Thornton, Colorado 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

258
FXUS65 KBOU 182331
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
531 PM MDT Thu Jun 18 2026

.KEY MESSAGES...

- Elevated fire weather conditions in the mountains and valleys
  today and Friday with critical conditions expected on Saturday.

- Strong to severe storms possible across the eastern plains on
  Saturday.

- Scattered coverage of showers and storms on Sunday and Monday.


&&

.DISCUSSION /Through Thursday/...
Issued at 220 PM MDT Thu Jun 18 2026

Water vapor imagery shows dry air aloft over our forecast area
with northwesterly flow aloft. This has lead to a pleasant day
today with mostly sunny skies and near normal temperatures.

Ridging aloft will move over Colorado on Friday with weakening
winds aloft. The subsident flow will keep most of our forecast
area dry tomorrow. The exception will be over the southern
foothills and Palmer Divide. There is a weak boundary that will
move through tonight and will turn winds to the northeast in
those locations which will provide upslope flow. This will allow
for a few showers and storms to develop despite the limited
moisture. These storms could produce gusty winds up to 45 mph.
PoPs were increased in those areas to get a mention of storms in
the forecast.

Saturday will be an active weather day for multiple reasons. There
will likely be critical fire weather conditions across the
mountains and mountain valleys due to warm, dry, and windy
conditions. Relative humidity will drop to 10-15 percent with
gusts between 35-45 mph. Across the plains, there will be moderate
south-southeasterly winds that will bring in moisture and low
clouds across the eastern plains. Dew points will likely reach the
60s from Limon to Fort Morgan and eastward. Fog will be possible
mainly in Lincoln and Washington Counties. A dryline will develop
across the eastern plains of Colorado with model guidance mostly
showing it near Sterling to Akron. However, in these cases, the
dryline and moisture are often farther west than models predict
and it could be much closer to Denver International Airport.
There will be a shortwave moving across Colorado with moderate
deep layer shear between 45-55 knots, and with moderate to high
instability around 2,500 j/kg, strong to severe storms are
possible. Large hail and damaging wind gusts will be the primary
threats with a lower tornado threat. SPC may have to expand the
slight risk of severe storms in our forecast area farther
westward.

Another shortwave trough will be over Colorado on Sunday. Any
storms Saturday evening may push moisture westward towards the
foothills. Scattered showers and storms will develop again mainly
over the eastern plains. Monday will be similar although there
will be more zonal flow aloft. It is too early to have an idea
about the severe storm chances both days. However, at this time is
does appear there will be enough instability and deep layer shear
to produce at least a couple strong to severe storms each day.

Tuesday and Wednesday look cool with continued rain chances.
Temperatures will warm back up by the following weekend.

&&

.AVIATION /00Z TAFS through 00Z Saturday/...
Issued at 529 PM MDT Thu Jun 18 2026

VFR through the TAF period. Denver cyclone continues to sit over
the metro this afternoon, with the center of it near KBKF. DEN
remains in ENE flow with light/variable winds at BJC and APA at
the moment. Expect this to continue through 02-03z before the
cyclone lifts and drainage flow develops at DEN/APA.

A weak front is expected to reach the terminals by about 13-15z on
Friday morning, with a shift back to light northerly flow. Winds
should then slowly turn towards the northeast during the day with
speeds again remaining near about 10kt.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
Fire Weather Watch from Saturday afternoon through Saturday
evening for COZ211>214-217-218.

&&

$$

DISCUSSION...Danielson
AVIATION...Hiris