496
FXUS65 KBOU 281144
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
544 AM MDT Tue Apr 28 2026

.KEY MESSAGES...

- Scattered showers/weak thunderstorms across the plains and light
  mountain snow today.

- More active pattern continues through the week with multiple
  precipitation chances.

- Warmer and drier conditions expected by the weekend.

&&

.DISCUSSION /Through Monday/...
Issued at 1113 PM MDT Mon Apr 27 2026

Current radar imagery shows ongoing mountain snow and rain
showers/thunderstorms for the lower elevations. Expect scattered
showers to continue overnight tonight and into Tuesday morning ahead
of an approaching shortwave trough. Tuesday morning will see low
temperatures in the 30s across the plains, with areas of patchy fog
possible, particularly for the northeastern plains where dewpoint
depressions more likely to be smallest.

The upper level shortwave trough will trek eastward on Tuesday
morning, providing weak QG ascent and associated positive vorticity
advection. This and an increase in mid-level moisture will help
support another round of scattered mountain snow and rain showers
for the lower elevations. Hi-res guidance indicates precipitation
throughout the day before decreasing in the early evening as the
shortwave exits the region. With some instability over the plains
(guidance favors 100-300 J/kg CAPE in the afternoon) can`t rule
out a couple of rumbles of thunder and small hail.

We will likely get a break in precipitation overnight Tuesday and
into Wednesday morning for most of the forecast area with subsidence
aloft and surface high pressure sinking into the plains.
Temperatures will have the chance to warm up to seasonal values,
with the plains possibly reaching the low 60s. Another shortwave
trough is progged to be over Colorado by Wednesday afternoon. This
will bring yet another round of scattered showers (and mountain
snow) with the presence of afternoon instability promoting some
isolated thunderstorm activity. A cold front associated with the
system will trek across the plains in the evening, bringing cooler
air and below seasonal temperatures once again.

Some uncertainty remains in the forecast for Thursday and Friday as
models continue to resolve an upper level closed low as it travels
from Baja California east late this week. Recent deterministic runs
now favor a more southerly track of the closed low, with it trekking
into New Mexico and Texas by Friday evening. This will result in
less precipitation for our forecast area than our southern
neighbors. However, ensemble guidance still holds on to measurable
precipitation for us, with the GEFS/ECMWF ensembles indicating 60-
70% chance of 24-hr QPF amounts greater than 0.50" by Friday
morning, and a 10-20% chance of 24-hr QPF amounts greater than
1.00". Thursday will be our best chance for this precipitation, with
upslope flow throughout the day behind the cold front. The southern
mountains/foothills and Palmer Divide area is favored for highest
PoPs (and highest precipitation amounts) due to better QG ascent
associated with the low. If this trend continues, our southern
Front Range mountains and possibly foothills may see some travel
impacts on Thursday, as snowfall in the high terrain could impact
travel across the I-70 mountain corridor. The question remains if
we will get additional showers on Friday. Not sure yet, as
ensemble members diverge in solutions by then. Although, recent
NBM has slightly decreased PoPs on Friday morning for our forecast
area.

For the weekend, guidance favors an upper level ridge building
behind the exiting upper level low. This will promote a more warming
and drying trend. As of right now, GEFS shows warmer temperatures
than the ECMWF Ens due to the axis of the ridge being over the
Rockies, rather than western U.S. like the ECMWF shows. Temperatures
could get up to the mid-60s to low 70s by Sunday depending on the
placement of the ridge.

&&

.AVIATION /12Z TAFS through 12Z Wednesday/...
Issued at 544 AM MDT Tue Apr 28 2026

A moist airmass will remain over the area today. An area of
showers will track eastward across the Denver area 12-15Z this
morning. A northerly wind shift and ceilingsof 500 to 2000 feet
are also expected. After the showers move through, ceilings are
expected to climb to 3000-6000 feet. Scattered showers are
expected this afternoon, briefly lowering ceilings. There is also
a slight chance (~10%) for a brief thunderstorm. Drier air moves
in after 00Z Wednesday with ceilings climbing above 6000 feet, and
then clouds scatter out by 06Z. The next round of showers and
lower ceilings moves in 12-18Z Wednesday.

&&

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

&&

$$

DISCUSSION...MAI
AVIATION...12

NWS BOU Office Area Forecast Discussion