029
FXUS65 KBOU 191147
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
547 AM MDT Tue May 19 2026

.KEY MESSAGES...

- Near freezing temperatures and frost/freeze highlights for most
  of the plains through 8am.

- Unsettled Tuesday through Friday with scattered to numerous
  showers and a few storms, most numerous in/near the Front Range.

- Warming and drying trend for the weekend.

&&

.DISCUSSION /Through Monday/...
Issued at 146 AM MDT Tue May 19 2026

Scattered drizzle and light showers will continue throughout the
overnight period, clearing by the late morning. We do still have
some snow showers in the northern Front Range as well, that will
likely last into the early morning. Temperatures as of 1:30AM are
near freezing for the Palmer Divide and in the mid to upper 30s for
much of the plains. Thick low level clouds will make it hard for
temperatures to cool significantly, but the Freeze Warning and
Frost Advisory still look to be on track.

The forecast for this work week looks unsettled and cooler than
normal. An upper level trough is forecast to sit just off to our
west through Thursday. Upper level disturbances will move through
the flow aloft, providing some ascent. Additionally we`ll be sitting
under the right entrance region of the jet today and Wednesday,
providing another source of lift for the area. With the upper level
support and surface moisture, we`ll have rain chances for much of
the area with snow chances for the higher mountains elevations.
We`ll see higher moisture for Wednesday, which will allow for
slightly better coverage of showers, higher precip amounts, and
potentially some instability for thunderstorms.

Surface return flow on Thursday will bring increased moisture, with
dewpoints increasing into the 40s and 50s for the afternoon. Higher
moisture and increased instability will combine with strong low level
lapse rates and decent shear to provide a chance for a few strong to
severe thunderstorms across the plains Thursday afternoon and
evening. A cold front is forecast to move into northern Colorado
sometime late Thursday into early Friday. If that front ends up
moving through more Thursday evening rather than Friday morning, it
could act as a trigger for storms, potentially increasing storm
coverage.

The upper trough, which is a major player in our rain chances for
the week, is finally forecast to move over the area and to the
east overnight Thursday through Friday morning. However, models
are showing a secondary weaker trough following the original,
which could bring us another day of scattered showers for Friday.
Temperatures will remain below normal for Friday thanks to the
front and cloudy conditions. Storms will be less likely for Friday
compared to Thursday due to the more stable airmass following the
overnight front.

Upper level ridging begins to build over the area Saturday into
early next week, allowing temperatures to rise back above normal
by late this weekend.

&&

.AVIATION /12Z TAFS through 12Z Wednesday/...
Issued at 522 AM MDT Tue May 19 2026

Light drizzle will continue near the TAF sites for a couple more
hours, before it clears out. Ceilings will remain IFR to MVFR
through the morning, with occasional LIFR CIGs at KAPA. Ceilings
will rise to around 3000ft to 5000ft this afternoon, before CIGs
start to drop again as rain moves into the area. Scattered showers
will return in the late afternoon through late evening. The
highest coverage of rain looks to be between 06Z and 10Z
Wednesday, but rain could impact the terminals off and on starting
around 21Z and continuing through Wednesday morning. Winds will
generally remain below 12kts today.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
Frost Advisory until 8 AM MDT this morning for COZ038-042>051.

Freeze Warning until 8 AM MDT this morning for COZ041.

&&

$$

DISCUSSION...AP
AVIATION...AP

NWS BOU Office Area Forecast Discussion