509
FXUS65 KBOU 202354
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
454 PM MST Tue Jan 20 2026

.KEY MESSAGES...

- Elevated to critical fire weather conditions across the far
  northeast plains through this evening, with mild and dry
  conditions across the region.

- Slightly cooler Wednesday, but elevated fire weather conditions
  again across portions of the Front Range and urban corridor.

- Glancing arctic outbreak Friday and Saturday, with a slight
  moderation for Sunday. Light snow also possible Friday.

&&

.SHORT TERM /Through Wednesday/...
Issued at 210 PM MST Tue Jan 20 2026

Perhaps the driest airmass of the season was overhead today. A few
reliable stations reported dew points less than -30F, with many
others in the -10 to -25F range across South Park and southern
Foothills. There is quite a moisture gradient across the I-25
corridor today, with well-mixed areas in the southwest side of
Denver sitting in the low 50s (with dew points near 0 to -10),
while Longmont and Greeley never fully eroded the surface
inversion and remain in the upper 30s to mid 40s (with RH near
40-50%). Understandably, guidance has not handled this well and I
suspect those struggles will continue into this evening.

Zooming out a bit, a shortwave is tracking across Wyoming this
afternoon, and should race into the Central Great Plains by
tonight. This will only provide a glancing blow, in the form of a
very weak cold front. This should lead to temperatures ending up a
few degrees cooler during the day tomorrow. Unfortunately, surface
moisture still looks meager tomorrow... and we`ll see elevated
fire weather conditions across South Park/Front Range
Foothills/I-25 corridor where RH will likely fall back to the
single digits. The recent snowfall has provided just enough fuel
moisture to avoid any fire weather highlights.

&&

.LONG TERM /Wednesday night through Tuesday/...
Issued at 210 PM MST Tue Jan 20 2026

Longwave upper level trough will be over the Hudson Bay and Great
Lakes region the last half of the work week and into the weekend.
Northerly flow on the backside of the trough will push arctic air
southward. Colorado looks to be on the edge of the arctic air.
Typically we`ll see these arctic airmass advance southward along
the Continental Divide, which should result in at least a couple
cold days for the Front Range and eastern plains.

For Wednesday night and into Thursday, a weak cold front, more so
a wind shift to the northeast, is expected over northeast
Colorado. Colder air slowly seeps into the area with highs in the
30s expected over northeast Colorado. A strong surface high and
arctic air move into the Northern Rockies and Northern Plains
Thursday night. As the surface high slides southeastward.
Northeast low level flow will advect the arctic air into eastern
Colorado. Friday is expected to be cloudy and cold with highs in
the teens to mid 20s. The airmass moistens enough for light snow
and/or flurries for Friday night. There`s no strong lift and
limited moisture, so snowfall is expected to be light, less than 2
inches.

The temperature forecast becomes much more uncertain for Saturday
(and beyond). The arctic is expected to remain over the area
Saturday, which will result in continued cold temperatures with
highs in the teens and 20s for Saturday. However, there are some
ensemble members of the ECMWF and GEFS that scour out the colder
air and highs climb into the 40s. Think this is a little
aggressive bringing the warmer air and expect Saturday to be a
chilly day. The uncertainty continues for Sunday. Most models show
a lee side surface trough forming over eastern Colorado. This
would bring west winds and scour out the colder air. The 12Z GFS
changed and now shows a second shot of arctic air, which would
keeps highs well below freezing on Sunday. Will keep the forecast
closer to ensemble mean which warms temperatures into the 30s for
Sunday.

For Monday and Tuesday of next week, flow aloft becomes more
zonal. This brings milder air back to the region with temperatures
climbing into the 40s for Monday and possibly 50s for Tuesday.
Forecast remains dry for these periods with the lack of moisture
and forcing continuing.

&&

.AVIATION /00Z TAFS through 00Z Thursday/...
Issued at 444 PM MST Tue Jan 20 2026

VFR conditions through the TAF period. Winds have now transitioned
to NNE for all terminals, except BJC may see westerly winds at
times for the next hour. A weak cold front will bring gusty NE
winds up to 30 kts at DEN and APA between 02Z/03Z before winds
turn to drainage overnight. For tomorrow, drainage flow will
continue through 18Z at the latest, before transitioning to an
east/northeast component in the afternoon. There is a low chance
(~20%) that DEN could see gusty northwest winds in the late
morning/early afternoon. However, due to low confidence, have
kept it out of the TAF for now.

&&

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

&&

$$

SHORT TERM...Hiris
LONG TERM...12
AVIATION...MAI

NWS BOU Office Area Forecast Discussion