357
FXUS65 KBOU 050649
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
1149 PM MST Tue Feb 4 2025

.KEY MESSAGES...

- Much warmer Wednesday over the urban corridor and plains.

- Light alpine snow is expected from Wednesday into next week.
  Locally moderate snowfall expected Friday night into Saturday.

- Strong westerly winds are expected Wednesday with gusts up to 65
  mph over the mountains and foothills, and up to 45 mph over the
  plains.

&&

.UPDATE...
Issued at 940 PM MST Tue Feb 4 2025

No significant changes to the forecast. The shallow cold airmass
remains firmly in place across most of the metro and eastern
plains, with mild temperatures across the foothills and most of
the mountains. Main concern is the potential for some patchy fog
to develop near the edge of the cold. Added a brief mention in the
grids to cover that.

Only other update of note this evening was to blend in some
current obs and recent HRRR data which better captures the edge of
the cold across the metro/foothills.

&&

.SHORT TERM /Through Wednesday/...
Issued at 207 PM MST Tue Feb 4 2025

The cold, shallow airmass has barely budged today. It only
extends up to around 6500 feet MSL. Once above the cold layer, in
the foothills and Palmer Divide, temperatures have climbed into
the upper 50s to mid 60s. A Denver cyclone off to the southeast of
the metro will keep chilly northeasterly flow across the urban
corridor and eastern plains where temperatures will slowly
moderate, with 30s and 20s expected for highs late in the day.

For tonight, the coldest temperatures are expected around or a
little after midnight. A lee-side trough begins to develop in
advance of a shortwave trough. This will cause southwest to west
winds to spread down the foothills and onto the plains, most
locations across the urban corridor should see warming
temperatures towards sunrise.

Windy to very windy conditions are expected for Wednesday as the
lee- side trough deepens. It will be much warmer Wednesday below
6500 feet MSL where the cold air resided today. The westerly winds
will scour out the cold air and temperatures are expected to
climb into the 60s. This warming will also help mix stronger winds
aloft down. Wind gusts in the mountains and foothills could reach
65 mph, while across the lower elevations east of the mountains
wind gusts to 45 mph will be possible. As the shortwave trough
nears the region, moisture increases over the mountains, with snow
likely late in the day and lingering into Wednesday evening.

&&

.LONG TERM /Wednesday night through Tuesday/...
Issued at 207 PM MST Tue Feb 4 2025

Winds will decrease Wednesday night as the upper level trough in the
northern United States travels east. With that system moving
eastward, northern Colorado will be positioned under the right
entrance region of the jet streak. There is enough moisture and
orographics to support snow in the mountains overnight into Thursday
morning, although most of it will be concentrated in North Park.
Highest accumulations will be in the Park Range, where they could
get up to 5" whereas the Medicine Bow Mountains could see a couple
of inches. These areas could see travel impacts due to slick and
snow packed roads with minimal snow accumulation and impacts
expected elsewhere in the high country.

Thursday morning, a weak cold front will push southeastward which
will make temperatures cooler than Wednesday. Widespread high
40s/50s are expected for the plains and 30s for the high country.
Behind the cold front, winds from the east/southeast will be breezy
for the eastern plains with 25 mph and gusts up to 30 mph are
expected.

Friday has proven to be a little bit of a headache. We will be under
zonal flow aloft, but looking at 700mb winds, there is a shortwave
trough that will move through the area during the day Friday. Due to
model differences, the timing of this system as well as the daytime
temperatures are still uncertain. The Euro and Canadian ensembles
have the system arriving later in the day, allowing temperatures to
get up to the lower 60s. However, the GEFS has the system arriving a
little bit earlier, allowing the temperatures to rise up in the
lower 50s. Went ahead and kept maximum temperatures to be in the mid
50s as a happy medium between the two scenarios.

With this system, strong winds are expected over the high country
with gusts up to 60 mph expected for the highest elevations,
particularly the Park Range and Mosquito Range Friday afternoon into
the evening. Blowing snow could make travel difficult Friday
evening. The southern foothills could get gusts up to 40 mph. Palmer
Divide and eastern plains could see gusts up to 30 mph.

In terms of precipitation, the high country will see snow showers
Friday night into Saturday. Heavy rates of snowfall (1"/hr to
>1"/hr) is possible for Park Range Friday evening. Light to moderate
snowfall rates are expected for the rest of the mountains.

As for the plains, there is a small chance (30-40%) for
precipitation Friday night, however the warmer temperatures will
make it a rain/snow mix. The next chance for snow will be Sunday as
the broad upper level trough moves eastward. Very light
accumulations are expected due to limited moisture availability.
Minor travel impacts, if any, are expected on Sunday.

&&

.AVIATION /06Z TAFS through 06Z Thursday/...
Issued at 1144 PM MST Tue Feb 4 2025

Patchy fog is likely to form in the vicinity of KDEN in the next
few hours (60% chance), but impacts on the airport are
speculative. We`ve kept a brief period of LIFR ceilings in the
TAF, but the odds of this appear to be lessening. If there is
significant impact to the airport, we expect it to be brief and
done by 12z.

The more certain factor will be strong west winds developing,
threatening crosswind issues at KDEN/KAPA. Speeds of 20 to 30
knots are expected by 18z, with gusts up to 45 knots possible for
a few hours in the afternoon. West winds near crosswind thresholds
may continue into the evening, but lighter speeds are expected by
04z Thursday.

&&

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

&&

$$

UPDATE...Hiris
SHORT TERM...Meier
LONG TERM...Ideker/JK
AVIATION...Gimmestad