096
FXUS65 KBOU 070647
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
1147 PM MST Wed Nov 6 2024

.KEY MESSAGES...

- Road conditions may worsen after sunset due to cooling pavement
  temperatures and continuing light to moderate snowfall.

- Snow slowly decreases this evening, with a lull/break in snow
  late tonight.

- Next wave of snow arrives Thursday morning, heaviest south of
  I-70 and east of I-25.

- Another shot of snow Friday into Saturday as the upper low
  tracks northward across the region. Warm enough for rain across
  the lower plains.

&&

.UPDATE...
Issued at 751 PM MST Wed Nov 6 2024

Current radar shows light snow showers remain across the plains
this evening. The current forecast still aligns with the latest
guidance outputs, leaving little need for updating. Have included
the latest observations and will let the current forecast ride for
this update package. Conditions have improved over the
northeastern plains that have allowed us to expire the Winter
Weather Advisory a little ahead of schedule. There may still be
some light lingering snow showers, but not worthy of an advisory
any longer.

&&

.SHORT TERM /Through Thursday/...
Issued at 253 PM MST Wed Nov 6 2024

Snow is still going strong across parts of the Denver area and
eastern plains. The strong upper level low spinning along the
Colorado/Utah border has been slow to drift south, helping to keep
lift over the area longer. Water vapor satellite imagery also
showing broad divergence aloft. The heaviest snow seems to be
along convergence at 700mb. The 700mb trough weakens overnight
bringing most of the snow to an end this evening north of I-70.
However, water vapor satellite imagery shows a conveyor belt of
moisture still headed this way, so the lull in snow is expected to
be short lived tonight and may not totally end south of I-70.

As far as the Winter Storm Warnings and Winter Weather Advisories
go, the southern foothills and Denver metro area advisories will
expire at 06Z Thursday and the eastern plains warnings and
advisories expire at 12Z. Hopefully these can be canceled sooner,
but with this storm over performing decided not to move up the
expiration times. We did make changes and extended the Palmer
Divide, Elbert and Lincoln Counties through Thursday afternoon
(See below for details).

Next short wave and shot of snow lifts northward into the area
early Thursday morning. Heaviest snowfall amounts with this will
be east of I-25 and south of I-70. We upgraded all of Lincoln
County to a Winter Storm Warning until 00Z Friday. An additional 5
to 9 inches of snow is expected Thursday. Winds will be much
weaker with blowing snow much less of a concern. We also have a
Winter Weather Advisory for the Palmer Divide until 00Z Friday for
2 to 6 inches of new snowfall. The Denver metro area and the
eastern plains will see additional snowfall Thursday as well. The
snowfall will range from very little north of the Denver metro to
a few inches across the southern metro area.

&&

.LONG TERM /Thursday night through Wednesday/...
Issued at 253 PM MST Wed Nov 6 2024

It`s looking like a very active weather pattern for the start of
the forecast period as a potent storm system ejects from the
Desert Southwest into the Central Plains States. Latest models are
in good agreement with the track of the upper low with some
differences with precipitation and snowfall amounts.

Thursday night, the large 500 MB cut-off low will be drifting
across Southern New Mexico with light east to southeasterly flow
aloft over the CWA. Mostly cloudy skies are expected across the
forecast area with some light snow possible across our far
southeastern zones due to plenty of low level moisture and some
weak QG lift.

The models are showing the upper low lifting northeastward
through the day on Friday with most of the solutions having it
centered near the Southeastern corner of Colorado by Midnight
Friday. As the system shifts northeastward, rain and snow should
increase across plains as wrap around moisture combines with
plenty of QG lift. At this time, it`s looking like snow will ramp
up across our far southeastern zones by mid to late morning Friday
and spread westward into the Front Range Mountains/Foothills an
Urban Corridor by late afternoon. Further to the north, the
precipitation may be all rain, or a mixture of rain and snow, due
to warmer temperatures. Models are also suggesting quite a bit of
isentropic upglide, associated with a TROWAL, which would enhance
precipitation and snowfall amounts, especially from the Palmer
Divide eastward across the plains. In addition, cross sections are
hinting at a possible barrier jet setting up along the Front
Range Urban Corridor which could enhance snowfall amounts in these
areas as well.

Confidence is increasing that several inches of snow will fall
from the Palmer Divide eastward across portions of the plains from
Friday into Saturday with winter driving conditions expected.
However, there is still quite a bit of uncertainty in the
forecast, especially across the Front Range Foothills, and
portions of the Front Range Urban Corridor. This storm bears
watching as minor changes in the storm track could have a
significant effect in QPF and snowfall totals as well as travel
impacts. Winter Storm Watches my be needed in later forecast
packages; therefore stay tuned.

Warmer and drier weather is expected across the region by Sunday
as the upper low moves into the Upper Midwest. Cooler unsettled
weather is expected to return late Tuesday into Wednesday as the
next storm system moves into Colorado from the west.

&&

.AVIATION /06Z TAFS through 06Z Friday/...
Issued at 1135 PM MST Wed Nov 6 2024

Very light snow is falling at all terminals tonight with KAPA
seeing the lowest ceilings. This very light snow will continue
throughout the night with minimal change in current ceilings and
visibility. Models are in good agreement that a wave of snow will
move over the terminals from the south during the mid morning
Thursday. This will drop visibility to between 1-3 SM at KDEN and
KBJC and ceilings will fall to between 600-2,000 feet. At KAPA,
there will be a chance for lower ceilings and visibility with 200
feet and 1/2 SM possible. The wave of snow is expected to become
very light or even end in the mid afternoon. During the evening,
there will be dry conditions with a possible break in the low
ceilings.

A concern for Friday morning is a chance for fog at all
terminals. The best chance for fog would be a KDEN and KBJC as
there is a better chance for clearing at those locations. The
moisture from the recent snow along with cold temperatures may
create the conditions where fog is favorable. However, there is
low confidence in the forecast for Friday morning so only VCFG was
added to the KDEN TAF.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until 11 PM MST this evening for COZ036-
039-040.

Winter Weather Advisory until 5 PM MST Thursday for COZ041.

Winter Storm Warning until 5 AM MST Thursday for COZ045-049.

Winter Storm Warning until 5 PM MST Thursday for COZ046-047.

&&

$$

UPDATE...Bonner
SHORT TERM...Meier
LONG TERM...JK
AVIATION...Danielson