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fxus65 kbou 200935 

Area forecast discussion
National Weather Service Denver/Boulder Colorado
335 am MDT Fri Oct 20 2017

Short term...(today and tonight)
issued at 218 am MDT Fri Oct 20 2017

For today, a weak southwesterly flow aloft will be over the
region this morning as the first trough exits to the east. By this
afternoon the flow aloft will increase ahead of the next Pacific
trough. Weak mid level qg ascent will develop over western Colorado by
00z as the trough into ID/UT. Another very mild afternoon ahead
of this system. In the mountains, showers not expected to develop
until late this afternoon impacting primarily zone 31. Otherwise
dry and windy at times. Over the northeast plains, southwest winds
at the surface and aloft expected. The fire danger will remain
elevated due to the unseasonably warm temperatures. Less high
cloud over this afternoon and southwest winds should push the
highs to around 80. Southwest winds in the 10 to 15 mph range with
gusts to 25 mph over the Palmer Divide, with rh values in the mid
to upper teens in the driest areas. Marginal conditions in terms
of criteria so no highlights at this time. One may be necessary
however if the wind gets stronger or the rh values drop further
than anticipated.

This fast moving system is still expected to move across the
region tonight, with moderate qg ascent by 06z. A mix of rain and
snow showers in the high country early this evening will change
over to snow overnight. As the trough axis shifts eastward the mid
level winds will become west/northwesterly. Mainly light snowfall
in the mountains expected with up to 3 inches over the higher
west and northwest facing slopes. By 12z Saturday the mid level
trough axis will be over central Colorado. Snow showers should start to
decrease in coverage by this time as mid level subsidence will
start to kick in from the west, then primarily orographic
snow showers. Over the northeast plains, the cold front will push
across the region after 06z, with some stronger gusts to 35 mph
along the northern border. Gusty winds in the 40-50 mph may occur
for a brief time in the foothills of Boulder and Larimer counties
and along the Cheyenne Ridge.

Long term...(saturday through thursday)
issued at 218 am MDT Fri Oct 20 2017

Northwest flow behind the exiting upper level trough and surface
cold front will bring windy and cool conditions Saturday. Wind
gusts to 50 mph will be possible over the eastern plains and near
the Wyoming border. Orographic lift may keep light snow going
through mid morning in the mountains. Downslope flow will prevent
snow along the east slopes and Front Range. Farther east, away
from the downslope, a few weak showers will be possible over the
far northeast corner before drier subsident air moves in. It will
be chilly Saturday night/Sunday morning due to a cool dry airmass.
Overnight lows should drop into the mid 20s to mid 30s with most
locations falling below freezing. A mountain wave may form
Saturday night and produce windy conditions along the east slopes
and in/near the foothills. This will help keep temperatures
warmer in these areas.

A large upper level ridge will be centered along the West Coast
Sunday and early next week. This will result in a northwest flow
aloft over Colorado. Warmer conditions will prevail under mostly
sunny skies. Highs are expected to climb into the upper 60s to
lower 70s over northeast Colorado.

Models in good agreement showing the northwest flow aloft will
continue through next week. Short wave troughs embedded in the
northwest flow will bring shots of cooler and windy conditions.
The first one will graze the area late Monday as it passes
northeast of the state. This will usher in cooler temperatures for
Tuesday, and perhaps Monday over the northeast corner of the
state. A second and stronger wave on Thursday could bring
rain/snow to the area along with cooler temperatures.


Aviation...(for the 06z tafs through 06z Friday night)
issued at 218 am MDT Fri Oct 20 2017

VFR conditions expected over the next 24 hours with no
restrictions. Overall the wind will be primarily south/southwest
8-14 kts today and this evening. A cold front is expected push
into the terminals in the 08-09z time frame Saturday morning.
Ahead of the front, the sfc winds should start to transition to a
west/northwest direction by 06z tonight.


Bou watches/warnings/advisories...


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