National Weather Service Forecast Discussion

Thornton Weather Forecast   
Today's Forecast Story   
530
FXUS65 KBOU 180224
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
724 PM MST Tue Feb 17 2026

.KEY MESSAGES...

- Periods of snow and blowing snow through Thursday will likely
  lead to continued travel impacts through most of the week.

- Additional fire weather concerns for elevated to critical fire
  weather conditions Wednesday.

- The plains may see their first chance of measurable snow on
  Friday night.

&&

.UPDATE...
Issued at 721 PM MST Tue Feb 17 2026

An upper level jet has enhanced precip over the nrn mtns early
this evening.  In addition, some of this precip has held together
and affected nrn portions of the I-25 Corridor. Have adjusted
pops to account for precip along nrn areas of the I-25 Corridor.

&&

.DISCUSSION /Through Tuesday/...
Issued at 1135 AM MST Tue Feb 17 2026

A strong cold front moved through Colorado this morning briefly
producing heavy snow in the mountains and rain along and west of
the I-25 corridor. It is nice to receive rainfall across lower
elevations on a Red Flag Warning day but it will have little
impact on the critical fire weather conditions. We are already
seeing critical fire weather conditions on the plains and the
fire weather concerns are discussed further in the Fire Weather
section below.

Water vapor imagery shows strong subsidence and a dry intrusion
moving across the I-25 corridor. As it moves across our forecast
area, dew points are decreasing rapidly and winds are increasing.
Wind gusts will reach up to 65 mph on the plains and a High Wind
Warning remains in effect. The winds will decrease around sunset
so the warning goes through 5 pm.

Despite the subsidence aloft, there is enough moisture and
favorable orographic flow for scattered snow showers to form in
the mountains throughout the day today. Steep lapse rates mean
snow showers will be briefly moderate to heavy in intensity. The
western slopes of the mountains will see another 1-4" of snow
today.

Water vapor also shows another area of higher moisture in Utah
that will move across Colorado tonight. More widespread but less
intense snow will spread across the mountains tonight with another
few inches possible.

A shortwave trough will move from California to Colorado on
Wednesday. This will provide QG ascent across our forecast area.
The mountains will continue to see healthy coverage of snow.
Across the plains, it will be another mild and windy day with
southwest winds. The will be critical fire weather concerns
across the east-central plains that is discussed in the fire
weather section below. There will be steep lapse rates that
develop across the plains during the afternoon on Wednesday and
some rain showers will form with light precipitation reaching the
surface.

This same shortwave trough will slow its eastward progress and
become stronger Wednesday night into Thursday. 12Z guidance showed
two potential impacts for our forecast area from this trough. The
first is the potential for strong winds over the Front Range
foothills and adjacent plains early Thursday morning. Some gusts
could reach 60 mph in the typical windy spots in the foothills. No
highlights were issued at this time although if the mountain wave
setup intensifies, a High Wind Warning may be considered.

The other potential impact is moderate snow across the far
northeast corner of Colorado. 12Z guidance was more confident
that a TROWAL will move over far northeast Colorado with strong
700 mb frontogenesis. This would allow for a 12 hour period where
areas like Julesburg could receive up to 6" of snow although that
is the high end amount. PoPs were increased over the northeast
plains to account for this chance of snow. The exact impacts and
snow amounts will be hard to forecast until Wednesday night and
the northeast corner of Colorado should monitor the forecast.

Yet another shortwave trough will move over Colorado late Friday
and into Friday night. Recent model guidance has increased the
chance for precipitation to fall across the plains especially on
Friday night. This could end up being the first measurable snow of
the month for Denver. The mountains will see another round of
light to moderate snow from this system.

Ridging will build in over Colorado Sunday into early next week.
This will lead to warmer and drier conditions.

&&

.AVIATION /00Z TAFS through 00Z Thursday/...
Issued at 505 PM MST Tue Feb 17 2026

VFR is expected throughout the forecast period. Strong west winds
have persisted this afternoon at all 3 sites with gusts at DEN
reaching as high as 48 kts. West winds will stay strong, but
weaken through the evening hours to around 20 kts by 3z. Winds
could briefly be variable this evening, especially at DEN
according to the latest hi-res guidance. Drainage winds will then
occur later this evening with somewhat stronger than usual wind
speeds expected (sustained around 13 kts and gusts around 20 kts).

For tomorrow, strong winds will again be the main story, but they
should be a bit weaker than today. Gusts up to 30 kts or
potentially a little stronger are possible at all 3 TAF sites
according to hi-res guidance. Winds will generally be in a
WSW/SSW direction throughout the day tomorrow. RRFS soundings for
tomorrow show the potential for a high level deck at BJC tomorrow
afternoon as well.

&&

.FIRE WEATHER...
Issued at 1135 AM MST Tue Feb 17 2026

The Red Flag Warning for today is already verifying across the
I-25 corridor and eastern plains. The strong subsident flow has
allowed very dry air to be mixed down to the surface. Centennial
Airport has a dew point of -4 F which is resulting in a relative
humidity of 9%. Other areas will have relative humidity drop
below 10% across the plains especially along and south of I-70.
Wind gusts have reached over 60 mph across the plains and those
strong winds will continue through the afternoon. Critical to
extremely critical fire weather conditions will continue through
around 6-7pm this evening. No changes were made to the Red Flag
Warning.

Wednesday will have gusty winds potentially up to 50 mph over
Elbert and Lincoln Counties. In addition, there will be relative
humidity that will drop to around 15%. Given the very dry fuels
the decision was made to issue a Red Flag Warning for fire weather
zones 246 and 247 in Elbert and Lincoln Counties during the day
tomorrow. If there is confidence in higher winds than currently
forecast in Washington County and surrounding areas, then the Red
Flag Warning may need to be extended northward by a later shift.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until 11 PM MST Wednesday for COZ030-
032>034.

Winter Storm Warning until 5 AM MST Thursday for COZ031.

Red Flag Warning from 11 AM to 7 PM MST Wednesday for COZ246-247.

&&

$$

UPDATE...RPK
DISCUSSION...Danielson
AVIATION...MV
FIRE WEATHER...Danielson

NWS BOU Office Area Forecast Discussion