National Weather Service Forecast Discussion

000
FXUS65 KBOU 270544
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
1044 PM MST Fri Nov 26 2021


UPDATE Issued at 807 PM MST Fri Nov 26 2021

Mostly quiet weather continues across the region. A few of the
usual spots are still breezy this evening with a few gusts up to
40 mph noted. Winds should diminish over the next couple of hours
with quiet weather the rest of the night. A weak cold front is
still on track to reach the region late tonight/early Saturday
morning with highs only reaching the low/mid 50s across the
plains.

Have made some minor adjustments to the grids but otherwise the
previous forecast was on track.

&&

.SHORT TERM...(This evening through Saturday)
Issued at 232 PM MST Fri Nov 26 2021

A mostly sunny and mild afternoon over the region with temperatures
across the plains in the mid/upper 60s. Breezy conditions over the
eastern plains and foothills with gusts up to 30 mph. With RH
values in the teens to 20s, elevated fire danger will continue
this afternoon before humidity recovers tonight.

Friday night into Saturday morning, a weak shortwave trough passes
to the north of the area. No precipitation is expected with limited
moisture; however, a weak front is expected along with mid to upper
level clouds. Similar to the previous evening, downslope component
flow will keep temperatures warmer in the foothills and urban
corridor. Lows in the mid to upper 30s are likely in those areas
with areas further east being cooler in the 20s and low 30s.
Following a weak cold front, Saturday will be cooler and dry with
highs in the low 50s over the lower elevations and 30s/40s over
the higher terrain.

.LONG TERM...(Saturday night through Friday)
Issued at 232 PM MST Fri Nov 26 2021

We are hard pressed to find much hope for precipitation in the next
seven days.  In general it will be warm and dry into next week with
a cold front sometime on Tuesday.  The culprit for the warm and dry
conditions is a persistent ridge across the southwest US.  On Sunday
the broad ridge has an axis upstream and we are under weak northwest
flow. Weak downslope flow east of the Divide combined with 700 mb
temps around +4 degC will result in another warm and sunny day
across the area, with highs in the 60s across the plains and 40s
to low 50s in the mountain valleys. More of the same on Monday as
700 mb temps warm 1-2 degC and the downslope flow east of the
divide actually gets a little stronger. Temps should be in the
upper 60s across the plains and 50s in the mountain valleys.

Confidence is building in a decent cool down on Tuesday. A ~1030mb
surface high across the Dakotas should be in the wake of a Great
Lakes trough, which drives a cold front across the plains of
Colorado on Tuesday. There is a little cold air aloft as well so
the mountains will also see a slight cool down, with 700 mb temps
briefly dropping to 0 degC by later in the day. Gusty north winds
20G35-ish are likely across the plains with temperatures holding
steady or steadily dropping throughout the day depending on
frontal timing. Temps may only remain in the 40s if FROPA is on
the earlier side of guidance. Even with the front and northeast
upslope flow, it will likely remain dry across the plains with Tds
remaining in the 20s. Despite the cooldown and some west upslope
flow, PW along and west of the Divide will remain in the
0.10-0.15" range, and thus almost no chance for light snow across
the highest elevations. Overall there are not many ensemble
members from the ECMWF or GEFS that generate snow behind the
front, either across the plains or in the mountains.

A warming trend commences Wednesday and Thursday, with highs
returning into the mid and upper 60s across the plains, and a return
to the 50s in the mountain valleys.  No precipitation is expected.

Looking even further ahead, for Friday/Saturday of next week
ensemble output is hinting at a trough upstream of us with
significantly cooler air (as in probably below normal!) and more
moisture for our area. Roughly 30-40% of the EC ensemble members
generate some snow across plains and I-25 urban corridor, and half
of the GEFS do the same. We shall see.

&&

.AVIATION...(For the 06Z TAFS through 06Z Saturday night)
Issued at 1040 PM MST Fri Nov 26 2021

Mid and high level deck of clouds will be shifting south of the
terminals after 08z while a weak front system moves in around 11z
and shifts winds to the east and northeast after 11z and continue
with an easterly component through much of the day. No other
impacts expected.

&&

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

$$

UPDATE...Entrekin
SHORT TERM...Mensch
LONG TERM...Schlatter
AVIATION...Entrekin

NWS BOU Office Area Forecast Discussion