001
FXUS65 KBOU 211147
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
547 AM MDT Tue May 21 2024

.KEY MESSAGES...

- Cooler today, with another round of afternoon showers and
  thunderstorms. Small hail and gusty winds are possible from
  these storms but they will likely stay below severe limits.

- On and off snow showers across the high country through tonight,
  with light accumulations across the higher mountains. Some
  travel impacts possible along the mountain passes this morning
  and later this evening.

- Warming/drying trend for the second half of next week with
  elevated fire weather conditions likely Thursday.

&&

.SHORT TERM /Through tonight/...
Issued at 333 AM MDT Tue May 21 2024

The weather has settled down a bit since Monday evening, with
radar showing several areas of scattered showers and a couple of
thunderstorms across the eastern plains. Water vapor satellite
shows the initial shortwave lifting across northeast Colorado this
morning, with the main trough axis still lingering of to our
west. Meanwhile, a surface low is now located over west- central
Kansas, with our cold front now draped to our south, per WPC
surface analysis and recent obs.

Shower activity should decrease later this morning, with some low
cloud cover persisting through most of the day. Cooler
temperatures will prevail tomorrow behind the cold front, with
highs remaining in the upper 50s to low 60s for the plains and
urban corridor.

The trailing shortwave with this trough is expected to push
across the forecast area by this afternoon, and the lift from this
and the shallow but persistent upslope flow should provide the
forcing for another round of showers and a few thunderstorms.
Model soundings show meager CAPE this afternoon, and severe
weather is not anticipated. However, any stronger storms would be
capable of producing briefly gusty winds and small hail.

Meanwhile, snow levels will hover near 8500 feet today and
gradually lower later this evening. An ongoing burst of snow has
produced some slushy/snow covered roads across the I-70 mountain
corridor this morning... and snow showers will continue on and of
through the day with light accumulations. Widespread travel
impacts are not anticipated with this, but a few brief periods of
slick travel conditions will be possible through the evening.

Showers and storms may linger into the evening/early overnight
hours tonight for the plains with a few snow showers across the
higher elevations, but drier air will quickly work into the
region behind the trough. Expect clearing skies and cool overnight
lows into Wednesday AM.

&&

.LONG TERM /Wednesday through Monday/...
Issued at 333 AM MDT Tue May 21 2024

Wednesday will bring warmer and drier conditions to the forecast
area as the upper level low shifts to the northeast and relatively
weak zonal flow aloft develops. Weak ridging at the 500 mb level
will quickly traverse across the area as another upper level low
makes its way ashore over the PNW. High temperatures on Wednesday
will be a few degrees below normal, however, still climb to the low
70s across the foothills and plains, and high 50s to low 60s for
most of the mountains and valleys. Forecast soundings indicate
increasing instability in the afternoon as mid level lapse rates
steepen that could allow for some isolated showers or thunderstorms
to develop across the eastern plains.

Southwesterly flow will develop on Thursday as the aforementioned
upper level low over the PNW shifts east into
Idaho/Montana/Wyoming and skirts just to the north of Colorado.
Guidance is in agreement that the main forcings from this
disturbance will stay to the north of our forecast area, but we
will see some increasing moisture as well as an associated cold
frontal passage through northeastern colorado Thursday night.
Temperatures will be in the high 70s Thursday afternoon across the
plains and foothills, and 50s to 60s for the mountains, but with
the passing cold front, temperatures will drop into the 20s and
30s overnight for the mountains and valleys that could allow for
some light snow showers to develop over these areas. Ahead of the
cold front, warm and dry conditions will bring elevated fire
weather conditions to portions of the urban corridor, South Park,
and the Palmer Divide. Behind the cold front, Friday will be quite
cooler than Thursday with high temperatures barely reaching the
mid 60s for the foothills and plains, which is roughly 10 degrees
below the norm for this time of year.

The active weather pattern will continue through the weekend with
daily chances for afternoon scattered showers and thunderstorms as
temperatures return to the mid to high 70s for the weekend.

&&

.AVIATION /12Z TAFS through 12Z Wednesday/...
Issued at 541 AM MDT Tue May 21 2024

A batch of weak showers is pushing across the metro this morning,
which has also come with a push of light westerly winds. This has
been enough to push most of the stratus away from Boulder/BJC and
trends suggest that we`ll see a return to VFR in the next hour or
two at DEN/APA. VFR should continue into the early afternoon once
it does establish.

Additional showers and thunderstorms are forecast by early/mid
afternoon at the terminals. Better confidence in timing for today
with most guidance favoring somewhere between 20-00z this
afternoon. Main concern would be gusty winds but can`t rule out
some small hail as well. Beyond that, showers may linger into the
evening hours with the potential for some briefly lower cigs in
the evening. Cloud cover should diminish quickly as we approach
06z with drainage flow establishing around that time as well.

&&

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

&&

$$

SHORT TERM...Hiris
LONG TERM...Bonner
AVIATION...Hiris