATE TONIGHT THROUGH
FRIDAY AFTERNOON...

* WHAT...Heavy snow possible. Total snow accumulations of 2 to 6 
  inches in the valleys with 1 to 2 feet of snow possible in the 
  mountains.

* WHERE...Western Millard and Juab Counties, Eastern 
  Juab/Millard Counties, Central Mountains, Southwest Utah and 
  Southern Mountains.

* WHEN...From late Wednesday night through Friday afternoon.

* IMPACTS...Travel could be very difficult.

* ADDITIONAL DETAILS...Precipitation will begin as rain in many 
  valleys before changing to snow Thursday afternoon.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Monitor the latest forecasts for updates on this situation.

&&

$$

For more information from NOAA/National Weather Service visit...
http://weather.gov/saltlakecity

For information on potential travel impacts visit...
http://udottraffic.utah.gov/roadweatherforecast.aspx

430 
WWUS45 KSLC 082235
WSWSLC

URGENT - WINTER WEATHER MESSAGE
National Weather Service Salt Lake City UT
335 PM MST Wed Dec 8 2021

UTZ111-090615-
/O.UPG.KSLC.WS.A.0007.211209T0600Z-211211T0000Z/
/O.NEW.KSLC.WS.W.0007.211209T0700Z-211210T2300Z/
Wasatch Mountains South of I-80-
Including the cities of Alta and Brighton
335 PM MST Wed Dec 8 2021

...WINTER STORM WARNING IN EFFECT FROM MIDNIGHT TONIGHT TO 4 PM
MST FRIDAY...

* WHAT...Heavy snow expected. Total snow accumulations of 1 to 2
  feet, with locally higher amounts expected.

* WHERE...Wasatch Mountains South of I-80.

* WHEN...From midnight tonight to 4 PM MST Friday.

* IMPACTS...Travel could be very difficult to impossible.

* ADDITIONAL DETAILS...Heaviest snowfall is anticipated Thursday
  afternoon and again Friday morning with lighter snowfall during
  the overnight hours.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If you must travel, keep an extra flashlight, food, and water in
your vehicle in case of an emergency. 

For graphical depictions of the snowfall forecast, including
Official NWS Forecast, High End Amount, and Low End Amount, visit
weather.gov/slc/winter.

For winter road conditions from the Utah Department of
Transportation, visit
http://www.udottraffic.utah.gov/roadweatherforecast.aspx or dial
511.

&&

$$

UTZ108-113-090615-
/O.UPG.KSLC.WS.A.0007.211209T0600Z-211211T0000Z/
/O.NEW.KSLC.WS.W.0007.211209T0700Z-211210T0600Z/
Wasatch Back-Wasatch Plateau/Book Cliffs-
Including the cities of Huntsville, Park City, Heber City, 
Scofield, and Indian Canyon
335 PM MST Wed Dec 8 2021

...WINTER STORM WARNING IN EFFECT FROM MIDNIGHT TONIGHT TO 11 PM
MST THURSDAY...

* WHAT...Heavy snow expected. Total snow accumulations of 8 to 18
  inches in the mountains, with locally higher amounts. For the
  Wasatch Back, total snow accumulations of 6 to 12 inches.

* WHERE...Wasatch Back and Wasatch Plateau/Book Cliffs.

* WHEN...From midnight tonight to 11 PM MST Thursday.

* IMPACTS...Travel could be very difficult to impossible.

* ADDITIONAL DETAILS...Rain may mix with snow initially then
  transition to snow by early Thursday morning for the mountain
  valley areas.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If you must travel, keep an extra flashlight, food, and water in
your vehicle in case of an emergency. 

For graphical depictions of the snowfall forecast, including
Official NWS Forecast, High End Amount, and Low End Amount, visit
weather.gov/slc/winter.

For winter road conditions from the Utah Department of
Transportation, visit
http://www.udottraffic.utah.gov/roadweatherforecast.aspx or dial
511.

