Thornton, Colorado 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

918
FXUS65 KBOU 140544
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
1144 PM MDT Sun Jul 13 2025

.KEY MESSAGES...

- Warmer with isolated showers and thunderstorms across the high
  country this evening. Similar pattern again for Monday.

- Afternoon showers/thunderstorms to continue most days for the
  upcoming week. Best chance of rain across the plains comes
  Wednesday.

- High temperatures to linger in the 90s across the plains
  through mid-week.

&&

.DISCUSSION /Through Sunday/...
Issued at 247 PM MDT Sun Jul 13 2025

A few thunderstorms have started to form over the higher terrain
this afternoon. The question remains whether these will make their
way onto the lower elevations as we head into the evening. There
has been lot`s of back-and-forth between some of the hi-res
guidance since this morning, with the HRRR having a line of
convection developing this evening, moving across the plains
through late tonight, with most other CAMs having nothing push
off the terrain at all. The latest run (19Z) seems to have backed
off any storms making their way anywhere east of I-25, but with
the persistent signal through this morning for high-based showers
and storms to pass over the urban corridor and our TAF sites,
producing near 50 mph outflows, PoPs were increased to include a
slight chance for this scenario to unfold. Currently, we are
seeing ordinary thunderstorms over the higher elevations and
current ACARS soundings still show a smidge of CIN remains in
place with NNW flow aloft keeping the storms anchored to the
terrain. With winds aloft expected to make a more westerly
transition this evening, there is some potential that these storms
indeed try to push eastward, where the SPC mesoanalysis shows 500
to 1000 J/kg of MLCAPE in place, which would be sufficient to
sustain them. So despite the HRRR now backing off, still thinking
the slight chance is warranted through tonight, with gusty
outflows being the main concern.

As previously mentioned, flow aloft becomes more zonal for Monday
as the upper-level ridge over the southwest flattens out.
Temperatures will remain hot to start the week, with high`s
nearing 100F over portions of the plains. A more active pattern
will be in place through the period, with scattered to numerous
afternoon mountain showers and storms expected each afternoon. We
could see a few spill onto the plains Monday and Tuesday, but
more widespread moisture isn`t expected until Wednesday. With
forecast soundings showing DCAPE values surpassing 1500 J/kg on
Monday and Tuesday, there is plenty of potential for gusty
outflows and dry microbursts to develop, but at this time, the
severe threat looks to remain limited.

Cooler temperatures are still on track for Wednesday and Thursday
as a shortwave and associated cold front slide across the forecast
area. This will be the main driver for the widespread moisture
making it across the lower elevations. By Friday, temperatures
return to the 90s and remain there through the long term, with
afternoon showers and storms possible each afternoon.

&&

.AVIATION /06Z TAFS through 06Z Tuesday/...
Issued at 1139 PM MDT Sun Jul 13 2025

Brief convective burst this evening has thrown a wrench into most
of the TAFs. Well defined outflow boundary/wind shift sits
near/over DEN at the time of this discussion, and should briefly
push winds to a westerly component, much like APA/BJC. Though both
radar and satellite trends show that most of the convection has
weakened significantly, can`t rule out a brief TS at DEN/APA
through 07z.

The rest of the overnight should be quieter, with drainage winds
likely returning quickly after the convection dissipates. A little
more uncertainty in the wind direction by early Monday afternoon,
but guidance generally favors a southeast direction through most
of the day. Another round of disorganized convection is expected
by mid/late afternoon, with variable and gusty winds as the main
threat. Drainage winds are expected to redevelop after 03z
tomorrow evening.

&&

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

&&

$$

DISCUSSION...Bonner
AVIATION...Hiris