432
FXUS65 KBOU 271739
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
1139 AM MDT Wed May 27 2026

.KEY MESSAGES...

- Expect widespread showers along with scattered thunderstorms
  today. A few spots may see locally heavy rainfall. There will be
  a limited risk of flash flooding in the burn scars.

- Thursday will scattered showers and thunderstorms over the far
  northeast plains and in and near the foothills.

- Thunderstorm chances will increase Friday through Saturday,
  across the plains, with a chance of severe thunderstorms
  especially on Saturday.

- Thunderstorm chances may decrease on Sunday over the plains.


&&

.DISCUSSION /Through Tuesday/...
Issued at 226 AM MDT Wed May 27 2026

A weak upper level low/disturbance is over nern New Mexico early
this morning and is fcst to lift slowly northeast into sern CO/swrn
KS by tonight.  This will result in decent coverage of showers and a
few tstms over sern portions of the CWA thru this aftn.  With SSE
low level flow in the mid levels, some of this activity will spread
NNW across the rest of the plains this aftn.  Although precipitable
water values will gradually increase up to an inch, SBCAPE is
generally 500 j/kg or less.  So the threat of stronger tstms appears
to be on the low side although some spots may still receive locally
heavy rain. Across the higher terrain, there will be a good chc of
showers and tstms as well this aftn.  Highs across the plains will
be in the mid 60`s to mid 70`s with the warmest readings over nrn
areas.

For tonight, the weak upper level low is fcst to slowly move NNE
across ern CO and wrn KS. As a result, this may lead to
additional shower activity along with a few tstms over the far ern
plains overnight.

On Thu, the ECMWF has the weak upper level low over nwrn KS by
midday while the GFS has it over far nern CO. With a blocking upper
level high over the nrn Plains, more than likely this feature will
move nearly do north.  In the vicinity of the weak upper level low
expect more showers thru at least midday over the far nern plains.
Further to the west from the I-25 Corridor into the mtns there will
be a chc of showers and tstms in the aftn.  Depending on how much
heating occurs SBCAPE may range from 500-800 j/kg.  Thus may see a
few stronger storms with locally heavy rainfall due to expected slow
movement.  As for highs, readings will stay in the 70`s over nern
CO.

Looking ahead to Fri, the blocking pattern of the nrn Plains will
shift eastward as a storm system moves into the Great Basin.  As a
result, the flow aloft will become more SSW (albeit weak) with SE
low level flow over the plains. Depending on how much heating occurs
SBCAPE may reach 1500 j/kg over the plains in the aftn. Although
Bulk Shear is rather weak still can`t rule out an isold svr storm or
two from late aftn thru the early evening hours.  Over the higher
terrain, there will be a chc of higher based showers and storms.
Meanwhile highs across the plains will range from the upper 70`s to
mid 80`s.

For Sat, the upper level low over the Great Basin will weaken and
move into wrn WY with the flow aloft becoming more SW across the
area.  At the sfc, a lee trough will extend from sern WY into sern
CO.  Across the plains, SBCAPE will range from 1500-2000 j/kg by
aftn with better Bulk Shear.  Thus will likely see a few svr storms,
across portions of the northeast plains in the aftn thru the early
evening hours.  Across the higher terrain, tstm chances will be on
the low side as drier air spreads across.

By Sun, the upper level low will be over the nrn Rockies with WSW
flow aloft across the area.  At the sfc, current data is showing
lower level moisture decreasing on Sun across the plains. If that
occurs then tstm chances would decrease.  Over the higher terrain
will keep in a slight chc of higher based showers and tstms.

Looking ahead to Mon, the upper level low will still be over Montana
with SW flow aloft across the area.  Depending on how much low level
moisture there is, over the plains, will determine tstm chances.
Across the higher terrain there will be a slight chc of higher based
showers and tstms.

&&

.AVIATION /18Z TAFS through 18Z Thursday/...
Issued at 1128 AM MDT Wed May 27 2026

MVFR or borderline MVFR conditions are expected to prevail today
with ample mid-level moisture streaming in from the southeast. We
don`t expect the low-to-mid-level deck to break until Thursday
midday. When it`s not raining, CIGS should remain between 050 and
070 through this evening. However, there are chances of several
rounds of showers after 20Z. For now handling with a PROB30 for
-TSRA from roughly 20Z through 02Z. If any -TSRA or slightly
 heavier rain showers move over the terminals, CIGS are likely to
 drop to 040. Winds for the most part should be out of the
 southeast all day into the evening, turning more southerly after
 03Z. At DEN gusts could exceed 20 kt. If -TSRA occur, which is a
 low probability, then there could be some brief gusty winds to
 30 kts but again, a PROB30 should cover that potential.

All showers should either diminish or move out of the area after
03Z. CAMs have CIGs dropping to 030 at the terminals sometime
after 08Z, but those should be short lived once the almost June
sun mixes those low clouds out. On Thursday a weak Denver Cyclone
is expected which will reliably result in weak NW winds at BJC,
VRB at APA, and eventually ESE early afternoon at DEN after light
out of the SSE through Thursday morning. Only at DEN could the
winds exceed 10-12 kts Thursday afternoon. The TAFs don`t have it
yet, but we`ll likely need to introduce a PROB30 for -TSRA after
19Z. Instability will be higher Thursday (but still weak for this
time of year) than today.

&&

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

&&

$$

DISCUSSION...RPK
AVIATION...Schlatter

NWS BOU Office Area Forecast Discussion