National Weather Service Forecast Discussion

Thornton Weather Forecast   
Today's Forecast Story   
972
FXUS65 KBOU 261957
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
157 PM MDT Thu Mar 26 2026

.KEY MESSAGES...

- Much cooler air on the way, with below normal normal
  temperatures for Friday.

- Light showers tonight into Friday morning, mostly concentrated
  in/near the Front Range. A few snowflakes possible down into the
  I-25 Urban Corridor.

- Temperatures warm to much above normal again for the weekend
  into early next week.

- Pattern change by the mid to latter portions of next week, but
  highest chances of meaningful precipitation still focused on the
  mountains.

&&

.DISCUSSION /Through Thursday/...
Issued at 157 PM MDT Thu Mar 26 2026

Earlier frontal push this morning was stronger and faster than
advertised (consistent model bias here in the High Plains). As a
result, we earlier reduced forecast high temperatures by a few
degrees although sunshine and mixing is offsetting some of the
cold advection and upslope flow. The stronger cold front with
temperatures in the upper 30s and 40s behind it is still moving
this way from eastern Wyoming and Nebraska, and will push across
the plains during the mid to late afternoon hours. That`s when
more significant cooling occurs, along with sufficient moisture
advection to bring clouds and a few showers. It appears we`ll have
upslope deepen to about mountain top, and there is some
instability (MUCAPE 100-200 j/kg) and weak frontogenesis. However,
as has been the case most of this winter/spring season, moisture
profiles are quite shallow. Thus, we expect only light rain and
snow showers. Snow levels will gradually lower this evening with
cold advection. A few snowflakes are still expected down into the
I-25 Corridor but zero accumulation, while foothills should see a
dusting to locally 1-2" possible in a couple spots. Also, with
the upslope being the main forcing mechanism we`ll continue to
have the highest PoPs in/near the foothills. Finally, a smoke
plume originating from the Ashby and Minor Fires in the Sandhills
of Nebraska has already brought some visibility restriction to
areas around Fort Morgan and Akron this morning and early
afternoon. We`ve included some smoke in the forecast due to
continued advection from the east, although some thinning should
be noted with some mixing through the rest of the afternoon and
then light precipitation overnight.

Some of the light rain and snow showers/drizzle may linger into
the morning hours Friday before dissipating with slight drying
and daytime heating. This will also aid the stratus breakup for
the afternoon. However, temperatures will be rather cool with high
pressure locked over the Central Plains and a weak upslope
component through the day. Highs are forecast to be several
degrees below normal for a change.

A quick warmup is in store this weekend, as lee troughing
develops allowing downslope flow to resume. At the same time, flat
ridging occurs with further warm advection. The downslope means a
quick return to above normal temperatures for Saturday, with highs
pushing near the 80 degree mark once again. Similar temperatures
can be expected Sunday, with a couple records possibly being
broken across the area this weekend. Denver`s record for Sunday
the 29th is 79F, for example. There is enough heating and
lingering moisture for just a slight chance of a light shower or
virga each afternoon/evening, but most locations will remain dry.

By Monday, the ensembles and operational runs are still indicating
a bit of subtropical moisture sneaking up from the southwest, just
enough to bring an increasing chance of light showers or even a
weak storm to the mountains.

We`ll finally get into a more active and precipitation productive
weather pattern by late Tuesday or Wednesday as a shortwave or two
impacts the region. Moisture will continue to improve in this flow
pattern as additional moisture arrives from the Pacific, and ensembles
continue to show a change to above normal precipitation anomalies
during the latter half of next week. For the plains, it`s still more
uncertain as we`ll be on the edge of the storm track. We are more
likely to be sheltered by the mountains (~70% chance) due to
southwest flow aloft. That would only result in very light
precipitation amounts for the lower elevations. However, if the
storm track is slightly farther south we may be able to tag some
upslope with beneficial precipitation (30% chance of QPF >
0.3-0.4"). Considerable uncertainty enters the picture with regard
to temperatures as well, with large spreads of 15 degrees F just
in the 25-75th percentile alone. Thus, a lot of model variability
dealing with surface pressure patterns and frontal locations as
well.

&&

.AVIATION /18Z TAFS through 18Z Friday/...
Issued at 1149 AM MDT Thu Mar 26 2026

A lot of uncertainty for the near term at all terminals today. A
pre-frontal surge arrived earlier today, with NE winds gusting up
to 25 kts. Winds have since turned ENE. The actual cold front is
progged to arrive at DEN between 21Z and 22Z (slightly later at
BJC and an hour later at APA). Gusts between 30-35 kts are
possible from 22Z-06Z, although expect a gradual weakening of
gusts around 03-06Z. There is a chance (

NWS BOU Office Area Forecast Discussion