744
FXUS65 KBOU 031655
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
1055 AM MDT Mon Jun 3 2024

.KEY MESSAGES...

- Summer heat through most of this week, with a few 90 degree
  readings over the plains

- Chance of showers and storms tonight

- Breezy but a little cooler Tuesday

- Return to more normal temperatures and a chance of storms this
  upcoming weekend.

&&

.UPDATE...
Issued at 1055 AM MDT Mon Jun 3 2024

Satellite showing nearly continuous cloud cover from northwest
Colorado west to the Pacific Ocean. This is associated with the
strong system (atmospheric river) moving onto the west coast. Mid
and high cloud cover will increase today with mostly cloudy skies
for tonight. Dew points will be mainly in the 30s this afternoon
and should result in weak convection late this afternoon. Expect
very little if any rainfall from this. Gusty outflow winds will be
the main impact. Best chance for rain will be tonight as the wave
moves across the region. Just minor adjustments to the forecast
to line up with the current trends.

&&

.SHORT TERM /Through tonight/...
Issued at 334 AM MDT Mon Jun 3 2024

GOES water vapor imagery currently shows the next approaching
shortwave over the PNW early this morning heading east. As we begin
today under weak ridging, northwesterly flow aloft and mostly clear
skies across the CWA, this broad, low amplitude shortwave will
continue eastward across the northern US putting Colorado downstream
of its axis. Cross sections indicate mid and upper-level moisture
will increase throughout the day, increasing cloud coverage with it.
With marginal instability from daytime heating and synoptic forcings
mixed with orographics, chances for showers and embedded
thunderstorms increase into the evening hours across the high
elevations mainly after the 2Z to 3Z time frame. With dry low levels
portrayed in forecast soundings, there is high potential for high-
based virga showers to develop across the plains. These could cause
dry microbursts as the NAM shows DCAPE values over 1000 J/kg in the
afternoon. Chances for storms and showers will diminish early
Tuesday morning as the shortwave exits the area and is replaced with
northwesterly flow aloft. It will be another warm day with another
chance of reaching 90 across portions of the plains.

&&

.LONG TERM /Tuesday through Sunday/...
Issued at 334 AM MDT Mon Jun 3 2024

Tuesday will feature breezy to windy conditions across the plains
and Front Range mountains as unseasonably strong west/northwest
flow dominates in the wake of tonight`s shortwave. There are
indications for a near mountain top stable layer, and combined
with 40-45 kt cross mountain component will support potential for
gusty winds up to 40-60 mph above timberline and some of the wind
prone slopes in the higher foothills early Tuesday morning. Those
gusty winds, albeit lighter, will spread across the plains in the
late morning and afternoon given daytime heating and mixing, and
large scale subsidence. Most gusts on the plains should range
between 20 and 30 mph, except near the windy Wyoming border where
gusts will likely range between 30 and 40 mph. Temperatures will
be a few degrees cooler than today given some cold advection
associated with tonight`s disturbance. Outside of a couple
lingering morning showers in the mountains, dry weather will
prevail although a fair amount of high level cloudiness is
possible per latest model cross sections.

Wednesday and Thursday are still looking quite warm and dry.
Downslope flow on Wednesday will likely contribute to highs near
90F across most of the plains and I-25 Corridor. Thursday may end
up a couple degrees cooler with potential for a backdoor cold
front.

The main change in tonight`s forecast package was to delay any
sort of cooling and lower the PoPs a little for Friday. Model
ensembles were a little farther east with the Great Lakes region
upper low, which means a delay and uncertain timing regarding
additional backdoor cold fronts. There is still reasonable
agreement in the EC ensembles for a cooldown starting Saturday
into Sunday, although the 00Z GEFS was now showing less. We still
think we`ll trend at least a little cooler by next weekend with
closer to normal temperatures. And, enough moisture advects in
from the Central Plains under persistent but weak easterly flow
for a higher chance of showers and storms.

&&

.AVIATION /18Z TAFS through 18Z Tuesday/...
Issued at 1055 AM MDT Mon Jun 3 2024

South-southwest winds are expected to linger through at least
18Z. After this, wind direction becomes more uncertain. Mid and
high cloud cover should limit heating enough that we don`t mix
into the stronger westerly wind aloft. Leaning toward winds
staying southerly until outflow from the high-based showers move
through, which looks to be after 22Z.

Cloud cover thickens after 00Z, as Pacific moisture increase over
Colorado. Ceilings will remain high, above 8000 feet. Could see
light rain overnight, but gusty outflow winds will be more
likely.

&&

.HYDROLOGY...
Issued at 300 AM MDT Mon Jun 3 2024

Alpine snowmelt will increase runoff the next several days with
the arrival of summer heat.  Hydrologic forecasts from the River
Forecast Centers now show a few streams getting to action stage
later this week, which means flows will be high and fast but
flooding threat limited. Please use caution and respect these fast
moving and cold flows in the high country.

&&

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

&&

$$

UPDATE...Meier
SHORT TERM...Bonner
LONG TERM...Barjenbruch
AVIATION...Meier
HYDROLOGY...Barjenbruch