548
FXUS65 KBOU 091903
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
103 PM MDT Tue Jun 9 2026

.KEY MESSAGES...

- Widespread critical fire weather conditions expected in fuel-
  prone areas today and Wednesday.

- Virga showers capable of producing strong outflow winds possible
  this afternoon.

- More heat ahead, with the hottest temperatures today. Highs
  generally in the lower to mid 90s across the I-25 Corridor, but
  just shy of 100 over the northeast plains.

- Brief heat relief expected Thursday, before a more substantial
  cooldown starting Sunday.

&&

.DISCUSSION /Through Tuesday/...
Issued at 100 PM MDT Tue Jun 9 2026

Warm and windy conditions expected across the forecast area today
as strong southwest flow aloft mixes down to the surface. We have
been a bit slow to warm this morning due to cloud cover and a
Denver cyclone keeping the strong southwest winds farther south
and east. Areas that have seen the southwest winds have already
warmed up to the mid-80s to low 90s (compared to 73 dg at KDEN
currently!) due to compressional heating. As the cyclone washes
out this afternoon, expect temperatures to quickly warm, with
relative humidity values dropping to low teens and single digits.
A Red Flag Warning will still be in effect this afternoon and
evening due to these expected conditions (see Fire Weather
Discussion below).

There is a marginal risk (1/5) for of severe storms for our far
northeastern plains this afternoon/evening. Modeled Skew-T soundings
have LCLs up to 3 Km, with DCAPE between 1500-1800 J/kg. Expect
virga showers across the plains this afternoon, with strong outflow
winds possible, particularly towards the far eastern plains.
Sounding analogs did show hail up to 1" which seems possible with
the strongest storms due to expected MLCAPE values between 500-1000
J/kg, EBWD around 30-35 kts and decent mid-level lapse rates.

Overnight, a front will bring slightly cooler temperatures for
Wednesday, with highs in the upper 80s to low 90s. There could be
some gusty winds behind this front, with northerly gusts up to 30-35
mph possible at times. Another round of elevated-to-critical fire
weather conditions are likely for the plains due to low relative
humidity values and breezy conditions. A 500-mb jet is progged to be
over Colorado, with cross-barrier flow of 40-50 kts. This will lead
to gusts up to 50-60 mph across the high terrain throughout the day.
For the plains, it won`t be as windy, however gusts up to 40 mph are
expected, particularly the wind prone areas along I-25 Corridor and
northern plains.

Overnight Wednesday, a stronger cold front will race through the
forecast area and will likely pack a punch. Hi-res guidance
indicates northerly wind gusts of 35-45 mph behind the frontal
passage, especially for the northern and eastern plains. After that,
relatively quiet conditions are expected towards the end of the
week. Thursday will be the coolest day of the week, with highs
hovering around the high 70s, with some portions of the plains
reaching up to the low 80s. However, expect that to be short lived
as the heat returns on Friday and Saturday, with 80s to 90s
expected again.

Next chance for precipitation looks to be on Saturday and Sunday
ahead of an incoming upper level trough. Ensemble guidance has been
in good agreement of high temperatures in the low-to-mid 70s for
Sunday and Monday, which will be a nice reprieve from the heat.
However, the heat should return by midweek as an upper level ridge
builds over the southwestern United States.

&&

.AVIATION /18Z TAFS through 18Z Wednesday/...
Issued at 1145 AM MDT Tue Jun 9 2026

A cyclone is currently sitting of to the east of DEN, bringing
weak northwesterly winds to KDEN and KAPA, with gusty southwest
winds just to the east of each airport. This cyclone should move
away from the area over the next hour or two, letting the gusty SW
winds move into KDEN and KAPA. The gusty SW winds are expected to
hold off at KBJC until around 20Z. Isolated to scattered showers
will move northeast off the foothills this afternoon. The
majority of the activity near the airports is expected to be
virga, leading to temporary stronger gusts (closer to 40kts) as
some of this activity moves nearby. Wind gusts will decrease
around 03Z. A weak front will move through overnight, turning
winds more northerly at KDEN. A few models are showing some
gustier winds along the front to the east of KDEN, but there is a
low chance those winds could impact the airport around 06Z with
the frontal passage. The fronts impact at KBJC and KAPA will be
less pronounced with winds becoming more light and variable with
the frontal passage. Winds will pick back up late tomorrow
morning/early afternoon, with gusts out of the west around 20 to
30kts. No ceiling concerns with this TAF package.

&&

.FIRE WEATHER...
Issued at 100 PM MDT Tue Jun 9 2026

Elevated to critical fire weather conditions are expected across the
plains this afternoon and evening. Despite recent precipitation, the
majority of the fuels remain receptive to burning according to
recent fuels status. Therefore, areas that did not receive
significant rainfall will have conditions favorable for rapid fire
spread.  It is important to note that areas around Denver metro and
northern plains have not reached critical fire weather conditions
yet due to a Denver cyclone keeping the strong, dry southwest
winds out of the area. However, as that cyclone washes out, expect
conditions to rapidly detieorate, with relative humidity values
dropping to low teens (and single digits in some areas) and winds
gusting up to 30-40 mph. Overnight humidity recoveries will be
fair, with most places reaching up to 40-50%.

Another round of elevated to critical fire weather conditions are
expected on Wednesday, with RH values dropping to single digits and
teens, and westerly winds gusting up to 40 mph. There is some
uncertainty with the eastern extent of the strongest winds. Due
to this, have decided to keep the far eastern plains in a watch,
and upgrade the rest of the area to a Red Flag Warning. If new
guidance indicates stronger winds, then the next forecast package
will have the entire plains in a warning.

Elevated fire weather conditions are possible Thursday and Friday.
However, winds will be the limiting factor as guidance indicates
more localized nature of stronger winds.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning until 9 PM MDT this evening for COZ240>251.

Red Flag Warning from noon to 8 PM MDT Wednesday for COZ240>245-
248-250-251.

Fire Weather Watch from Wednesday afternoon through Wednesday
evening for COZ246-247-249.

&&

$$

DISCUSSION...MAI
AVIATION...AP
FIRE WEATHER...MAI

NWS BOU Office Area Forecast Discussion