&&

$$

UTZ112-090615-
/O.UPG.KSLC.WS.A.0007.211209T0000Z-211210T0000Z/
/O.NEW.KSLC.WS.W.0007.211209T0700Z-211210T0600Z/
Western Uinta Mountains-
Including the cities of Mirror Lake Highway and Moon Lake
335 PM MST Wed Dec 8 2021

...WINTER STORM WARNING IN EFFECT FROM MIDNIGHT TONIGHT TO 11 PM
MST THURSDAY...

* WHAT...Heavy snow expected. Total snow accumulations of 1 to 2
  feet.

* WHERE...Western Uinta Mountains.

* WHEN...From midnight tonight to 11 PM MST Thursday.

* IMPACTS...Travel could be very difficult.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If you must travel, keep an extra flashlight, food, and water in
your vehicle in case of an emergency. 

For graphical depictions of the snowfall forecast, including
Official NWS Forecast, High End Amount, and Low End Amount, visit
weather.gov/slc/winter.

For winter road conditions from the Utah Department of
Transportation, visit
http://www.udottraffic.utah.gov/roadweatherforecast.aspx or dial
511.

&&

$$

UTZ117-125-090615-
/O.UPG.KSLC.WS.A.0007.211209T1200Z-211211T0000Z/
/O.NEW.KSLC.WS.W.0007.211209T1200Z-211210T0600Z/
Central Mountains-Southern Mountains-
Including the cities of Cove Fort, Fish Lake, Joes Valley, 
Brian Head, and Alton
335 PM MST Wed Dec 8 2021

...WINTER STORM WARNING IN EFFECT FROM 5 AM TO 11 PM MST
THURSDAY...

* WHAT...Heavy snow expected. Total snow accumulations of 1 to 2
  feet. Winds gusting as high as 35 mph.

* WHERE...Central Mountains and Southern Mountains.

* WHEN...From 5 AM to 11 PM MST Thursday.

* IMPACTS...Travel could be very difficult.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If you must travel, keep an extra flashlight, food, and water in
your vehicle in case of an emergency. 

For graphical depictions of the snowfall forecast, including
Official NWS Forecast, High End Amount, and Low End Amount, visit
weather.gov/slc/winter.

For winter road conditions from the Utah Department of
Transportation, visit
http://www.udottraffic.utah.gov/roadweatherforecast.aspx or dial
511.

&&

$$

UTZ110-090615-
/O.UPG.KSLC.WS.A.0007.211209T0000Z-211210T0000Z/
/O.NEW.KSLC.WW.Y.0021.211209T0700Z-211210T2300Z/
Wasatch Mountains I-80 North-
Including the cities of Mantua and Logan Summit
335 PM MST Wed Dec 8 2021

...WINTER WEATHER ADVISORY IN EFFECT FROM MIDNIGHT TONIGHT TO
4 PM MST FRIDAY...

* WHAT...Snow expected. Total snow accumulations of 6 to 14 inches
  with locally higher amounts south of I-84.

* WHERE...Wasatch Mountains I-80 North.

* WHEN...From midnight tonight to 4 PM MST Friday.

* IMPACTS...Travel could be very difficult.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Slow down and use caution while traveling. 

For graphical depictions of the snowfall forecast, including
Official NWS Forecast, High End Amount, and Low End Amount, visit
weather.gov/slc/winter.

For winter road conditions from the Utah Department of
Transportation, visit
http://www.udottraffic.utah.gov/roadweatherforecast.aspx or dial
511.

&&

$$

WYZ021-090615-
/O.UPG.KSLC.WS.A.0007.211209T0000Z-211210T0000Z/
/O.NEW.KSLC.WW.Y.0021.211209T1200Z-211210T0300Z/
Southwest Wyoming-
Including the cities of Evanston and Lyman
335 PM MST Wed Dec 8 2021

...WINTER WEATHER ADVISORY IN EFFECT FROM 5 AM TO 8 PM MST
THURSDAY...

* WHAT...Snow expected. Total snow accumulations of 5 to 10 
  inches.

* WHERE...Southwest Wyoming.

* WHEN...From 5 AM to 8 PM MST Thursday.

