Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 011801
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
1101 AM MST Thu Dec 1 2016

.UPDATE...
Issued at 1051 AM MST Thu Dec 1 2016

Light snow showers over areas in the mountains high valleys and
passes. Light snow will continue on and off through the day with
orographic influence. Increased cloud coverage due to influx of
moisture over the mountains from the incoming disturbance now
entering northern Utah and portions of NW Colorado. This system
will move in by this evening increasing snow coverage over the
mountains with a chance of light snow over the foothills by Friday
morning.

&&

.SHORT TERM...(Today and tonight)
Issued at 247 AM MST Thu Dec 1 2016

An upper level trough will move southward fm the nrn Rockies as an
upper level low develops over Utah by late tonight.  Ahead of this
system there will be an increase in mid lvl moisture.  Cross-
sections show the mid lvl flow will switch fm wly to more swly by
late in the aftn with weak orographic component. QG ascent is weak
as well although there will be some improvement in lapse rates.
Overall there will be a chc of light snow in the mtns mainly north
of I-70. Across nern CO outside of increasing cloud cover it will
be dry with highs similar to Wed.

For tonight wk swly mid lvl flow will continue in the mtns with a
continued chc of light snow.  Across nern CO the low lvl flow will
become light ese with a dry layer abv the sfc.  After 09z the lower
levles may become more saturated which may lead to a slight chc of
light snow in and nr the foothills.  Across the rest of nern CO it
will remain dry.

.LONG TERM...(Friday through Wednesday)
Issued at 247 AM MST Thu Dec 1 2016

The upper trof will continue to dig south and southeast into
southern Arizona during the day on Friday as the low becomes
closed off. Meanwhile over Colorado,  there is still some weak QG
ascent remaining while northern branch of the trof sweeps across
Colorado on Friday night and early Saturday. At the surface...high
pressure will build through region with light and shallow upslope
flow on Friday before shifting southeast Friday night. There is a
moist layer from 750-550mb and given shallow upslope component may
be enough for scattered snow showers especially in/near the
foothills. Not much in the way of orographic flow in the mountains
so any accumulations will be on the light side.

Drier conditions will move into Colorado on the weekend as a
moderate northwest flow pattern sets up. Could be a few lingering
snow showers in the mountains with the northwest flow and some
gusty winds over mountains and higher east slopes with speeds
generally under 35 mph. Expect some moderation in temperatures
across lower elevations with readings back into the 40s.

Next major system digs into the Great Basin early next week with
the next shot of much colder temperatures and the chance of snow.
Still some significant differences showing up between the GFS and
European solutions with the GFS now more progressive than earlier
runs while European is slower but still moves the trof across
Colorado as an open wave. Even GFS ensemble memers are quite
varied. Regardless temperatures will be much colder with this
system. Have lowered temperatures on the plains for Tuesday and
Wednesday while maintaining chances of snow.

&&

.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
Issued at 1051 AM MST Thu Dec 1 2016

Winds will continue to be light and turn more easterly by 18z with
a deepening lee side low over the foothills. Increasing moisture
from the incoming shortwave will keep a BKN deck through the
period but expect VFR conditions through the TAF period. According
to short term models the surface low will deepen over Park county
allowing for a push to NNE winds by this evening. For Friday...winds
will remain light with decreasing ceilings to 080 as snow moves
into the foothills. Do not expect snow over the airports with
winds from the E turing SE by 21z Friday.

&&

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

$$

UPDATE...Bowen
SHORT TERM...RPK
LONG TERM...Entrekin
AVIATION...Bowen



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