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Area forecast discussion
National Weather Service Denver/Boulder Colorado
835 am MST Thu Nov 21 2019

Update...
issued at 835 am MST Thu Nov 21 2019

Will let the Winter Weather Advisory expire at 9am. Even though
freezing drizzle may linger a little longer near and in the
foothills, little to no impacts have been observed. Light snow is
starting to move into the area which will also help end the
freezing drizzle. There is an area of lift over western Colorado
producing snow at this time. This lift will progress eastward
today and is expected to bring areas of light snow this afternoon
to the mountains, Front Range, and eastern plains. Additional
snowfall this afternoon is expected to be light and mainly less
than 2 inches.

&&

Short term...(today and tonight)
issued at 358 am MST Thu Nov 21 2019

Northeast Colorado was left under widespread low stratus overnight
as the first weather disturbance left the state. Near the
foothills of Boulder, Jefferson and Douglas counties there has
been just enough upslope flow to generate areas of freezing fog
and freezing drizzle, which has left a glaze of ice on surfaces.
This freezing drizzle will continue through sunrise, when the
approach of upper clouds from the next weather system causes
precipitation to change over to light snow. However, with ice
already on the ground, will issue a Winter Weather Advisory for
freezing drizzle through 9 am this morning, covering the Denver
Metro area and the southern Front Range foothills. Light snow
falling onto the ice will create very slippery driving conditions,
especially on bridges and overpasses.

For the rest of today, light snow is expected as a second weather
disturbance lifts northward over the state. Moisture amounts are
rather limited, so only light accumulations of snow are expected
through this evening. Mountain areas will pick up a few inches of
new snow, while the plains see one inch or less. Temperatures will
remain in the upper 20s to lower 30s as a cold airmass is well
entrenched over the forecast area.

Snow will gradually taper off late tonight as the upper
disturbance is not forecast to clear the state until Friday
morning. Additional accumulations overnight will continue to be
light.

Long term...(friday through wednesday)
issued at 358 am MST Thu Nov 21 2019

A weak upper level low will be over ern Colorado Friday morning and will
move eastward into Kansas by aftn. Over the mtns, orographic
component will be favorable for periods of light snow thru midday.
This activity should lessen thru the aftn hours as moisture
gradually decreases. At lower elevations, still can't rule out
some light snow in the morning, although confidence isn't high as
to where it may focus. Thus have kept pops in the chance range. As
for highs, will keep readings in the upper 30s to lower 40s over
most of nern Colorado.

For the weekend, the flow aloft will be from the northwest as a sfc
Lee trough becomes established, especially by Sunday. Overall,
there will be some mid and high level moisture embedded in the flow,
however, lower levels will be dry. Thus will keep fcst dry both
days. Temperatures will rise into lower to mid 50s on Sat, across
nern co, with 55 to 60 on sun.

Looking ahead to Mon, there are still some differences between the
European model (ecmwf) and GFS. The European model (ecmwf) has remained rather consistent in
showing a disturbance and associated upper level jet, moving
across nrn co, Mon aftn thru Monday night. Meanwhile, the GFS has
been all over the place the last few days. 24 hours ago it showed
a stg storm system affecting the area, which has completely
disappeared in the last few runs. Meanwhile it now shows a similar
pattern like the European model (ecmwf). Overall, there still should be a good chc
of snow across the area from Mon aftn into Mon night with the
European model (ecmwf) solution preferred. Highs on Mon will drop back into the
lower to mid 40s over nern Colorado as a cold front moves across during
the day.

By Tue, drier air, in west-northwest flow aloft, will gradually spread over the
area. However, can't rule out a chc of light in the mtns and
possibly over the plains, in the morning. Highs will be in the
30s over nern Colorado. On Wed, an upper level ridge is now forecast to
build into the area with stg SW flow aloft. This would lead to
generally dry conditions with warmer temperatures over nern Colorado. In
the mtns, will keep in a chc of snow.

&&

Aviation...(for the 18z tafs through 18z Friday afternoon)
issued at 835 am MST Thu Nov 21 2019

Low clouds with ceilings under 1000 feet will persist through
today. Freezing drizzle will occur prior to 18z, mainly near the
foothills. Light snow is expected to move into the Denver area
later this morning and early afternoon. Snowfall amounts will be
light and are expected to be around an inch or less. After 00z,
low clouds will continue through the night and into Friday
morning. Ceilings are expected to stay under 1000 feet. Periods of
light snow and flurries will be possible tonight. Little to no
additional accumulation is expected.

&&

Bou watches/warnings/advisories...
Winter Weather Advisory until 9 am MST this morning for coz036-
039>041.

&&

$$

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