038
FXUS65 KBOU 161841
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
1241 PM MDT Sat May 16 2026

.KEY MESSAGES...

- Scattered showers and thunderstorms through early this evening,
  a few storms will be strong to severe.

- Another active shower/storm day Sunday, although threat of
  severe weather is more uncertain.

- Rain and mountain/foothill snow increases Sunday night through
  Monday with much colder temperatures arriving.

- Accumulating snow (>70% chance of 4-10+ inches) for the
  mountains, and >60% chance of accumulation in the foothills.
  Only a few wet snowflakes possibly mixed in for the I-25
  Corridor.

- One last spring freeze possible on some of the plains Monday
  night.

- Gradually drier with a warming trend through the end of next
  week.

&&

.DISCUSSION /Through Saturday/...
Issued at 1240 PM MDT Sat May 16 2026

Active weather pattern is shaping up through the rest of the
weekend and Monday, potentially lasting into Tuesday.

Satellite shows convection is already starting before the noon
hour as an increase in moisture combines with daytime heating and
growing instability. Low level moisture is also gradually
increasing across the plains this afternoon, with MLCAPE expected
to grow to 600-1200 J/kg over the eastern plains, and less than
600 J/kg along the I-25 Corridor. While those values and low level
moisture is rather marginal, deep layer bulk shear is increasing
to 45-55 kts and low level southeast flow is expected to increase
as well. Low level helicity values are still not terribly strong,
with 0-1 km values mostly under 100 m2/s2 and 0-3km in the
100-200 m2/s2 range. It appears these will be maximized closer to
the decaying weak cyclone and maximized convergence/low level
vorticity from southeast of Denver metro (near Arapahoe/Elbert
County line) eastward into southern Washington county. There is
also potential for stronger low level flow and moisture advection
into early this evening over the far eastern plains. Thus, if we
were to see a brief tornado or two, those would be the most likely
areas. Otherwise the main threat will be large hail and a couple
damaging wind gusts as storms migrate eastward into the higher
instability on the eastern plains late this afternoon and early
evening.

For Sunday, the question remains the severe weather threat. Much
of that will be determined by how far south the front pushes and
whether it actually stalls over/near the Palmer Divide into east
central Colorado. At this point, the far southern and eastern
portions of our forecast area from the crest of the Palmer Divide
eastward to about Limon toward points south and east of Akron
would be most favored for strong/severe storm development with
MLCAPE of 500-1200 J/kg, but again only if that front can stall.
Even if the front does come through, there is still a risk of an
elevated severe storm or two due to sufficient elevated
instability and shear. Hail would be the primary threat from the
stronger elevated storms, while a brief tornado or landspout would
be possible from any convective initiation along the
aforementioned (if stalled) boundary.

The main concern then shifts to Sunday night and Monday with
high potential for accumulating snow in the mountains and higher
foothills. The threat of snowflakes mixing in down into the I-25
Corridor has lowered, as ensembles stepped back from the solution
of one stronger compact shortwave moving across. Now, the first
piece of more organized energy Sunday night and Monday is slightly
weaker/warmer and another piece of energy is held back for
Tuesday. Thus, the chance of any accumulation for the I-25
Corridor is quite low (

NWS BOU Office Area Forecast Discussion