Lafayette, Colorado 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

686
FXUS65 KBOU 130534
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
1134 PM MDT Tue Aug 12 2025

.KEY MESSAGES...

- Hot weather Wednesday and Thursday.

- Elevated fire weather concerns Wednesday. Critical fire weather
  conditions possible Thursday in the mountains due to dry
  lightning.

- Moisture increases sufficiently for a chance of storms most
  areas Friday through the weekend.

&&

.DISCUSSION /Through Tuesday/...
Issued at 248 PM MDT Tue Aug 12 2025

Any isolated showers/weak storms that form over the mountains and
higher terrain will be dissipating with the loss of daytime
heating and instability early this evening. We`ll then see mostly
clear skies overnight, with temperatures settling to near normal
levels in the dry but warming airmass.

Wednesday we`ll turn up the heat, as the upper level ridge axis
and thermal ridge shift our way. High temperatures should reach
the mid to upper 90s over the plains and I-25 Corridor. We still
expect enough moisture and heating for isolated high based showers
and storms again during the afternoon and early evening. In fact,
we think we`ll reach convective temperatures so some virga with
gusty winds/microbursts reaching the I-25 Urban Corridor can be
expected. We`ve added some low chance of -TSRA with gusty winds
attributes for that.

Thursday features much of the same, with a slight further bump in
temperatures and enough for a couple spots on the plains to reach
100F. The record for Denver is 100F set in 1962, and we`ll be
getting close to that but most likely stay just shy around 98-99F
given latest thermal prognostications. Once again, most convection
will be high based due to deep mixing and dry low levels. At the
same time, mid/upper level moisture starts to increase, and that
should lead to higher weak shower/storm coverage. With that comes
concerns for dry lightning and new fire starts, see more in the
Fire Weather Discussion section below.

Ensembles show good agreement that moisture increases further for
Friday, so storms should be more numerous, a little stronger, and
produce more meaningful rainfall. It`s not terribly rich though
with precipitable water values just slightly above normal
(100-120%) over the mountains. The increased clouds and showers
should take a couple degrees off highs from Friday, but it will
still be above normal.

Ensembles are generally in agreement bringing a weak shortwave out
fo the southwest by sometime Saturday. This could bring one more
fairly active weather day but overall instability and moisture are
not terribly high. Then, some drying would still be anticipated in
the shortwaves wake, leading to less convective activity by early
next week. Ensemble averages show temperatures averaging just
above normal.

&&

.AVIATION /06Z TAFS through 06Z Thursday/...
Issued at 1131 PM MDT Tue Aug 12 2025

Winds will remain south thru 14Z and then become more WSW. By
19Z Wed winds will become light NNE and then turn more east
by 22Z. There is a slight chance of a few high based showers
by 22z which will produce gusty outflow winds up to 40 mph.
Ceilings will be high based and at or above 10000 ft. The shower
threat should end by 01z.

&&

.FIRE WEATHER...
Issued at 248 PM MDT Tue Aug 12 2025

On Wednesday, hot temperatures will bring low humidity of 15% or
less over the high mountain valleys, foothills, and I-25
Corridor and nearby adjacent plains. Winds will be relatively
light and under critical values, although Fire Weather Zones 211,
213, and 217 will see gusts of 20-25 mph and thus at least
elevated fire weather conditions there.

On Thursday, critical fire weather conditions will be possible due
to dry lightning. We expect an increase to scattered storm
coverage as upper level moisture increases slightly. However,
humidities will remain very low in the mountains due to very warm
and dry low levels. Thus, dry thunderstorms (storms with lightning
but little rainfall) will be possible, in addition to gusty
outflow winds.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
Fire Weather Watch from Thursday afternoon through Thursday
evening for COZ211>218.

&&

$$

DISCUSSION.....Barjenbruch
AVIATION...RPK
FIRE WEATHER...Barjenbruch