347
FXUS65 KBOU 241649
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
1049 AM MDT Mon Mar 24 2025

.KEY MESSAGES...

- Strong winds will impact the mountains, foothills and adjacent
  lower elevations into early this morning with gusts 55-70 mph
  expected.

- Near-critical fire weather conditions will exist across the
  plains today due to mild, dry, and breezy conditions.

- Mainly dry weather expected Tuesday through Thursday, with near
  record high temperatures likely by Thursday.

- Cooler with a chance of precipitation Friday night through
  Saturday night. Chance of a more significant storm still seems
  rather limited.

&&

.UPDATE...
Issued at 1033 AM MDT Mon Mar 24 2025

The mountain wave which brought strong winds to the foothills and
adjacent plains has weakened this morning with gusts between 40-55
mph in Boulder and Jefferson Counties now. High level moisture
along with some lee wave enhancement has created expansive cirrus
clouds over our area. This may keep the mixing in the low levels
down today and winds will be slightly less gusty as a result.
There was much consideration for a Red Flag Warning but with this
high cloud cover, minimum relative humidity expected to stay above
17-22%, and slightly less gusty winds than feared, no highlight
will be issued. Some adjustments were made to the winds and high
temperatures today but the rest of the forecast is on track.

&&

.SHORT TERM /Through Tonight/...
Issued at 207 AM MDT Mon Mar 24 2025

Light radar returns are evident across our northern mountains and
northeast plains early this morning as a weak shortwave clips the
state with a jet max to our north. Any elevated showers over the
plains (which shouldn`t be producing much more than a sprinkle)
will dissipate by sunrise, whilst shallow moisture trapped below
the 600mb level will still succeed in producing light orographic
snow showers mainly for the park and Medicine Bow Ranges through
this morning. Most of the snow accumulation will remain over the
higher peaks, with no travel impacts expected.

Also peaking this morning will be our cross-barrier flow, reaching
around 50 kts at mountaintop with modest stable and critical
layers in place over the next several hours. It`s thus no surprise
that we`re beginning to see stronger gusts near 70 mph emerge in
our typical wind-prone mountain and foothills sites. The mountain
wave will gradually break and dissipate through the day and, in so
doing, breezy winds will spread into the lower elevations. The
strongest winds will be focused near the base of the foothills
(e.g. Rocky Flats) in addition to our northern plains extending
off the Cheyenne Ridge, where gusts 35-50 mph can be expected.

Sky cover should be somewhat reduced for the lower elevations
today, although wave clouds will be more persistent along/west of
I-25. With rising heights, increased subsidence and downslope
flow, highs will climb into the lower 70`s for most plains and
urban corridor cities, with 40`s and 50`s for mountain communities.
Humidity values generally near and above 20% will help buffer the
severity of fire weather conditions, but the gustier locations
will still see near-critical conditions this afternoon.

&&

.LONG TERM /Tuesday through Sunday/...
Issued at 207 AM MDT Mon Mar 24 2025

A weak backdoor cool front will support slight cooling of 2-3
degrees across most of the plains for Tuesday. Much lighter winds
will prevail across the entire area with lighter gradients and
flow aloft.

Wednesday will resume the warmup and this warming trend will
continue through Thursday as the upper level ridge axis shifts
east across the Central Rockies. As discussed previously, we`ll
see high temperatures warm accordingly, with potential record
highs for Thursday (Denver`s record is 78 set in 1988, Fort
Collins is 80 set in 1895). Dry weather will persist, although
with strong diurnal heating can`t rule out an isolated light
afternoon shower or two in the mountains.

Friday is almost certainly shaping up to be another warm day,
with slight but continued slowing in the approach of the next
upper level trough. That said, we should still shave a few
degrees off Thursday`s "heat" due to increasing cloud cover and
potential for an initial cool front to drop across the plains.

Now shifting our focus to the next incoming storm system;
Ensembles haven`t shown much of a significant trend over the last
24 hours, outside of slowing it down a bit. There is still
considerable uncertainty in the track and intensity of the storm,
but only about 10% show a significant spring storm/heavy
precipitation event - with those colder runs also showing more
potential for accumulating snow in the lower elevations. It was
interesting to see the 00Z operational GFS come in as one of the
colder, heavier solutions, but this also shows the value of
ensemble forecasting as the average solution is still farther
north and more progressive. While yes, the GFS could verify, it`s
worth noting at this time there`s only about a 10% chance of that
to occur. However, if the system continues to slow, then those
odds would increase. We just haven`t seen a meaningful trend
toward a stronger and more impactful storm at this point,
including the latest ECMWF and EPS guidance.

At least the majority of guidance points to light to moderate
precipitation amounts, with ensembles averaging about 0.3 to 0.4
inch of total liquid across the plains and I-25 Corridor, and a
couple tenths more than that in the high country. The vast
majority of that would translate to several inches of snow for the
high country, but likely the majority falls in the form of rain
for the I-25 Corridor and plains. As per slowing guidance, the
highest chances for precipitation will be from Friday night
through Saturday night, but could linger a bit longer than that
per slowing trends.

&&

.AVIATION /12Z TAFS through 12Z Tuesday/...
Issued at 530 AM MDT Mon Mar 24 2025

Strong mountain wave is resulting in very strong winds with gusts
greater than 50 kts in/next to the base of the foothills near
Boulder. Gusty winds have spread toward KDEN, just at less
magnitude and closer to 25 kts. There may be a little lull yet
this morning, before stronger WNW develop 16Z-18Z with gusts 25-30
kts fairly common through 00Z. Then winds gradually weaken with
the loss of daytime heating, and should gradually turn more
west/southwest through the night. Weak backdoor cold front should
result in an anticyclone by 15Z Tuesday morning for southeasterly
winds. KBJC will see more impacts from mountain wave this morning,
with a shot of stronger gusts into the 45 kt range likely (60-70%
probability), so added that as a TEMPO group there til 14Z. Then
mountain wave should continue to break down with patterns
following more closely to KDEN. VFR will persist.

&&

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

&&

$$

UPDATE...Danielson
SHORT TERM...Rodriguez
LONG TERM...Barjenbruch
AVIATION...Barjenbruch

NWS BOU Office Area Forecast Discussion