243
FXUS65 KBOU 150604
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
1204 AM MDT Fri May 15 2026

.KEY MESSAGES...

- Summerlike warmth continues for Friday with isolated high based
  showers and a renegade storm or two.

- Elevated to locally critical fire weather conditions Friday.

- Shower and storm chances will gradually increase this weekend
  through early next week, but some uncertainty as to when and how
  much.

- Accumulating snow likely (>70% chance) for mountains and
  possibly foothills (30-50% chance above 7,500 feet) as
  temperatures turn colder toward Monday.

&&

.DISCUSSION /Through Thursday/...
Issued at 129 PM MDT Thu May 14 2026

Main concern in the very short term is elevated to critical fire
weather conditions. We`ve seen the gusty west winds up to 20-30
mph spread off the foothills, and with further mixing and more
sunshine this afternoon they will also spread across the northern
plains with gusts as high as 35 mph there. Humidity readings will
subsequently drop into the 9-12% range. Those conditions will
only slowly improve as winds relax through the course of the
evening. The current Red Flag Warning for the northern tier of
plains counties is on track and will remain in effect until those
winds decrease.

Also, despite the slow heating today, with more sunshine we
should still reach convective temperatures where a bit more
moisture holds on to our south. Thus, an isolated high based
shower/storm is still possible over the Palmer Divide area and far
eastern plains well into this evening. While temperatures remain
mild overnight, it won`t be as warm as last night since we`ll have
less clouds and little if any downslope component.

Friday will feature another mainly dry and very warm day. Winds
will be lighter in all but the mountains and high valleys (where
fuels were noted as being not receptive to rapid wildfire
spread), so no fire weather highlights are needed. A return flow
of low/mid level moisture will support at least a slight chance of
thunderstorms from the Palmer Divide into the eastern plains of
Colorado by Friday evening and overnight.

Saturday`s main concern will shift toward thunderstorm chances and
even the threat of a couple severe storms. Models are pointing to
building low level moisture over the eastern plains, which means
increasing MLCAPE of 500-1000 J/kg. Right now, we think the main
threat of the strong/severe storms would be east of a Sterling to
Akron to Limon line, but will watch closely as models can
sometimes overestimate the amount of lee troughing and eastward
push of the dryline, especially under the influence of weak
upward QG forcing. Temperatures should trend down slightly with
earlier development of clouds and convection.

For Sunday, more uncertainty enters the forecast. The overall
trend was still for a deeper low pressure system dropping into the
Great Basin. At the same time, a cold front is forecast to push
across northeast Colorado, resulting in at least shallow upslope
flow. Depending on the amount of heating/instability (heavily
reliant on strength/depth of cold front), we could see another
threat of severe storms. We would think the front would mostly sag
just to our south, keeping the main threat south and east of our
forecast area or over the Palmer Divide at the very most. However,
the trends of a deeper trough and stronger southerly flow
component aloft are also supporting a slower advancement or stalling
of the front over northeast Colorado. Therefore, Sunday could
bring another day of strong or severe storms.

We do think showers and storms will still become more widespread
Sunday night into Monday as upper level QG support as the trough
starts to eject east/northeast across Wyoming and northern
Colorado. Northern Colorado would be most favored for meaningful
precipitation, while points farther south could stay mostly dry
depending on the trajectory of the ejecting upper trough. There
are also differences with timing, as some models bring the trough
cleanly northeast, while others hold energy back into the mean
trough over the Great Basin. Thus, it could still stay showery
and cooler through mid week before drier and warmer conditions
develop for the latter half of next week. Overall, ensembles point
to modest precipitation amounts, with 25th-75th percentiles in
the 0.50 - 1.0 inch range for Denver metro, greater amounts to the
north and lesser amounts to the south. Still a baseline of just
0.10-0.20" on the 10th percentile, which would be more likely if
the trough ejects farther north.

&&

.AVIATION /06Z TAFS through 06Z Saturday/...
Issued at 1147 PM MDT Thu May 14 2026

VFR conditions are expected through this TAF package. Winds at
KDEN and KAPA will be out of the E/SE in the near term before
turning more southerly over the next couple of hours. KBJC will be
more variable overnight, with winds turning W/SW by early tomorrow
morning. An anticyclone is expected to set up by late tomorrow
morning, turning winds more E/SE for the late morning and
afternoon. Light showers and virga will be possible again tomorrow
afternoon to the south of KAPA and KDEN. These showers could
produce a few gusts from the south in the late afternoon and
evening, but they should be relatively few and far between.

&&

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

&&

$$

DISCUSSION...20
AVIATION...AP

NWS BOU Office Area Forecast Discussion