Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 231029
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
429 AM MDT Mon Apr 23 2018

.SHORT TERM...(Today and tonight)
Issued at 429 AM MDT Mon Apr 23 2018

Models are trending toward a bit more disorganized system over the
next 36 hours. The best lift will move across Wyoming today,
weakening as the tail end of the trough drags across Colorado
tonight and early Tuesday. As so often happens, the lift over us
will be working on relatively dry air, with some low/mid level
moisture along the frontal band. This means the best window of
saturated/slightly unstable air with some QG lift will be a few
hours during the night, a few hours slower than previously
forecast.

For today there will be a little instability over the mountains
that should generate some showers/storms. East of the mountains
the low levels will be a bit too dry to encourage the convection,
so we`ll mainly see whatever happens over the mountains drifting
east in the late afternoon/early evening. Further east on the
plains it will be a little cooler but there will be some moisture,
perhaps enough to allow showers to continue to propagate east in
the evening.

The main event will be the frontal band. Low level cold front will
probably rush ahead of the upper feature in the evening with sharp
cooling and gusty north winds on the plains during the middle of
the night. Deeper shower activity is probably more toward the
later part of the night. Still looking for sharp enough cooling to
give a chance of snow by sunrise over much of the plains, though
air temperatures will be near freezing and everything else will
be warm so the impact will be very limited. Some high mountain
areas will pick up several inches of snow, but again temperatures
will limit the impact to the higher mountain areas.

.LONG TERM...(Tuesday through Sunday)
Issued at 429 AM MDT Mon Apr 23 2018

It will be cold Tuesday morning behind tonight`s cold front. An
upper level trough over Wyoming will produce lift across far eastern
Colorado and into the Central Plains early Tuesday. The upper level
trough and best lift will shift eastward through Tuesday. Northeast
upslope flow along the Front Range will also produce low level lift
resulting in low clouds, snow, and possibly drizzle/freezing drizzle
Tuesday morning. Given the warm ground temperatures any ice
accumulation will occur on elevated surfaces. Up to 3 inches of
snow will be possible in the foothills and mountains. Due to the
cloud cover and cold airmass, highs are expected to be in the 40s
across northeast Colorado. Surface high pressure will settle over
Colorado Tuesday night bringing clearing skies, chilly
temperatures, and possibly fog.

Ridging in the northwest flow aloft will bring mild and dry
conditions for Wednesday. The next trough will drop southeast across
the region Thursday. The cold front associated with this system will
push south through Colorado late Wednesday night and early Thursday.
This system is weaker than tonight`s/Tuesday`s system. Cooler
temperatures will prevail Thursday. Will have low pops for this
system as well. If any precipitation occurs, it will be light.

For Friday and next weekend, upper level ridge moves across Colorado
Friday and then shifts over the central part of the county for the
weekend. Temperatures will be mild under this pattern and warm well
into the 70s this weekend as southwest flow aloft prevails behind
the ridge. Models show a short wave trough embedded in the southwest
flow for this weekend. However, quite a bit of uncertainty on the
timing, placement, and the amount of moisture and instability. This
system could bring a round of showers and thunderstorms with it.
Will have low pops in the forecast for this system with the highest
pops over the mountains.

&&

.AVIATION...(For the 06Z TAFS through 06Z Monday night)
Issued at 429 AM MDT Mon Apr 23 2018

VFR today, with isolated thunderstorms by late afternoon that
could produce gusts to 30 knots. A cold front is expected to pass
between 02z and 06z, followed by north winds gusting to 30 knots.
MVFR conditions in rain and snow showers will likely develop a
couple of hours later and continue into Tuesday morning. Little or
no snow accumulation is expected in the Denver area.

&&

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

$$

SHORT TERM...Gimmestad
LONG TERM...Meier
AVIATION...Gimmestad


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