694
FXUS65 KBOU 182029
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
229 PM MDT Fri Apr 18 2025

.KEY MESSAGES...

- Hazardous mountain roads through Saturday morning with ongoing
  moderate snow.

- Steady snow through this evening for the urban corridor,
  diminishing overnight, with bulk of accumulations limited to
  colder surfaces.

- Warmer pattern Sunday into next week, with a chance of
  afternoon/evening showers most days.

&&

.SHORT TERM /Through Saturday/...
Issued at 228 PM MDT Fri Apr 18 2025

Deepening moisture and a slight enhancement of the upslope component
in the low-level winds will support continued snow across the
high country, foothills and urban corridor, gaining some intensity
and persistence this afternoon and evening. Despite ambient
temperatures near or below freezing around the Denver metro,
pavement temperatures remain markedly warm at this hour courtesy
of the April sun, effective even with the cloud cover. With
increased snowfall rates and roadway temperatures anticipated to
drop near freezing between 5-8pm, some slushy accumulations will
become possible for the urban corridor this evening, primarily
west of I-25 where snow will be heaviest/most persistent. Thus,
minor impacts to the very tail end of the commute will be
possible, but there just isn`t enough road temperature, snowfall
intensity, and snowfall duration alignment to necessitate any
expansion of current headlines. The extent of travel impacts is
similarly questionable for the Palmer Divide, but there`s enough
potential for snow to drag on longer into the evening for us to
retain the Advisory and see how things play out. In the high
country, the focus for the heaviest snow will focus along and
south of I-70, especially in and around Park County, with
hazardous road conditions expected to extend into Saturday.

That being said, one consideration for the overnight period will
be the freezing of road surfaces as snow gradually diminishes and
temperatures fall below into the 20`s, making roads slick early
Saturday. Patchy fog can`t be ruled out either for the lower
elevations in the morning.

For Saturday, we`ll see modest warming into the 50`s for the
plains/urban corridor (low 50`s in the northeast corner), and
mostly 30`s for our mountain communities. Southeasterly low-level
flow combined with lingering mid-level moisture will sustain
scattered snow showers in the mountains, again favoring I-70
southward, whereas most other areas will be mostly dry past
midday. Cloud cover will be slower to clear however.

&&

.LONG TERM /Saturday night through Friday/...
Issued at 228 PM MDT Fri Apr 18 2025

Saturday night, an upper level trough of low pressure will be over
the Rocky Mountain Region with a closed upper low tracking across
New Mexico. Cross sections show diminished upslope flow east of the
mountains which should result in mostly dry weather across the
plains. The high country could see scattered snow showers overnight
due to some weak orographic lift combined with QG lift from a
passing shortwave.

Warmer and drier weather is expected on Sunday as the upper trough
moves into the Central Plains States and a weak upper ridge builds
over Colorado.

Early next week, a zonal flow aloft sets up over the state with mild
and dry weather across the plains, with temperatures climbing into
the lower to mid 70s. Across the high country, there should be
enough available moisture combined with some orographic lift to
produce isolated to scattered rain and snow showers. On Monday, the
flow aloft will be the strongest which will produce breezy
conditions across the higher mountains and foothills. In addition,
the plains could also see gusty winds due to a downsloping flow. The
gusty winds combined with low relative humidity will lead to
increasing fire danger during the afternoon hours.

For the Wednesday night through Friday period, the upper flow turns
southwesterly in response to an upper level trough deepening along
the west coast of the U.S. At the surface, the gradient between
higher pressure over the Central U.S. and lower pressure over
Colorado should allow east to southeasterly winds to advect higher
moisture onto the plains. This moisture combined with daytime
heating may lead to a better chance for afternoon and early
evening showers and storms through this period.

&&

.AVIATION /18Z TAFS through 18Z Saturday/...
Issued at 1141 AM MDT Fri Apr 18 2025

Snow will become more persistent through early evening, with vis
reducing to 2-4SM most of the time for KAPA and KDEN, and at times
1SM or less possible, especially for KBJC. CIGS will hover between
006-010, with sustained northeast winds near 10kts for the
remainder of the day.

SHSN will diminish through the overnight period, although there`s
some uncertainty as far as just how quickly showers and CIGS will
lift. Additionally, there`s some potential for lower stratus
10-15Z Sat and FG for Denver terminals, although development of SE
winds Sat AM could hamper this, so confidence is relatively low.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until 6 AM MDT Saturday for COZ031-
033>037-041.

&&

$$

SHORT TERM...Rodriguez
LONG TERM...JK
AVIATION...Rodriguez