Area Forecast Discussion
Issued by NWS Grand Junction, CO

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913
FXUS65 KGJT 131816
AFDGJT

Area Forecast Discussion
National Weather Service Grand Junction CO
1116 AM MST Fri Jan 13 2017

.UPDATE...
Issued at 1050 AM MST Fri Jan 13 2017

Areas of dense fog formed this morning and continue to linger
along I-70. Areas of particular concern remain the corridor
between Mac and Grand Junction and also Rifle to Silt. a dense fog
advisory remains in effect until 2 PM this afternoon. Otherwise, a
winter storm system continues to impact the area with mountain
snow and low elevation rain snow mix. The focal point of this
storm will switch to the San Juan Mountains overnight into the
weekend.

&&

.SHORT TERM...(Today through Saturday)
Issued at 307 AM MST Fri Jan 13 2017

Models initialized quite well this morning. Models nailed the area
of low pressure centered over central California and also location
of precipitation over the CWA. The low is still progged to drop
southward through the day, dropping into old Mexico by late
tonight. As this occurs, the jet stream will remain over our area
and will keep plenty of moisture pumping into the Intermountain
West. Not much advection will take place today at the surface or
aloft thanks to the trajectory of the low pressure so no big
changes as far as high or low temperatures are concerned.

Plenty of rain and snow continues at this hour as the jet overhead
is providing enough lift, while being aided by some embedded vort
maxes. At the moment, portions of the I-70 corridor from about
Glenwood Springs east to Vail show signs of some light snow. Will
keep an eye on webcams this morning to see if a quick advisory is
needed to highlight possible travel impacts. Will hold off for
now however. Added the Craig and Meeker areas to an advisory as
snow has continued there for much of the night. Remaining
advisories and warnings remain in place. A bit concerned about
warnings over San Juans as models indicate a lull today (or fairly
significant downturn in precip) with more snow moving in later
this evening. When dealing with the mountains though, anything can
happen so more than happy to keep the warnings going for now. Day
shift can pull down if necessary.

From noon onwards, most precipitation looks to favor eastern Utah
and areas north of I-70 but intensity and coverage should
decrease as the day moves on. Some residual showers are possible
over the Flat Tops and the Park and Gore ranges but amounts look
to be on the low side. It`s at this time that favorable
orographics kick in down south and bring more snow to the San
Juans.

By daybreak Saturday a `col` sets up over central Utah with us
under the eastern portion of the feature. Some orographics will
bring snow to the San Juans and central mountains while most
precipitation outside of those areas will end. A few showers are
certainly possible but nothing to get excited about. Clouds will
likely hang around with some breaks from time to time as
temperatures remain near normal. Looks safe to say that most areas
outside of the mountains will remain dry.

Almost forgot to mention a dense fog advisory has been issued for
the Uintah Basin and also the Debeque to Silt corridor through
10AM. Local observations have reported visibilities fluctuating
from 1/4 mile to 3 miles all night long and webcams do show some
fog banks around both areas. Thought it better to be safe than
sorry to get advisory out with so much going on at the moment.

.LONG TERM...(Sunday through Thursday)
Issued at 400 PM MST Thu Jan 12 2017

By Sunday morning, the closed low will have shifted just to the
south of central New Mexico. Cyclonic flow around the low will
allow some snow to continue for the San Juans and central
mountains but coverage looks to be on the low side especially
considering easterly flow sets up which will favor eastern facing
slopes.

The low will progress across the Texas panhandle by the beginning
of the work week with some wraparound moisture resulting in
lingering showers down south. Weak transitory ridging builds
across the area on Wednesday seeing the return of benign weather
for the first time in a while! This break will be short-lived,
however, as a broad upper level trough moves onshore and brings an
increased chance for clouds and showers for the latter half of the
work week.

&&

.AVIATION...(For the 18Z TAFS through 18Z Saturday morning)
Issued at 1107 AM MST Fri Jan 13 2017

Moist southwesterly flow continues across the forecast area this
morning, supporting mountain snows and a rain snow mix in the
valleys. The focus of the winter storm that is directing this
moisture into our area shifts to the south overnight tonight into
the weekend. Otherwise expect a mix of MVFR to VFR conditions
around the forecast area today with snow showers possible at the
higher elevation terminals and a rain or rain snow mix at the
lower elevation terminals. Heavy snow will be a possibility for
for Durango and Telluride Airports Saturday morning, however
forecast confidence is low due to warm southerly flow potentially
lifting the snow levels.

Overall forecast confidence is moderate.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...
CO...Winter Weather Advisory until 2 PM MST this afternoon for
     COZ002>004-013.

     Winter Weather Advisory until 5 PM MST Saturday for COZ009-012-
     017-018.

     Winter Storm Warning until 5 PM MST Saturday for COZ019.

     Dense Fog Advisory until 2 PM MST this afternoon for COZ006-007.

UT...Winter Weather Advisory until 2 PM MST this afternoon for UTZ025.

     Winter Storm Warning until 5 PM MST this afternoon for UTZ028.

&&

$$

UPDATE...Larry
SHORT TERM...TGR
LONG TERM...TGR/MMS
AVIATION...TGJT



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