Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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446
FXUS65 KBOU 142152
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
252 PM MST Sun Jan 14 2018

.SHORT TERM...(This evening through Monday)
Issued at 146 PM MST Sun Jan 14 2018

Surface analysis shows cold front is moving into northeast Wyoming
and the Northern High Plains this afternoon. This front will push
through northeast Colorado this evening, with shallow but moist
upslope flow developing. In addition, there is weak but deep Q-G
lift later tonight through Monday morning, moderate to strong mid
level frontogenesis, and the right rear entrance region of an
upper level jet streaking across the Central Plains. The
combination of these factors should bring a fairly well organized
band of light snow across the plains. This band is already
becoming better organized over the last few hours per latest radar
returns and satellite imagery.

The band of snow should first reach the northeastern corner of
Colorado this evening, and then push back to the I-25 Corridor
between 2 and 5 AM. Per cross sections and forecast soundings,
there may be some freezing drizzle on this initial push of light
precipitation as temps in the moist layer hold slightly warmer
than -10C until about 12Z. Therefore, we have added a little
mention of that into the forecast.

Light snow will continue along the Front Range and I-25 Corridor
for the Monday morning commute with the favorable parameters
mentioned above. Most areas should see about an inch of snow
although a few bands on the plains given the proximity of the
upper level jet could produce a couple inches. Also shallow
upslope focused into the foothills may produce local amounts of
3 or 4 inches in this environment.

Snow will decrease from north to south across the forecast area on
Monday afternoon as drier air works in from the northwest.

The other story will be the colder temperatures. Source region air
is currently in the single digits, so even with some moderation we
may see teens/lower 20s across the plains through a good portion
of Monday, and little if any diurnal warming.

.LONG TERM...(Monday night through Sunday)
Issued at 146 PM MST Sun Jan 14 2018

For Monday night into Tuesday subsidence will start to build in
behind the trough helping to bring snow to an end from North to
South. Northeast upslope flow will decrease with some lingering
snow along the southern foothills and Palmer Divide into the early
morning hours on Tuesday. Overnight lows will also be on the cold
side with temperatures in the negative digits possible on the far
NE plains. As drying continues into Tuesday lingering cloud cover
will subside and temperatures will be able to reach into the mid
30s by Tuesday afternoon.

For Tuesday through Friday an upper level ridge will build in
keeping conditions dry with temperatures getting well above
normal. By Thursday, highs will be reaching close to the 60
degree mark and will continue into Friday before the next upper
level feature moves in.

By Friday afternoon and evening an open, positively tilted trough
will makes its way onto the western coast. Moisture will increase
over the western portions of the state bringing increased chances
of snow to the mountains by Friday evening. Models are fairly in
line with the speed and placement of the trough at this time. A
front will accompany this system moving south over the plains by
Saturday morning. This will help to increase snow along the
foothills and plains along with the higher terrain for Saturday
afternoon. Temperatures will drop to below zero with lows into
Sunday dipping into the teens overnight.

&&

.AVIATION...(For the 18Z TAFS through 18Z Monday afternoon)
Issued at 146 PM MST Sun Jan 14 2018

Cold front is expected to push across the Front Range airports
toward 05Z with a wind shift to the northeast. Then low clouds and
light snow will fill in behind this, most likely by 09Z with LIFR
possible through Monday morning with light snow and low ceilings.
There is a chance of a period of light freezing drizzle 09Z-12Z
due to the initial shallow nature of the moist airmass.
Visibilities expected to be in the 1-3 mile range with light snow
and fog. Snow accumulations should average around 1 inch, with
locally up to 2 inches right next to the foothills. Improving
conditions expected toward 21Z Monday and continuing to improve
through 00Z Tuesday as drier air moves in with VFR conditions
developing.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
None.
&&

$$

SHORT TERM...Barjenbruch
LONG TERM...Bowen
AVIATION...Barjenbruch



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