751
FXUS65 KBOU 041639
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
1039 AM MDT Thu Jul 4 2024

.KEY MESSAGES...

- Quiet weather for the 4th of July, with just a weak stray shower
  or two this evening

- Critical fire weather conditions across Park County this
  afternoon

- 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 1027 AM MDT Thu Jul 4 2024

Cooler start to the day today thanks to the passage of a cold
front last evening. Temperatures earlier this morning can even be
classified as "chilly" in the mountains/valleys with 30s around.
Satellite shows a clear picture this morning, blue skies on this
Fourth of July. Clouds develop this afternoon. There is a low
chance of a stray shower or storm this afternoon/evening in the
foothills, northern Larimer and Weld, and the Palmer Divide. No
updates needed to the previous forecast.


&&

.SHORT TERM /Through tonight/...
Issued at 249 AM MDT Thu Jul 4 2024

Today`s forecast features quiet weather for the first time in
several days, much to the relief of this tired midnight shift
forecaster.

The northeast plains are off to a cool start this (early) morning.
The post-frontal airmass did have just enough moisture for some
stratus across the southwestern Denver metro, but low cloud cover
is slowly diminishing per the GOES Nighttime Microphysics RGB. We
should have mostly clear skies by sunrise, and mostly sunny
conditions will continue through most of the day today.

High temperatures today should remain on the cool side, with upper
70s to low 80s expected across most of the plains. We`ll hold on
to some modest surface moisture, and mid-level moisture is also
expected to increase slightly during the afternoon and evening
hours. However, there`s very little instability to work with and
moisture overall is still expected to be below normal across the
region. Only an isolated shower or two is forecast this afternoon
and evening, primarily over the Front Range Foothills where
surface convergence is maximized. Even if these showers form, they
aren`t expected to be impactful with very brief/light rain and
perhaps briefly gusty winds. A few elevated showers are also
possible overnight as modest instability develops across the
plains, but models are not very enthused with this potential.

The main story of the day will be elevated to critical fire
weather conditions across the high country. See the Fire Wx
section of the AFD for additional details.

&&

.LONG TERM /Friday through Wednesday/...
Issued at 249 AM MDT Thu Jul 4 2024

Friday will be another gorgeous weather day as a weak shortwave
trough will move through during the morning hours. This may create a
few morning showers across the northern plains but the majority of
the area will be dry. By the afternoon, the NVA behind the departing
trough will keep any light showers that form limited in coverage and
intensity.

By Saturday, the flow aloft will turn more westerly ahead of a
shortwave trough that will arrive late Saturday night. The more
westerly flow will lead to downslope winds and with 700 mb
temperatures around 17 C, highs will likely reach the upper 80s to
low 90s across the plains.

The shortwave trough will continue to move across Colorado Sunday as
a cold front moves through the eastern plains. This front will have
better moisture behind it and with the QG ascent from the trough,
there will be scattered showers and storms that form mainly in the
afternoon. The southern foothills and Palmer Divide will be favored
for storms due to the northeast low levels winds enhancing upslope
flow there.

The shortwave trough will move past our forecast area on Monday as
slight ridging aloft builds in. This will lead to another gorgeous
day as temperatures will remain below normal with plenty of
sunshine.

An upper level ridge over the west coast of the US will begin moving
eastward by the middle of next week. This ridge is already producing
an expansive heat wave and it will have a lot of hot air associated
with it. The good news is that it will take a while for this ridge
to reach Colorado and the global ensembles seemly delay it slightly
each run. The bad news is that the slow-moving nature of the ridge
will only be able to delay the inevitable for so long. There will
eventually be a heat wave in Colorado and ensembles favor that
beginning either on Thursday or Friday of next week.

&&

.AVIATION /12Z TAFS through 12Z Friday/...
Issued at 535 AM MDT Thu Jul 4 2024

VFR through the TAF period. Light and variable winds this morning
will gradually turn more northeasterly. Speeds should generally be
10kt or less. There may be a slight increase in mid/high cloud
cover this evening and perhaps a stray high-based shower or two
across the metro. Light winds will continue overnight tonight.

&&

.FIRE WEATHER...
Issued at 249 AM MDT Thu Jul 4 2024

Continued dry conditions are forecast tomorrow. Main concern is
Park County (Fire Zone 214) where critical fire weather conditions
are forecast. RH yesterday fell to around 15% in the afternoon in
that zone with some gusts to 30 mph. Forecast guidance is
generally a couple of percent lower with humidity and should fall
below 14% across most of the zone. Forecast soundings suggest PBL
top winds of roughly 25-30kt, and it seems reasonable to expect
gusts of 25-35 mph through the afternoon. Therefore we opted for a
Red Flag Warning this afternoon.

Across the rest of the forecast area, humidity values should
remain above critical thresholds. Elevated fire weather conditions
are likely across the higher elevations and portions of the plains
where breezy winds are forecast.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning until 7 PM MDT this evening for COZ214.

&&

$$

UPDATE...Mensch
SHORT TERM...Hiris
LONG TERM...Danielson
AVIATION...Hiris
FIRE WEATHER...Hiris