046 
FXUS65 KBOU 230158
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
758 PM MDT Thu Apr 22 2021

.UPDATE...
Issued at 754 PM MDT Thu Apr 22 2021

Some areas of light snowfall are ongoing in the high country, and
some isolated showers are making it east out over the adjacent 
plains but producing only light rain and virga. We made some minor
adjustments to PoP to match observed precipitation, mainly in the
Front Range Mountains along the Continental Divide where there 
was a few hours of moderate snowfall in the late afternoon and 
early evening. Showers are already rapidly diminishing for the 
evening behind the exiting shortwave. Expect partly cloudy skies 
overnight ahead of the next shortwave, which is currently 
advancing in to the Desert Southwest. It still looks like lows 
tonight will be slightly warmer than those last night, in the 
upper 20s and lower 30s F on the plains and upper teens to lower 
20s F in the mountains. The forecast is on track with only minor 
adjustments this evening.

&&

.SHORT TERM...(This evening through Friday)
Issued at 240 PM MDT Thu Apr 22 2021

Area radars have some light rain showers now getting over the 
western plains. There are some snow showers in the mountains and 
foothills. The convection is moving due easterly. Can't find any 
lightning at this time. 

Models show an upper level trough to move slowly eastward across the 
CWA tonight and Friday morning.  There is north-northwesterly flow 
aloft in place over the CWA by Friday afternoon.  There is upward 
vertical velocity progged for the CWA on the QG Omega fields later 
tonight into early Friday afternoon, then downward velocity moves 
in.  The low level winds are progged to be normal diurnal trends 
tonight an Friday. 

Cross sections indicate some moisture to stick around overnight, 
with decent moisture expected on Friday. There is limited CAPE 
progged on Friday as well, covering most of the CWA. For pops, 
will go with 10-40%s for the mountains, foothills and adjacent 
plains through about mid evening. Will go with "chance"s for the 
plains on Friday and "likely"s in the mountains and foothills. For
temperatures, Friday's highs should be 1-4 C warmer than this 
afternoon's readings. 

.LONG TERM...(Friday night through Thursday)
Issued at 130 PM MDT Thu Apr 22 2021

On Friday evening, a weak disturbance in the northwest flow will 
be moving across far Northern Colorado. Current forecast has a 
slight chance of showers over northern sections in this looks 
fine as the trof passes by. 

On Saturday, there will be weak ridging of high pressure across 
Colorado as the flow aloft shifts back more westerly. Expect the 
warmup to continue as 700mb temperatures rise to close to +4c at 
Denver with readings across the plains rising into the 60s. There 
could be a few showers in the mountains late Saturday with a bit of 
moisture and marginal instability. 

For Sunday, the flow aloft will shift to the southwest as the Pacific
disturbance moves inland across the west coast. Even warmer yet 
as 700mb temperatures jumps to close to +9c and readings another 
10 degrees warmer. The airmass will be a bit drier with the 
southwest flow so no pops needed. Monday will be another warm day 
as an approaching system moves into the Great Basin. Any showers
in the mountains will likely hold off until Monday evening. 

Bigger changes in store from Monday night through early Wednesday 
the Western trof moves across Colorado with moderate QG ascent, 
much colder temperatures and a cold front with a good upslope 
component along the Front Range. There are some timing differences
between the GFS and European with the GFS still the most progressive
model while the European is a bit slower. Still forecast in good 
shape with the trend for cooler conditions and a return to rain 
and snow showers.

&&

.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 754 PM MDT Thu Apr 22 2021

Expect VFR conditions to persist overnight and possibly through 
the TAF period. Light showers should be in the vicinity of the 
terminals until around 03Z, then rapidly diminish this evening 
behind the exiting shortwave. Skies should remain scattered 
overnight and Friday, then mid and upper level cloudiness 
increases again in the afternoon with more light showers or even 
isolated thunderstorms possible in the vicinity of the terminals 
by around 20Z as the next weak shortwave moves over Colorado. They
may be periods of MVFR conditions with passing showers or storms 
Friday afternoon and evening.

&&

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

$$

UPDATE...Direnzo
SHORT TERM...RJK
LONG TERM....Entrekin
AVIATION...Direnzo