* IMPACTS...Travel could be very difficult to impossible.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Slow down and use caution while traveling. 

For graphical depictions of the snowfall forecast, including
Official NWS Forecast, High End Amount, and Low End Amount, visit
weather.gov/slc/winter.

For winter road conditions from the Wyoming Department of
Transportation, visit http://www.wyoroad.info or dial 511.

&&

$$

UTZ115-116-122-090615-
/O.UPG.KSLC.WS.A.0007.211209T1200Z-211211T0000Z/
/O.NEW.KSLC.WW.Y.0021.211209T1800Z-211210T0600Z/
Western Millard and Juab Counties-Eastern Juab/Millard Counties-
Southwest Utah-
Including the cities of Delta, Little Sahara, Nephi, Scipio, 
Fillmore, Beaver, Cedar City, and Milford
335 PM MST Wed Dec 8 2021

...WINTER WEATHER ADVISORY IN EFFECT FROM 11 AM TO 11 PM MST
THURSDAY...

* WHAT...Snow expected. Total snow accumulations of 3 to 6 inches,
  with up to 10 inches possible along the I-15 corridor from
  Santaquin to Scipio.

* WHERE...Western Millard and Juab Counties, Eastern 
  Juab/Millard Counties and Southwest Utah.

* WHEN...From 11 AM to 11 PM MST Thursday.

* IMPACTS...Travel could be very difficult.

* ADDITIONAL DETAILS...Rain will mix with snow initially then
  transition to snow during the late morning through afternoon 
  hours.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Slow down and use caution while traveling. 

For graphical depictions of the snowfall forecast, including
Official NWS Forecast, High End Amount, and Low End Amount, visit
weather.gov/slc/winter.

For winter road conditions from the Utah Department of
Transportation, visit
http://www.udottraffic.utah.gov/roadweatherforecast.aspx or dial
511.

&&

$$

UTZ109-090615-
/O.NEW.KSLC.WW.Y.0021.211209T1200Z-211210T0300Z/
Bear Lake and Bear River Valley-
Including the cities of Woodruff, Randolph, and Garden City
335 PM MST Wed Dec 8 2021

...WINTER WEATHER ADVISORY IN EFFECT FROM 5 AM TO 8 PM MST
THURSDAY...

* WHAT...Snow expected. Total snow accumulations of 3 to 5 
  inches.

* WHERE...Bear Lake and Bear River Valley.

* WHEN...From 5 AM to 8 PM MST Thursday.

* IMPACTS...Plan on slippery road conditions.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Slow down and use caution while traveling. 

For graphical depictions of the snowfall forecast, including
Official NWS Forecast, High End Amount, and Low End Amount, visit
weather.gov/slc/winter.

For winter road conditions from the Utah Department of
Transportation, visit
http://www.udottraffic.utah.gov/roadweatherforecast.aspx or dial
511.

&&

$$

UTZ104-105-090615-
/O.NEW.KSLC.WW.Y.0021.211209T1500Z-211210T2300Z/
Northern Wasatch Front-Salt Lake Valley-
Including the cities of Ogden, Bountiful, Salt Lake City, 
West Jordan, and Sandy
335 PM MST Wed Dec 8 2021

...WINTER WEATHER ADVISORY IN EFFECT FROM 8 AM THURSDAY TO 4 PM
MST FRIDAY...

* WHAT...Snow expected. Total snow accumulations of 3 to 6 inches
  for Davis County, with up to 10 inches on the benches. For the
  Salt Lake Valley, total snow accumulations of 4 to 10 inches.

* WHERE...Northern Wasatch Front and Salt Lake Valley.

* WHEN...From 8 AM Thursday to 4 PM MST Friday.

* IMPACTS...Plan on slippery road conditions. The hazardous
  conditions could impact the Thursday morning and evening
  commute, as well as the Friday morning commute.

* ADDITIONAL DETAILS...Precipitation will start as rain then
  transition to snow during the early morning hours. Heaviest snow
  expected Thursday afternoon and Friday morning with lighter
  snowfall expected overnight.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Slow down and use caution while traveling. 

