418
FXUS65 KBOU 281847
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
1247 PM MDT Thu May 28 2026

.KEY MESSAGES...

- Today will bring scattered showers and thunderstorms over the
  far northeast plains and in and near the foothills and I-25
  corridor. Stronger storms could produce some hail.

- Thunderstorm chances will increase Friday through Saturday,
  across the plains. Highest chance for severe weather will be
  Saturday afternoon in the northeast plains.

- Afternoon showers and thunderstorms will be possible through the
  long-term forecast period with slightly above-normal
  temperatures expected.


&&

.DISCUSSION /Through Thursday/...
Issued at 1219 PM MDT Thu May 28 2026

We have a few showers across the higher terrain and northeast
plains, with a thunderstorm or two mixed in there. Coverage of
showers and storms is expected to increase into the late afternoon
for the higher terrain, foothills, and potentially I-25 corridor, with
some scattered activity in the northeast plains. We still have a
cap in the mid levels as of early this afternoon, which will
hinder stronger convective development along the foothills and
Denver Metro. However, if we can get past the cap, MLCAPEs around
500 to 800 J/kg, mid level lapse rates around 8 to 9 C/km, and
bulk shear around 25 to 30 kts could be enough for an isolated
strong to marginally severe storm or two. The main threats with
any storms today will be dangerous lightning and hail.

The upper level trough to our west will start to approach the
area tomorrow. It looks like the trough may lag just enough that
the strongest lift will hold off until the late evening and
overnight time frame Friday into Saturday. But a wave ahead of
the main trough will be enough to provide some upper level lift
Friday afternoon. We`ll also have some surface convergence/lift
as the Denver Cyclone develops in the morning/afternoon. While
moisture, MLCAPEs, and lapse rates look pretty good, shear is on
the weaker side. This could lead to more pulse like thunderstorms
rather than supercells, meaning the main threat will likely be
strong winds as the thunderstorms collapse, but hail and brief
heavy rainfall will also be possible.

Things start to dry out a bit for Saturday as a surface low
develops on the lee side of the Rockies, ushering in lower dew
points for areas to the west and south of the low. The positioning
of this low will have a significant impact on the moisture and
instability across our area, making the severe threat more
uncertain. MLCAPEs and lapse rates will remain decent on Saturday
for the areas that keep their moisture and shear looks to improve
slightly compared to Friday, making the chance for supercells a
bit higher for Saturday afternoon and evening. Convergence along
the surface trough will be a focal point for convective
development. Convective development will likely start in the
afternoon in our northern and northeastern counties, with coverage
increasing into the evening as storms move northeast with the
surface low. Isolated to scattered severe storms will be possible
in the afternoon and evening, mainly in our northeastern
counties.

The upper level low is forecast to move to our north/northeast and
remain in that general area Sunday into early next week, before it
pushes north starting Tuesday. As this low sits to our north, upper
level disturbance will rotate through the flow aloft, providing low to
medium end rain chances each afternoon. The severe threat during
this time is still uncertain, instability looks okay Monday and
Tuesday if we can get over the cap, but shear might be on the
lower end. Either way, we can expect isolated to scattered showers
and thunderstorms each afternoon into the middle of next week.

&&

.AVIATION /18Z TAFS through 18Z Friday/...
Issued at 1128 AM MDT Thu May 28 2026

E/SE winds will continue to increase in prevalence over the next
couple of hours and remain established through the afternoon. An
unstable environment will promote development of -TSRA to the SW
of the Denver metro near 20Z, with said activity pushing NE
through the afternoon/evening as it undergoes some
weakening and dissipation. KAPA will have the highest potential
for -TSRA impacts. Outflows may produce gusts to 25 kts, generally
favoring a SW direction given predominant placement of convection.
Expect periodic CIGS of 040-050 during -TSRA.

Tonight, drainage flow is favored to prevail for KDEN/KAPA through
at least 12Z. VFR conditions will prevail over that timeframe.
Near and shortly after sunrise, there is a remote possibility for
an intrusion of lower stratus/fog into the northern metro (higher
confidence for the S. Platte River Valley). There`s some
indication of an earlier transition to W/NW flow after 13Z which
would open the door to this scenario (most likely for KBJC,
smaller but nonzero chance for KDEN), but confidence remains low
given inconsistency in wind guidance during this time.

&&

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

&&

$$

DISCUSSION...AP
AVIATION...BRQ