783
FXUS65 KBOU 251035
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
435 AM MDT Sat May 25 2024

.KEY MESSAGES...

- Seasonal temperatures through this weekend with isolated to
  scattered mainly afternoon thunderstorms. Storms will be most
  numerous in the mountains on Saturday afternoon.

- Elevated fire weather conditions across parts of the plains
  Sunday, but green fuels will limit the fire danger.

- Warm through the coming week. There will be limited late day
  thunderstorm activity on Tuesday with better coverage Wednesday
  through Friday.

&&

.SHORT TERM /Through tonight/...
Issued at 419 AM MDT Sat May 25 2024

GOES-16 water vapor imagery currently shows the next approaching
trough making its way into Nevada late on this Friday night. It is
expected to shift eastward and through the Great Basin Saturday
morning increasing west/southwest flow aloft and bringing Pacific
moisture into Colorado. Broad scale ascent from this passing
disturbance mixed with orographics will bring rain and snow
showers to the mountains today with increasing chances likely
around noon. Ensemble means show CAPE values increase through the
day reaching upwards of 500 J/kg across portions of the mountains
and northern plains, which would support a slight chance for some
storms to develop. Most of the activity for the mountains looks to
be focused around the Park and northern Front Range mountains
where chances for rain/snow showers will linger through Sunday
morning. A few inches of snow may accumulate at the higher
elevations mainly above 10,000 feet. The best chance for
thunderstorms looks to be Sedgwick and Phillips Counties as CAPE
values increase to the 750 - 1000 J/kg range in the afternoon. Max
temperatures for today are likely to be widespread 70s for the
plains, 60s for the foothills, and 50s for the mountains.

As the trough axis shifts east overnight tonight, a more westerly
flow aloft will return. Cross sections indicate a mountain wave
signature developing early Sunday morning that could mean some
enhanced downslope winds for the lee side of the Front Range
Mountains and Cheyenne Ridge. There is a roughly 60% chance that
these could gust up to 45 mph.

&&

.LONG TERM /Sunday through Friday/...
Issued at 419 AM MDT Sat May 25 2024

Subsidence and drying with a little warm advection aloft will move
in behind the shortwave on Sunday. The little bit of wave
amplification should fade by afternoon, though it will remain
windy across the foothills and plains, with some decrease in the
blocked area around Denver. There may be a few showers left in the
early part of the morning along the northern border and mountain
ridges, but then this should get squashed by the subsidence.

Winds aloft will gradually decrease through Monday, and we should
have a pretty quiet day with lighter diurnal winds east of the
mountains. There may be enough moisture for some weak convection
late in the day from the central mountains drifting east in the
evening, but this will likely just be capped cumulus with perhaps
a few sprinkles.

The ridge axis will be over us on Tuesday, leading to light
southwest flow Wednesday and then a gradual increase in the flow
through the end of the week as a trough develops west and
northwest of us. There`s pretty good agreement on holding this
back through Thursday, then stronger flow and probably some QG
lift and a frontal passage by Friday.

The air aloft should remain dry through Thursday, and this
pattern probably favors a dry line somewhere over the eastern part
of the plains or near the eastern border. There will be sustained
southeast low level winds so moisture should increase enough for
some thunderstorms, but how much we get over the foothills and
adjacent plains is in doubt, as is potential capping of the
moisture over the east. Can`t really argue with the NBM PoPs too
much, but the severe threat should start as pretty low in the
middle of the week without much shear and relatively warm
temperatures aloft. There could be better moisture by Thursday but
it might be a dry line day. Then the usual post frontal questions
for Friday. It`s likely a more active day with some QG forcing,
and shear will be greater, but it may also be too cool for much
CAPE. The solutions with a weaker front are probably more
favorable for stronger storms.

&&

.AVIATION /06Z TAFS through 06Z Sunday/...
Issued at 1157 PM MDT Fri May 24 2024

Winds have gone more easterly than anticipated at DEN tonight, we
are expecting a more southerly component to return in the next few
hours. Early tomorrow afternoon (~19Z), southwest winds are
likely with gusts up to 30 mph, then after roughly 21Z some
passing showers are likely over all airports. These are expected
to be high based showers that could produce some gusty and erratic
outflows up to 40 mph.

&&

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

&&

$$

SHORT TERM...Bonner
LONG TERM...Gimmestad
AVIATION...Bonner