Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 270104
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
704 PM MDT Tue Oct 26 2021

.UPDATE...
Issued at 608 PM MDT Tue Oct 26 2021

The Red Flag Warning for fire weather zones 246, 247, and 249
was allowed to expire due to recovering humidity ranging from
70-80 above warning criteria. Gusty winds will continue through
Wednesday afternoon.


&&

.SHORT TERM...(This evening through Wednesday)
Issued at 232 PM MDT Tue Oct 26 2021

Satellite imagery showing the upper level trough axis tracking
east over Colorado at this time. Radar and web cameras indicate a
lull in snowfall over the central and north central Colorado
mountains. As the trough axis shifts over eastern Colorado, snow
will form over the mountains due to increasing northwest flow and
cold air advection leading to good orographic lift. New snowfall
for the mountains is expected to be 3-6 inches with up to 8 inches
around Rabbit Ears Pass. Current Winter Weather Advisory still
looks on track. As temperatures fall this afternoon and evening,
mountains roads will become slick, mainly after sunset.

Over the plains, a second front drops southward late this
afternoon and QG ascent moves overhead. This will bring rain
showers from late afternoon through the evening. Downslope flow
will limit the rain west of I-25. For the Palmer Divide area,
temperatures should get cold enough for snow later this evening.
Can`t rule out some slushy roads over higher parts of I-25. Main
impact this evening will be strong winds behind the second cold
front. Models showing winds just off the surface reaching 40-60
knots. Strong cold air advection leading to steep low level lapse
rates should help these stronger winds mix to the surface. The
High Wind Warning begins at 6pm, may need to move it up an hour or
two over far northern Colorado since the front will arrive a
little earlier than expected.

By Wednesday morning, the trough and precipitation associated
with it will be east of Colorado. Strong northwest flow aloft will
be over the state. Expect windy conditions to prevail over the
mountains and eastern plains with gusts to 45 mph. Looks to be
enough moisture embedded in the northwest flow aloft for light
snow over the north central mountains. Additional snowfall over
the mountains should be less than 3 inches. The warmest
temperatures Wednesday will be found from Fort Collins to Fort
Morgan due to downslope flow off the Cheyenne Ridge where highs
will be around 60 degrees. Elsewhere across northeast Colorado,
highs should be in the mid 50s.

.LONG TERM...(Wednesday night through Tuesday)
Issued at 232 PM MDT Tue Oct 26 2021

Colorado will be under a moderate northwest flow pattern Wednesday
night and Thursday. There will still be enough upstream mountain
level moisture to generate continued chance of snow showers for
the mountains along with continued gusty winds. Expect a warming
trend across the plains Thursday and Friday along with dry
conditions as high pressure ridge shifts across the state. For
Saturday, the flow shifts more westerly but still generally dry
conditions and seasonable temperatures.

Changes are still expected from late weekend through early next week
as next upper trof drops southward from the Northern Rockies.
Initial cold front looks to drop southward across the plains for
cooler temperatures on Sunday but still on the dry side. The GFS
is showing a slower trend in this development with the upper trof
with the main bulk of the precipitation not showing up until late
Monday and Tuesday time frame. Temperatures for this event look to
be turning to all snow, even across lower elevations as 700mb
temperatures drop to -11c Monday evening. The new 12 European run
also is showing similar timing now with the GFS also targeting
Monday night and Tuesday morning for snowfall. Both GFS/European
showing some snow accumulation over all of Northern Colorado for
the first snow of the season for the majority of the plains. Still
6-7 days out, so won`t get too excited yet but certainly the potential
is there. For now will carry slightly higher snow chances, into the
chance category. Will also drop high temperatures on Friday into
the lower to mid 40s, but may end up being even colder.

&&

.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 608 PM MDT Tue Oct 26 2021

Clearing of rain showers and lower cloud decks will begin by
Wednesday morning. The upper level low will push into Nebraska
keeping all terminals gusty until 00Z Wednesday evening. Winds
will continue north to northwesterly flow. The strongest wind
gusts will occur 18Z-00Z Wednesday up to 28kts. By Wednesday
evening, wind will shift west to northwest with SCT to FEW cloud
decks at 10k ft.

&&

.FIRE WEATHER...
Issued at 232 PM MDT Tue Oct 26 2021

A cold front will bring a wind shift to the west mid afternoon and
falling temperatures. This will lead to higher relative humidities
as well. A second cold front will bring northerly winds and rain
showers for this evening. The Red Flag Warning may be canceled
sooner than 6pm due to higher humidities behind the cold fronts.
Gusty north winds will prevail Wednesday, but humidities are
expected to be higher than today and above red flag warning
criteria.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
High Wind Warning until midnight MDT tonight for COZ042-044-
048>051.

Winter Weather Advisory until midnight MDT tonight for COZ031.

High Wind Warning until 3 AM MDT Wednesday for COZ046-047.

&&

$$

UPDATE...AD
SHORT TERM...Meier
LONG TERM...Entrekin
AVIATION...AD
FIRE WEATHER...Meier


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