652
FXUS65 KBOU 111802
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
1102 AM MST Thu Dec 11 2025

.KEY MESSAGES...

- Strong winds will continue along the Front Range mountains and
  foothills through midday today. Gusts will be between 70-80 mph.

- Critical fire weather conditions expected today for the lower
  foothills, I-25 Corridor and adjacent plains through early this
  evening.

- An extended period of dry and mild weather will last through the
  middle of next week, with well above normal temperatures
  expected.


&&

.UPDATE...
Issued at 817 AM MST Thu Dec 11 2025

The decision was made to issue a Red Flag Warning for the lower
foothills, I-25 Corridor and adjacent plains through 5 PM today.
Current surface observations show widespread relative humidity
values already reaching critical thresholds, as downsloping winds
have allowed ample mixing across the foothills. Even if RH values
remain marginal this afternoon (>15% RH), wind gusts up to 40-50
mph will support red flag conditions.

&&

.SHORT TERM /Through Thursday/...
Issued at 256 PM MST Wed Dec 10 2025

Current surface observations across the high country show wind gusts
up to 70 mph, with gusts up to 50 mph (aside from an isolated gust
up to 68 near the Rocky Flats) across the wind-prone areas along the
foothills. While we haven`t met high wind criteria yet, we do expect
the winds to peak later this afternoon and into the evening.

SPC upper air analysis shows northwest flow aloft, with Colorado
generally being in the right exit region of the jet stream.
Modeled cross-sections have a decent ridgetop stable layer as well
as a wave induced critical layer for this afternoon/evening. In
addition, surface pressure gradients between Grand Junction and
Denver will likely increase to 11-14 mb. With these ingredients,
we do expect winds to gust up to 80 mph periodically across the
high country. High resolution models have consistently been
indicating channels of winds along the foothills and adjacent
plains, so expect isolated wind gusts up to 55 mph through the
evening. Overnight Wednesday, there will be a brief lull in strong
winds before it could pick up again Thursday morning, as cross-
sections indicate another critical layer forming. For this reason,
still expect High Wind Warning to continue till 11 AM Thursday
morning. However, if guidance changes this evening/overnight, the
warning could expire earlier.

Due to continuous downsloping winds, Thursday morning low
temperatures will be above normal. Across the plains, expect to wake
up to temperatures between high 30s and mid 40s. Denver`s record
warmest minimum temperature for December 11th is 44 degrees (set in
1933) and our current forecasted low is 43. We will keep any eye out
for any record-breaking minimum temperatures. The warming trend
will continue throughout the day Thursday, as breezy northwest
winds (gusting up to 45 mph a times) will aid in compressional
heating and allow temperatures to reach the mid-to-high 60s across
the plains (~20 degrees above normal!). Other than that, dry
conditions will prevail for the forecast area.

&&

.LONG TERM /Thursday night through Wednesday/...
Issued at 256 PM MST Wed Dec 10 2025

Pressure gradients will continue to slacken Thursday night, bringing
significant improvements to windy conditions across the mountains
and foothills through the overnight hours. An anomalous surface high
(2.4 - 3.1 sigma above normal) over western Canada will start to
usher arctic air into the northern US. This will be the main area of
uncertainty for the extended period, as the northern corner of
Colorado is situated along the temperature gradient, with Colorado
being on the warmer extent of the cold air. If the cold air pushes
just slightly southward, temperatures across the far northeast
plains could be 5-10 degrees colder than what is in the current
forecast, though the extreme cold temperatures are not expected to
make it into Colorado. The coldest temperatures are expected
overnight Saturday into Sunday, and though there is around a 6
degree spread between ensemble means, temps are forecast to drop
into the teens for locations along the Nebraska border. While
temperatures will be colder over the northeastern plains, well
above normal temperatures are expected across the forecast area
through the period, with afternoon high temperatures forecast to
reach the upper 50s/low 60s along the urban corridor each day.

Persistent northwesterly flow on the eastern side of upper level
ridging will remain in place for the majority of the extended
period. Despite the influx of Pacific moisture pumping into the
Pacific Northwest over the coming days, Colorado will remain too
far south to reap any benefits. Ensembles show widespread dry
conditions are expected through the weekend, with only some light
snowfall potential for the mountains towards the tail end of the
forecast period. The ridge is expected to gradually shift eastward
early next week, and ensembles are still holding onto a weak
shortwave traversing the region around Monday/Tuesday, though
they still show slight discrepancies on strength and timing.

&&

.AVIATION /18Z TAFS through 18Z Friday/...
Issued at 1041 AM MST Thu Dec 11 2025

VFR conditions through the TAF period. Strong westerly winds
gusting up to 40 kts a times will continue for all TAF sites this
afternoon. By 23Z, expect winds to decrease to 25 kts for DEN and
APA (BJC should continue with the strong wind gusts this
evening), before weakening to less than 15 kts by 02Z/03Z.

Tonight, a weak front will quickly transition winds from the west
to southeast for DEN and APA. There was considerable model
uncertainty if the front will make it to BJC. If it does, light NE
winds may filter into the airport between 10Z-15Z. If it doesn`t,
expect winds to be from the W/NW

Tomorrow, gusty downsloping winds should return by 16Z/17Z, with gusts
up to 25 kts possible. However, APA may stay generally under 15
kts tomorrow, as high resolution guidance indicates wind
channeling only to BJC and DEN.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
High Wind Warning until 11 AM MST this morning for COZ033>035.

Red Flag Warning until 5 PM MST this afternoon for COZ216-
238>243-245>247.

&&

$$

UPDATE...MAI
SHORT TERM...MAI
LONG TERM...9
AVIATION...MAI

NWS BOU Office Area Forecast Discussion