847
FXUS65 KBOU 290248
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
848 PM MDT Fri Jun 28 2024

.KEY MESSAGES...

- Scattered showers and storms could produce gusty conditions
  until early evening across the mountains to the plains. Expect
  wind gusts up to 50 mph. A severe storm cannot be ruled for the
  northeast corner which could produce small hail and wind gusts
  up to 60 mph.

- Isolated to scattered thunderstorms this weekend, with a few
  strong to severe storms possible Sunday afternoon and evening.

- Drier conditions possible by mid next week.

&&

.UPDATE...
Issued at 838 PM MDT Fri Jun 28 2024

Scattered showers and storms are currently ongoing across our CWA.
The peak intensity of the storms has decreased in the last hour or
so due to the lack of daytime heating. For the rest of the
evening, gusty winds will be the primary threat as winds could
reach 50 mph beneath dying showers. The PoPs were increased
through 11pm to get a mention of showers and storms in the
forecast. Forecast models and observations would indicate storms
will last a bit longer than originally expected. Otherwise, the
forecast remains on track with a cold front moving through the
eastern plains after midnight.

&&

.SHORT TERM /Through Saturday/...
Issued at 242 PM MDT Fri Jun 28 2024

CSU TIME SLICE sounding this afternoon displays weak shear and
MLCAPE values near 400-500 J/kg. With large DCAPE values shown on
CSU and ACARS soundings between 1000-1400 J/kg, any delayed
convection that arrives will bring strong wind gusts up to 50 mph.
CAMs favor scattered showers and storms rolling off the foothills
into the plains between 4-8 PM MDT. In terms of severe chances, an
isolated storm or two could produce wind gusts up to 60 mph and
small hail but given our late warm up and dry soundings, the chances
are low. Partly cloudy skies clear tonight. A few hours after
midnight tonight, a cold front will sweep through the CWA. Northerly
winds could produce wind gusts up to 20-30 mph briefly overnight.
700mb temperatures drop between 9-12C as much cooler air
approaches from the north Saturday morning. Cold air advection
will lead to a afternoon temperatures slightly below normal
conditions. Expect low to mid 80s for the urban corridor and
plains; low 60s to mid 70s for the mountains, foothills and
valleys. Diurnal thunderstorms will develop once more mainly
south of I-70 for areas such as South Park, Douglas, Elbert and
Lincoln counties. These areas line up with SPC marginal risk of
severe storms. With decent conditions for development such as
steep mid- level rates between 7-8C/km, 25-30kt shear, and weak
instability, it is possible a few storms could produce small hail,
and gusty winds.

&&

.LONG TERM /Saturday night through Friday/...
Issued at 242 PM MDT Fri Jun 28 2024

Weak ridging aloft and subtle height rises increase mid-level
temperatures on Sunday. This will support a rebound in temperatures
back into the lower 90s across a good portion of the plains and
urban corridor. MLCAPE values are marginal (< 1000 J/kg) with normal
to slightly above normal moisture and weak ascent. The higher
chances will more likely be in the mountains/foothills, Park County,
and the Palmer Divide areas where the higher instability/moisture
is. Model soundings across the east plains show sufficient
instability, but are weakly capped, which may also thunderstorm
development/coverage. Shear will be sufficient to support a few
organized strong to severe thunderstorms.

Early next week to mid-week, the main axis of an upper level
trough positions to the west of Colorado. An upper jet situates to
the north, putting CO in an area of weak ascent. Moisture ranges
from above to just above average. As a result, each day will
feature afternoon/evening chances for scattered, lower coverage
thunderstorms with the higher chances for the higher terrain and
Palmer Divide. Towards the end of the week, moisture gradually
decreases as an upper ridge slowly pushes eastward across the
western CONUS.

&&

.AVIATION /00Z TAFS through 00Z Saturday/...
Issued at 620 PM MDT Fri Jun 28 2024

Scattered showers and storms have formed this afternoon mainly
over the higher terrain. Considering the hot and dry airmass over
the terminals, these showers and storms are unlikely to have a
direct impact. However, as they produce virga, strong winds will
form with gusts around 40 knots possible. Given the strong
instability and high moisture across the western slope of
Colorado, showers and storms will continue well into the evening.
This means that gusty winds could continue beyond the 04Z end
time currently in the TAF although the majority of showers should
come to an end around midnight.

A cold front will move through the terminals around 07-09Z
Saturday. There will be gusty north winds behind this front that
could reach 30 knots. By 11Z, there will be better moisture that
arrives from the north and with the northeast, upslope winds,
stratus could form. The confidence in not very high in stratus
forming but since it is slightly greater than 50%, a broken layer
around 3 kft was included.

Winds will be out of the southeast for most of the day tomorrow.
While conditions are much more stable than previous days, a few
light showers may form over the Denver metro. These could produce
wind gusts up to 35 knots in the late afternoon/evening.

&&

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

&&

$$

UPDATE...Danielson
SHORT TERM...AD
LONG TERM...Mensch
AVIATION...Danielson