National Weather Service Forecast Discussion

Thornton Weather Forecast   
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722
FXUS65 KBOU 091757
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
1157 AM MDT Tue Jun 9 2026

.KEY MESSAGES...

- Widespread critical fire weather conditions expected in fuel-
  prone areas today and Wednesday.

- More heat ahead, with the hottest temperatures today. Highs
  generally in the lower to mid 90s across the I-25 Corridor, but
  just shy of 100 over the northeast plains.

- Brief heat relief expected Thursday, before a more substantial
  cooldown starting Sunday.

&&

.DISCUSSION /Through Monday/...
Issued at 242 AM MDT Tue Jun 9 2026

GOES-19 satellite imagery is showing some areas of stratus across
our area. In addition, radar shows some isolated strong showers
and thunderstorms for our northeastern counties particularly in
Weld County. Some fog is possible into the early morning for areas
where winds are light given the dewpoints in the 50s and the rain
that occurred on Monday afternoon and evening.

Hot and windy conditions are the main story for today and
Wednesday. Given southwest flow aloft and downsloping winds, high
temperatures for today will easily reach the low to mid 90s for
the plains. The record high at Denver International Airport is 95
degrees F, which is within reach, but we will likely fall just shy
of it. Today also brings a low risk of severe weather for the far
northeastern plains, where a marginal risk is in effect (Level 1
out of 5). MLCAPE is expected to be between 500 to 1000 J/kg for
these locations. The highest threats will be strong gusty winds
and isolated hail of about 1 inch in diameter. Additionally, high-
based showers/virga (with little to no measurable precipitation)
are possible mainly from Denver eastward this afternoon. DCAPE
values could exceed 1500 J/kg. Given environmental winds of 30 to
35 kts and any additional acceleration from passing
showers/thunderstorms, localized areas of wind gusts between 45
and 60 mph are possible this afternoon. A Red Flag Warning remains
in effect for the plains east of I-25 from 12pm to 9pm today. No
changes were made to the RFW in this forecast package. A weak cold
front will move through late tonight.

Thus, Wednesday will be slightly "cooler" than Tuesday with high
temperatures for the plains right around 90 degrees F. Wednesday
will also be another day of critical fire weather conditions. We
have issued a Fire Weather Watch for the plains east of I-25 from
12pm to 8pm. See the Fire Weather Discussion for more details.
Cross sections show a strong jet overhead with cross barrier flow
and winds of about 35 kts in the 500 to 700 mb layer. Thus, even
outside of the Fire Weather Watch area, winds gusts in the
mountains could reach 40 to 50 mph on Wednesday afternoon. For the
plains, wind gusts will be a touch lower, but the typical windy
locations near I- 25 north of Fort Collins and our northern tier
of counties could see wind gusts between 30 and 40 mph.

A stronger cold front is still expected to move through on
Wednesday night, briefly dropping high temperatures for the plains
into the upper 70s and low 80s on Thursday. By Thursday, zonal
flow aloft will be in place for the area. High temperatures on
Friday will be in the upper 80s to low 90s. Models continue to
show that the next decent chance for any measurable precipitation
could come on Saturday with a trough moving in from Canada. The
trough will bring a cooldown for the area with below average
temperatures becoming increasingly likely starting on Sunday and
lasting into early next week.

&&

.AVIATION /18Z TAFS through 18Z Wednesday/...
Issued at 1145 AM MDT Tue Jun 9 2026

A cyclone is currently sitting of to the east of DEN, bringing
weak northwesterly winds to KDEN and KAPA, with gusty southwest
winds just to the east of each airport. This cyclone should move
away from the area over the next hour or two, letting the gusty SW
winds move into KDEN and KAPA. The gusty SW winds are expected to
hold off at KBJC until around 20Z. Isolated to scattered showers
will move northeast off the foothills this afternoon. The
majority of the activity near the airports is expected to be
virga, leading to temporary stronger gusts (closer to 40kts) as
some of this activity moves nearby. Wind gusts will decrease
around 03Z. A weak front will move through overnight, turning
winds more northerly at KDEN. A few models are showing some
gustier winds along the front to the east of KDEN, but there is a
low chance those winds could impact the airport around 06Z with
the frontal passage. The fronts impact at KBJC and KAPA will be
less pronounced with winds becoming more light and variable with
the frontal passage. Winds will pick back up late tomorrow
morning/early afternoon, with gusts out of the west around 20 to
30kts. No ceiling concerns with this TAF package.

&&

.FIRE WEATHER...
Issued at 242 AM MDT Tue Jun 9 2026

Critical fire weather conditions are expected in some areas for
today and Wednesday. The fuel status update we received on Monday
shows that vegetation remains quite dry in the lower elevations.
Therefore, conditions will be favorable for rapid fire spread,
mainly for areas that did not receive significant rainfall on
Monday. We have kept the Red Flag Warning in place from 12pm to
9pm today for the plains east of I-25. Winds could gust between 30
and 40 mph and relative humidity will drop into the lower teens
this afternoon. For Wednesday, we have issued a Fire Weather Watch
from 12pm to 8pm for the plains east of I-25. Similar conditions
to today are expected for Wednesday afternoon. Some spotty fire
weather conditions are possible on Thursday and Friday, but will
be limited in duration and scope, especially on Friday.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning until 9 PM MDT this evening for COZ240>251.

Fire Weather Watch from Wednesday afternoon through Wednesday
evening for COZ240>251.

&&

$$

DISCUSSION...MV
AVIATION...AP
FIRE WEATHER...MV

NWS BOU Office Area Forecast Discussion