164
FXUS65 KBOU 300017
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
617 PM MDT Mon Apr 29 2024

.KEY MESSAGES...

- Quick showers northern mountains late tonight.

- Cooler Wednesday night and Thursday with a chance of showers.

&&

.SHORT TERM /Through Tuesday/...
Issued at 315 PM MDT Mon Apr 29 2024

Satellite imagery shows surface heating has produced a nice cumulus
field across the plains. Under today`s weak ridging, temperatures
have reached the mid to high 60s across the plains and foothills,
and the mountains aren`t far behind having reached the 50s. Winds
are generally light across the forecast area with some occasional
gusts reaching up to 25 kts mainly in the foothills of Boulder
County. Tonight will bring some snow showers to the northern
Colorado Rockies as an upper level low tracks eastward across
Montana. The passing disturbance will usher in just enough Pacific
moisture, PVA, and a jet streak overhead to create enough forcing
for Jackson, Grand, and Larimer Counties mountains to see some
rain and snow showers, and with enough instability present, a
chance for a thunderstorm. A cold front associated with the
passing disturbance will pass through from northwest to southeast
somewhere between 9Z and 12Z Tuesday morning, extending the
precipitation and transitioning winds to northwesterly in its wake.
All snow and rain showers are expected to diminish by late
morning. High temperatures will feel little impact from the
passing front aside from being a few degrees cooler than today`s.
Cross sections indicate a mountain wave developing in the morning
hours. Gusty westerly winds will develop over the mountains,
foothills, and portions of the plains that could gust 30-40 mph at
times.

&&

.LONG TERM /Tuesday night through Monday/...
Issued at 315 PM MDT Mon Apr 29 2024

The next in a series of shortwave troughs will move across
Wednesday afternoon and evening. It`s a quick shot, but there`s
enough moisture and instability for a pretty good chance of
showers and thunderstorms as the trough passes. Ahead of the
trough, it still looks pretty warm for the plains during the day
Wednesday.

Temperatures drop behind the front, although quick drying and
subsidence in its wake should provide lots of sunshine on
Thursday. We lowered Thursday morning`s lows a little in line with
the latest guidance, then Thursday`s highs look alright, mainly in
the 50s at lower elevations. We had been expecting some diurnal
shower activity Thursday afternoon, but this is looking more
questionable with the amount of drying now in the models so we
trimmed the PoPs back a bit more.

There`s reasonable agreement on another shortwave trough about
Friday night. Once again, there should be enough moisture and
instability for a quick shot of showers. Less agreement after
that. Most model runs have WSW flow possibly becoming more SW into
early next week, some with a shortwave going north of us. This is
a generally warmer and drier pattern, at least through Monday.
We`re a bit surprised the NBM is still dry Monday given some model
runs showing either a large upstream trough nearing or a shortwave
passing over Colorado. Apparently not enough members and/or a
pretty dry environment by then. We left it for now, but this may
be a case of the NBM favoring GFS solutions over mainly cooler and
possibly wetter EC solutions. We`ll revisit this tonight and
tomorrow.

&&

.AVIATION /00Z TAFS through 00Z Wednesday/...
Issued at 602 PM MDT Mon Apr 29 2024

VFR conditions are expected through the TAF period. A mixed bag of
light winds at the terminals early this evening. Light easterlies
at DEN turn SE and eventually to SSW/SW drainage around midnight
at 08-12 kts. SW/W winds at APA/BJC early this evening becoming
southerly 03-06Z. A weak front moves through early Tuesday
morning, likely in the 13-15z timeframe accompanied by a switch to
northerly component flow. Winds should mix down in the afternoon
(17-19z) bringing WNW winds at 08-12 kts. Can`t rule out some
gusts at BJC up to 22 kts, but confidence is low.

&&

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

&&

$$

SHORT TERM...Bonner
LONG TERM...Gimmestad
AVIATION...Mensch