448
FXUS65 KBOU 171127
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
527 AM MDT Fri Apr 17 2026

.KEY MESSAGES...

- Spring storm moves in today with snow showers for much of
  forecast area and a much colder airmass. Winter Weather Advisory
  in effect for this morning and afternoon in the higher mountain
  elevations and Southern Foothills.

- Hard freeze expected across the plains Friday night.

- Dry and warmer weather returns for early next week.

&&

.UPDATE...
Issued at 248 AM MDT Fri Apr 17 2026

Forecast is generally on track with only minor adjustments needed.
May see some travel impacts over the higher portions of the
Palmer Divide, for a few hours this aftn, along I-25.

&&

.DISCUSSION /Through Thursday/...
Issued at 1104 PM MDT Thu Apr 16 2026

The cold front is approaching the WY/CO border as of late this
evening. Winds behind the front are generally gusting around 30 to
45 mph, but we have seen a few gusts around 55mph as the front moved
through. Temperatures are also dropping quickly behind it, with
stations in WY recording around a 30 degree decrease in about 2
hours after frontal passage. The front is forecast to move through
Colorado overnight, impacting Denver between 1AM and 2AM, and moving
out of our southern counties by the early morning. The gusty winds
and colder temperatures behind the front will lead to wind chills
staying near or below freezing for much of the day tomorrow, with
values in the teens to low 20s in the morning.

Snow showers will start in the mountains in the early morning,
continuing into the early to mid afternoon. Snow accumulations
around 2 to 9 inches are forecast for areas in the higher elevations
(>9000ft). For the Foothills and Palmer Divide, snow amounts look a
bit closer to the 2 to 6 inch range, with the highest amounts in the
Foothills in Jefferson County. This area does include I-70, which
could see a period of hazardous driving conditions late Friday
morning through early Friday afternoon. In the plains, were
looking at the lowest amounts, with a trace to up to 3 inches (but
most of the area will be on the lower end). Now the big question
is what impacts this snow will cause, which is a bit tricky. Road
temperatures and therefore road conditions are a bit of a question
mark. The cold front will help cool them down pretty
significantly, but with how warm we`ve been recently, will it be
enough for snow to accumulate and cause hazardous driving
conditions? Right now, we`re thinking a good amount of the snow
will melt limiting road impacts. However, in the areas that see
the larger snow amounts and heavier snow rates under snow bands,
we could see some road accumulations and hazardous travel. There
is potential for some snow banding with this activity. Areas under
the stronger bands could see higher amounts than previously
mentioned and increased travel impacts. Due to the potential for
travel impacts, particularly along I-70 and in mountain passes,
we`ve issued a Winter Weather Advisory for the higher elevations
and southern Foothills.

Models have skies clearing and winds weakening overnight Friday into
Saturday. This will allow temperatures to drop significantly,
putting lows Saturday morning in the upper teens to lower 20s across
the plains, with temps in the single digits for portions of the
mountains. And with how warm we`ve been the past few weeks, this
hard freeze could have larger impacts than what we would typically
see in April. These temperatures could damage sensitive plants,
damage trees which have already started to bud, and could damage
above ground irrigation lines if they are not drained.
Additionally, any slush or water left on the roads in the late
evening could freeze overnight, potentially creating some slick
spots in the morning.

As the upper level trough moves off to the east, upper level ridging
will begin to build over the area. This will lead to a warming trend
with mostly dry conditions through Tuesday. The only exception to
this will be in the mountains where weak disturbances and upslope
winds could be enough or some precip, leading to low end
rain/snow chances for both Monday and Tuesday in the higher
elevations. Highs by Tuesday afternoon are forecast to reach into
the upper 70s to mid 80s across the plains.

Things start to look a bit more interesting for the second half of
the week. Models still are not sure what they want to do with the
strong upper low which is forecast to sit over the West Coast for
the first half of the week. Models have the low splitting into two
separate lows/troughs, which vary in both location and speed
between models and model runs. We`ll likely have to wait and see
what this system actually ends up doing, as models struggle with
this sort of set up. Because of this uncertainty, we have low end
PoPs for much of the period Wednesday through Friday. We are not
expecting precipitation during this whole period, rather we`re
expecting one or maybe 2 shots at precip Wednesday through the
weekend. But the timing is too uncertain to try and nail it down
this far out. Similarly, depending on the track of these systems,
we could see a front or two Wednesday into the weekend.

&&

.AVIATION /12Z TAFS through 12Z Saturday/...
Issued at 519 AM MDT Fri Apr 17 2026

Winds have gone light east to southeast, however, another surge
will move in around 14z with NE winds increasing. Not sure when
stratus may develop so have just included a tempo group for 2500
ft ceilings thru 14z. After 14z should see stratus develop at all
three airports. Best chc of snow looks to be between 16z and 21z
with visbility down to 1 mile during its peak, although may see
brief periods down to 3/4 mile in heavier bands. Ceilings during
the heavier bands will drop to 1000 ft. Winds by 19z will become
more northerly. Expect snow to gradually diminish between 21z and
23z. By 00Z winds will decrease with ceilings rising to 6000 ft
and then scattering out by 02z.  Winds by 02z will become light
and variable and then switch to light drainage by 04z.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until 3 PM MDT this afternoon for COZ031-
033.

Winter Weather Advisory from 9 AM this morning to 5 PM MDT this
afternoon for COZ034-036.

Freeze Warning from 8 PM this evening to 8 AM MDT Saturday for
COZ038>051.

&&

$$

UPDATE...RPK
DISCUSSION...AP
AVIATION...RPK

NWS BOU Office Area Forecast Discussion