National Weather Service Forecast Discussion

Thornton Weather Forecast   
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951
FXUS65 KBOU 031952
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
152 PM MDT Fri Apr 3 2026

.KEY MESSAGES...

- Critical fire weather conditions expected across the plains through
  early this evening.

- Light snow showers in mountains will gradually come to an end
  tonight.

- Strong, gusty winds for the forecast area through this evening.
  Breezy winds overnight, mainly for the Front Range mountains
  and eastern plains

- Dry with a gradual warming trend (outside of Monday) through the
  middle of next week. Elevated fire weather conditions possible
  for South Park and portions of the plains.

&&

.DISCUSSION /Through Friday/...
Issued at 149 PM MDT Fri Apr 3 2026

Current water vapor satellite imagery shows the 500-mb closed low
over eastern Wyoming, with moisture wrapping behind the low and
causing light snow showers for the mountains. With a 100-115 kt
upper level jet over Colorado, and QG fields showing deep
subsidence aloft, winds have been transferring down to the
surface throughout this morning, with observations showing peak
gusts up to 60-70 mph in the wind prone locations. West/northwest
winds will continue to gust up to 45-60 mph for the Front Range
mountains (slightly weaker for the foothills) and 35-50 mph for
the plains this afternoon. The only exception will be for the I-25
corridor between Denver and Fort Collins, where a period of
weaker winds up to 20-30 mph are possible this afternoon as that
area can typically be sheltered from the strongest northwest
winds. With the strong winds and dry conditions across the plains,
elevated-to-critical fire weather conditions will continue
through the early evening (See Fire Weather Discussion below).

Dry and warming conditions are expected over the weekend as an upper
level ridge begins to build over the Rockies, with a surface high
pressure sinking south into the Great Plains. Ensemble guidance is
in good agreement of temperatures reaching the 60s across the plains
both Saturday and Sunday. Saturday will be breezy across the eastern
plains due to continued subsidence aloft mixing the 700-mb winds to
the surface as the low continues east. Winds could gust up to 35-40
mph, which will bring another round of elevated fire weather
conditions.

On Monday, model guidance shows the upper level ridge begin to
flatten due to a system trekking over northwestern U.S. with enough
moisture embedded in the flow to allow a few light snow showers for
the mountains. The plains look to remain mostly dry on Monday and
Tuesday. However, some ensemble solutions on the GEFS and ECMWF do
show light QPF amounts (less than 0.10") for portions of the plains.
NBM has about 20% chance of PoPs Monday afternoon, which seem
reasonable at this time. In terms of temperatures on Monday for the
plains, guidance continues to struggle to handle how far west the
backdoor cold front will bring in cooler temperatures. The GEFS
seems to be a bit more aggressive with the front, with max
temperatures in the 50s for the plains, while the ECMWF keeps
temperatures in the mid-to-high 60s. With the NBM trending cooler
these past few runs, won`t be surprised if we end up seeing
temperatures between high 50s to low 60s across the plains on
Monday, with the far northeastern plains cooler than areas close to
the foothills.

By mid-week, breezy conditions are possible across the forecast area
as the aforementioned system treks across the northern U.S. This
will result in increased westerly flow aloft, with downsloping winds
allowing compressional heating over the plains, and temperatures
peaking at mid-to-high 70s. As of right now, the system looks to be
too far north for any measurable precipitation for our forecast
area. But do not lose hope! Ensembles suggest our next chance of
beneficial precipitation closer to the end of the week/weekend. Stay
tuned for updates!


&&

.AVIATION /18Z TAFS through 18Z Saturday/...
Issued at 1139 AM MDT Fri Apr 3 2026

VFR conditions to persist through the TAF period. Gusty westerly
winds remain in place across all Denver TAF sites this morning.
We are starting to see a slight decrease in wind speeds over the
past hour, and are anticipating a farther decrease in the next
hour (around 19Z). With the decrease, winds are expected to see a
slight turn towards the NW at KDEN/KAPA, with a predominate
westerly direction remaining at KBJC. There is a higher chance of
gusts remaining elevated at KBJC, therefore have a TEMPO in place
through 20Z.

Have added a TEMPO for another period of potential gusty W to WNW
winds at KDEN from 22-01Z this afternoon, where gusts between
25-30 kts will be possible. Right around sunset, much lighter
northerly winds are expected at KDEN/KAPA before settling into
drainage sometime between 8Z to 11Z. While winds are expected to
become light and variable at KBJC early Saturday morning, can`t
rule out a few westerly gusts between 20-24kts making their way
across the field through the morning before NE to E winds are
expected by late morning.

Can`t rule out an anticyclone developing (~20%-30% chance) at some
point Saturday afternoon with enhanced NW winds expected along
the Cheyenne Ridge.

&&

.FIRE WEATHER...
Issued at 149 PM MDT Fri Apr 3 2026

Elevated to critical fire weather conditions expected across the
plains through this evening. Strong west/northwest wind gusts up to
35-50 mph will continue across most of the plains through 7/8 PM
before weakening to 25 mph or below tonight. The only exception will
be the I-25 corridor between Denver and Fort Collins, which will be
sheltered from the strongest winds. While most of the plains will
see relative humidities between 15-20%, critically dry fuels
combined with strong winds will help promote rapid fire spread.

Another round of elevated fire weather conditions are expected for
the eastern plains on Saturday due to continued breezy winds of 35-
40 mph. However, have held off on any fire weather highlights due to
relative humidity values staying between 18-23% where the strongest
winds will be.

Daily elevated fire weather conditions are expected for the
plains and South Park this weekend and into next week due to
continued warm and mostly dry conditions. However, winds will be
the limiting factor, as gusts should stay below 25-30 mph. The
exception will be Wednesday, where peak heating combined with
breezy downsloping winds and low dew point temperatures could
reach critical thresholds. Will continue to monitor. &&

.BOU WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning until 7 PM MDT this evening for COZ238>251.

&&

$$

DISCUSSION...MAI
AVIATION...9
FIRE WEATHER...MAI

NWS BOU Office Area Forecast Discussion