318
FXUS65 KBOU 050215
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
815 PM MDT Thu Jul 4 2024

.KEY MESSAGES...

- Chance of showers and a few storms over the northeast plains
  after midnight

- Somewhat cool and mainly dry conditions will persist Friday through
  early next week.

- Best chance for showers and storms in the extended will be
  Sunday.

&&

.UPDATE...
Issued at 813 PM MDT Thu Jul 4 2024

NW flow aloft is over the area with nrn CO on the srn end of an
upper level jet. This feaure was allowing for a few high based
showers mainly near the WY-NE border. Overnight, there appears to
be a disturbance embedded in the flow which will move across late
tonight into Fri morning. This feature may enhance shower
development along with a few storms over the nern plains after
midnight.

&&

.SHORT TERM /Through Friday/...
Issued at 228 PM MDT Thu Jul 4 2024

Current satellite imagery shows cumulus development mainly across
Jackson, Larimer, Weld, and Logan Counties this afternoon. SPC
mesoanalysis shows low instability (SBCAPE < 250 J/kg) across the
northern sector of northeast CO. A few weak showers are visible on
radar along the WY border in Weld County. As the afternoon
continues, expected more cumulus and shower development along the
northern tier and foothills. A stray storm is possible. Early
evening, the Palmer Divide may see a few showers as well. They will
likely be low in coverage and high-based. Brief gusty winds up to 30-
40 mph are possible if a more developed shower or a weak storm is
nearby. Overall, chances are less than < 15%.

Cooler night expected again tonight with lows in the 50s across the
lower elevations and 30s for high country. Can`t rule out a few
showers across the plains. Friday`s weather will be similar to
Thursday with fair weather with highs in the upper 70s to low 80s
for the plains and 50s and 60s for a good portion of the high
country. Most of the region will remain dry with the exception of a
low chance for the Palmer divide and southern foothills where there
is marginal instability.

&&

.LONG TERM /Friday night through Thursday/...
Issued at 228 PM MDT Thu Jul 4 2024

Upper level high over California and Nevada will continue to
bring a heat wave to the western states while northwest flow
ushers in "coolish" air over Colorado. For Friday night and
Saturday, an upper level trough passing northeast of Colorado may
bring showers and storms to the eastern plains late Friday night
and Saturday. Lower elevation may see a surge of northeast winds
from showers and storms over the Central Plains. If this pushes
through, this may keep highs from reaching the lower 90s over
northeast Colorado. If not, a westerly downslope flow is expected
to push highs into the lower 90s over northeast Colorado. Elevated
fire weather conditions will be possible over the higher terrain
where westerly winds will be a little stronger.

Cold front pushes south through the area Saturday night. Behind
it, we could see showers/storms, mainly over the eastern plains
where the better and deeper moisture will reside. This will lead
to a cool day Sunday with temperatures expected only to be in the
mid to upper 70s over northeast Colorado. Models are in pretty
good agreement showing an upper level trough will produce at least
scattered showers and thunderstorms Sunday afternoon/evening.
Soundings show the airmass is well capped to begin the day, so
something watch as this system nears. Cooling aloft and lift as
the trough nears should be enough to overcome the cap. For Monday,
subsidence behind the trough should result in a mostly dry day.
Temperatures start to warm, but highs are expected to stay below
normal with readings in the lower to mid 80s.

For Tuesday through Thursday, the upper level high creeps closer
to Colorado. Even though the high is still west of the state (over
Utah) and flow aloft is northerly, warmer air will be filtering
into the area. The GFS model remains quicker with the eastward
progression of the ridge and thus a day early with 90 degree heat
returning to the area. Expect highs to be near 90F Wednesday over
northeast Colorado. If we don`t hit 90F Wednesday, we will very
likely hit it Thursday as the ridge crawls eastward. Chances for
showers and thunderstorms will be low with no well defined system
or plume of moisture headed for Colorado. Could see a weak trough
in the northerly flow aloft bring a round or two of
isolated/scattered convection, so will have low PoPs (10-30) in
for the afternoon/evening hours.

&&

.AVIATION /00Z TAFS through 00Z Friday/...
Issued at 511 PM MDT Thu Jul 4 2024

Winds will stay mainly from the east thru late evening and then
become more north by 09z. On Fri, winds will be generally
northeast from late morning thru the aftn. VFR conditions expected
thru the period.

&&

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

&&

$$

UPDATE...RPK
SHORT TERM...Mensch
LONG TERM...Meier
AVIATION...RPK