National Weather Service Forecast Discussion

Thornton Weather Forecast   
Today's Forecast Story   
126
FXUS65 KBOU 300840
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
240 AM MDT Tue Jun 30 2026

.KEY MESSAGES...

- Critical fire weather conditions will be present in the high
  country today due to warm, dry and windy conditions.

- A couple strong storms possible across far northeastern Colorado
  late this afternoon/evening.

- Mainly dry Wednesday through Friday with elevated to critical
  fire conditions across much of the area.

&&

.DISCUSSION /Through Monday/...
Issued at 224 AM MDT Tue Jun 30 2026

SW flow aloft will continue as a disturbance moves from the Great
Basin into Wyoming by tonight.  At the sfc, the low level flow will
become S/SSE across the plains as a lee trough develops along the
I-25 Corridor. Eventually, low level moisture will begin to
increase over the plains by late aftn into the evening hours with
MLCAPE ranging from 1500-2000 kg over the far nern plains by
evening. Overall, will see a chc of high based showers/isold tstms
by late aftn over nrn portions of the I-25 corridor which will
move northeast. DCAPE values will be in the 1000-1500 range and
with decent mid level flow may see brief gusty winds of 50-55 mph
with some of the higher based activity. Meanwhile, as this
activity moves into better MLCAPE by this evening, may see a few
svr storms over the far nern plains. Across the higher terrain,
it will remain dry. Highs this aftn over nern CO will be in the
upper 80`s to lower 90`s.

For Wed thru Fri, the flow aloft will continue from the SW but be
weaker. Overall, still don`t see much moisture embedded in the
flow so the higher terrain will likely remain dry. Across the
plains, a sfc lee trogh will remain over the plains. Although
there will be some low level moisture and favorable CAPE, over
portions of the plains, there is still a decent cap. Thus any tstm
activity will probably be rather isold. Highs across the plains
will be in the upper 80`s to mid 90`s each day.

Looking ahead to the 4th of July, the flow aloft will become more
westerly as a weak system moves across the nrn Rockies. This may
allow for a cool front to move across nern CO Fri night into Sat.
Depending on how much low level moisture there is behind this
front, will determine tstm chances across nern CO during the
aftn/evening hours. For now have kept pops in the 20-30% range.
Across the higher terrain it looks mainly dry.

By Sun, an upper level high will begin to build over the srn Rockies.
Some subtropical may begin to move into the area which may lead to a
slight chc of storms over the area.

&&

.AVIATION /06Z TAFS through 06Z Wednesday/...
Issued at 1125 PM MDT Mon Jun 29 2026

Winds will be SE to S overnight and continue thru 16Z on Tue.
Winds by late morning will increase at APA and DIA with gusts
from 25 to 30 mph after 19z. At BJC will keep winds SE but speeds
will be lighter. By 21Z, there will be widely sct high based
showers. With mid level flow still decent brief gusts from 40 to
50 mph certainly can`t be ruled out.  As far as smoke, will keep
it in the tafs as skies will remain hazy. For Tue evening, winds
may turn more north for a few hours at BJC and DIA before shifting
to drainage in the 03z-05z timeframe.

&&

.FIRE WEATHER...
Issued at 224 AM MDT Tue Jun 30 2026

Crirical fire conditions will remain over the higher terrain
this afternoon into the early evening hours as gusty southwest
winds and low humiditity levels will continue.

For Wednesday, the flow aloft will weaken, however, humidity
levels will be low across much of the area. Looking at data, it
appears areas along and south of I-70 over the higher terrain will
still see gusty winds up frm 30-35 mph. In addition, areas over
the Palmer Divide may see gusty winds south winds so have issued a
Fire Weather Watch for these areas. Eslewhere elevated fire
conditions will be in place.

Looking ahead to Thursday and Friday, it will remain very warm
and dry with low humidity levels both days. However, winds will be
lighter. Thus most areas will have elevated fire conditions with
critical fire conditions becoming more localized.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning from noon today to 9 PM MDT this evening for
COZ211>214-216>218.

Fire Weather Watch from Wednesday afternoon through Wednesday
evening for COZ212-214-216-241.

&&

$$

DISCUSSION...RPK
AVIATION...RPK
FIRE WEATHER...RPK

NWS BOU Office Area Forecast Discussion