263
FXUS65 KBOU 081829
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
1129 AM MST Wed Jan 8 2025

.KEY MESSAGES...

- Dry and slightly milder tonight; Light mountain snow showers
  developing overnight.

- The next storm is expected Thursday with light snow for the CWA.

- More alpine snows on Saturday into Sunday.

- Below normal temperatures will continue Thursday through
  Tuesday.

&&

.UPDATE...
Issued at 1055 AM MST Wed Jan 8 2025

Some minor adjustments were made to include some of our lowest
overnight temperatures and slightly enhanced winds around KDEN,
besides that, little attention was required. The Dense Fog
Advisory was allowed to expire as fog cleared out as expected.
Looking at the latest guidance this morning, it`s looking like
there is a slight increase in snowfall accumulations for areas
south of Denver. With gusty winds expected and a few inches of
existing snow on the ground from yesterday`s storm, the afternoon
package may come with some winter highlights for the Palmer Divide
and adjacent plains, as we are seeing increasing potential for
blowing snow leading to hazardous travel conditions for the
morning commute. All else looks on track for the current forecast.

&&

.SHORT TERM /Through Tonight/...
Issued at 222 AM MST Wed Jan 8 2025

It`s a cold morning in northeast Colorado, with some pronounced
cold spots in both the lower elevations and high country. Weld
County is the frontrunner in the plains with temperatures
currently hovering near 10 below zero in the northern half of the
county. In the mountains, the Fraser River Valley (-23 to -27F)
and Stub Creek at -30F (below the Medicine Bow Range) are leading
the pack. Despite these temperatures, we`ll see modest warming
today as diurnal temperatures rebound above freezing across the
lower elevations, with clear sky conditions prevailing and weak
northerly flow aloft. Fog remains confined to the South Platte
River Valley at this hour, and may persist through mid-morning, so
no changes planned to the current Dense Fog Advisories.

Overnight, an upper-level shortwave will dig south, closing off
over southwestern Colorado by early Thursday morning. This will
drive a surface cold front southward through the overnight hours,
with development of cold advection and increasing northwest winds
in the plains. Deeper moisture will arrive closer to sunrise, but
downslope flow off the Front Range should limit potential for any
pre-sunrise snow showers in the lower elevations to below 20%,
with slightly higher chances for the Cheyenne Ridge and Palmer
Divide. Light snow will begin closer to midnight tonight in the
high country, with minor accumulations on mountain roadways by
sunrise Thursday, especially around Grand/Jackson Counties.
Temperatures will remain on the chilly side overnight, but
increased winds and cloud cover will moderate them compared to
this morning`s values.

&&

.LONG TERM /Thursday through Tuesday/...
Issued at 317 AM MST Wed Jan 8 2025

An upper trough is to push across the CWA on Thursday into Thursday
evening with very strong north-northeasterly flow aloft behind it
for Friday as brief upper ridging moves across. There is weaker
northwesterly then westerly flow aloft on Friday night.

There is some upward synoptic scale velocity expected with the
trough on Thursday. Moisture is okay with the trough on Thursday and
there is some northerly low level upslope for the plains early.
However, models do not generate much in the way of QPF or snowfall
with the system. Same for the mountains, just some light snow on
Thursday. No orographic help with snow for the mountains.  Will
leave the 60-90% pops going in the mountains and the 40-70%s pops
over the plains, but no highlights with only light accumulations
expected. Fairly strong north-northwesterly winds are expected
over the plains by Thursday afternoon and evening. Skies are
expected to clear out Thursday overnight with more below normal
low temperatures.

Friday is dry, then pops will increase in the mountains Friday night
with the next weak upper trough moving in for the weekend.

Temperatures look to stay below normals. Thursday`s highs should
stay in the 20s over the plains. Friday monring`s lows look cold
with single digits for the plains and sub zero readings over the
mountains and high valleys. Friday`s highs are expected to warm
into the 30s over the plains, but still below seasonal normals.

For the later days, Saturday through Tuesday, models have another
upper trough on Saturday, mainly affecting the mountains with
snowfall. This system will have only fair moisture for the
mountains, but there will be orographic enhancement, so snowfall
amounts will be a bit healthier than Thursday`s snowfall. The
Saturday trough doesn`t appear to bring much snow to the plains.
More zonal flow is progged on Sunday through Tuesday with some
moisture for alpine snow Sunday, then drier Monday and Tuesday
with little moisture available.

&&

.AVIATION /18Z TAFS through 18Z Thursday/...
Issued at 1055 AM MST Wed Jan 8 2025

VFR conditions are expected through the overnight hours with
generally light SSW winds in place through the evening at
KDEN/KAPA, KBJC will remain light and variable. A cold front is
expected to pass south across Colorado that will bring gusty
northerly winds by 11/12Z. Gusts between 25 to 40kts will be
possible through the afternoon behind the front. Ceilings are
expected to lower beginning around 9Z with IMC conditions expected
beginning by 10Z. Light snow is expected at all TAF sites, with
KAPA being more favored with the northerly flow in place.
Visibility may drop as low as 1SM between 12Z to 15Z when snow
showers are occurring, but expecting more like 2SM. Expecting
ceilings to begin lifting by 18Z, with VFR conditions kicking
back in for the afternoon ~21/22Z. It will take KAPA a little
longer to clear out.

&&

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

&&

$$

UPDATE...Bonner
SHORT TERM...Rodriguez
LONG TERM....RJK
AVIATION...Bonner