710
FXUS65 KBOU 251806
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
1206 PM 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.

&&

.UPDATE...
Issued at 1203 PM MDT Sat May 25 2024

An upper trough over western Utah is pushing eastward at this
time.  Convection is developing over the northern half of the
mountains and foothills at this time with only light precipitation.
There is some lightning with the cells in north central Larimer
County right now.  Temperatures have warmed into the mid 60s to
lower 70s over the plains already.

As far as this update goes, will up pops a tad over the plains,
especially the northern half where the best best CAPE is
expected. Will up temperatures a tiny bit as well with current
readings in mind. The main threat with the convection today will
be strong wind gusts.

&&

.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 roughly a 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 /18Z TAFS through 18Z Sunday/...
Issued at 1204 PM MDT Sat May 25 2024

Models have brisk northwesterly low level winds this afternoon for
DIA. They become more northerly during the evening then settle
into normal drainage patterns sometime around 06Z tonight. Will
keep the treat of -SHRA going in the late afternoon and early
evening along with VCTS. Convection around could bring wind gusts
to 40 knots to the airfield.  There shouldn`t be any ceiling
issues.

&&

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

&&

$$

UPDATE.......RJK
SHORT TERM...Bonner
LONG TERM....Gimmestad
AVIATION.....RJK