461
FXUS65 KBOU 281809
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
1209 PM MDT Fri Jun 28 2024

.KEY MESSAGES...

- Slight risk of severe storms across NE Colorado this afternoon,
  with large hail and strong winds the main hazards.

- Gusty conditions likely at times for almost all areas this
  afternoon.

- 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 1021 AM MDT Fri Jun 28 2024

With high clouds in place limiting our warm up this morning, it is
possible the threat of severe storms for the eastern plains is
much lower. In fact, with DCAPE values approaching 1200 J/kg,
storms will likely produce more wind than rain. Scattered storms
are still expected late this afternoon producing wind gusts up to
50 mph. It seems the greatest instability sits along and above the
I-76 corridor thus it is possible a storm could produce small
hail, lightning and wind gusts up 60 mph in this area until this
evening.

&&

.SHORT TERM /Through tonight/...
Issued at 140 AM MDT Fri Jun 28 2024

Relatively quiet early this morning now that most of the
precipitation has dissipated or moved east of us. Locally breezy
conditions still exist extending across the northern half of our
forecast area, and are keeping nocturnal temperatures quite
elevated - still hovering around 80 degrees in Phillips County as
of 2AM! Meanwhile, a secondary wave of moisture is evident in
water vapor imagery across the Western Slope along the leading
edge of the approaching shortwave, with a disorganized cluster of
showers and thunderstorms moving eastward. Although some weakening
is likely as they near our northern mountains, it`s worth
maintaining at least a chance (30%) of showers across our higher
elevations through around or a little past sunrise. A weak front
is also descending into our northern plains currently and will
bring a period of lighter northeasterly winds to much of the
plains this morning. It could knock a couple degrees off our
temperatures today, but compressional warming will kick in later
today and help reduce its effects. We should still climb to near
or slightly above 90F across the I-25 corridor and plains.

Moisture today will be more limited, with peak PWAT values closer
to 0.7-0.8" for the urban corridor and around 1" in the eastern
plains. With enhanced drying downslope winds this afternoon, and
marginal instability, suspect that storms initiating in the high
country early afternoon will struggle to hold together along the
I-25 corridor. Have adjusted PoPs downward slightly to better
reflect this. MLCAPE will be somewhat more favorable from about
Fort Morgan northeastward (anywhere between 300-900 J/Kg), and
robust deep-layer shear in the 35-45 kt range should support a
few stronger to severe storms late afternoon and early evening in
the northeast plains. It`s worth emphasizing that free air winds
will be stronger today and, with continued dry conditions near the
surface and DCAPE values in excess of 1,000 J/Kg, it would be no
surprise to see somewhat of a repeat of yesterday`s strong
convective winds across our lower elevations, which could locally
reach or exceed 50-60 mph. Widespread fire weather concerns are
not expected given humidity levels mostly above 15-20%, but brief
periods of elevated/near critical conditions will be possible
below ~8,000 ft if any particularly strong outflows coincide with
areas of low humidity.

A secondary cold front will then descend into the plains tonight,
ushering in a cooler night and potentially even some low-level
cloud cover east of the Front Range, setting the stage for more
seasonable temperatures on Saturday.

&&

.LONG TERM /Saturday through Thursday/...
Issued at 140 AM MDT Fri Jun 28 2024

As mentioned in the short term AFD, temperatures should be cooler
on Saturday behind the cold front. Afternoon highs will likely
remain in the low to mid 80s across the plains. Deeper moisture
will gradually advect into the region during the day as it wraps
around the southwestern edge of an upper level ridge located over
the southern Great Plains. There should be isolated to scattered
thunderstorm development, mainly across the Front Range/Foothills
during the afternoon hours, with less coverage across the plains
where the airmass is fairly stable.

The cooler weather will be short-lived, as warmer mid-level
temperatures advect back into the region by Sunday. Some question
as to how much cloud cover there will be in the afternoon hours,
but models generally support a return to low/mid 90s. With
moisture lingering across the region, forecast soundings do show a
better convective environment with modest CAPE along with good
deep-layer shear. Still don`t think overall storm coverage will be
too widespread, but a couple of strong to severe storms would be
possible.

Storm chances will continue on Monday and Tuesday afternoon, with
near normal to above normal precipitable water values in place.
Temperatures should remain pretty warm with highs near or above
90F. A gradual drying trend expected for the latter half of the
week, as a strong upper ridge begins to build off the Pacific
coast.

&&

.AVIATION /18Z TAFS through 18Z Saturday/...
Issued at 1141 AM MDT Fri Jun 28 2024

VFR conditions are possible through the TAF period. There is a
chance of low clouds Saturday morning near 2-4k ft for all
terminals. This afternoon, scattered showers and storms will bring
wind gusts up to 35kts until 02Z. Typical drainage winds are
unlikely as a cold front will arrive between 07-0Z bringing
northerly winds between 12-15kts. By Saturday morning, weak
easterly winds are possible.

&&

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

&&

$$

UPDATE...AD
SHORT TERM...Rodriguez
LONG TERM...Hiris
AVIATION...AD