197
FXUS65 KBOU 252006
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
206 PM MDT Wed Sep 25 2024

.KEY MESSAGES...

- Warm and dry for the foreseeable future with very limited
  chances of precipitation. The mountains have a 10-20% chance of
  showers late Friday into Saturday.

- Record highs possible on Thursday and Sunday.

&&

.SHORT TERM /Through Thursday/...
Issued at 201 PM MDT Wed Sep 25 2024

Recent satellite imagery reveals clear skies abound across the
region, setting the stage for tranquil weather as high pressure
dominates the short term forecast period. Another calm and cool
night is on tap for the CWA tonight. Temperatures will be a few
degrees warmer than last night as northerly flow aloft transitions
to a more westerly component. Temperatures are forecast to be in the
upper 40s to mid 50s across the plains, with areas at the base of
the foothills likely remaining in the 60s. 30s and 40s are forecast
for the mountains and high valleys.

With an anomalous 500mb ridge overhead and a dry airmass in place,
the main highlight for tomorrow`s forecast will be whether Denver
reaches 90 degrees or not, possibly tying (or surpassing?) the
current record high of 90F, last set on this day in 2010. Conditions
look to have high potential as a shortwave passing to the north will
temporarily flatten the 500mb ridge centered over the southwest,
bringing a westerly downslope component that will nudge temperatures
upwards at the base of the Rockies through adiabatic warming. With
700mb temperatures between 15-17C expected, and dry conditions
keeping clear skies through the morning, it will be a hot day for
the end of September, whether records are met or not. Our persistent
clear skies will likely come to an end by tomorrow afternoon as some
moisture associated with the passing shortwave makes it under the
ridge and forecast cross sections indicate a few clouds forming over
the mountains by the afternoon.

&&

.LONG TERM /Thursday night through Wednesday/...
Issued at 201 PM MDT Wed Sep 25 2024

A weak and dry cold front Thursday night into early Friday morning
will leave very light easterly flow in its wake and provide for a
minor relaxation of temperatures as highs fall to the low 80`s
for the plains and urban corridor - still well above normal for
these dates. Some mid-level moisture may sustain scattered cloud
cover, mainly in the mountains, but it will be a very quiet
weather day all around.

The upper-level ridge will hold strong into the weekend, with
slight rises in geopotential heights during this period and large
scale subsidence forcing temperatures to rebound to near-record
territory by Sunday. Even the high country won`t escape the
warmth, with highs peaking 10-15 degrees above average. Increased
low-level southeasterly flow later on Sunday could lead to pockets
of near-critical fire weather conditions in the plains - arguably
the only weather concern of the next several days.

Come Monday, a sizable chunk of ensemble members push a cold
front southward into Colorado in association with a broad and
quite northerly upper-level trough, with substantial cooling and a
surge of breezier north winds, but a very slim (~10%) chance for
any precipitation. Agreement isn`t consistent however, and WPC
clusters indicate at least a 30-40% potential for the ridge to
hold in place with the trough taking a more northerly track well
into Canada. This would of course retain the anomalous warmth
another day. For now, NBM temperatures appear reasonable with
moderate cooling behind a front, depicting a blend of both
scenarios. With uncertainty in timing, these more seasonal
conditions could extend into Tuesday. Guidance actually shows
slightly better agreement looking farther ahead, with signs of
enhanced ridging once more as we move into Wednesday, bringing a
return to well above normal temperatures and keeping the region
dry.

&&

.AVIATION /18Z TAFS through 18Z Thursday/...
Issued at 1139 AM MDT Wed Sep 25 2024

VFR conditions expected through the TAF period. Light winds are
currently making the shift to ESE at all TAF sites where they
should remain through the afternoon. Drainage winds are expected
overnight before becoming light and variable Thursday morning.

&&

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

&&

$$

SHORT TERM...Bonner
LONG TERM...Rodriguez
AVIATION...Bonner