National Weather Service Forecast Discussion

000
FXUS65 KBOU 250228
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
828 PM MDT Fri Jun 24 2022

.UPDATE...
Issued at 823 PM MDT Fri Jun 24 2022

Upper level trof moving across Northern Colorado with drying
noted on water vapor moving into Northern Mountains. Appears most
of the activity has ended in the mountains and just left with
isolated rain showers across lower elevations, but a bit more
scattered coverage across Elbert and Lincoln counties. Only expect
brief light rain and gusty winds with the remainder of the
showers. Will adjust evening forecast for for local conditions
with continued drying from west to east through midnight.

Cold front up over Northern Wyoming which will push southward across
the northeast plains later tonight through early Saturday morning.
Expect gusty northeast winds developing and low clouds ushering in
behind the front towards dawn.

UPDATE Issued at 556 PM MDT Fri Jun 24 2022

Quick update as convective redevelopment occurring in areas north
of Denver across Boulder and Weld counties. Redevelopment of
storms due to approaching upper trof and jet streak over us now.
Have updated forecast to keep scattered showers and thunderstorms
ongoing through the evening hours, especially over locations North
of Denver and spreading northeast over the plains.

&&

.SHORT TERM...(This evening through Saturday)
Issued at 230 PM MDT Fri Jun 24 2022

Showers and storms are attempting to organize along the Front
Range this afternoon as the shortwave approaches. This area will
continue to push eastward across the plains through late
afternoon/early evening and that should take the main brunt of the
gusty outflow winds with it. Behind that, we still see some
lingering convection with weaker instability left behind, but
overall coverage and intensity of gusty outflow winds will be
diminishing. Stronger subsidence builds in behind the shortwave
by late this evening with clearing skies.

Then, a cold front will move across the plains with moist low
level upslope developing. This will bring areas of stratus to the
Front Range and Plains, and also set the stage for storms with
more significant rainfall later tomorrow. The airmass on the
plains will initially be quite stable with the cooler and cloudier
start to the day. Convective initiation will likely start in the
Park and Summit County areas where MLCAPE reaches 500-1000 J/kg
and CIN is eroded first, and then perhaps extending northward
across portions of the Front Range by early afternoon. Showers and
storms should become more widespread with persistent moist
upslope flow, and gradually spread eastward. Taking initial
stability into consideration, it could take most of the day
before we see showers/storms spread across the Denver metro area,
while the northeast plains will remain dry through the afternoon.

.LONG TERM...(Saturday night through Friday)
Issued at 230 PM MDT Fri Jun 24 2022

A cooler and unsettled pattern will continue Saturday night and
Sunday. Widespread showers and thunderstorms across the southern
Foothills and Palmer Divide are expected to increase in coverage
and spread into at least portions of the Denver metro overnight as
weak lift remains in place. Skinny CAPE profiles are evident on
BUFKIT soundings, especially along and south of I-70. Light
upslope flow and weak synoptic scale ascent from some mid-level
FGEN and a departing jet streak should be enough to get showers
into the metro, with the better odds of seeing a soaking rainfall
in Park County and the Palmer Divide. Much of this precipitation
will shift into southeast Colorado by Sunday morning. Model QPF
varies quite a bit, especially in the higher resolution guidance,
but 0.20-0.50 inches of rain seems like a decent bet along and
south of a line from Boulder to Denver, with locally higher totals
(up to an inch or two) in the southern Foothills, Park County,
and Palmer Divide.

Cool temperatures are expected to persist across the plains on
Sunday with highs in the upper 60s to low 70s and just an isolated
shower or two. Guidance shows better moisture returning to the
mountains - especially along/west of the divide - and another
round of showers and storms is likely across the high country.
Soundings only show modest instability, but PWATs near 0.5-0.8
inches and weak winds through the cloud layer cause some concern
for burn area flash flooding.

A gradual warming and drying trend is expected early next week.
Temperatures on Monday should bounce back into the 80s, with 90s
possible Tuesday through the rest of the week. Monsoonal moisture
should still be over the area Monday with scattered showers and
thunderstorms. Drier conditions are forecast Tuesday. Guidance
hints at ridging breaking down by mid/late next week while a
better surge of moisture also tries to creep into our area...
which would lead to an increase in thunderstorms. To quote the
midnight shift, "we`ll see".

&&

.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 825 PM MDT Fri Jun 24 2022

A few light showers still lingering around Denver but these will
be ending by 03z. Surface winds still are generally west to
northwest for now but should settle back to a southwest wind after
04z. Cold front expected into terminals around 11-12z with MVFR
cigs developing behind it with increasing low level moisture and
northeast upslope flow. Airmass will be stable much of the day but
may get some thunderstorms going after 23z.

&&

.HYDROLOGY...
Issued at 215 PM MDT Fri Jun 24 2022

The main threat of storms with locally heavy rain will be shifting
east of the mountains and out of the burn areas late this
afternoon and early evening. There would only be a limited threat
of flash flooding for the burn areas until ~6 pm.

On Saturday, moisture and higher Precipitable Water (PW) values
near 1" pool in/near the southern Front Range Foothills and Palmer
Divide. This is shaping up to be a potential locally heavy rain
event with warm cloud depth increasing to >5000 feet and skinny
CAPE profile supporting efficient rain processes. Deep
east/southeast flow pushes up into Park County and the southern
foothills. Overall, this setup really favors locations just to our
south in El Paso and Teller Counties (given the southeast flow),
but locally heavy rainfall totals of 1-2" will be possible in our
southern foothills and Park County through Saturday evening.
Fortunately, we don`t have any recent burn areas where the
heaviest rain should fall. However, we`ll still have a limited
flash flood threat for the rest of our burn areas as they will
likely be on the edge of more widespread and heavier convection.

A limited threat of burn area flash flooding will persist through
much of the week as we continue to see monsoonal moisture in the
area. Sunday`s threat should generally be west of the divide (East
Troublesome) where there should be enough instability for
thunderstorms in a moist environment. Storm motions will also be
relatively slow. Widely scattered thunderstorms should develop
Monday afternoon, with the overall environment is again marginally
supportive of heavy rain. Tuesday will be the driest day of the
week, before another push of monsoonal moisture arrives by the
second half of next week.

&&

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

$$

UPDATE...Entrekin
SHORT TERM...Barjenbruch
LONG TERM...Hiris
AVIATION...Entrekin
HYDROLOGY...Barjenbruch

NWS BOU Office Area Forecast Discussion