980
FXUS65 KBOU 031741
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
1141 AM MDT Tue Jun 3 2025

.KEY MESSAGES...

- Cool with scattered showers and a few storms today. Temperatures
  well below normal across the Foothills and plains.

- Slow warming trend into the weekend, with several chances for
  more showers and storms through the week.

&&

.UPDATE...
Issued at 332 AM MDT Tue Jun 3 2025

Rain has diminished across the Denver metro over the past couple
of hours. The main precipitation shield has shifted east of the
I-25 corridor as the surface low continues to drift southeastward
into the OK panhandle/far SW KS. There`s still enough moisture and
upslope to support some light showers across most of the metro,
but the majority of the rainfall event has ended. Rainfall totals
from automated gauges across the area suggest a few spots have
picked up over an inch of rain tonight (S/SE Boulder, most of the
Palmer Divide), with totals closer to a half inch for a majority
of the Denver area.

Today`s weather certainly won`t feel like early June. A deep
stratus deck is expected to persist through the day today, and
we`ll struggle to warm up into the upper 50s across most of the
plains... with 40s likely across portions of the Foothills. Some
drizzle/fog is possible this morning, with some eventual
development of some scattered showers and perhaps a thunderstorm
by this afternoon. The warmest temperatures in the CWA will likely
be over Middle and North Park where mid/upper 60s are forecast.

Beyond that, the overall forecast hasn`t changed significantly. An
increase in showers/storms is likely for Wednesday, though I would
think the severe weather threat is a little lower than mentioned
from the previous discussion. A series of weak shortwaves will
keep showers/storms in the forecast through the week, with a
modest warming/drying trend this weekend. NBM PoPs are probably a
little overdone on Thursday and Friday, but the focus for now has
been on today/tomorrow`s systems.

&&

.DISCUSSION /Through Monday/...
Issued at 244 PM MDT Mon Jun 2 2025

A fairly expansive deck of mid/high clouds continues to spread
across the forecast area this afternoon. This had reduced solar
insolation and destabilization, as evidenced by the local ACARS
soundings and SPC surface analysis showing CIN greater than 50
J/kg over all of the plains as of 20Z. Mountain areas, being an
elevated heat source and weaker inversions, have essentially
reached convective temperature despite the cloud cover and we`ve
seen a few showers/storms develop. Also, we`ve just recently seen
stronger storms fire in southeast Wyoming, where CIN was eroding
quicker due to earlier sunshine. These will become more widespread
through the late afternoon/early evening, and should eventually
spill onto the plains of northeast Colorado. While the cloud cover
somewhat dampens the threat of severe weather over the northeast
plains, there is still forcing from an approaching cold front and
existing storms from the north which will aid in breaking the cap.
MLCAPE is growing to 1000-1500 J/kg over the northeast plains.
Thus, we could still certainly see a couple strong/severe storms
out there early this evening.

The cold front will also be responsible for widespread shower/
isolated storm development over the rest of the plains and Front
Range later this evening. Within an hour or two of the front`s
passage, sufficient upslope in a neutral/slightly unstable airmass
and synoptic scale lift will all join forces. That means
widespread showers and even a few embedded thunderstorms. Locally
heavy rain could occur in/near the foothills of Jefferson County,
western Denver suburbs, and down across the Palmer Divide area
where best upslope focus occurs. More in the hydro discussion
below.

For Tuesday, we still expect most precipitation to be shifting
off to the south/east as the dominant northern U.S. trough
continues to push southeast, and rather rapid stabilization
occurs behind it. Forecast soundings show it will be difficult to
regenerate any convection with daytime heating as it will be
limited by low level stratus and a deep, cool boundary layer. The
main chance of afternoon convective showers/isolated storms would
be over the high country.

Wednesday will likely warm a little, and there`s another
disturbance well advertised to approach from the west/southwest.
Thus, we think shower/storm coverage and intensity will pick up.
While MLCAPE should stay under 1000 J/kg, the shear profile will
be favorable for more organized storm development. Therefore,
despite somewhat limited MLCAPE we wouldn`t be surprised for a
couple strong/severe storms, with the greatest odds over the
Palmer Divide onto the adjacent east central plains.

Thursday and Friday are expected to remain rather unstable with a
round of at least scattered showers and storms each afternoon and
evening. MLCAPE remains on the modest side during this period,
but it`s early June so certainly any of these days could see a
threat of a couple severe storms.

There are signs for less storm coverage and temperatures warming
to near normal levels by the weekend. That said, we`ll likely be
in northwest flow aloft which means embedded shortwaves and a few
stronger/severe storms will still be possible should sufficient
instability build.

&&

.AVIATION /18Z TAFS through 18Z Wednesday/...
Issued at 1141 AM MDT Tue Jun 3 2025

Northeast to east winds will continue to bring cool moist air to
the area. The lowest ceilings/visibility will be closer to the
foothills (BJC) due to upslope conditions. Low clouds will persist
through today and tonight. Ceilings are expected to remain under
5000 feet through tonight. Drier air moves into towards sunrise
Wednesday morning bringing mostly clear skies 12-14Z Wednesday
morning. However, a cyclone is expected to form bringing north-
northwest winds and possibly keeping/returning low clouds for
Wednesday morning. There will be a good chance for thunderstorms
late Wednesday afternoon and into Wednesday evening (23Z Wednesday
to 04Z Thursday).

&&

.HYDROLOGY...
Issued at 244 PM MDT Mon Jun 2 2025

Continued snowmelt and modest rainfall will be enough to cause
additional rises on streams in the mountains, as well as some of
our Front Range streams. At this time, only the upper Colorado
River above Grand Lake is under enough threat of rises to warrant
an Advisory.

The main threat of flooding along and east of the Front Range
would be more localized and "flashier", given storms will still be
capable of producing heavy rain, but the total amounts remain
relatively consistent. Any risk of flash flooding would be from
1) an isolated strong storm moving over a burn scar this
afternoon/early evening, or 2) stronger storms merging or
training on the northeast plains into mid evening. Even after the
cold front, warm cloud depths are near 6,000 feet for a few hours
which is pretty impressive. As a result, locally heavy rain, even
in the shallow convection, is likely into the late evening hours.
We also think the highest probability of that would be in/near
the foothills of Jefferson County, western suburbs, and down
across the Palmer Divide area where best upslope focus occurs.
Thus, some rises can also be anticipated on local streams
including Bear Creek, Plum Creek, and Cherry Creek. However, at
this time we do not see a high probability of anything greater
than nuisance/minor low land flooding. Still something to watch
trough late this evening into the early morning hours where local
totals of 1-2" will be possible.

&&

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

&&

$$

UPDATE...Hiris
DISCUSSION...Barjenbruch
AVIATION...Meier
HYDROLOGY...Barjenbruch

NWS BOU Office Area Forecast Discussion