National Weather Service Forecast Discussion

000
FXUS65 KBOU 290605
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
1105 PM MST Sat Jan 28 2023

.UPDATE...
Issued at 742 PM MST Sat Jan 28 2023

Radar and observations showing light snow gradually filling in
across much of the plains of northeast Colorado this evening.
Light snow also just inching into northern portions of the Denver
area as well. There has been light accumulations over the far
northern plains, generally a dusting to close to an inch like
locations around Fort Collins. FTG 88D only showing shallow
northeast upslope flow to lowest 2 gates but there is a jet core
over northwest Colorado which will slide across northern Colorado
through late tonight. Based on above observations have increased
pops to likely for light snow over norther sections and bumped up
accumulations a couple of tenths this evening. Expect the light
snow to gradually decrease after midnight but low clouds/patchy
fog will remain over lower elevations. Not seeing much in the way
of freezing drizzle but did see a few web cams on the plains
earlier with iced up lenses. Expect temperatures to continue to
drop tonight given single digits already moving into northern
border areas with Wyoming and Nebraska.

&&

.SHORT TERM...(This evening through Sunday)
Issued at 136 PM MST Sat Jan 28 2023

A moderate to strong zonal flow is will be over northern CO
through this evening, with an area of weak mid/upper level qg ascent
in place as a short wave trough move across WY.  MRMS is showing
some snow banding occurring over the mountains and spreading into
the urban corridor early this afternoon.  A colder airmass has
spread into nearly all of northeast plains and will settle along the
Front Range Foothills and Palmer Divide through Sunday.  The best
chance of snow through this evening will be through this evening as
the Pacific moisture continues to overrun the shallow arctic
airmass. Although the depth of the moisture will be fairly shallow
from the urban corridor eastward, there will be enough moisture
in the mid/upper level coupled with the upper level jet to keep
the banded snowfall in place until 01-02z. Will continue with the
Winter highlights for the mountains through 5 pm this afternoon,
but no plans to extend them at this time. The banded snowfall
could be an issue for skiers making their way back to Denver this
afternoon, so be prepared for possible delays. Later in the
evening, spatial cross-sections show some drying in the mid/upper
levels which could lead to a brief period of light freezing later
this evening. Late tonight into Sunday, light snowfall may linger
primarily along the west facing slopes north of Interstate 70, but
decreasing elsewhere with weakening upper level support. Across
the northeast plains, the low level moisture will deepen slightly,
but it will be cold enough to stay as light snow. South of
Interstate 70 over eastern Elbert and Lincoln counties, there will
be less moisture aloft with no seeders. Best chance of fog will
be down in this area tonight into Sunday morning. On Sunday
another trough drops southward out of the Pacific Northwest.
Generally weak mid/upper level qg ascent with the best moisture
through the afternoon over zone 31. Although the best chance of
accumulating snowfall will be north of I-70, there are no plans
to expand the winter weather highlights into zone 33 at this time.

.LONG TERM...(Sunday night through Saturday)
Issued at 136 PM MST Sat Jan 28 2023

A shortwave trough looks to move over northeastern Colorado
Sunday to Monday night. There is some model variability in timing
and location. The surface low will likely be located over
southeastern Colorado which will bring weak upslope flow to the
area. Along with this trough a cold air mass will be in place and
near record temperatures could be reached early in the week.

Sunday we increased POPs over what NBM had, with weak upslope flow
less than one inch of snow is expected for lower elevations
through Monday. The northern mountains will continue to see
heavier snowfall. Along the I-70 mountain corridor lighter
snowfall amounts are expected. Temperatures will drop off
significantly with highs in the teens and lows into the negative
single digits. Windchill temperatures will be well into the
negative teens.

Monday will remain cold and snow will begin to lessen over the
northern mountains as the trough exits. Light upslope flow will
continue which could give light flurries to the front range and
plains with less than one inch of accumulation. Windchill
temperatures will be much colder Monday morning especially for the
plains with values close the the negative 20 degree mark.

Tuesday the trough will hopefully have passed and winds switch
back to a more westerly flow. Thanks to this downslope flow we
will see some warming across the front range. Temperatures could
climb back into the high 20s to low 30s.

Wednesday through Friday show drying and warming with a small
ridge building Wednesday night through Friday. Another chance at
a shortwave trough comes through Friday evening into Saturday.

&&

.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
Issued at 1041 PM MST Sat Jan 28 2023

A band of snow showers is currently over the Denver metro area
which is impacting all terminals. DEN and APA will see visibility
between 1-2 miles due to snow along with ceilings in the 1-3 kft
range until 08Z. Then, the band of snow will dissipate and only a
few passing flurries are expected overnight tonight and during the
day Sunday. The tricky part will be whether low clouds and/or fog
develop later tonight and Sunday morning. The current thinking is
that fog will not develop due to the snow reducing the amount of
low level moisture. However, fog remains a possibility with
visibility reaching a half mile at all terminals if fog were to
develop tonight. IFR conditions will last through the majority of
the day on Sunday as ceilings will be in the 1-3 kft range with
visibility between 2-4 miles. Snow showers are expected to develop
again Sunday evening. Otherwise, winds will be rather light.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
Winter Storm Warning from 5 AM Sunday to 5 PM MST Monday for
COZ031.

&&

$$

UPDATE...Entrekin
SHORT TERM...Cooper
LONG TERM...Chavez/Gimmestad
AVIATION...Danielson

NWS BOU Office Area Forecast Discussion