For graphical depictions of the snowfall forecast, including
Official NWS Forecast, High End Amount, and Low End Amount, visit
weather.gov/slc/winter.

For winter road conditions from the Utah Department of
Transportation, visit
http://www.udottraffic.utah.gov/roadweatherforecast.aspx or dial
511.

&&

$$

UTZ102-106-090615-
/O.NEW.KSLC.WW.Y.0021.211209T1500Z-211210T0600Z/
Tooele and Rush Valleys-Utah Valley-
Including the cities of Tooele, Grantsville, Vernon, Lehi, Provo,
and Payson
335 PM MST Wed Dec 8 2021

...WINTER WEATHER ADVISORY IN EFFECT FROM 8 AM TO 11 PM MST
THURSDAY...

* WHAT...Snow expected. Total snow accumulations of 4 to 8 
  inches.

* WHERE...Tooele and Rush Valleys and Utah Valley.

* WHEN...From 8 AM to 11 PM MST Thursday.

* IMPACTS...Travel could be very difficult. The hazardous
  conditions could impact the Thursday morning and evening 
  commute.

* ADDITIONAL DETAILS...Precipitation will start as rain then
  transition to snow during the early morning hours. Heaviest
  snowfall is expected late Thursday morning into late Thursday 
  afternoon.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Slow down and use caution while traveling. 

For graphical depictions of the snowfall forecast, including
Official NWS Forecast, High End Amount, and Low End Amount, visit
weather.gov/slc/winter.

For winter road conditions from the Utah Department of
Transportation, visit
http://www.udottraffic.utah.gov/roadweatherforecast.aspx or dial
511.

&&

$$

UTZ118-126-127-090615-
/O.NEW.KSLC.WW.Y.0021.211209T1800Z-211210T0600Z/
Sanpete Valley-Upper Sevier River Valleys-Bryce Canyon Country-
Including the cities of Manti, Ephraim, Mt Pleasant, Panguitch, 
Circleville, Koosharem, and Bryce Canyon City
335 PM MST Wed Dec 8 2021

...WINTER WEATHER ADVISORY IN EFFECT FROM 11 AM TO 11 PM MST
THURSDAY...

* WHAT...Snow expected. Total snow accumulations of 3 to 6 inches
  with locally higher amounts in the northern Sanpete Valley.
  Winds gusting as high as 35 mph.

* WHERE...Sanpete Valley, Upper Sevier River Valleys and Bryce 
  Canyon Country.

* WHEN...From 11 AM to 11 PM MST Thursday.

* IMPACTS...Plan on slippery road conditions.

* ADDITIONAL DETAILS...Rain may mix with snow during the early
  afternoon hours, mainly in the Sanpete Valley, then transition
  to snow.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Slow down and use caution while traveling. 

For graphical depictions of the snowfall forecast, including
Official NWS Forecast, High End Amount, and Low End Amount, visit
weather.gov/slc/winter.

For winter road conditions from the Utah Department of
Transportation, visit
http://www.udottraffic.utah.gov/roadweatherforecast.aspx or dial
511.

&&

$$

For more information from NOAA/National Weather Service visit...
http://weather.gov/saltlakecity

For information on potential travel impacts visit...
http://udottraffic.utah.gov/roadweatherforecast.aspx

Area Forecast Discussion
National Weather Service Salt Lake City UT
452 AM MST Tue Dec 7 2021

.SYNOPSIS...The southern branch of the split flow and associated
weak baroclinic zone will continue to produce light precipitation
across southern Utah this morning. Precipitation chances should
end by afternoon across southern Utah. Clouds will increase on
Wednesday with mild temperatures. A winter storm will impact the
state Thursday into Friday.

