115
FXUS65 KBOU 221725
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
1125 AM MDT Sun Sep 22 2024

.KEY MESSAGES...

- Storm system exiting the area, with rain diminishing on the
  plains and only a few light snow showers remaining in the high
  country.

- Well below normal temperatures for today. Patchy frost possible
  on the plains tonight.

- Warmer and drier this upcoming week with no significant
  precipitation chances.

&&

.UPDATE...
Issued at 946 AM MDT Sun Sep 22 2024

Satellite shows the upper level low shearing out as it head
eastward across the northeast plains this morning. There was a
well defined deformation zone across northeast Colorado, with an
enhanced band of precipitation stretching from roughly Boulder
county eastward toward Fort Morgan and Holyoke. This rotated a bit
farther north early this morning, but will be collapsing into
early afternoon and weakening as the upper low continues to shear
out and push east. We`ve cancelled the Winter Weather Advisory in
the mountains (most locations only saw about 1-3 inches), and
there are no lingering travel impacts per latest camera
observations.

We should see some breaks in the clouds develop from northwest to
southeast across the area later in the afternoon. Temperatures
will be far below normal for this first day Autumn, but enough
breaks/thinning of the clouds to help it warm into the upper 50s
to lower 60s across most of the plains.

&&

.SHORT TERM /Through Tonight/...
Issued at 346 AM MDT Sun Sep 22 2024

Upslope flow continues over northeastern Colorado this morning
producing stratiform rainfall for lower elevations. Weather stations
suggest a few areas along the plains and Palmer Divide received 0.10-
0.40 inches overnight. Scattered showers will continue for these
areas until early afternoon as the upper level trough pushes
northeast. Light snow continues across mountain webcams this
morning. Snow showers should begin to decrease in intensity this
morning leading to an additional 1-2 inches for areas above 10
thousand feet. As upper level forcing exits the region by this
afternoon, cross sections indicate low to mid level clouds
clearing over the forecast areas through this evening. Tonight,
drier air enters.

&&

.LONG TERM /Monday through Saturday/...
Issued at 346 AM MDT Sun Sep 22 2024

Some patchy fog and/or frost may linger into the first half of the
morning, but otherwise Monday should be a quiet day as drier
northwesterly flow develops. Mostly sunny skies should prevail
through the day with temperatures back above normal (mid/upper
70s).

Though we`ve talked about the potential for a shortwave/cold front
passing through late Monday into Tuesday, guidance has started to
back away from this, keeping the better moisture/cooler
temperatures off to the east of our CWA. Can`t completely rule out
a couple of showers overnight but have reduced PoPs quite a bit
compared to a few cycles ago.

Guidance is also in much better agreement in the longer term,
developing a large ridge axis over the region Tuesday into
Wednesday. There`s a pretty good signal for temperatures to reach
the mid/upper 80s, especially on Thursday. The ridge should slowly
break down towards next weekend, but above normal temperatures
will likely persist through at least Saturday.

&&

.AVIATION /18Z TAFS through 18Z Monday/...
Issued at 1125 AM MDT Sun Sep 22 2024

Rain has ended, but one last band of rain extends north of the
airports, still trying to back in from the northeast. We think
that band mostly dissipates through ~19-20Z so just VCSH to
start, then dry. Ceilings will be improving through the afternoon.
Light southeast flow has taken care of the MVFR ceilings for the
most part, at least for KDEN and KAPA. We expect a break of the
4000-5000 ft AGL ceilings around 22Z, give or take an hour or two.
Then VFR conditions will prevail with mostly clear skies overnight
through Monday. Patchy fog threat tonight will stay north of the
Denver TAF sites with light drainage winds almost certain (95%) to
prevail.

&&

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

&&

$$

UPDATE...Barjenbruch
SHORT TERM...AD
LONG TERM...Hiris
AVIATION...Barjenbruch