597
FXUS65 KBOU 071126
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
526 AM MDT Sun Jun 7 2026

.KEY MESSAGES...

- More heat ahead, with the hottest temperatures today and then
  again Tuesday. Highs generally in the mid 90s across the I-25
  Corridor and plains, but near 100 possible over the northeast
  plains Tuesday.

- Widespread critical fire weather conditions expected (>80%
  confidence) in fuel-prone areas by Tuesday, potentially (60%
  chance) lasting into Wednesday.

- Brief respite in the heat Monday, but that also brings a risk of
  severe storms.

- More substantial heat relief expected by Thursday.

&&

.DISCUSSION /Through Saturday/...
Issued at 248 AM MDT Sun Jun 7 2026

The upper level low over the Southern Plains states will lift
north-northeast today, with the flow across Colorado becoming
more southwesterly as the ridge axis over us this morning shifts
slowly east. That means a deeper and drier downslope component
developing at least along the Front Range. Meanwhile, a developing
lee trough will push slowly east across the plains. With the
increased downslope component, we should be able to add on a
degree or two to yesterday`s highs despite the slightest cool
advection noted aloft. Thus, look for highs mostly in the lower to
mid 90s across most of the plains. With regard to convection,
there is still plenty of low level moisture and modest instability
(MLCAPE near 1000 J/kg) east of the lee trough. This could still
be enough despite limited shear for an isolated stronger storm or
two across the eastern plains (generally along/east of a Sterling
to Akron line) late this afternoon through tonight. Otherwise
mostly dry conditions can be expected with mostly virga or just a
few sprinkles, but those too could produce strong, gusty outflow
winds with deep inverted-v profiles past 500 mb.

A weak backdoor cold front will push across the plains late
tonight, bringing temperatures down a few degrees for Monday with
highs mostly in the upper 80s for the plains and I-25 Corridor. At
the same time, low level moisture will return to most of the
plains. That means more instability and MLCAPE growing to
1000-2000 J/kg over the northeast plains. We`re uncertain how far
west the richer airmass makes it, but there is some potential to
get close to the I-25 Corridor. We expect isolated to scattered
storms develop in the afternoon and intensify as they move
eastward into the more unstable airmass. Given increasing shear
profiles and available CAPE, supercells will be favored and be
capable of producing very large hail, along with a high wind
threat and even a brief tornado possible as storms begin to
encounter better low level inflow. SPC has outlooked areas
north and east of Denver as a Slight Risk and this looks
appropriate.

For Tuesday, we`ll shift back quickly to a much drier and windier
environment, leading to a significant jump in fire weather
concerns - see more in the Fire Weather section below. Southwest
flow aloft increases considerably as the low and mid level
gradients strengthen in between a deep trough moving across the
Pacific Northwest/Northern Rockies and a ridge building over the
Southern Plains. The resultant lee trough is expected to push
farther east in this setup, likely clearing most if not all of the
northeast plains by late in the day. With warm advection, strong
downslope, and less moisture, Tuesday is shaping up to be the
hottest day of the year so far, with mid 90s expected for all of
the I-25 Corridor and potentially 100F in the lower elevations of
the northeast plains as long as the lee trough passes by.

Wednesday is expected to be a transition day with slight cooling
aloft, but still potentially breezy conditions due to strength of
the upper level flow and low level gradients. Highs should still
surpass (>70% confidence) 90F over most of the plains.

We`re still on track for cooler weather by Thursday per all the
latest data, but the deterministic forecast still lies on the
warmer side of guidance. Highs could struggle to reach 80F across
the plains if the latest guidance verifies. What was interesting
to see was the bump in temperatures for Friday, but there is still
more confidence that we cool off again next weekend into early
the following week as we see northwesterly flow aloft develop.
This should eventually lead to a better chance of showers after
mostly dry weather Tuesday through Friday.

&&

.AVIATION /12Z TAFS through 12Z Monday/...
Issued at 525 AM MDT Sun Jun 7 2026

We`ll start this period with fairly normal S-SW winds 8-14 kts
through about 14Z, then winds should become VRB for a few hours
15Z-21Z. The chance of persistent W-NW winds 18Z-22Z is becoming
less certain (30-40% chance) as strong diurnal heating and
resultant upslope will offset the mixing component. What is more
concerning is what seems to be increasing potential for virga and
thus VRB G35+ kt microburst winds. We are expected to warm dry
adiabatically through about 17-18K ft MSL, and resultant DCAPE is
advertised to be at least 1400 J/kg. Mesoscale models including
the HRRR are showing greater potential now for those microburst
winds from virga/sprinkles. We still kept the Prob30 to message
that gust potential, most likely 20Z-24Z. However, given latest
trends would not be surprised if TEMPO VRB G30+ kts needed for a
couple hours this afternoon.

For tonight, it appears winds will become mainly light and VRB
thanks to a weak gradient but some lingering clouds, and then a
weak front closer to or shortly after midnight. That front should
support a propensity for winds to go more northerly, and opted
for an average light NW 07Z-15Z, before a more easterly wind
component is expected to develop 15Z-18Z Monday.

&&

.FIRE WEATHER...
Issued at 525 AM MDT Sun Jun 7 2026

Hot weather and a drier airmass in all but the far eastern plains
today will result in a drop in humidity readings, with some
single digit RHs along the I-25 Corridor. Winds will be lighter
across the plains, however. In contrast, breezy conditions will
develop in the mountains and high mountain valleys, but fuels
have yet to reach critical dryness. Thus, no fire highlights are
anticipated.

Monday will feature a bump in humidity readings especially across
the plains, while mountains and mountain valleys remain dry and
breezy especially during the afternoon hours.

Widespread critical fire weather conditions are still expected
Tuesday, depending on local fuel status. Widespread wind gusts of
30-40 mph can be expected by afternoon with humidity readings
likely dropping into the 6-12% range in elevations below 9500
feet. HDWI still continues to show Tuesday likely reaching the
90th-95th percentile or greater, but slightly lower probabilities
for Wednesday as just slight cooling and a possible decrease in
winds occurs. However, it will still be very dry and warm, so
critical conditions may very well persist through Wednesday. Forecast
Energy Release Component (ERC) for many stations are approaching
historical highs (data since 2005) for this time of year. There
is now more certainty regarding cooler temperatures by Thursday,
but not much recovery in humidity.

&&

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

&&

$$

DISCUSSION...20
AVIATION...20
FIRE WEATHER...20

NWS BOU Office Area Forecast Discussion