National Weather Service Forecast Discussion

Thornton Weather Forecast   
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609
FXUS65 KBOU 121853
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
1253 PM MDT Fri Jun 12 2026

.KEY MESSAGES...

- Elevated to near critical fire weather conditions today and
  possible on Saturday across the high country.

- Cooler for Saturday and Sunday behind a cold front.

- The best chances for showers/thunderstorms will be Sunday.

- Temperatures warm back up next week.

&&

.DISCUSSION /Through Friday/...
Issued at 1253 PM MDT Fri Jun 12 2026

Westerly flow aloft will prevail over Colorado today as an upper
level trough moves across the Northern Rockies. This will bring
warm and dry conditions to the area today. Cross sections show a
dry airmass with only few high-based cumulus clouds this
afternoon. Gusty west winds, with gusts up to 40 mph, will prevail
over the mountains and mountain valleys. Highs this afternoon are
expected to reach the upper 80s to lower 90s across northeast
Colorado.

A cold front associated with the upper level trough
passing to our north will push south through the area Saturday
morning. High temperatures will be about 10 degrees cooler with
highs in the upper 70s to lower 80s. A slight increasein low
level moisture is expected, though dew points will only reach the
30s Saturday afternoon. A second surge of cooler air will increase
northeast winds late Saturday afternoon and evening leading to
increased upslope flow. This is about the only source of lift,
thus the best chance for showers and thunderstorms will be over
the foothills and Palmer Divide. Limited instability and moisture
combined with a somewhat capped airmass will make it difficult for
showers and thunderstorms to survive moving off the higher
terrain. Cooler air and low level moisture continue to move in
behind this second surge resulting in mostly cloudy skies and cool
temperatures come Sunday morning. Temperatures will struggle to
get out of the 60s Sunday afternoon due to the cooler air and
cloud cover. Expect a better chance for showers and thunderstorms
over the foothills (mainly south of I-70) and Palmer Divide. The
urban corridor again looks to be too cool and capped. A shortwave
moving across Wyoming Sunday could help produce showers off the
higher terrain, thus we will keep a chance for showers in the
forecast. One thing to note, the last few model runs have
significantly reduced rainfall chances for this weekendacross
northeast Colorado.

For Monday, northwest flow aloft will prevail over the Central
Rockies as upper level ridge intensifies along the west coast.
Temperatures rebound with highs in the upper 70s to lower 80s
across northeast Colorado. Drier air returns, but there could be
enough lingering moisture for isolated showers and thunderstorms
along and east of the Palmer Divide. Colorado will remain just on
the east edge of the ridge Tuesday through Thursday under
northwest flow aloft. Temperatures continue to warm Tuesday and
Wednesday with highs reaching the upper 80s to mid 90s by
Wednesday. A shortwave trough passing north of Colorado will bring
a cold front to northeast Colorado sometime Wednesday. If the
front arrives late in the day, downslope flow ahead of the cold
front could push highs well into the 90s. If the cold front
arrives early in the day, highs may only reach the upper 80s. The
cold front should bring cooler temperatures for Thursday, any
relief from the heat will be short-lived as ridging moves over
Colorado. Chances for rainfall next week (Monday through Friday)
look very low, as ridging pushes the storm track north of Colorado
and subtropical moisture stays well south.

&&

.AVIATION /18Z TAFS through 18Z Saturday/...
Issued at 1159 AM MDT Fri Jun 12 2026

Winds are currently light and variable across the Denver metro area,
and model guidance suggests light NW to NE winds this afternoon.
Daytime mixing and downsloping enhancement could bring sporadic
northwest gusts of around 20KT, but the chance appears to be too low
(20% chance) to introduce in the TAFs at this time, and impacts
should be minimal.

A cold front will move through the region between 12Z and 14Z
Saturday morning, bringing northerly winds and a few gusts up to 20-
25KT. Winds after the cold frontal passage will generally remain
steady at KDEN and KAPA, taking on a more easterly component by 22Z.
No precipitation is expected, and mostly clear skies prevail through
the TAF period.

&&

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

&&

$$

DISCUSSION...12
AVIATION...AA

NWS BOU Office Area Forecast Discussion