143
FXUS65 KBOU 101726
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
1126 AM MDT Mon Jun 10 2024

.KEY MESSAGES...

- Scattered thunderstorms this afternoon. A few strong to severe
  storms along with a risk of heavy rain, localized flooding with
  some storms.

- Snowmelt producing minor impacts from high streams, mainly in
  Grand County.

- Hot and mainly dry weather towards the middle to end of next
  week. There is potential for a day or two to need a Heat
  Advisory, most likely Thursday.

- Cooler conditions will arrive Friday and Saturday with scattered
  showers and storms. Some of these storms could be strong to
  severe with heavy rain.

&&

.UPDATE...
Issued at 947 AM MDT Mon Jun 10 2024

Still on track for another round of afternoon/evening
thunderstorms. Airmass not quite as unstable as yesterday, but
with MLCAPE up to 1500 J/kg, a few strong/severe storms will be
possible. Best lift from an upper level trough moving across the
Northern and Central Rockies will be north of Colorado, but enough
lift will move across the area to trigger storms. Expect better
storm coverage to be across northern Colorado, thus increased PoPs
a little more for this area.

&&

.SHORT TERM /Through tonight/...
Issued at 412 AM MDT Mon Jun 10 2024

The region remains under an upper level ridge today. Flow aloft is
still on the weaker side out of the WNW, but perhaps not as weak as
yesterday. A mid-level shortwave trough moves through the flow later
this afternoon. The stronger synoptic support is further north of
Colorado; however, it should provide sufficient ascent out ahead
of it aligning with peak heating. Current Mid-Level Water Vapor
satellite imagery depicts rich moisture transporting from the
south, wrapping around the upper ridge over CO this morning. This
correlates well with ensemble guidance keeping above normal
moisture in the area today around 140-175% of normal. Precipitable
water values rise to around 0.4-0.6" for the higher elevations
and 0.8-1.1" across the plains/urban corridor. MLCAPE values range
from 600-1500 J/kg. High level clouds will be around for the day,
but shouldn`t limit instability as much as lower clouds would.
With weaker upper level winds, 0-6km shear will be on the weaker
side with some slightly better values closer to the northeast
corner(20-30kts). Overall, this environment should support
scattered thunderstorms with a couple strong to severe storms.

Thunderstorms develop over the high terrain by early afternoon
moving east onto the adjacent plains. The suite of high-res CAMs
generally show a broken line/wave of storms pushing off of the
higher terrain then filling in more as it moves across the east
plains where the richer moisture and instability are. Hail 1-1.5"
and strong gusts are possible with any severe storms. Storm
motions should be a bit higher today, but can`t rule out a few
strong storms capable of producing heavy rain for a period of
time. This could still result in minor impacts in prone areas if
a storm stays over an area long enough. Storms move east across
the plains through the late afternoon-early evening hours. For
temperatures today, highs rise into the 80s for the plains/urban
corridor, 70s for the foothills, and 50s/60s for the mountains.

&&

.LONG TERM /Tuesday through Sunday/...
Issued at 412 AM MDT Mon Jun 10 2024

Little change to the extended forecast this morning. It does look
like the drying aloft from the northwest on Tuesday is coming
along towards the faster end of what we`d been thinking, and we`ve
backed off a bit more on PoPs for Tuesday afternoon and evening.
There should still be enough moisture and instability for a few
storms, mainly over the Front Range.

Temperatures rebound sharply for Wednesday and Thursday as an
upper ridge pokes northward across the Rockies. There will
probably be some late day cloud development drifting from the
mountains onto the plains, but that`s about it. Thursday probably
has the warmest air aloft, but there is a puff of northerly winds
from the tail end of a shortwave that`s focused up on the Canadian
border. There may also be a bit of cloud cover and attempted
showers along the northern border in the afternoon. We`ll also be
hot enough to generate some high based weak convection away from
that forcing near the end of the day. All of that may take a
couple of degrees off of the highs if there`s enough of it.

There continues to be some vacillation about the details for
Friday and Saturday, chiefly how strong the push of cooler air
into the plains will be. There`s also been a trend towards a bit
more mid level moisture drifting up from the south. The variations
don`t really change the story though, of decent thunderstorm
coverage and highs dropping back into the 80s for Friday. The
upper trough coming out of the southwest will provide some lift in
a favorable atmosphere, but timing varies on this from Friday
night into Saturday. After that passes, we should have warming and
drying again for less activity, but still some moisture east of
the mountains.

&&

.AVIATION /18Z TAFS through 18Z Tuesday/...
Issued at 1126 AM MDT Mon Jun 10 2024

Showers and thunderstorms will track across the Denver area again
today. Time frame for storms looks to be 20-02z, with the best
chance for storms at DEN 22-24Z. Heavy rain, small hail, and wind
gusts to around 35 knots will be possible with the stronger
storms. Winds prior to convection should be light, though south to
southeast winds to 20 knots could spread into the area towards
20Z. Outflow winds from convection will likely dictate wind
direction in the 21- 01Z window. After this southeast winds are
expected through the evening. A weak front moves through overnight
bringing north winds around 07-08Z.

Slight chance (10-20%) for low clouds/patchy fog around 12Z
Tuesday morning. Will have few005 in the TAF for this. Any low
clouds or fog should dissipate quickly Tuesday morning with drier
air moving into the area. Any storms that form Tuesday afternoon
are expected be south of the Denver. Outflow from these storms
could produce a wind shift with southerly winds.

&&

.HYDROLOGY...
Issued at 412 AM MDT Mon Jun 10 2024

Remaining runoff from last night`s rain in Douglas county is
reaching the downstream reservoirs this morning and remaining
lowland flooding should be ending within the next few hours.

Elevated flows continue across the upper Colorado River basin and
additional rainfall could lead to further increase in the flows.
Remain cognizant of the dangers of these cold flows, and be aware
of any Flood Advisories and Warnings.

Winds aloft remain on the weaker side today, leading to slower
storm motions, but a bit faster than Sunday. There is a minor
threat for burn area flash flooding on Cameron Peak today. Periods
of heavy rain are possible in storms today which may lead to
localized flood impacts if a storm stays over a prone area long
enough.

Warmer and drier weather will follow, with the next threat of
heavy rain on Friday and Saturday. Snowmelt may peak on the
hottest days at the end of this week.

&&

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

&&

$$

UPDATE...Meier
SHORT TERM...Mensch
LONG TERM...Gimmestad
AVIATION...Meier
HYDROLOGY...Gimmestad/Mensch