Longmont, Colorado 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

696
FXUS65 KBOU 072019
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
219 PM 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.

- Brief heat relief expected Thursday, before a more substantial
  cooldown for the weekend.

&&

.DISCUSSION /Through Sunday/...
Issued at 119 PM MDT Sun Jun 7 2026

It`s a hot one out there today with current observations showing
widespread 90s already in place across much of the plains, with a
few hours still left to go until peak heating. ACARS soundings
show dry conditions in place, but looking at water vapor imagery,
there is some mid and upper level moisture currently tracking into
the southern portions of our higher elevations and Palmer Divide.
This will likely be enough to pop a few high-based showers over
the higher terrain this afternoon that would result in mainly some
gusty outflows as they come off the terrain and possibly a few
sprinkles. Hi-res guidance suggests these gusts could be as strong
as 50 mph, and with DCAPE values over 1500 J/kg possible this
doesn`t seem unreasonable. Any folks out on the water today
should be alert to this potential and put on those life vests as
these can quickly sneak up and catch you off guard. With greater
moisture present over the northeastern plains (dewpoints in the
50s), and 500 to 1,000 J/kg of MLCAPE in place, we could see a few
stronger thunderstorms develop as the aforementioned showers push
eastward into the better conditions, with the best chances being
early evening and for the northeast corner of Colorado.


While Monday will see a slight cool down over this weekend`s
summer- like heat, a surface low over western Kansas and a late
night/early morning cool front pushing south from WY will result
in increasing low-level moisture across our eastern plains, with
40s and 50s dewpoints expected. This will reduce fire weather
concerns, but by the afternoon, instability will be sufficient for
isolated to scattered storms to develop. With increasing
southwesterly flow aloft expected to enhance shear throughout the
day (40-60 kts of 0-6 km bulk shear), mixed with 1000-2000 J/kg
MLCAPE, supercells capable of producing large to very large hail,
strong winds, and a few brief tornadoes will be possible. The SPC
continues to highlight this potential with a Slight Risk (2/5) for
areas generally just north and east of Denver, from I-25 eastward
along the I-76 corridor, and a sliver of Marginal Risk (1/5)
along the I-25 corridor north of Denver as far west as Fort
Collins, and including the majority of the plains east of Denver
along the I-70 corridor. Expecting showers/storms to develop by
the afternoon over the higher elevations and push northeastward
over the plains where they are expected to strengthen as they tap
into the better moisture and instability.

Both winds and heat are expected to ramp up on Tuesday with a
deepening lee trough expected to tighten pressure gradients, both at
the surface and aloft. Temperatures are expected to climb into the
mid to upper 90s along the urban corridor, with some locations
across the northeastern plains shooting for the low 100s. Even
the high mountain valleys will feel some of the warmth as they
warm into the 70s and 80s. This will put afternoon high temps
between 12 to 20 degrees above normal for this time of year
across the lower elevations, and we will likely come close to or
break a few records (KDEN`s current record sits at 95F last set in
2018). Dewpoints will plummet compared to Monday`s, and with the
hot temps and windy conditions, we are expecting widespread
critical fire weather conditions to develop by late morning, more
on this in Fire Weather Discussion below. Therefore, a Fire
Weather Watch has been issued from Tuesday morning to Tuesday
evening for all of our lower elevations.

Wednesday will remain hot but we should see some slight cooling as
the upper-level trough moves across the Northern Rockies. The main
concerns will remain with elevated to critical fire weather
conditions persisting, especially with only modest recoveries to
RH expected overnight Tuesday coinciding with another breezy day.
A cold front is expected to slide south across the forecast area
Wednesday night that will bring afternoon highs back closer to the
norm for early June.

Ensembles show mostly dry conditions to continue into at least
Saturday. They are also trending towards potential for below
normal temperatures by the end of the weekend into early next
week.




&&

.AVIATION /18Z TAFS through 18Z Monday/...
Issued at 1136 AM MDT Sun Jun 7 2026

VFR conditions expected through the TAF period. Winds are
currently light and VRB at all TAF sites and should have some sort
of west/northwesterly direction by 20Z/21Z as daytime mixing
continues. However, convection spilling off the foothills could
make winds more northerly than advertised. Guidance is in good
agreement of scattered virga showers this afternoon, mainly
between 20Z-24Z, with gusty outflows up to 35 kts possible. There
is still come uncertainty of exact coverage of these showers and
thus have opted to keep the PROB30 instead of adding a TEMPO.

Some uncertainty with wind direction after convection this
evening, but they should stay light (under 10 kts) and VRB.
Guidance shows a slightly later timing for a weak frontal passage,
closer to 07Z-09Z, that will bring winds more northwesterly before
they become more easterly by 14Z-15Z.

For tomorrow afternoon, confidence is increasing of better
coverage of showers and thunderstorms. However, it looks like the
best instability will be east of the airports, so have opted for a
PROB30 for showers over thunderstorms. If future guidance starts
trending towards the better moisture and instability being over
I-25 corridor, would then need to add thunderstorms into the TAF.

&&

.FIRE WEATHER...
Issued at 119 PM MDT Sun Jun 7 2026

As we have been advertising, Tuesday and Wednesday are expected to
bring critical fire weather conditions to a large majority of our
plains. We are still hoping for a zone-by-zone update tomorrow
from some of our fire partners, but with single-digit RH and
gusty southwesterly winds picking up through the afternoon (gusts
to 40 mph), we have gone ahead and issued a Fire Weather Watch
for Tuesday for all of our lower elevations. HDWI (Hot Dry Windy
Index) still continues to show Tuesday likely reaching the
90th-95th percentile or greater, but lower probabilities for
Wednesday as 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. There is now
more certainty regarding cooler temperatures by Thursday, but not
much recovery in humidity. Friday is forecast to warm back up to
the upper 80s and lower 90s across the plains and RH will remain
below critical thresholds, so at least elevated to patchy
critical fire weather conditons are likely to persist through the
week.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
Fire Weather Watch from Tuesday afternoon through Tuesday
evening for COZ238>251.

&&

$$

DISCUSSION...9
AVIATION...MAI
FIRE WEATHER...9