806
FXUS65 KBOU 190759
AFDBOU

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

.KEY MESSAGES...

- Near freezing temperatures and frost/freeze highlights for most
  of the plains, but some uncertainty as to how cold with more
  lingering cloud cover.

- 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 /06Z TAFS through 06Z Wednesday/...
Issued at 1125 PM MDT Mon May 18 2026

MVFR and IFR conditions are still prevalent across the area, with
isolated to scattered light rain and drizzle near the TAF sites.
Isolated light showers are expected to continue on and off for the
next few hours before we see a brief break in precip chances in
the late morning and early afternoon. This break will be short
lived as additional scattered showers move over the area in the
mid afternoon through the late evening. High res models are
showing slightly better rain coverage for the 00Z to 06Z time
frame, compared to a bit earlier in the afternoon. MVFR and IFR
conditions are expected to continue overnight, with CIGs around
600ft to 2000ft. Ceilings will start to lift tomorrow late morning
and afternoon, but CIGs will still remain around 3000ft to 5000ft
at their max before starting to lower again for Tuesday night.
Winds during this TAF package will generally remain on the
lighter side,with speeds mainly staying below 12kts. Wind
directions are a bit uncertain in the late morning and afternoon
as some models are showing outflow boundaries from overnight and
morning convection moving through the area.

&&

.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