Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 271751
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
1151 AM MDT Wed Mar 27 2024

.KEY MESSAGES...

- Scattered light snow showers in the mountains today. Warmer
  across the plains.

- Mainly light snow in the mountains Thursday night, then
  occasional snow showers in the mountains and scattered showers
  for the northern plains through Saturday.

- Mountain snow, with a mix of rain and snow likely for the
  plains, late Sunday into Monday. Mostly light but there could be
  some impact for the mountains and foothills.

&&

.UPDATE...
Issued at 1038 AM MDT Wed Mar 27 2024

Fairly quiet morning. A few snow showers are ongoing over the
higher mountains. Day Cloud Phase satellite show cumulus clouds
developed over the high country as temperatures warm and lapse
rates steepen more. Forecast is still on track for light
orographic snow showers in the mountains through early this
evening. As for the plains, little cloud cover around this
morning. Temperatures are warming past the recorded highs
yesterday which puts us on track for a warmer day with highs in
the 50s across the plains & urban corridor.

&&

.SHORT TERM /Through tonight/...
Issued at 428 AM MDT Wed Mar 27 2024

NW flow aloft will be in place today with some moisture embedded in
the flow.  Once again, decent lapse rates combined with favorable
orographics will lead to light snow shower activity in the mtns.
Across the plains, there may be some virga this aftn but overall it
should be mainly dry. Highs this aftn will be in the lower to mid
50`s over nern CO.

For tonight, the flow aloft will become more WNW with a decrease in
moisture.  This will end the threat of snow showers in the mtns.
Overnight, a mtn wave will develop with cross-barrier flow
increasing to 35-40 kts.  This will allow for gusty winds to occur
over the favored windy areas of the mtns and foothills.  However,
gusts should stay blo high wind criteria.

&&

.LONG TERM /Thursday through Tuesday/...
Issued at 428 AM MDT Wed Mar 27 2024

Model trends are leading towards a little cooler temperatures,
along with higher PoPs over the mountains and northern border
areas for Thursday through Sunday. The jet-related lift does not
lift north quite as far as was earlier predicted, keeping some
moisture over northern areas and after one wave along the mid
level front Thursday night, another ripple with some lift late
Friday. There is also enough moisture and instability for some
diurnally driven showers. All of this also feeds a tendency for
cooler low level air on the plains as the cooler air that drops
down behind the Thursday night wave doesn`t get displaced as
thoroughly and the low level convergence stays over our area,
likely helped by a Denver cyclone developing Saturday forcing the
convergence over our area. Most of the jet-driven showers should
stay north of Denver, though with the cyclone boundary there could
be a better chance Saturday night and Sunday.

For the large trough in the Sunday night/Monday time frame, the
trends are towards a less coherent trough passage. There should be
a time window where there`s moisture and lift. With cool low level
air likely coming in earlier (Sunday afternoon or evening) and low
level convergence in place, it`s looking like the earlier part of
the trough will be the most productive, mainly Sunday night into
Monday. There`s pretty good agreement now on the precip being over
Monday night even in the runs that have a decent shortwave behind
the northern stream trough Tuesday--it`s in drier air behind the
main trough axis. Ensemble members continue to have a trend
towards slower/weaker with the southern part of the trough than
the operational runs, and notably weaker with the northern part of
the trough. That also hints at a lower chance of a significant
snow, although there`s still pretty good consensus on at least a
quarter inch of precipitation as the main area of lift passes.

NBM presents most of these trends pretty well, although we did
load in PoPs from a later NBM run and then bump them up a little
more in the prime time Sunday night and Monday to focus on that
window. The trend is also away from cold, and the timing would
bring the precip through before it could get cold enough to
definitively say snow. Monday morning could be a mixture in the
I-25 corridor, or possibly even just rain. The foothills should
have mostly snow and there`s still potential for a short period of
focused upslope for brief heavy snow. All in all, it looks like a
quick shot of wet spring snow, with the odds of an impactful event
low for the foothills (<40%) and quite low (<20%) for Denver, with
the main threat time Monday morning.

&&

.AVIATION /18Z TAFS through 18Z Thursday/...
Issued at 1146 AM MDT Wed Mar 27 2024

VFR conditions expected for the TAF period. Winds are turning SW
to WSW late this morning. Winds become W/NW by mid afternoon at
07-11 kts. Winds turn back west then to drainage between 00z and
04Z. Healthier drainage establishes closer to 06Z at 08-12 kts.
SSW flow continues Thursday morning.

&&

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

&&

$$

UPDATE...Mensch
SHORT TERM...RPK
LONG TERM...Gimmestad
AVIATION...Mensch


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