Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 041113
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
413 AM MST Mon Dec 4 2017

.SHORT TERM...(Today and tonight)
Issued at 413 AM MST Mon Dec 4 2017

Upper trough passing over Colorado this morning. Westerly winds
have increased ahead of the cold front now entering southern
Wyoming. Expect winds just below high wind criteria over the
northeast plains during the middle of the day, then decreasing
considerably in the later part of the afternoon as the pressure
surge moves past.

The deeper moisture that produced snow over the mountains
overnight is gone, but there is still a shallow moist unstable
layer with decent winds. Expect a steady but mainly light
orographic snow to continue through mid morning, then as winds
become more northwesterly and lessen, even lighter snow that will
cling to the peaks and possibly over the valleys of Grand/Jackson
counties most of the day. The previous forecast is in pretty good
shape, so only some minor timing adjustments at this time.

.LONG TERM...(Tuesday through Sunday)
Issued at 413 AM MST Mon Dec 4 2017

Little change in the weather pattern over North America for the
upcoming weak with a large upper level ridge along the Pacific
Coast and an upper level low over the Great Lakes to Hudson Bay. A
north to northwest flow aloft will persist over Colorado. This
pattern will leave the state open to cold intrusions from the
north.

For Tuesday and Wednesday, a dry northerly flow aloft will keep
cool air over the region. Highs over northeast Colorado are
expected to be in the upper 30s to lower 40s. Strong surface high
pressure centered over the western U.S. will help produce windy
conditions at times over the higher terrain and across the eastern
plains.

An upper level trough embedded in the northerly flow aloft will
push through the region Thursday. This will help to reinforce the
colder air on Thursday. Models indicate there may be enough
moisture for light snow with this system. Best chance for this
will be over the mountains where orographic lift will help wring
out the moisture. Snowfall amounts at this time look light with
just a few inches possible over the northwest facing slopes.

For Friday and the weekend. The upper level ridge will shift
slightly eastward. This should be enough to nudge the colder air
east of the state. Dry conditions are expected to prevail with
temperatures climbing above normal. If the ridge doesn`t shift
east, cooler air may stay in place or be slow to leave the area.

&&

.AVIATION...(For the 12Z TAFS through 12Z Tuesday morning)
Issued at 413 AM MST Mon Dec 4 2017

VFR through tonight. Strong west winds will continue until about
16z, with gusts to around 30 knots at KDEN and as high as 50 knots
at KBJC. Winds will then become north to northwest with gusts
around 30 knots. KAPA is a bit sheltered from the strong west
winds, but should develop north to northwest winds gusting to
20-30 knots by 16z. The winds will decrease significantly and
switch to north to northeast around 22z.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until noon MST today for COZ031-033.

&&

$$

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



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