Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 201908

Area Forecast Discussion
National Weather Service Denver/Boulder CO
1208 PM MST Tue Feb 20 2018

Issued at 1206 PM MST Tue Feb 20 2018

Lowered some max temperatures over the plains today while
increasing some in the high mountain valleys due to recent
observations and trends. Currently have a forecast high of 16
degrees for Denver International Airport, which would tie the
record low max temperature for the day.

UPDATE Issued at 910 AM MST Tue Feb 20 2018

Windchill Advisory has expired as temperatures begin to slowly
warm up. Current windchill readings are now into the -5 to -15
degree range and should keep improving. Shortwave now over eastern
UT and western CO is still expected to push in this afternoon to
increase snowfall over the mountains and bring a slight chance of
light snow to the urban corridor and Palmer Divide due to weak
upslope. No major changes needed to the current forecast as all
this looks good timing wise.


.SHORT TERM...(Today and tonight)
Issued at 350 AM MST Tue Feb 20 2018

Very light snowfall continues to diminish across northeast
Colorado this morning as the upper jet responsible for the snow
has moved northeast into the northern high plains. Only some
lingering light banded snowfall across far northeast Colorado and
over portions of Douglas and Elbert counties remains. Appears
this will also diminish before sunrise. Will let the wind chill
advisory run its course through early this morning as observations
still showing wind chill readings in the -12 to -27 degrees below
zero, coldest up along the Wyoming border and over Jackson county.
Decided to also add remainder of far northeast Colorado and
extending down to Lincoln county as well as winds are still brisk
there. As winds continue to relax after sunrise, wind chill
issues will diminish.

Despite the exiting weather maker, there still remains lingering
troughiness across the Great Basin this morning and a weak wave
will push across the area this afternoon and evening. This will
result in continued scattered snow showers in the mountains and
some of this expected to spill east over the adjacent plains this
afternoon under shallow upslope flow. Moisture depth is rather
shallow so expect any accumulation`s on the plains less than 1/2
inch of snow. Improving conditions later tonight with clearing

Temperatures will remain quite cold today under the influence of
cold surface high pressure building south and east across the
central plains. Readings will struggle to get out of the teens
from Denver northward.

.LONG TERM...(Wednesday through Monday)
Issued at 320 AM MST Tue Feb 20 2018

Active weather pattern for the long term with persistent pieces of
energy moving around the base of an elongated, nearly stationary
upper trough. The trough extends from the North into Canada south
across the Great Basin and into the Pacific where it wobbles but
stays persistent through Saturday with the help of a strong,
nearly 590 decameter high over the Atlantic. The synoptic pattern
will keep SW flow over the State keeping decent moisture moving
into the SW and central mountains with slightly less for the
Northern mountains and adjacent plains. For Wednesday moisture and
SW flow ahead of the upper trough will help to keep a slight
chance of snow for the central mountains with dry conditions on
the plains. Temperatures will rebound slightly from Tuesday but
highs will still be hovering around freezing. Light snow will fall
in the mountains into the early morning with little accumulation.

For Thursday a piece of energy moves up with the SW flow providing
enough lift for increasing snow chances for the high country. Cold
air will continue to dominate the plains with increasing clouds
and temperatures staying around or just below the freezing mark.
Thursday into Thursday evening moisture deepens with high RH
levels through the 350 mb level. Friday another upper trough will
drop out of the Pacific NW and settle into the Great Basin
maintaining the SW moist flow into the state. the upper jet will
shift slightly northward helping to increase the chances of a more
convective CSI set-up for Friday snow. The main thing that seems
to be lacking is a strong cold push with the small chances of
freezing drizzle where there is increased drying. Will have to
monitor model consistency with Friday`s set-up.

Over the weekend, the GFS and to an extent the EC shows the trough
that brought weather to the region on Friday move eastward over
the central US. This will be followed up with more zonal flow as
a new trough develops over the Pacific NW. Models still hinting at
some CSI produced precip returns into Saturday morning before
stabilizing and drying out Sunday. Temperatures for the weekend at
this time look to be in the 30s reaching into the 40s by Sunday.


.AVIATION...(For the 12Z TAFS through 12Z Wednesday morning)
Issued at 910 AM MST Tue Feb 20 2018

VFR conditions now as ceilings have eroded. Mostly clear
conditions now until this afternoon when a weak shortwave will
combine with the weak upslope over the plains and urban corridor
to bring additional light snow/flurries back into terminals mid
afternoon through evening. Best chance will be at BJC and APA and
may also make it to DEN as well. Looks real light so any
accumulations will be under a half inch. Gradual clearing later
tonight as surface winds return to drainage.




SHORT TERM...Entrekin
AVIATION...Kriederman is the U.S. government's official web portal to all federal, state and local government web resources and services.