283
FXUS65 KBOU 221732
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
1132 AM MDT Tue Apr 22 2025

.KEY MESSAGES...

- Isolated high-based showers today, with some briefly gusty winds
  and little rainfall.

- Active pattern expected for most of the forecast period, with
  daily chances of afternoon and evening showers and thunderstorms.
  Snow levels will remain above 9,000 ft elevation.

- Well above normal temperatures possible this weekend.

&&

.UPDATE...
Issued at 942 AM MDT Tue Apr 22 2025

No changes to the forecast this morning. We are still on track to
see high-based showers today. Gusty outflow winds to 30 mph will
be possible with the showers and any rainfall will be light.

&&

.SHORT TERM /Through Tonight/...
Issued at 333 AM MDT Tue Apr 22 2025

Another day of above normal temperatures is expected today under a
zonal flow aloft. The mid-level flow is much weaker today and we
should see less gusty winds across the plains. Deep mixing today
will lead to widely scattered showers across the forecast area
this afternoon. Model soundings show meager CAPE (~250 J/kg) in a
deeply mixed environment... and as a result any high-based
convection that develops will have a hard time producing anything
more than some sprinkles and briefly gusty winds.

Any showers should quickly diminish as we lose the surface heating
this evening, but a few showers could persist across the far
northeastern corner, where slightly better moisture will be
advecting in.

&&

.LONG TERM /Wednesday through Monday/...
Issued at 333 AM MDT Tue Apr 22 2025

Modest zonal flow will gradually transition to a more
southwesterly direction as a broad trough develops near the
west coast and gradually drifts eastward. A broad lee trough will
turn the surface flow more southeasterly, leading to broad
moisture advection into Colorado by Wednesday.

Wednesday should be a pretty active spring day across the state.
The increase in moisture should allow for at least modest
destabilization across the plains, with bulk shear magnitudes near
30-35kt as a result of the strengthening easterly surface flow.
Meanwhile, a weak shortwave moving across the state should provide
ample lift for scattered convection to develop during the
afternoon hours. Can`t completely rule out a few stronger storms
wherever the best overlap of CAPE/shear sets up. At this point
the instability axis looks to set up east of the I-25 corridor,
but there should still be widely scattered showers/storms across
the high country and adjacent plains. It`s also worth noting that
the NAM/NAMnest are much cooler than other guidance Wednesday
afternoon, which would limit precipitation chances north of I-70.

A couple weak surface fronts are expected to push into the region
Thursday and/or Friday, with continued moisture advection in the
east/northeasterly surface flow. Temperatures look to be a little
cooler... especially on Friday. Guidance develops quite a few
showers/storms across the Front Range Thursday afternoon, but this
would likely be dependent on how well any instability can
redevelop each afternoon. Traditionally, the first day or two here
in a pattern like this will be more active, before a cold
front/outflow boundary limits the overall convective potential...
so confidence in any particular day is a little lower than normal.

Guidance is generally in good agreement that the upper trough will
advance a little closer to the forecast area by this weekend.
Overnight runs generally keep the main low to our north, with
stronger, drier southwesterly flow aloft over our area.
Temperatures this weekend may bounce back into the mid/upper 70s,
with limited PoPs.

Guidance diverges quite a bit by early next week as there`s
little consistency with the handling over the numerous shortwaves
pivoting around the larger-scale trough axis.

&&

.AVIATION /18Z TAFS through 18Z Wednesday/...
Issued at 1132 AM MDT Tue Apr 22 2025

Widely scattered high-based showers have formed over the
mountains to the west of Denver. This activity will spread
eastward and bring gusty outflow winds to the Denver airports this
afternoon, mainly 20Z to 01Z. South-southeast winds are expected
to prevail ahead of the gusty outflows. We still may see a brief
period when a cyclone forms with variable winds before the outflow
winds disrupt the cyclonic wind pattern.

Once the gusty outflow winds settle, expect a southerly drainage
direction to prevail at DEN and APA. A weak cold front pushes
south through the area around 12Z Wednesday bringing north to
northeast winds. There remains a slight chance (~10-20%) for low
clouds, but most of the models don`t show it and the 12Z NAM has
backed off some from the low clouds as well. Scattered
thunderstorms are expected after 20Z Wednesday, with the best
chance to the east of Denver where the better moisture will
reside.

&&

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

&&

$$

UPDATE...Meier
SHORT TERM...Hiris
LONG TERM...Hiris
AVIATION...Meier