&&

.NEAR TERM (Through 00z Thursday)...Radar trends this morning show
a weak baroclinic zone across far southern Utah with several
pulses of light precipitation continuing across this area. Most
noticeably, Bryce Canyon has experienced two different pulses of
light snow this morning. Moving forward, the upper level split
flow regime holds serve as the northern branch pushes east into
southern Wyoming/northern Colorado, while the southern branch
continues to dig to the southwest across central California. Over
the next ~12hrs, this southern branch will undergo a phase change
and become a weak, closed low and become elongated across
southern California through southern Nevada. This will eventually
push the remnants of the baroclinic zone out of southern Utah,
putting an end to the remaining PoP chances. As this weakening
closed low moves through Utah, little to no QPF is expected to be
in place, so we can just expect and increase in the cloud cover
across the much of the northern two thirds of the state as we
head into Wednesday morning. Some light mountain showers could be
possible across the southern mountains Wednesday morning. Overall,
Wednesday will be overshadowed by the incoming winter storm for
the end of the work week.

.SHORT TERM (00Z Thursday through 12Z Saturday)...
A winter storm system will take aim at the forecast area Thursday
and Thursday night with lingering impacts into Friday. While
forecast confidence in the overall event remains highs, confidence
in some of the finer details is starting to increase.

The storm system will develop from a Pacific wave that will crest
the ridge over the eastern Pacific and move into the Great Basin
while tapping into a much colder airmass over western Canada and the
Pacific Northwest. This will tighten a baroclinic zone over northern
Utah on Thursday, while the mid-level wave interacting with this
baroclinic zone will result in a strengthening storms system with a
weak surface low reflection developing in eastern Utah before
jumping to the lee of the Rocky Mountains in Colorado. Widespread
precipitation will develop, initially across northern Utah early
Thursday morning, but will fill in across much of the state through
midday Thursday as synoptic lift maximizes with a broad right
entrance region of a jet streak aligning with the low to mid level
frontal axis over much of central and southern Utah. Expect a
northern periphery of the precipitation shield to develop from
around Wendover to Logan by midday Thursday with the higher
precipitation amounts maximizing south and eastward from around
Great Basin NP, to Salt Lake to Evanston. Eastern Utah valleys,
however, will become shadowed as stronger downslope northwesterly
flow develops late Thursday with the cold front moving through, thus
precipitation totals and any snow accumulations will be more limited
there. On the flip side, there is potential for orographically
enhanced precipitation totals along the I-15 corridor, especially
from Provo to Cedar City as the moist northwesterly flow develops.
This signal seems to bear out in the EPS Extreme Forecast Index
plots of QPF and snow accumulations. Have started trending QPF and
snow fall totals up along this corridor for Thursday evening,
however will need to keep a close eye on impacts along this travel
corridor should snowfall trends continue upward.

Precipitation will initially start as a mixture of valley rain and
mountain snow Wednesday night into early Thursday morning, with snow
levels around 5000 to 6500 feet. However snow levels will quickly
fall from northwest to southeast on Thursday as the cold front moves
through, and the transition will likely be aided by heavier
precipitation rates with the frontal passage, potentially making for
an abrupt change from rain to briefly heavy snow with the frontal
passage. Snow levels will crash to valley floors from north to south
Thursday evening through Friday morning, with even the potential for
rain to transition and a few wet flakes as precipitation ends in St
George Friday morning.

Confidence is medium and increasing for a lake effect snow event to
develop Friday morning southeast of the Great Salt Lake, with the
most likely impact area across the Salt Lake Valley and into the
central Wasatch, including the Cottonwood Canyons. As with all lake
effect snow events, small details matter, and thus this is still not
a sure bet, but there are a few forecast trends across the global
models and their ensembles that point toward an increasing threat.
First, synoptically, global models are keying in on a secondary mid-
level wave that moves into northern Utah Friday morning, phasing
with and delaying the eastward progression of the mean trough axis.
This secondary wave will also bring additional low to mid level
moisture, quite cold 700-500 mb temperatures resulting in steep
lapse rates through and well above the dendritic growth zone, as
well as enhanced synoptic support for ascent Friday morning, which
also coincides with the diurnal max in surface convergence generated
by the lake-land temperature gradient. Combine this with
unidirectional northwesterly flow that models keep persistent for a
little over 12 hours and there could impactful snow accumulations
Friday morning through early afternoon before drier air and
subsidence finally moves into the area by late Friday afternoon and
evening. Have trended the PoP / QPF and snow forecast up for the
Salt Lake Valley and central Wasatch through the day on Friday to
reflect this idea, but if trends continue this may need to be
increased more.

