National Weather Service Forecast Discussion

Thornton Weather Forecast   
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305
FXUS65 KBOU 271131
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
531 AM MDT Fri Mar 27 2026

.KEY MESSAGES...

- Much cooler today.

- Well above normal temperatures again for the weekend into early
  next week.

- Areas of elevated to locally critical fire weather conditions
  possible over the weekend and Monday.

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

&&

.UPDATE...
Issued at 313 AM MDT Fri Mar 27 2026

Radar and webcams show a few pockets of flurries yet in the
mountains and foothills, but for the most part the chance for
showers has ended. Forecast and ACARS soundings show the cloud layer
east of the mountains, not very thick, with cloud bases higher than
previously expected. Therefore, lowered/removed precipitation
chances for this morning. Light snow/flurries remain possible in the
mountains and higher foothills, otherwise dry conditions are
expected elsewhere.

&&

.DISCUSSION /Through Thursday/...
Issued at 1146 PM MDT Thu Mar 26 2026

Thursday`s cold front has successfully passed across the forecast
area leaving cooler temperatures, gusty northeasterly winds,
smoke, and increased moisture in its wake. With the persistent and
slightly deepening upslope flow in place, light rain showers have
developed over the foothills and adjacent plains. This is still
anticipated to bring light precipitation to the foothills and
adjacent plains overnight tonight and into Friday morning, with
even a light dusting of snow possible for the Front Range
Foothills and the Palmer Divide. PoPs were slightly lowered based
on the latest guidance, but the forecast largely remains unchanged
for Friday. While the increased moisture and cooler temps will
keep fire weather conditions at bay across the forecast area on
Friday, unfortunately we will still feel the impacts from
wildfires burning outside of the forecast area, as the latest HRRR
surface smoke indicates wildfire smoke from the Nebraska
panhandle will continue to be a nuisance through at least Friday
afternoon across the lower elevations before southerly winds
potentially draw in smoke from the 24 Fire south of Colorado
Springs for a few hours Friday evening. Therefore, grids were
updated to include a few more hours of smoke through Friday
afternoon, with the areas of densest smoke expected to be along
the South Platte River Valley.

We`ll see temperatures rebound to 10-25 degrees above normal
across the forecast area on Saturday, once again, as 700 mb temps
warm by 10-15 degrees under the persistent upper-level ridging. A
tightening pressure gradient will bring gusty surface winds across
the eastern plains late Friday night into Saturday afternoon.
Elevated to near-critical fire weather conditions will be the main
concern as relative humidity values are expected to lower into
the low to mid teens over the majority of the forecast area, but
it`s looking like the strongest gusts (40-50 mph) are expected
early enough that they won`t coincide with the lowest RH values in
the afternoon. This will limit potential for critical fire
weather conditions to remain under the three hour critical
criteria (for areas along the Palmer and east across Lincoln and
southern Washington Counties). Therefore, will give it another
forecast package to make any fire highlight decisions. Outside of
fire weather, a surface trough is progged to develop over eastern
Colorado by the afternoon, and mid-level moisture will increase
enough to support the chance for some virga showers in the late
afternoon/early evening. Similar conditions are expected each day
through Monday when the aforementioned persistent upper-level
ridge finally starts to shift to the east, and southwesterly flow
aloft begins to dominate over the Southwest ahead of an
approaching trough. Periods of elevated to critical fire weather
conditions will be possible each afternoon.

Ensembles have persistently shown mid-week being the beginning of
a much needed pattern change. While southwestern Colorado will
likely be the recipient of the greatest precipitation amounts,
almost every member of the GFS and ECMWF ensembles show QPF for
our mountains (including accumulating snowfall!), whereas 60% of
the GFS members and 80% of the ECMWF members have QPF for our
lower elevations by the middle of next week. While it`s not
expected to be significant, trends are showing more than just a
few hundredths for the first time in quite a while. There is still
some time to figure out the specifics, but confidence is growing
that it will feel much more like spring than summer as we enter
April.

&&

.AVIATION /12Z TAFS through 12Z Saturday/...
Issued at 531 AM MDT Fri Mar 27 2026

Low clouds with ceilings of 3000 to 4000 feet will prevail
through this morning and into the early afternoon. Can`t rule out
ceilings briefly falling below 3000 feet (~20% chance) through
15Z. The lower clouds are expected burn off early to mid afternoon
(19-21Z). Once the lower clouds burn off, only high clouds will
prevail through tonight. As far as winds go, weak northeast to
east winds will turn clockwise, becoming southeast 14-17Z.
Southeast winds increase this afternoon with gusts to 25 knots.
Then this evening after 02-03Z, enhanced southerly drainage winds
develop with gusts to 35 knots possible at DEN and APA. These
stronger winds linger into early Saturday morning, but decrease
and turn southwest by 12Z Saturday.

&&

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

&&

$$

UPDATE...12
DISCUSSION...9
AVIATION...12

NWS BOU Office Area Forecast Discussion