National Weather Service Forecast Discussion

Thornton Weather Forecast   
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176
FXUS65 KBOU 242355
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
455 PM MST Tue Feb 24 2026

.KEY MESSAGES...

- Strong winds expected along the east slopes of the Front Range
  Mountains and foothills through this evening, with a few gusts
  of 80 mph possible.

- Heavy, wet snow will form over the mountains late this afternoon
  and will continue through Wednesday night. The heaviest snow
  amounts and worst travel conditions will be in the Park and
  Medicine Bow Ranges.

- Critical fire weather conditions today and Wednesday. Elevated
  fire weather conditions expected Thursday and back to critical
  fire weather conditions on Friday.

&&

.DISCUSSION /Through Tuesday/...
Issued at 106 PM MST Tue Feb 24 2026

It`s quite a windy day today with some surprising wind gusts on
the plains. The most surprising was a 61 mph gust at Denver
International Airport. A gust up to 83 mph occurred in the
foothills at Dakota Hill. Other gusts above 70 mph have occurred
in the Front Range Mountains and Foothills. The High Wind Warning
and the Red Flag Warning are verifying and those warnings were
left unchanged in this update.

Temperatures warmed up quickly across the plains and a couple
record highs are possible. Denver will likely tie the record high
of 71 set back in 1995.

Visible satellite imagery shows low to mid level clouds
increasing over the mountains this afternoon and that trend will
continue through the rest of the day. Dew points are increasing in
southwest Wyoming and this moisture will allow snow showers to
develop in the northern mountains of Colorado this afternoon.
Models are showing some significant moisture reaching the
mountains of our forecast area. Precipitable water anomalies are
forecast to reach 5 sigma above normal in Grand County. This
moisture, combined with strong orographic flow for the Park and
Medicine Bow Ranges, will create heavy, wet snow late this
afternoon through late Wednesday night. Model guidance increased
QPF over the northern mountains for this event but the NBM had way
too high amounts since it incorporated the NAM Nest which
incorrectly has forecast amounts of over 7" of QPF for this event.
The QPF and snowfall forecast was trended towards the consensus
of models which still has over 2" of QPF in the Park and Medicine
Bow Ranges. Snow ratios will be on the very low side for a
February event with snow ratios below 10:1 possible. Wording for
the Winter Storm Warnings were increased to 10-20 inches for the
Park Range and 8 to 16 inches in the Medicine Bow Range.

The forecast for tomorrow was a big focus due to fire weather
concerns. The fire weather is discussed in further detail in the
fire weather section below. A strong surface pressure gradient
will develop across the state of Colorado tomorrow out ahead of a
shortwave trough which will make it to southern Wyoming by the
late afternoon. There will be widespread strong winds with gusts
up to 55 mph across the plains and the higher terrain. Both areas
should stay below High Wind Warning criteria. On Wednesday
evening, a surface cold front will move across our forecast area.
The frontogenesis will be strong enough to create some rain
showers across lower elevations. Some snow could mix in on the
Palmer Divide overnight Wednesday night but amounts will be
minimal. The cold front will enhance snow rates in the mountains
Wednesday evening and then will largely put an end to the snow
overnight Wednesday night.

The hope is that Thursday will have a post-cold frontal airmass
that will have cooler temperatures and lighter winds. Highs will
likely be in the low 60s across the plains. Very dry air will move
into place after the cold front so low relative humidity will
potentially be an issue if winds are stronger than expected.

A west-northwest jet stream will stay positioned just to the north
of Colorado on Friday. There will be subsident flow which will
keep conditions dry. Gusty northwest winds will lead to fire
weather concerns again.

Pacific moisture will move from the west coast over the mountains
of Colorado this weekend. This will allow for some light snow
showers to form over the northern mountains. Limited impacts are
expected from light snow amounts during this period.

A cut-off trough will move over the southern Nevada and Utah area
Monday into Tuesday of next week. There is significant uncertainty
with this pattern and the positioning and strength of the cut-off
trough. There is a chance that this trough brings healthy
precipitation amounts to the state of Colorado. The most likely
scenario is that it will bring moderate snow to the southern
mountains. At this time, precipitation would more likely be rain
across the plains.

&&

.AVIATION /00Z TAFS through 00Z Thursday/...
Issued at 440 PM MST Tue Feb 24 2026

VFR conditions expected through the TAF period. Westerly winds
should weaken in the next two hours. There is a high level
uncertainty with how the winds will evolve after that, due to
multiple boundaries still in place over the plains. We could
gradually transition to the SE through the night, continue with
northwest before drainage takes place, or transition immediately to
drainage this evening. With either of these scenarios, expect
winds to generally stay under 15 kts this evening and tonight.

Another round of strong winds are expected tomorrow for all
terminals. Westerly winds will begin to strengthen around 17Z/18Z
(slightly earlier for BJC), with gusts up to 45 kts possible at
times. Expect weaker winds by 00Z/01Z, however the direction is
still unclear at this time.


&&

.FIRE WEATHER...
Issued at 106 PM MST Tue Feb 24 2026

For Wednesday, there is high confidence in strong winds across the
entire forecast area with gusts up to 55 mph. What is more
uncertain is the relative humidity. Pacific moisture will make
its way over the mountains and through the plains of Colorado.
Some models have dew points up to 37 F across the plains. However,
there is concern that the models are over-predicting the dew
points and some drier air will mix down in the afternoon. Forecast
dew points are around 23-28 F tomorrow afternoon which would put
minimum relative humidity between 15-20%. While the relative
humidity won`t likely reach Red Flag criteria, a Red Flag Warning
was issued due to the strong winds and very dry fuels. If a fire
does start, the conditions could allow for it to spread quickly.

For Thursday, some models have moderate winds and very dry air
moving into northeast Colorado. However, models do not seem to be
representing the chance for rain Wednesday night across the plains
and the strength of the cold front well enough. The hope is that
temperatures will be slightly cooler than currently forecast with
slightly higher dew points. If that were to be the case, a Red
Flag Warning may be avoidable. However, critical fire weather
conditions are possible so it will need to be monitored.

Temperatures will increase on Friday with wind gusts of 30-35 mph.
It seems likely that critical fire weather conditions will develop
especially across the northern plains.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
Winter Storm Warning until midnight MST Wednesday night for
COZ031.

High Wind Warning until 6 PM MST this evening for COZ033>035.

Winter Storm Warning from 8 PM this evening to midnight MST
Wednesday night for COZ033.

Winter Weather Advisory from midnight tonight to midnight MST
Wednesday night for COZ034.

Red Flag Warning until 5 PM MST this afternoon for COZ215-216-
238>240-242-243-248.

Red Flag Warning from 10 AM to 6 PM MST Wednesday for COZ238>251.

&&

$$

DISCUSSION...Danielson
AVIATION...MAI
FIRE WEATHER...Danielson

NWS BOU Office Area Forecast Discussion