Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 211046
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
346 AM MST Wed Feb 21 2018

.SHORT TERM...(Today and tonight)
Issued at 235 AM MST Wed Feb 21 2018

Clear and cold early this morning across Colorado with single
digits across much of northeast Colorado and a few spots below
zero over the S Platte river valley. Could be a few pockets of
patchy fog early this morning but looks like there is enough t/td
spreads to keep fog from growing too much in areal extent.

Water vapor imagery showing next system developing over the Great
Basin early this morning. This will begin to spread moisture back
into Western Colorado and mountains this afternoon with some light
snow spreading into the mountains this evening and especially
overnight. QG fields showing increasing light to moderate ascent
moving into the mountains tonight along with approaching 100kt
jet streak. Have increased pops in the mountains, especially along
and south of the interstate 70 corridor for tonight for some
light snow accumulations.

Across lower elevations today, skies will start out mostly sunny
but then some increasing mid-hi clouds this afternoon and evening.
As low level flow turns southeast tonight could be some low level
moisture increasing and resulting in low clouds and possible fog.
There will some slow warmup in temperatures but readings this
afternoon will remain in the 20s, lower than previous forecast.

.LONG TERM...(Thursday through Tuesday)
Issued at 235 AM MST Wed Feb 21 2018

The upper trough over the West Coast extending into Canada will
interact with the 595 DM high over the Atlantic to keep moderately
strong NW flow over the state. Pieces of energy moving around the
base of the trough will continue to bring a chance of light snow
showers to the mountains through Saturday. On the plains a surface
high will keep temperatures slightly cooler with a gradual trend
upward into next week. By Thursday afternoon there is a decent
shortwave moving NE through the region bringing enhanced lift and
good QG ascent to portions of the plains. NAM upper air model
soundings show enough moisture in the column for ice nucleation
and the possibility of light snow for the plains by Thursday
morning into the afternoon. Not a ton of QPF with this system but
less than half an inch will be possible. Snow coverage over the
higher terrain will expand and continue with a 2-4 inches possible
by Thursday evening. As moist SW flow continues the upper jet
will shift over the state increasing the potential for some banded
snow by early Saturday as the trough that was over the SW moves
eastward. The plains could pick up a quick inch during this time.

For the weekend the snow will gradually come to an end through the
morning Saturday with continued light accumulations in the
mountains. Temperatures will warm into the lower 40s by Sunday
with increased subsidence provided by upper level ridging ahead of
the next system. Warm air advection and downsloping provided by
the increased westerly flow will allow for temperatures to rebound
into the upper 40s by Monday. Even as another upper trough moves
through the region Sunday night into Monday keeping the mountains
cooler and under continued snow showers.

&&

.AVIATION...(For the 12Z TAFS through 12Z Thursday morning)
Issued at 235 AM MST Wed Feb 21 2018

Clear skies and VFR for the moment. However could be a few patches
of fog at bjc/den. Current obs at kden showing fog bank to the NW
and given winds shifting a bit west and northwest the chances of
fog have increased. Will likely add in a tempo group for lower fog
at kden early this am. Potential for a Denver cyclone later
tonight and could usher in more low clouds and fog. Will address
this more in the next 12z taf cycle.

&&

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

$$

SHORT TERM...Entrekin
LONG TERM...Bowen
AVIATION...Entrekin


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