986
FXUS65 KBOU 291136
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
536 AM MDT Fri May 29 2026

.KEY MESSAGES...

- Another Marginal Risk (Level 1 out of 5) of severe thunderstorms
  Friday afternoon, mainly along and east of I-25.

- Storm chances shift north on Saturday, with strong storms again
  possible over far northeastern Colorado.

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


&&

.DISCUSSION /Through Thursday/...
Issued at 1235 AM MDT Fri May 29 2026

A few weak showers continue over the foothills and western Denver
metro early this morning, which have produced more gusty winds
than meaningful rainfall. Meanwhile, widespread stratus has
developed across the northeastern plains over the past several
hours with steady moist/easterly flow. Most of the I-25 corridor
should avoid the low cloud cover overnight, with a weak cyclone
noted north of Erie... which is expected to drift off to the east
overnight.

Friday will likely see another round of isolated or widely
scattered strong to severe thunderstorms. Another weak shortwave
is expected to track across the forecast area, arriving sometime
late this morning or early afternoon. A gradually more defined lee
trough/lee cyclone is expected to develop over the I-25 corridor
during the day, leading to the formation of a dryline (or at least
just some sort of surface convergent boundary). Surface dew points
east of this boundary should be in the low to mid 50s, with drier
conditions across most of the I-25 corridor. Coverage of storms
should be limited a bit by the early arrival of the shortwave and
questions about the lingering stratus and resultant
destabilization across most of the eastern plains. SPC`s marginal
risk seems appropriate until we have a clearer idea how the low-
level moisture/stratus evolves later this morning.

Saturday will finally see the arrival of a stronger shortwave, as
the closed low currently over the CA/NV border finally manages to
eject the primary shortwave into CO/WY. Westerly flow will
continue to dry out most of the I-25 corridor, leading to limited
chances of storms for most locations along/south of I-70 in the
plains. There could be more widely scattered showers/storms across
the mountains Saturday afternoon, driven by the synoptic scale
ascent/orographic lift... with more isolated coverage across the
Cheyenne ridge and far northeast plains. I suppose there`s a
chance for a few more strong/severe storms across the far
northeast corner if we manage to hold onto some
moisture/instability, with higher probabilities of convection
north of our forecast area.

That trough is expected to lift almost due north into eastern
Montana by Sunday, where it then camps out for a few days as it
goes through a period of deepening early in the weak, before
filling in once again. In Colorado, the zonal flow looks to
establish for a couple of days before the flow aloft weakens
substantially by the latter half of the week. Most guidance keeps
just enough moisture around for daily chances of showers/storms,
though the chances of any meaningful, widespread precipitation
will remain low. A very slow warming trend is expected through
most of next week, with highs generally in the low to mid 80s
across the plains.

&&

.AVIATION /12Z TAFS through 12Z Saturday/...
Issued at 529 AM MDT Fri May 29 2026

Well-defined surface boundary/cyclone continues to inch towards
DEN this morning. On the more moist side of the boundary there`s
been enough for some IFR cigs across the northwestern Denver
metro, though observations out the window here suggest that the
stratus will be fairly quick to scatter out over the next couple
of hours. That leaves a chance (~30%) of some brief impacts at DEN
with less concern for APA.

The rest of the TAF was relatively unchanged. Despite some
uncertainty in the wind direction this morning, there should be a
gradual turn back to an east/southeast wind late this morning or
early afternoon as the lee trough becomes better defined. Most
guidance still hints at weak convection developing around 19-20z
before lifting north and east of the terminals. Another round of
SHRA will be possible in the evening hours as well. Winds will at
least attempt to go to drainage overnight tonight, but may be
impacted by another cyclone or outflow at times.

&&

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

&&

$$

DISCUSSION...Hiris
AVIATION...Hiris

NWS BOU Office Area Forecast Discussion