National Weather Service Forecast Discussion

Thornton Weather Forecast   
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126
FXUS65 KBOU 081146
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
546 AM MDT Wed Jul 8 2026

.KEY MESSAGES...

- Scattered to numerous thunderstorms, with a few strong to severe
  storms, are expected from the Front Range eastward today and
  Thursday.

- Prolonged period of hot temperatures arrive Saturday, lasting
  through at least Tuesday. Thunderstorm chances remain low during
  this period.

&&

.DISCUSSION /Through Tuesday/...
Issued at 202 AM MDT Wed Jul 8 2026

Storms are expected to form over the foothills and I-25 corridor
early this afternoon, progressing eastward throughout the
afternoon and early evening. The strength and coverage of these
initial storms near I-25 and the urban corridor will depend
heavily on surface moisture. Some of the high res models have the
higher dewpoints mixing out and pulling east in the early
afternoon, which will hinder storms. Others, keep the moisture
closer to the foothills. If the surface moisture does end up
staying further west, we could see a few isolated strong to
severe storms near the I-25 corridor, with the coverage and
intensity of storms increasing as they move east. While strong
winds will be the primarily hazard, mid level lapse rates and
shear will be large enough that we could see a few storms produce
severe sized hail. The threat for strong winds will increase later
in the event as storms start to merge together in our eastern
plains counties. Isolated areas could see periods of heavy
rainfall as well with these storms. This activity is expected to
exit our area by the late evening.

On Thursday, it looks like we could see a Denver Cyclone set up
and a weak disturbance move through the flow aloft. The
east/southeasterly surface winds will keep dewpoints on the higher
end for a good portion of the plains. These ingredients will
combine to produce scattered to numerous thunderstorms Thursday
afternoon. Once again, the main threat will be strong winds,
particularly in our eastern counties, but we could see a few
initial supercells which produce severe sized hail in the
afternoon. I do want to put a caveat in here though that with the
decent thunderstorm coverage we`re expecting today, outflow
boundaries will likely linger somewhere over the area early
Friday, which could impact initial conditions and the location of
convective development for Thursday afternoon. We could see some
additional thunderstorm development on Friday, but coverage and
confidence in storms is lower compared to today and tomorrow.

The upper level ridge will strengthen and shift north and west
starting Saturday, putting the center of the high in the
Colorado/Wyoming/Utah area for the weekend. Models are currently
indicating that this ridge could strengthen to around 600dm
(which is very strong). The ridge will sit over our area through
at least the middle of next week. Strong subsidence under the
upper level ridge will act to limit rain chances for this weekend
and into the middle part of next week and will allow for clear
skies, sunshine, and plenty of warming. We do have 2 things that
could help us to keep temperatures below record breaking levels.
The first is that models are actually keeping the warmest
temperatures aloft to our west and north during this time period.
And the second is that surface winds look like they may have more
of an easterly component than a westerly component. This will
provide weak upslope rather than the warm,dry downslope
conditions that we see with westerly surface winds. With this
being said, we`re still looking at a prolonged period of above
normal temperatures for the whole area, but we may be able to
escape record breaking high temperatures.

&&

.AVIATION /12Z TAFS through 12Z Thursday/...
Issued at 428 AM MDT Wed Jul 8 2026

West/southwest winds will gradually turn northwest then northeast
throughout the morning. Thunderstorms are expected to form in the
higher elevations and foothills around noon before progressing
east towards the terminals. The most likely timing for storms
this afternoon will be 19Z-23Z at KBJC and 20Z to 24Z at KDEN and
KAPA. Storms will be scattered and intermittent during these time
periods, producing gusty and variable winds. This activity is
forecast to move out of the TAF sites by 00Z, with a chance for a
few lingering showers or storms. In the evening, outflow from the
storms to the east and northeast could impact the airports in the
mid to late evening. However, confidence in wind speed and wind
direction from any outflow boundaries are low.

&&

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

&&

$$

DISCUSSION...AP
AVIATION...AP

NWS BOU Office Area Forecast Discussion