363
FXUS65 KBOU 301040
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
440 AM MDT Sat Aug 30 2025

.KEY MESSAGES...

- Scattered showers this morning, then another round of showers
  and thunderstorms this afternoon. Brief heavy rain, gusty winds, and
  small hail with the stronger storms.

- Warmer and drier Sunday through Tuesday.

&&

.UPDATE...
Issued at 437 AM MDT Sat Aug 30 2025

Forecast updated this morning for more showers and cloud cover,
and adjusting timing for a midday decrease in showers before the
afternoon convection. Little change to the rest of the forecast.

&&

.DISCUSSION /Through Friday/...
Issued at 256 PM MDT Fri Aug 29 2025

Water vapor imagery shows a shortwave trough over eastern Utah
with healthy mid-level moisture out ahead of it over western
Colorado. As this trough progresses eastward, it will provide
forcing to help generate storms across our CWA. Currently, there
has been enough clearing during peak heating to allow temperatures
to reach the low 80s on the plains. 1,000 j/kg of mixed-layer CAPE
has formed over Lincoln County and with moderate deep layer shear
ahead of the trough, strong to severe storms will form. A Severe
Thunderstorm Watch was issued for Lincoln County until 11pm.
Elsewhere, instability is lower with the ACARS soundings showing
almost no CAPE at the moment. For the majority of our CWA, there
will be widespread showers and weak thunderstorms late this
afternoon and through tonight.

The shortwave trough will move directly over northeast Colorado
late tonight. Some high resolution models indicate an area of
showers and storms producing very heavy rainfall over the
northeast corner of Colorado. The HREF indicates there is a chance
that over 3" of rain could occur by Akron and Sterling. There was
consideration for issuing a Flood Watch but it seems the limited
instability will make it tough for storms to be intense enough to
produce such heavy rainfall. Therefore, a Flood Watch was not
issued.

There will be northwest flow aloft during the day Saturday with
lingering low level moisture. There will be isolated showers and
storms throughout much of the day. There is very little threat of
strong to severe storms and the storms will be moving fast enough
to not be worried about heavy rain.

Colorado will be under northwest flow from Sunday through most of
next week. On Sunday and Monday, there will be subsident flow with
cool surface temperatures which will lead to dry conditions. A
shortwave trough within the northwest flow will near the area on
Tuesday and Wednesday. This will bring a chance for showers and
storms back into the forecast. Models differ greatly on the trough
placement during the end of next week. Overall, the long term
period will be cool with most days having highs in the 70s across
the plains.

&&

.AVIATION /12Z TAFS through 12Z Sunday/...
Issued at 437 AM MDT Sat Aug 30 2025

VFR conditions through tonight, but there will likely be periods
where ceilings in the 5000 to 6000 foot range may require
instrument approaches to KDEN at times. This is most likely with
rain showers in the area through about 15z, and then when there
are scattered showers and thunderstorms 21z-02z. Wind directions
are uncertain, but mostly a northerly component and under 10
knots. Variable gusts of 20 to 30 knots are possible (20% chance)
with the afternoon thunderstorms.

&&

.HYDROLOGY...
Issued at 256 PM MDT Fri Aug 29 2025

There is ample moisture across northeast Colorado and there will
be moderate forcing from a shortwave trough that will pass
through tonight. Heavy rainfall is possible from a cluster of
storms overnight tonight. There was consideration for issuing a
Flood Watch but there will be limited instability which will make
it tough for storms to be intense enough to produce such heavy
rainfall. Therefore, a Flood Watch was not issued. Nonetheless,
heavy rain and flooding is possible across the northeast corner.

&&

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

&&

$$

UPDATE...Gimmestad
DISCUSSION...Danielson
AVIATION...Gimmestad
HYDROLOGY...Danielson