985
FXUS65 KBOU 302102
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
302 PM MDT Thu Jul 30 2026

.KEY MESSAGES...

- Isolated showers and thunderstorms this afternoon, with a few
  strong-to-severe storms possible, mainly for the eastern plains.

- Another round of isolated thunderstorms possible Friday
  afternoon.

- Heat returns by the weekend, with temperatures possibly reaching
  up to 100 F on Sunday and Monday.


&&

.DISCUSSION /Through Thursday/...
Issued at 259 PM MDT Thu Jul 30 2026

The dissolution of the upper level ridge previously centered over
the high plains brought west to northwesterly winds aloft this
morning and interrupted the flow of monsoonal moisture until further
notice. However, precipitable water (PW) values remain around 1.0"
east of the Colorado mountains, which is still around the 70th-85th
percentile of climatology. At the same time, surface winds have
remained more northwesterly than expected, in part due to slight
downsloping, which has caused dewpoints to remain in the low to
mid 50s across the Denver metro and east Colorado plains. Any
storms that develop over the foothills and Palmer Divide will
likely be high-based, with the primary hazard being gusty outflows
up to 45 mph. An isolated strong thunderstorm cannot be ruled out
over the eastern Colorado plains, particularly in the late
afternoon, where slightly better moisture (1.2"-1.4" PWs) and
instability (MLCAPE 700-1000 J/kg) will reside. Unlike yesterday
afternoon, we expect storm motion to be much faster due to cloud
layer mean winds around 30KT.

For tomorrow, there is quite a bit of uncertainty regarding the
shower and thunderstorm potential due to the expected shortwave and
frontal passage in the early morning hours. On one hand, the
shortwave will bring additional lift. However, some high-res model
guidance is suggesting the development of low stratus, which would
inhibit convective initiation until the late afternoon or early
evening. If low clouds are able to clear out early enough and
surface winds become south or southeasterly, there will be a decent
chance (20%-30%) for a few isolated strong to severe thunderstorms
to develop. The primary hazard with any storms that develop will be
gusty outflows up to 40-50 mph. While locally heavy rainfall may
occur with the strongest storms, we are not overly concerned
about flash flooding due to the fast storm motions in place, and
given PW values down to about average for the time of year
(~0.75").

The upper level ridge will redevelop over the Four Corners this
Saturday and Sunday and give way to another weekend of scorching hot
temperatures, likely reaching 100 over eastern plains and parts of
the Denver metro for Sunday and Monday. Heat advisory criteria will
likely be met on either or both days.

Global models suggest an amplified upper level trough tracking
through northern Montana late Monday night and with it a moderately
strong cold front for the time of year. It is difficult to tell at
this point whether enough moisture for significant rainfall to occur
will accompany this front. At the very least, this front should
bring a day of heat relief on Tuesday with afternoon temperatures
likely only reaching the mid to upper 80s over the low elevations. Daily
chances for afternoon showers and storms return on Wednesday,
with long-range ensembles hinting at another round of monsoonal
moisture on the way for late next week and into the weekend.


&&

.AVIATION /18Z TAFS through 18Z Friday/...
Issued at 1134 AM MDT Thu Jul 30 2026

TDEN and KTFG velocity data show a channel of stronger WNWerly
winds stretching from BJC towards DEN. There is also a weak
boundary off to the north that should eventually help turn winds
to a steadier NW/NNW direction by about 20-21z. There is still at
least a chance of an isolated shower or storm this afternoon, but
given the deeper mixing across the Denver area so far,
instability will be rather weak. The main threat would be for
gusty outflow winds from any weak SHRA/TSRA with low chances of
any direct TS impacts at any terminal.

Tonight`s forecast is a bit more complicated, as a weak frontal
push is expected to arrive sometime around 06z. Most of the 12z
guidance so far offers little consistency in how strong this front
is (and as a result, how much moisture will arrive with it). The
general model consensus has a push of weak NNE winds with light
and variable winds closer to 12z on Friday. However, a few models
are rather bullish with the stratus potential overnight into
Friday AM. Have introduced a few hours of FEW010 at DEN/BJC for
now but would like to see how the front looks later this afternoon
before committing to any sort of lower CIGS.

There is better agreement in broad northeasterly flow by Friday.
Any convective potential will be largely dominated by the
previously discussed post-frontal moisture, but overall convective
coverage looks limited.

&&

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

&&

$$

DISCUSSION...AA
AVIATION...Hiris

NWS BOU Office Area Forecast Discussion