710
FXUS65 KBOU 311030
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
330 AM MST Fri Jan 31 2025

.KEY MESSAGES...

- Dry and milder Friday.

- Strong downslope winds will develop in the Front Range mountains
  and foothills Friday night through Saturday morning. Gusts up to
  70 mph are possible in the higher foothills.

- Periods of light to moderate snow across the northern mountains,
  with travel impacts possible at times this weekend, mainly over
  the Park Range.

- Potentially very mild Saturday through Tuesday with 60s to low
  70s possible on the plains. Confidence is increasing that
  Monday and Tuesday will see well above normal temperatures.

&&

.SHORT TERM /Through Tonight/...
Issued at 225 AM MST Fri Jan 31 2025

The flow aloft will gradually become more westerly today with some
higher level moisture embedded in the flow by aftn.  Overall, it
will be dry with warmer temperatures as downslope low level flow
develops this aftn.  Based on 850-700 mb temps, readings in the 55
to 60 degree range will occur this aftn over the plains.  The only
exception will be in recent snow covered areas where highs may stay
in the upper 40s to near 50.

For tonight, there will be a gradual increase in moisture after
midnight in the nrn mtns which will lead to a chc of light snow
late, mainly over the Park Range.  In addition, will see gusty winds
overnight over the mtns and higher foothills but speeds will stay
blo high wind thresholds.

&&

.LONG TERM /Saturday through Thursday/...
Issued at 225 AM MST Fri Jan 31 2025

Strong zonal flow will be in place this weekend, with a plume of
Pacific moisture expected to the mountains by Saturday afternoon.
The bulk of the moisture will be just north of the CO/WY border,
but there should be enough orographic lift for snow showers to
develop across the northern mountains during the day Saturday.
Snow levels will likely be pretty high for this time of year -
close to 7kft - and some rain is possible across the mountain
valleys (albeit light). There may be a bit of a break in
precipitation Saturday night before a more organized push of
moisture arrives early Sunday. Strong warm air advection will
raise snow levels closer to 8500-9500ft as ridgetop/650mb
temperatures end up pretty close to -1 to -2C. Snowfall totals
across the northern mountains (COZ031-033) will likely reach
advisory criteria snow, but wanted to hold off for another
forecast cycle to see if there`s any significant model shifts. Any
snow that falls would be blown by the wind... see the next
paragraph.

In addition to the snow, gutsy winds are likely across most of
the higher elevations. Ridgetop flow will hover near 50kt through
most of the weekend with stronger winds aloft. Most of the region
should be in a subsident regime in the right entrance region of
the upper jet streak, with some modest QG subsidence as well.
While this should lead to some mountain wave amplification, pretty
deep moisture depths may end up dampening the wave a bit. In
general, wind gusts of 40-50 mph will be likely, with some 50-70
mph gusts across the higher elevations of the Front Range.

The subsident/downslope flow will also contribute to above normal
temperatures across the region this weekend. Both the ECMWF/GFS
and their respective ensembles have highs in the mid 50s to low
60s across the plains, though some high cloud cover may limit how
warm we get.

As we get into early next week, well above normal temperatures
are favored on Monday and Tuesday. As the day shift mentioned,
there`s still quite a spread in the guidance, as there`s some
uncertainty regarding the position/strength of a backdoor cold
front over northeastern Colorado. The ECMWF is still more bullish
on the warmth here for the metro (~60% of members >70F), but both
ensemble suites still have a wide range of solutions (as cold as
20-30F highs!). There`s an even better signal for warmth on
Tuesday.

Eventually guidance does push in colder air into the region, with
another round or two of mountain snow. A gradual cooling trend is
in the grids which mirrors NBM, along with an increase of PoPs
near midweek.

&&

.AVIATION /06Z TAFS through 06Z Saturday/...
Issued at 1001 PM MST Thu Jan 30 2025

VFR thru the period.  Light WSW winds will become more southerly
by 08z and continue thru Fri aftn.

&&

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

&&

$$

SHORT TERM...RPK
LONG TERM...Hiris
AVIATION...RPK