235
FXUS65 KBOU 160552
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
1152 PM MDT Wed Apr 15 2026

.KEY MESSAGES...

- Locally critical fire weather conditions over the plains
  Thursday afternoon.

- Next system moves in Friday with much colder temperatures and
  the potential for snow for most locations.

- Hard freeze Friday night and into Saturday morning with lows in
  the upper teens to mid 20s.

&&

.DISCUSSION /Through Wednesday/...
Issued at 1105 PM MDT Wed Apr 15 2026

Temperatures will warm into the mid 70s to near 80 degrees for much
of the plains on Thursday. Winds tomorrow will turn more to the
south/southwest, with gusts around 20 to 35 mph. Breezy winds
combined with RHs in the single digits to low teens across the
plains will lead to another day of elevated to critical fire
weather conditions. A Red Flag Warning will be in effect for
tomorrow afternoon for the southern Foothills, Palmer Divide, and
areas generally east of the Urban Corridor and south of US 34.

A strong cold front will move through late Thursday through early
Friday. Winds behind the front will be strong from the north, with
gusts around 35 to 50mph overnight. Much colder temperatures and the
potential for some snow accumulations will follow behind the front.
Snow chances will increase for the mountains overnight Thursday into
Friday, with snow chances spilling into the plains early Friday into
Friday afternoon as an upper level trough moves into the area. We`re
a little concerned about the potential for anticyclonic upslope and
convergence against the southern Foothills and Palmer Divide. This
combined with strong 700mb frontogenesis in these areas for the late
morning and early afternoon could lead to heavier snowfall than
currently forecast. We increased snowfall amounts in these areas to
account for this potential, but amounts may need to be adjusted up
further if banding potential becomes more prominent. Most likely
snowfall totals across the urban corridor, northern I-25 corridor,
and east is a trace to around 2 inches of snow. The most likely
amounts in the Foothills and Palmer Divide area are more in the 1 to
4 inch range, however there is a low chance (~10%) that amounts
could approach around 8 inches in portions of this area. The
mountains are looking at most likely accumulations around 2 to 8
inches. With how warm the road temperatures will be to start this
event in the Foothills and plains (and the more borderline freezing
temperatures during the afternoon), accumulations on roadways should
be limited.

Snow chances will begin to taper off in the evening as the upper
level trough moves through and subsidence builds in behind it. At
the surface winds will begin to weaken and temperatures are forecast
to drop significantly overnight. Minimum temperatures will likely be
in the low to mid 20s across the plains Saturday morning, with
colder temperatures in the mountains and across the Palmer. This
will lead to a hard freeze, potentially impacting sprinkler systems
and plants which have started to bud. A Freeze Watch is in effect
for all of the plains for Saturday morning.

Upper level ridging will begin to build into the area between the
exiting trough and a strong upper low over the West Coast. A warming
trend will begin Saturday, with highs increasing into the lower 80s
for portions of the plains by Tuesday afternoon. Conditions are
expected to remain mostly dry through this period. Things start to
get a bit more uncertain on Wednesday as models try to figure out
how that upper low will move into the central U.S., but a majority
of the ensemble members keep the plains dry and give a low chance of
precip for the mountains.

&&

.AVIATION /06Z TAFS through 06Z Friday/...
Issued at 1151 PM MDT Wed Apr 15 2026

VFR will persist through most of this period. Strong cold front
arrives Friday evening. The main concern in the shorter term will
be winds.

We`ll start this period with the typical S-SW winds at the TAF
sites, continuing through at least 15Z. Then, as diurnal heating
and mixing occurs, we`ll start to see uncertainty enter the
forecast. In this southwest flow pattern, it`s not unusual to see
a shear zone develop, and today could be the same especially with
expected increase in high level clouds. That typically leads to
differential heating and corresponding development of a shear
zone off the Palmer Divide. There are some hints of this in the
HRRR, keeping a small area of light/VRB winds near or just north
of KDEN and KBJC through the morning, and that could potentially
late into mid to late afternoon (not depicted by models) depending
on development and amount of opaque cloud cover. KAPA will have
the highest odds (80%) of getting properly mixed and staying south
of the shear zone, and thus we`ll start winds increasing there by
15Z with a further well mixed G24-28kt scenario 20Z-02Z. For
KDEN, we think a more southerly component is most likely through
19Z, but a 20-30% chance of light E or NE. After that, we`ll see
higher chances of a mixed SW flow wind pushing through KDEN but
the lee troughing is rather limited and thus it might take as late
as 22-24Z before those stronger W-SW winds with gusts near 25 kts
develop. The same can be said for KBJC. Winds should start to
relax again by 01Z-02Z with loss of daytime heating.

Then, a strong cold front will bring gusty north winds (30-40 kts
possible at KDEN), most likely 05-07Z Friday. Low clouds could
start to develop within a few hours of that but most likely
holding off til closer to 12Z Friday.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning from 11 AM to 9 PM MDT Thursday for COZ214-216-
241-245>247-249.

Freeze Watch from Friday evening through Saturday morning for
COZ038>051.

&&

$$

DISCUSSION...AP
AVIATION...20

NWS BOU Office Area Forecast Discussion