692
FXUS65 KBOU 042047
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
247 PM MDT Sat May 4 2024

.KEY MESSAGES...

- Isolated showers and storms across the high country south of
  I-70 through this evening.

- Warmer and windy on Sunday.

- Periods of snow showers in the mountains late Sunday night
  through mid week. There could be travel impacts for the Monday
  morning commute along the I-70 Mountain Corridor.

- Highs winds possible in the mountains and foothills Monday into
  Tuesday.

- Across the plains, expect very windy conditions Monday and
  Tuesday with critical fire conditions across southeast Elbert
  and southern Lincoln counties.

&&

.SHORT TERM /Through Sunday/...
Issued at 215 PM MDT Sat May 4 2024

Satellite this afternoon shows cloud cover slowly building across
southern Colorado towards the I-70 mountains, though radar remains
quiet at this hour. We still expect showers to gradually increase
in coverage across the high country this afternoon into the
evening as better moisture slowly advects into the region. Still
can`t rule out a stray shower or storm making its way into the
southwestern metro but chances of this remain slim. Showers
should end quickly this evening/early tonight and should just
about be wrapped up by midnight.

A potent storm system is expected to bring much warmer and windier
conditions to the region on Sunday. A deep 500mb trough axis is
forecast to track across northern California/Nevada by Sunday
afternoon, with impressive southerly mid-level flow over our
region. Deep mixing is anticipated during the day with highs
peaking the mid/upper 70s across the plains. With 700-500mb mean
winds (near the top of the boundary layer in the better mixed
models) near 40-45kt, it wouldn`t be surprising to get a few
gusts of 50-55 mph across the plains during the afternoon/evening
hours. Along the I-25 corridor, we may see a bit of protection
from the strongest winds (especially up by Fort Collins), but
"breezy" will still be the theme of the day.

In terms of precipitation... there won`t be much, at least through
the day Sunday. The better moisture/lift should remain well west
of the region. A few rain or snow showers may develop across the
high country in the late afternoon. The lower elevations will
likely be too dry/mixed or too capped for any showers or storms
during the daytime.

&&

.LONG TERM /Sunday night through Saturday/...
Issued at 215 PM MDT Sat May 4 2024

Sunday night and Monday a potent upper level storm system will move
across the Central and Northern Rockies. Snow is expected to
increase across the high country Sunday night as moisture and lift
increase. Snowfall rates should generally be light due to poor
southwesterly orographic flow. The exception may be the Park Range
where a few inches of accumulation will be possible. Surface low
pressure east of the Rockies should result in windy conditions
across Northeastern Colorado overnight with gusts to 55 mph from a
south to southeasterly direction. There should be enough lift and
moisture to produce storms across the far Northeastern Plains Sunday
evening. However, models are showing a very strong cap around 700 mb
which should inhibit storms and keep them north and east of the
state line. However, it is May and there is a remote chance that a
strong elevated storm could develop over the far northern plains due
to boundary interactions and moisture convergence.

On Monday, the upper level storm system moves into the Northern
Great Plains States with a moderate westerly flow aloft over
Colorado. This pattern should bring continued light snow in the
mountains, mainly north of U.S. 40 along with breezy to windy
conditions. Models are suggesting quite a bit of subsidence over the
area which may result in a bora like setup resulting in cooler
temperatures and breezy to windy conditions east of the divide. The
strongest winds should be focused from the Front Range
Mountains/Foothills into the nearby plains where winds could gust to
75 mph.

Monday night through Tuesday night, the large upper low will
be centered over the Eastern Montana/Western North Dakota border
with a strong westerly flow aloft over Colorado. This pattern should
result in continued snow and windy conditions in the high country.
The snow may decrease in the mountains Monday evening then increase
again by sunrise. With a 135KT upper jet over Central Colorado,
can`t rule out some localized heavy snow bands during the morning
and afternoon hours on Tuesday. Further east across the plains,
cool, dry and breezy condition are expected.

On Wednesday, the upper trough moves into the Midwestern States with
a broad upper trough remaining over the Western and Central States.
Mid level winds and moisture are expected to decrease with only
isolated to scattered light snow showers possible over the higher
mountain peaks.

The weather pattern get more complicated for the Thursday through
Saturday period. On Thursday, a closed upper low develops over the
Intermountain West with a secondary trough over the Northern Plains
States. Shortwaves on the backside of this trough may push
occasional cold fronts into Northeastern Colorado resulting in cool
and unsettled weather through the period.

&&

.AVIATION /18Z TAFS through 18Z Sunday/...
Issued at 1137 AM MDT Sat May 4 2024

VFR through the TAF period. Stratus observed this morning has
quickly broken up and should completely clear out before 19z.
Southeasterly winds will persist today with occasional gusts near
20kt. An isolated shower or two can`t be ruled out at BJC but we
should stay dry at DEN/APA. Drainage flow tonight should be a bit
stronger than typical.

Stronger flow is expected tomorrow with wind gusts steadily
increasing through the day. A few wind gusts of 30-35kt will be
possible, especially after 18z tomorrow.

&&

.FIRE WEATHER...
Issued at 215 PM MDT Sat May 4 2024

Warm and windy conditions are forecast for Sunday, with a few
gusts up to 50-55 mph possible across the plains. Guidance has
held onto moisture in the region with mid/upper 40s dew points
east of State Highway 71. There may be some locally elevated/near
critical conditions across the urban corridor where there is
better overlap of dry/breezy conditions, but widespread critical
fire weather conditions are not anticipated.

Monday and Tuesday, very windy conditions will continue across
the plains. The most likely area for critical fire conditions will
be over southeast Elbert and southern Lincoln counties where
relative humidity will be drop as low as 10 percent in the
afternoon.

&&

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

&&

$$

SHORT TERM...Hiris
LONG TERM...JK
AVIATION...Hiris
FIRE WEATHER...Hiris/JK