641
FXUS65 KBOU 160805
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
205 AM MDT Sat May 16 2026

.KEY MESSAGES...

- Scattered showers and thunderstorms are expected this afternoon.
  A few storms could be strong to severe.

- Precipitation chances continue for Sunday and Monday, with
  shower and storm coverage increasing late Sunday into Monday.

- Much colder temperatures by Monday.

- Accumulating snow (>70% chance of 4-10+ inches) for the
  mountains, and >60% chance of accumulation in the foothills.
  Less than 20% chance of any snow accumulating for the I-25
  Corridor.

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

&&

.DISCUSSION /Through Friday/...
Issued at 147 AM MDT Sat May 16 2026

Temperatures will remain above normal today, with a chance for
storms this afternoon and evening. A shortwave will move through the
flow aloft this afternoon providing some upper level support for
precip to develop. At the surface, a boundary will sit over (or
near) the area, separating a moist air mass to the south and east
from a dry airmass to the north and west. While showers and storms
are expected on both sides of this boundary, the location of it
this afternoon will be crucial for determining severe thunderstorm
potential in our area. Areas to the east of this boundary will
see much higher dewpoints and instability compared to the western
side, leading to a significant increase in the potential for
severe weather. High res models vary with the positioning of this
boundary, with some keeping it off to our east in Kansas and
others putting it over our eastern plains. This slight change in
location is the difference between MLCAPEs around 300 J/kg vs 1300
J/kg in our northeastern counties. If we do see a further
westward positioning, storms in our eastern counties will have the
potential for large hail (possibly around 2"), strong winds (up
to 70mph), and potentially and isolated tornado.

The upper level trough off to our west today will begin to deepen
and progress east towards our area on Sunday. As a result, we`ll see
another chance for showers and thunderstorms Sunday afternoon
through Monday. The severe threat for Sunday still looks a bit
complicated. A strong surface low is forecast to develop near our
area early Sunday and progress east during the day. As the low
moves east, we`ll see breezy north winds develop over much of the
area. Areas just to the west of the surface low will see moisture
wrap around, funneling into that location. However, as you move
further west away from the low, the breezy north winds will bring
drier air in. So, we`re going to have another day where the
westward extent of moisture is highly uncertain. The instability
doesn`t look great for severe storm development thanks to the
front, but the shear will be very impressive which could push
storms into the strong to severe category. Additionally, we`ll
have a stalled front somewhere near the southern border of the
CWA. The exact location of this front is uncertain, but it will
likely act as a trigger for storms in the afternoon and evening.

Precipitation chances will continue through much of the day Monday
as the upper level trough approaches. The late Sunday through mid
Monday time frame will be our best chance for seeing widespread
precipitation. The best chance for precip on the plains will be to
be north of I-70 and I-76. The most likely rain totals still look
to be in the 0.5 to 1.25 inch range for this area. Lower totals
are expected further south and east. As for snow chances, snow
levels will start off around 10,000ft, but will slowly drop
overnight and throughout the day Monday. This means that while
some areas, like the lower mountains elevations, Foothills, and
Palmer Divide will likely start off as rain, they could see a
transition to snow sometime Monday morning to early afternoon.
While we could see a few flurries mix in across the I-25 corridor
Monday afternoon, chances for any accumulations remain low (

NWS BOU Office Area Forecast Discussion