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Area forecast discussion
National Weather Service Denver/Boulder Colorado
1122 am MST Tue Dec 10 2019

issued at 1118 am MST Tue Dec 10 2019

It looks like the mountain snow is about done for now. Winds
continue with 40-60 mph gusts over the ridges. These should
decrease a bit by evening as the flow decreases. There's quite a
bit of cirrus upstream, though much of it is thin, and there
should be enough of a wave to keep skies partly cloudy overnight.
Forecast temperatures look about right.


Short term...(today and tonight)
issued at 357 am MST Tue Dec 10 2019

A disturbance, in northwest flow aloft, will affect far nern Colorado this
morning, with a slight chc of snow showers thru 15z or so.
Elsewhere, there is enough moisture embedded in the flow, to
bring a chc of snow showers to the nrn mtns as well, due to
favorable orographic flow. It will also remain windy, over the
higher terrain, with some gusts up to 50 mph and blowing snow over
the higher passes. As far as highs, 850-700 mb temps only rise a
few degrees today, so readings will be near seasonal normals in
most areas.

For tonight, the flow aloft will become more west-northwest with a drier
airmass moving into the area. Thus will keep a dry fcst in place.
Winds will decrease over the higher terrain as component along
winds are under 20 kts.

Long term...(wednesday through monday)
issued at 357 am MST Tue Dec 10 2019

Medium and long range models continue to show a progressive and
generally zonal flow pattern into the weekend with some moisture
at times which will produce some mountain snowfall. Wednesday and
Thursday look like they will be dry, even as a short wave trough
embedded in the westerly flow moves across the state. Moisture
seems to be the missing ingredient. Temperatures at low and mid
levels will warm over the two days, allowing afternoon highs to
rise to the mid and upper 40s across the plains on both days.
Mountain areas could see gusty winds at times, but all pops will
be near zero.

From Thursday night through the weekend, things start to change as
models forecast an increase in moisture moving over the mountains
along with the arrival of a strong upper level jet stream.
Orographic forcing at lower and mid levels should combine with jet
stream dynamics to produce light to moderate snowfall in the
mountains. The plains should remain dry because of the strong
westerly component to the flow aloft. The upper level jet is
expected to remain over Colorado through Saturday evening, so
mountain areas could end up seeing 36 to 48 hour period of
snowfall. At this time, it looks like accumulations in the 4 to 8
inch range will be possible during the first half of the storm. No
highlights are necessary for now, but as the event approaches,
that may change. It will depend on how much Pacific moisture is
brought into the state by the westerly flow. Low probability of
precipitation forecasts will spread onto the plains by Friday
evening, but the best chances for snow on the plains will not be
until Saturday evening and Sunday. A weak cold front will also
move in Saturday night which will keep temperatures on Sunday much
cooler. Dry weather is expected to return next Monday as an upper
ridge develops and moves in from the west.


Aviation...(for the 18z tafs through 18z Wednesday afternoon)
issued at 1118 am MST Tue Dec 10 2019

VFR through tonight. There may be some variability in the wind
direction today but speeds should be under 10 knots. By evening
winds will be back to short wave drainage.


Bou watches/warnings/advisories...


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