137
FXUS65 KBOU 031053
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
353 AM MST Mon Mar 3 2025

.KEY MESSAGES...

- Blizzard conditions to produce in significant travel impacts
  across the eastern plains late tonight and Tuesday due to snow
  and strong winds.

- High winds expected across the eastern plains late tonight and
  Tuesday with gusts to 70 mph possible.

- Heavy snowfall and windy conditions for the Front Range
  Mountains tonight and Tuesday with difficult travel conditions
  expected.

- The next storm system affects the region late Thursday and Friday.

&&

.SHORT TERM /Through Tonight/...
Issued at 352 AM MST Mon Mar 3 2025

Current satellite pictures are showing upper level cloudiness
getting into the western and southwestern CWA moving
northeastward in the southwesterly flow aloft ahead of the next
upper trough/closed low. That circulation is centered over
northeastern Nevada/northwestern Utah at this time.

Models show the closed circulation to track eastward across
southern Colorado fairly quickly and be over the east central
border of out state by 06Z tonight. There is pretty decent QG
ascent with this system for much of the CWA, especially this
afternoon and evening. By 12Z Tuesday morning, there is weak
northwesterly flow aloft over the CWA. The low level winds are a
different story. The low level pressure fields show a strong
gradient overnight with models showing 50 plus knot wind speeds
at 850 mb out on the plains and 75 knot speeds at 700 mb. So we
went with a high wind highlights for most of the plains zones
that do not have the blizzard warning in effect.

There is still some disagreement with precipitation and snowfall
amounts between the models, however there will be decent synoptic
scale energy, pretty deep moisture according to cross sections,
and some cold air advection. Another issue concerning the heavy
snow potential is the timing when the rain turns over to snow over
the plains. There is cooling expected, but it has been pretty
warm, and even today the plains will see lower 60s before it cools
off significantly this evening. There is also the lack of decent
upslope flow over the plains, as wind directions are progged to
be from 330-350 degrees late this afternoon and tonight. With that
said, there was enough confidence for Winter Storm Warnings for
the Palmer Divide. Also, the high mountains should have decent
enough orographic enhancement along with the rest to warrant
warnings for snow.

For the foothills and immediate plains, the downsloping will
cause some drying and some warming, so the majority of the
precipitation may be rain, especially over the Denver-Boulder
areas.

Will go with Blizzard Warnings for northern Lincoln, Washington,
Sedgwick, and Phillips Counties commencing late this evening.  There
looks to be enough snowfall in combination with the strong winds in
those areas for blizzard conditions. For the rest of the plains,
will let the Winter Storm Watching going with little clarity in
the model solutions at this time.

&&

.LONG TERM /Tuesday through Sunday/...
Issued at 233 AM MST Mon Mar 3 2025

At 12Z Tuesday, vertically stacked low will be somewhere over
western Kansas. This will produce a north-northwest flow aloft
over Colorado. Over the past 24 hours, models have trended
slightly farther south and east. This has shifted the deformation
zone with the heavier snowfall eastward, likely ending up east of
a line from Akron to Limon. However the strong northerly flow will
result in upslope conditions for the Palmer Divide eastward
across northern Lincoln County. Deep surface low over Kansas will
produce very windy conditions across the plains on Tuesday. It
should only take 2-3 inches to produce blizzard conditions across
the plains. Will upgrade northern Lincoln, Washington, Sedgwick,
and Phillips Counties to a Blizzard Warning where a few inches of
snow appears likely along with winds to 60 mph. For the Palmer
Divide will upgrade to a Winter Storm Warning. Confidence isn`t
there that the best snowfall and strong winds will line up, though
a chance this could be upgraded to a Blizzard Warning at a later
time. Elsewhere, uncertainty in the snowfall forecast is too great
to upgrade to warnings or cancel at this time.

In addition to the Blizzard condition over the plains, here is
what we have high confidence in come Tuesday morning...

1. Very windy conditions over the eastern plains that continue
through the day Tuesday. Just how strong will depend on the
strength of the surface low. Confidence is high enough at this
time to warrant a High Wind Watch for Tuesday across the eastern
plains and a warning for southern Lincoln County where gusts to 70
mph are expected.

2. Light to occasionally moderate snow continues in the mountains
through the day on Tuesday.

3. Light precipitation to dry conditions along the urban corridor
due to downslope winds.

For Wednesday, upper level ridging will prevail over the Southern
and Central Rockies ahead of a storm system moving onto the
California coast. Mild and dry will prevail under the ridge. This
will be short lived as flow aloft turns southwesterly on Thursday
as the upper level trough nears the region. A surface low develops
over southeast Colorado during the day on Thursday. This will
produce an east to northeast low level flow across northeast
Colorado. This will cause cooler air to enter the region. There
are several shortwave trough embedded in the larger trough with
the lead wave expected to bring rain and mountain snow late
Thursday. It eventually gets cold enough for snow across the
plains sometime Thursday evening or night. The trough moves over
the area Friday. Models generally show a northerly push of cold
air sometime late Thursday or early Friday, so highs Friday should
be on the cool side. A large majority of the models (~85%) show
precipitation for Thursday night and Friday. However, the ensemble
means are on the low side showing less than a quarter inch of
precipitation. The ECMWF mean is lower showing a tenth inch or
less.

For next weekend, models in decent agreement showing the
troughiness moving off to the east with a cool northwest flow
aloft for Saturday. Temperatures then should warm up for Sunday as
ridging moves over the Central Rockies.

&&

.AVIATION /06Z TAFS through 06Z Tuesday/...
Issued at 1130 PM MST Sun Mar 2 2025

Winds look to be due southwesterly at DIA overnight, with normal
diurnal patterns on Monday. Models show a decent front to push
down over the airport around 00Z late Monday afternoon. Winds will
be from 340-350 at 18-25 knots. Gusts from 30-40 knots are
possible. There will be no ceiling issues for the TAF from now
through late Monday afternoon.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory from 11 AM this morning to 5 PM MST
Tuesday for COZ031.

Winter Storm Warning from 3 PM this afternoon to 5 PM MST
Tuesday for COZ033-034.

High Wind Watch from late tonight through Tuesday morning for
COZ038-042>045-048.

Winter Storm Warning from 8 PM this evening to noon MST Tuesday
for COZ041.

Winter Storm Watch from this evening through Tuesday afternoon
for COZ042-048.

Winter Storm Watch from this evening through Tuesday afternoon
for COZ045-047.

Blizzard Warning from 11 PM this evening to 5 PM MST Tuesday for
COZ046-049.

Red Flag Warning from 11 AM this morning to 6 PM MST this
evening for COZ247.

High Wind Warning from 2 AM to 5 PM MST Tuesday for COZ047.

Blizzard Warning from 2 AM to 5 PM MST Tuesday for COZ050-051.

&&

$$

SHORT TERM...rjk
LONG TERM....Meier
AVIATION.....rjk

NWS BOU Office Area Forecast Discussion