942
FXUS65 KBOU 031841
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
1241 PM MDT Thu Apr 3 2025

.KEY MESSAGES...

- Snow will spread from southwest to northeast today, mixed with
  rain on the plains. Warm temperatures at lower elevations will
  limit impacts.

- More rain and snow showers Friday into Saturday, with light snow
  accumulations across the Foothills and Palmer Divide.

- Warmer and drier next week.

&&

.UPDATE...
Issued at 1043 AM MDT Thu Apr 3 2025

Radar shows an area of showers spreading over Elbert, Lincoln, and
eastern Arapahoe Counties. This will continue to spread over the
rest of our forecast area through the afternoon. Webcams and
surface observations show these showers are falling as mostly snow
so the precipitation type forecast seems to be on track. With
temperatures staying in the mid to upper 30s, it is still expected
that impacts from this snow across the plains will be minimal. The
latest model guidance has not drastically shifted QPF amounts so
the forecast was largely left the same.

&&

.SHORT TERM /Through Tonight/...
Issued at 423 AM MDT Thu Apr 3 2025

We have a conceptually simple forecast today, but the details are
really messy. A wave will ride up the low/mid level frontal zone
that`s south of us, producing moderately strong QG lift moving
from southwest to northeast through the day, waning this evening.
Models vary on the resulting precipitation, particularly the
potential for convection south and east of Denver.

Low levels are pretty dry to start with, so as the forcing arrives
to Denver in the middle of the day, it will likely take a few
hours to saturate. But there will be steady lift and increasing
easterly winds bringing in better moisture, so by early afternoon
we should have steady precipitation. It`s probably cold enough in
Denver for this to be mostly snow, but with temperatures in the
mid to upper 30s so there should be little impact on roads and
lots of melting on the ground.

I see two main areas of focus. One is related to the synoptic
scale lift moving SSE to NNW east of the Denver area, producing a
broad swath of 0.25 to 0.5 inch precipitation amounts over a 12
hour period starting south of Denver in the late morning. This
seems reasonable and there`s decent agreement on it. Denver and
the I-25 corridor will be on the edge of this and will probably
have somewhat lighter amounts. The second feature with less
agreement is ascent driven by low level convergence from south of
Denver towards the NE/KS/CO triple point in the late afternoon and
overnight. It remains to be seen how focused this will be, and how
strong. Some models put down a swatch of 1 to 1.5 inch QPF from
this, mainly southeast of our area, but close. If this happens,
that should mean that the warm advection/convergence is stronger
and would tip this area more towards rain then snow, although
higher places like Elbert County/Limon/possibly Akron could still
have some snow in that scenario if this feature is further north.
For now, we`re counting on this either being further southeast, or
warmer, or weaker, and not worrying too much about heavy snowfall
from it. But there could be an inch of QPF with a few inches of
wet snow tonight over the Limon-Akron-Holyoke axis if this pans
out.

Otherwise, we have gradual warming occurring aloft through this
period, and a pretty limited diurnal swing at the surface once we
get a little heating this morning. While there will be a mix of
rain and snow across much of the plains it will be at warm
temperatures. Even in the lower foothills, the temperatures should
limit impacts. We may need to consider a southern foothills
advisory if the upslope is sustained and productive enough, but I
wouldn`t expect more than a little slush under heavier showers until
nightfall.

Without much wind, the high mountains won`t have the orographic
component, so they`ll have a moist showery airmass, but probably
without much focus. The best QG forcing looks to be east of our
mountains.

As the synoptic scale lift exits, we`re left with a lot of
moisture, temperatures around freezing, and not much wind. If
there`s still a little upslope, the snow may not end entirely but
should be much lighter. There`s some potential for the clouds to
settle into more of a fog/drizzle situation, but that`s more
likely in the foothills and Douglas/Elbert counties than for
elsewhere. There`s a small chance of dense fog or freezing drizzle
issues later tonight in those areas.

&&

.LONG TERM /Friday through Wednesday/...
Issued at 423 AM MDT Thu Apr 3 2025

Friday and Friday night a large upper level trough will be centered
over the Central and Southern Rockies with a closed upper low
tracking from Southern Arizona into Southern New Mexico. Due to the
position of the upper low, most of the QG lift with this system will
stay over New Mexico with minimal lift over our CWA. An upper level
shortwave diving south across the Northern Plains States will help
push a cold front across Northeastern Colorado Friday morning, with
north to northeasterly upslope flow behind it. Precipitation is
expected to increase across the Front Range Mountains, foothills,
adjacent plains and Palmer Divide by late morning or early afternoon
as the upslope flow combines with weak QG lift and some instability.
The precipitation should be in the form of snow above 6,000 feet
with a mix of rain and snow across the lower elevations. The
precipitation is expected to continue through the afternoon and
evening before tapering off after midnight. With this type of
scenario, would expect the heaviest snow to focus over the
Southern Foothills and western sections of the Palmer Divide where
frontal forcing and moisture convergence are maximized. These
areas could see between 3 and 8 inches of accumulation which could
result in some travel impacts. Much lighter amounts are expected
across Metro Denver with only an inch or two expected with even
lighter amounts (Trace-1") across the northern urban corridor and
adjacent plains.

On Saturday, the upper trough moves into the Southern Plains
States as a large upper ridge pushes into the Western U.S. The
forecast area will remain cool with afternoon snow showers
possible over the high country. Drier and much warmer weather is
expected Sunday and Monday as the upper ridge moves across the
Rocky Mountain Region. By Tuesday, the chance for snow showers may
increase across the mountains as the upper ridge flattens and a
moist northwesterly flow aloft sets up over Colorado. Further east
across the plains, dry weather and warm temperatures around 70
degrees will continue due to a downsloping flow. There may be
enough mid level moisture, combined with some instability, to
produce a few high based showers and storms with gusty winds and
little rain. In addition, portions of the plains could see
increasing fire danger Tuesday and Wednesday due to low relative
humidity and increasing winds.

&&

.AVIATION /18Z TAFS through 18Z Friday/...
Issued at 1158 AM MDT Thu Apr 3 2025

A moderate band of snow has moved across DEN with visibility
dropping to half a mile. While this band may not last for long, it
gives us an indication of the strength of these bands throughout
the day. At all terminals, there may be a period of 1/2 SM and
moderate snow with ceilings down to 1,000 feet. The majority of
the time there will be visibility around 3-4SM with ceilings
closer to 2,000 feet. The majority of the snow will come to an end
this evening.

There is a chance for fog at all airports overnight tonight.
At the moment, it looks more likely that low clouds around 800
feet will be in place but fog with visibility down to a quarter
mile is a possibility. A cold front will move through during the
late morning hours on Friday. This will increase winds out of the
NE. There will also be snow showers associated with this front
and visibility could get down to 1 SM under the heavier snow
showers. However, much of the snow showers will be lighter and
will have visibility around 4 SM.

&&

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

&&

$$

UPDATE...Danielson
SHORT TERM...Gimmestad
LONG TERM...JK
AVIATION...Danielson