404
FXUS65 KBOU 150154
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
754 PM MDT Mon Apr 14 2025

.KEY MESSAGES...

- Warmer temperatures expected Tuesday through midweek.

- Active weather pattern to end the week, starting with fire
  weather concerns Thursday, then potential for widespread
  precipitation Thursday night into Friday night. Mountain and
  foothills snow with potential travel impacts. Rain and snow on
  the plains, favoring the I-25 Corridor.

&&

.UPDATE...
Issued at 749 PM MDT Mon Apr 14 2025

It`s a quiet evening across the region, with a nearly cloudless
sunset for most of our CWA. Quiescent conditions are forecast
overnight tonight through most of Tuesday, and unsurprisingly
there were very few updates needed to the previous forecast grids.

&&

.SHORT TERM /Through Tuesday/...
Issued at 230 PM MDT Mon Apr 14 2025

Clouds have finally cleared out across the plains this afternoon,
with a patch still trying to burn off over the foothills. The
clearing skies have allowed for temperatures to warm to the mid
50s, with 30s still holding on underneath the lingering cloud
cover. Dry conditions will continue across the forecast area
through tonight and Tuesday morning. Clear skies will allow for
tonight`s overnight low temperatures to cool a few degrees over
last night, with widespread 20s expected across the forecast area.
As today`s WNW flow aloft turns westerly, compressional warming
will aid in keeping areas along the base of the foothills and
adjacent plains the warmest locations, where mid to upper 30s can
be expected.

For Tuesday, Colorado will be situated under broad upper-level
ridging, with 700 mb temperatures 5 to 12 deg C warmer than
today. Afternoon high temperatures will be roughly 8 to 13
degrees F above seasonal norms, with the plains seeing a return
to the 70s, and 50s and 60s for the foothills and mountain
valleys. By the afternoon, a shortwave is progged to traverse
through the broad ridge across the southern Rockies. Mid and
upper-level moisture will increase across the central mountains,
spreading north and east through the afternoon. Steepening lapse
rates and some weak QG ascent will create enough instability for
some scattered high based afternoon showers to develop, mainly for
the southern mountains and Palmer Divide, with a slight chance
for the southern foothills and adjacent plains into the evening.

&&

.LONG TERM /Tuesday night through Monday/...
Issued at 230 PM MDT Mon Apr 14 2025

Scattered diurnal showers over the mountains mainly south of I-70
and Palmer Divide area will come to an end Tuesday evening as the
airmass stabilizes. We could see a few sprinkles into Denver, but
that`s about as far as they`d make it.

Wednesday will see a continuation of the warming trend as the
upper level ridge builds across the Central Rockies and High
Plains. There`s good agreement that high temperatures will reach
the upper 70s to near 80F over the plains. Again, isolated to
scattered high based late day showers will be possible, this time
favoring mountains and plains north of I-70 where slightly better
moisture and weak instability is expected.

The main concern for this forecast period then shifts toward
Thursday through Saturday. Thursday will be a transition day as
the next upper level trough digs into the Great Basin from the
Northern Rockies. Southwest flow aloft increases ahead of that,
so that means we`ll have to watch for critical fire weather
conditions. That`s where quite a bit of uncertainty enters the
picture, as a cold front is expected to push across the plains,
but there is considerable uncertainty as to when it actually does.
At this time, we think the models are generally a bit slow, so
expectations would favor a frontal push during the early to mid
afternoon. Thus, the highest likelihood of fire weather concerns
will be areas to the south, or last affected by the front from
Park County and the southern Foothills across the Palmer Divide
area. Areas further north closer to the northern border would be
more likely to see influences from the cold front and less
concerning fire weather conditions.

Behind the front, we`ll see shallow upslope develop, although the
upslope strength will be determined by how far south and west the
upper level trough develops. That`s where there`s considerable
uncertainty in the evolution of the upper low, with some models
including the AIFS and ICON taking it into the depths of the
Mojave Desert, while the GFS/GEFS and even the operational 12Z EC
closer to the UT/AZ border and 4 Corners region. Those eastern
solutions would certainly be more favorable for more significant
precipitation in/near the Front Range due to stronger upslope,
while the farther south/west would mean much lighter
precipitation. Whatever the case, almost all models would suggest
temperatures cold enough for mostly snow at some point late
Thursday night - Friday. Therefore, we trimmed down forecast
temperatures a little closer to raw model guidance for this
period. Meanwhile, the eastern plains will likely only see light
if any precipitation, given the track of this next storm and lack
of large scale synoptic or meaningful orographic support.

Despite the differences in the model locations for the Friday -
Friday night time frame, there is reasonable ensemble agreement
the upper trough ejects east into the Central Plains by Sunday,
taking most precipitation with it. Temperatures will moderate
starting Sunday through early next week, but it`s springtime in
the Rockies and an upper level trough/shortwaves are still around.
Therefore, we`ll still have a chance/slight chance of showers
each day until we can define the timing of any shortwaves a bit
more.

&&

.AVIATION /00Z TAFS through 00Z Wednesday/...
Issued at 542 PM MDT Mon Apr 14 2025

VFR through the TAF period. Light winds this evening will
gradually turn back towards the southeast, then settle on
drainage later tonight. Winds will eventually turn back to the
northeast/east tomorrow afternoon.

There should be increasing mid/high cloud cover tomorrow
afternoon, with perhaps a few high based showers near the Palmer
Divide. Can`t rule out some gusty winds at the terminals, with
the best chance of seeing -SHRA/variable gusts by APA with lower
chances at DEN/BJC.

&&

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

&&

$$

UPDATE...Hiris
SHORT TERM...Bonner
LONG TERM...Barjenbruch
AVIATION...Hiris

NWS BOU Office Area Forecast Discussion