Otherwise, event total snowfall amounts have changed little from
previous forecast cycles. Continue to advertise a widespread 10-16
inches for the mountains, with localized favored areas seeing up 2
feet. For valley locations, most will see 1 to 4 inches, although we
will need to watch trends along the I-15 Provo to Cedar City
corridor for possible higher totals Thursday night, as well as in
the Salt Lake Valley with and central Wasatch on Friday with the
potential for lake effect.

Finally, much colder temperatures will take hold across the area for
the end of the week, with daytime highs not likely to make it above
freezing in most locations on Friday (outside of lower elevation
southern Utah locations), and nighttime lows Friday night in the
teens and single digits.

.LONG TERM (After 12z Saturday)...This portion of the long term
forecast will focus on the period post winter storm. What
transpires with this storm, in terms of valley snowfall amounts
will be factor in determining the magnitude of the inverted
conditions that could develop over the weekend. Models are in
relatively good agreement in building a broad, flat ridge across
much of the Great Basin and into Utah over the weekend. The
concern here is having a ridge move in soon after a valley snow
event that could rapidly intensify the inverted conditions. This
would significantly influence the temperature forecast,
especially since the valleys will just have been impacted by the
end of week winter storm. While the snowfall amounts have yet to
play out, we do know that this winter storm will bring much colder
temperatures to the valleys. On top of this, if the valleys
receive snowfall, the low level boundary layer will hold higher
levels of RH which could in turn, turn into low stratus/fog and as
the ridge builds over head, this could really keep the inverted
valleys locked into a cold pattern and significantly increase the
pollutants across these valleys.

The overall orientation of the ridge axis will come into play
that could limit or increase the severity of these inverted
conditions over the weekend. Currently model outputs are hinting
on a flatter ridge axis across Utah with a deep trough across the
Pacific northwest, and this interaction would develop a somewhat
weak, zonal flow across Utah allowing for, upper level moisture to
stream in in the form of high level clouds that could limit the
solar insulation and keep the ridgetops cooler and decreasing the
dT between the valleys and mountain tops. This flow would also
open the door for shortwave throughs to pass through the flow,
which is being supported by model and ensemble outputs. These
features would help mix out the inversion or not allow the
inversion to build over multiple days. The other piece to the
puzzle will be just how much snow falls across these valleys, so
with this part of the forecast predicated on the end of week
storm, the forecast approach was to stick with NBM for inverted valley
temperatures at this time.

As mentioned above, model and ensemble outputs suggest, far
northern Utah will remain in a somewhat "active" pattern with the
passages of these weak shortwaves. To early to tell just how
strong/weak these features will be so just kept with the light
PoPs across far northern Utah Sunday through next Monday, per the
NBM initialization.

&&

.AVIATION...VFR conditions are expected to prevail across the
terminal through the valid TAF period. Morning CIGs around 9kft
AGL will gradually lift and scour out by 19z. Light southerly flow
will shift to a light northerly flow between 19-20z. Wind speeds
will be 10kts or less.

REST OF UTAH AND SOUTHWEST WYOMING...A band of of precipitation is
bringing intermittent -SN to the KBCE terminal this morning. This
area of precipitation should dissipate by 16z. Outside this area
of precipitation, much of the airspace is seeing VFR conditions,
with CIGs between 6-9kft AGL. Some mountain obscurement will be
possible across the northern and southern mountains before skies
begin to clear out this afternoon. Winds will be light and
variable across most terminals, except at the KEVW terminal where
gusty winds up to 22kts are expected by 20z.

&&

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

Woodward/Church

For more information from NOAA's National Weather Service visit...
http://weather.gov/saltlakecity

For frequently asked questions about the Area Forecast Discussion
visit...
http://weather.gov/saltlakecity/general/afd_faqs.php