Four Square Mile, Colorado 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

389
FXUS65 KBOU 290007
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
607 PM MDT Sun Jun 28 2026

.KEY MESSAGES...

- Widespread and prolonged critical fire weather conditions will
  be present in the high country through at least Monday due to
  warm, dry and windy conditions.

- Little change in the forecast pattern through the middle part of
  next week. The only exception will be for a chance of
  thunderstorms over the plains on Tuesday.

&&

.DISCUSSION /Through Sunday/...
Issued at 140 PM MDT Sun Jun 28 2026

Much like yesterday, the main concern in the forecast remains a
prolonged period of elevated to critical fire weather conditions,
especially across the higher elevations. Southwesterly flow aloft
remains in place as a positively tilted upper trough axis
continues to edge closer to the forecast area. Unsurprisingly,
deep mixing has already developed across the high country, with
Kremmling recently reporting a T/Td of 79/19, with an 11% relative
humidity and a 34 mph gust. The Red Flag Warning will remain in
effect across most of the high country until later this evening.
Meanwhile, a pronounced Denver Cyclone has developed across the
southern Denver metro, which has left most of the I-25 corridor in
an easterly flow that`s limited the amount of surface heating so
far. That cyclone should lift a bit further north, but it will
likely mean temperatures along/north of I-70 will be a bit cooler
than originally forecast this afternoon due to the weaker mixing.

By tonight, a mid-level cold front is expected to push across the
northern high country into the northeastern plains late this
evening into the overnight hours, though the accompanying surface
front is rather weak. Meanwhile, smoke from ongoing wildfires
across Utah and western Colorado is likely to make it to the
region sometime this evening and continue through tomorrow
morning. Most HRRR/RAP cycles develop a fairly substantial plume
across the northwestern half of the CWA this evening which slowly
disperses and pushes southeastward overnight into Monday
morning... and we`ll likely see a pretty hazy sunset/sunrise
tonight/tomorrow.

The forecast this week has remained almost unchanged. A few
shortwaves will pivot around the longwave trough over the
northwestern US, while ridging builds across the Ohio Valley/Mid
Atlantic this week. In general, that leaves dry southwesterly flow
aloft in place across our forecast area. Temperatures across the
plains look to reach the upper 80s to mid 90s each day. With
700-500mb flow still around 25-40kt, that should translate to
gusty winds (especially across the high country) each afternoon,
meaning that critical fire weather conditions are likely to
continue through the week.

While the pattern will remain generally dry, there are a couple of
chances for some precipitation across the plains. The most likely
period is late Tuesday afternoon or Tuesday night, with
isolated/scattered showers and a few storms also possible as we
get closer to next weekend.

&&

.AVIATION /00Z TAFS through 00Z Tuesday/...
Issued at 605 PM MDT Sun Jun 28 2026

A cyclone is currently located just east of KDEN. Winds at KDEN are
currently a mix of NW-NE, while winds at KAPA and KBJC have turned
NW. Wind direction over the Denver metro will continue to turn
counterclockwise as this cyclone tracks east over the next one or
two hours. Winds will die down by around 03Z and turn to SSW
drainage flow until the arrival of a cold front between 09Z to 11Z.
A brief period of light (<10KT) northerly winds will accompany this
front in the early morning. Breezy westerly winds are expected at
the three airports tomorrow after 18Z, gusting up to 25KT at times.

Smoke concentrations will continue to increase starting now and
through the TAF period, impacting slant-range visibility. A smoke
plume from the wildfire near Leadville, CO continues to be
transported northeast and is already over the foothills, getting
closer to KBJC. Smoke concentrations aloft are expected to peak
around 06Z tonight, and again near sunset tomorrow.

&&

.FIRE WEATHER...
Issued at 140 PM MDT Sun Jun 28 2026

Critical fire weather conditions have been observed across a large
portion of the high country so far this afternoon. In fact, it`s
drier across many of the high mountain valleys than this time
yesterday, with a couple of sites starting to fall to around 10%
RH, with several RAWS also reporting 40-45 mph wind gusts. These
conditions are likely to persist through the rest of the afternoon
and evening, and no changes were made to today`s Red Flag Warning.

While a cold front is expected to bring some very modest relief to
the region overnight tonight, a continued southwesterly flow aloft
will lead to elevated/critical fire weather conditions yet again
on Monday. Given recent models underestimating the amount of
mixing/drying during the day, we lowered Td/RH a bit again... and
have a large swath of critical fire weather conditions forecast
across the higher elevations, especially along/south of I-70. The
previous Fire Weather Watch has been upgraded to a Red Flag
Warning across the same zones.

As we look towards the upcoming week, unfortunately there is very
little change in the large scale pattern. Elevated to critical
fire weather conditions look likely to continue across most of the
higher elevations each day, with the potential for some of the
warmest/driest air to reach the area by late in the week. There is
also some concern about fuels status along the northern Foothills
and most of the I-25 corridor/Palmer Divide... and if fuels status
changes over the next few days, some fire weather highlights may
need to be expanded into those regions going forward.

&&

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

Red Flag Warning from noon to 9 PM MDT Monday for COZ212>214-216.

&&

$$

DISCUSSION...Hiris
AVIATION...AA
FIRE WEATHER...Hiris