-- Discussion containing changed information from previous version are highlighted. --
089
FXUS65 KBOU 031109
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
509 AM MDT Thu Jul 3 2025

.KEY MESSAGES...

- Increased thunderstorm activity over the mountains this
  afternoon with a slight chance of thunderstorms over the plains
  tonight.

- A chance of thunderstorms and normal temperatures are expected
  for the Fourth of July and Independence Day weekend.

&&

.UPDATE...
Issued at 245 AM MDT Thu Jul 3 2025

Moisture will increase over the higher terrain today ahead of a
weak upper level trough. Will see a gradual increase in
shower/tstm development, over the higher terrain, by early to mid
aftn which will continue thru the early evening hours. Across the
plains it will be dry and windy thru the aftn.

For late tonight into Fri, the weak upper level trough will move
across the area.  This feature will be over the mtns by 12z and then
move across the far nern plains by 18z.  Latest data suggests there
could be scattered showers and a few tstms in the morning across the
plains with some potential for a few stronger storms over the far
nern plains thru 18z.

Once this feature exits the area, its not clear how much
redevelopment there will be in the aftn into the early evening
hours.  There will be some mid level cooling in the aftn which could
lead to some additional tstms behind the main trough but overall
confidence is low at this point.

&&

.DISCUSSION /Through Wednesday/...
Issued at 238 PM MDT Wed Jul 2 2025

Few changes to the forecast at this time, as weak convection
should be limited to the mountains today. South to southeast
steering winds should preclude anything drifting further east.
With CAPEs looking to be in the 400-800 J/kg range, threats should
be limited to subsevere gusty winds.

Mid level moisture will increase from the southwest on Thursday,
while low level moisture will increase from the southeast. This
will set the stage for a more active day, but the plains airmass
will likely remain capped most of the day. The strength of the
convection will still be limited by warm air aloft, but the
mountains should eventually see pretty good coverage of weak
convection, with a threat of gusty winds. On the plains, the storm
threat will likely wait until some combination of outflow from the
mountains, or more likely the shortwave aloft that will bring some
lift in the evening, and possibly lingering overnight in the
northeast corner. There could be up to 1000 J/kg of CAPE for the
plains in the evening, but with little shear, the threats are
mainly subsevere wind gusts, and possibly localized heavy rain if
there gets to be some organization to slow moving storms.

The timing of the shortwave Thursday night sets up an interesting
pattern for the Fourth of July. We`ll likely have convection
exiting in the early morning hours, and drying northwest flow
aloft by afternoon. There will also be some cooling aloft though,
enough to allow for another round of convection in the slightly
cooler and drier airmass. We`re hanging on to scattered
afternoon/early evening PoPs, but if the drying is enough there
may be less activity or a quicker end. In any event, it doesn`t
look like a particularly active day in terms of coverage or
intensity.

For the weekend and beyond, there are just subtle day to day
changes as we`ll be under a mean ridge with a couple of shortwaves
moving over the top of it. There`s enough variety in the low and
mid level moisture in the models to make it hard to pin down
details, though there is some tendency towards a little more
thunderstorm activity Sunday and Monday and then warming and
drying after that as the mean ridge strengthens. Overall, fairly
typical early July weather with lower elevation highs mostly in
the lower to mid 90s for an extended period and some threat of
storms each day.

&&

.AVIATION /12Z TAFS through 12Z Friday/...
-- Changed Discussion --
Issued at 504 AM MDT Thu Jul 3 2025

Winds were light south early this morning and may go light and
variable by 14z. By 17z winds will be SE and stay that general
direction thru the aftn. By 03z winds will become more southerly.
Late tonight, sct showers may develop after 10z with ceilings
lowering to 8000 ft or so. Winds may become north or northwest
by 10z if showers do develop.
-- End Changed Discussion --

&&

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

&&

$$

UPDATE...RPK
DISCUSSION...Gimmestad
AVIATION...RPK