729
FXUS65 KBOU 071116
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
516 AM MDT Tue May 7 2024

.KEY MESSAGES...

- Periods of snow and blowing snow today with some travel impacts,
  especially above 10000 feet and across the Park Range/Rabbit
  Ears Pass.

- Widespread gusty winds continue today, with the strongest winds
  expected across the higher Foothills and over portions of the
  Palmer Divide.

- Freezing temperatures will occur over the Palmer Divide late
  tonight and possibly across other areas of the plains as well.

- Cool and unsettled pattern Wednesday through Friday.

- Warming Saturday through Monday with more normal late day
  convective chances

&&

.SHORT TERM /Through tonight/...
Issued at 250 AM MDT Tue May 7 2024

A stg storm system will remain over the wrn portions of the nrn High
Plains with brisk WNW flow aloft across the area.  Cross-sections
show decent moisture in the mtns today with favorable orographics
along with lapse rates around 8 c/km.  In addition, position of
upper level jet may lead to some enhancement of activity as well.
Thus will issue an advisory for all of the mtns.  However, most
impacts will be at or above 10000 ft over the higher passes, as
very windy conditions continue with areas of blowing snow and poor
visbility at times.

Elsewhere, from the foothills across the plains it will be another
very windy day.  Cross-sections show cross barrier flow won`t
be as stg with no mtn wave development shown.  Thus winds should
stay blo high wind criteria in most areas.  There is one potential
area that could see some gusts approaching high wind criteria, for a
few hours early this aftn, across portions of ern Elbert and Lincoln
counties.  However, not sure how widespread it will be along with
duration so have held off on issuing a warning.  Meanwhile, with
position of upper level jet and decent lapse rates can`t rule out a
few higher based showers moving across portions of the foothills and
I-25 Corridor this aftn. As far as highs, will keep readings in
the upper 50s to mid 60`s across nern CO.

For tonight, moisture will linger in the mtns this evening. However,
lapse rates will become more stable so any additional snow should be
on the light side, with decreasing coverage by midnight.  Overnight,
a mtn wave is fcst to develop with cross-barrier flow increasing to
50-60kts.  Thus, there could be a window of stronger winds for a few
hours, in the 06z-12z time period, in the normal windy areas of the
foothills.  At this time, not sure about coverage and duration so
will hold off on a warning.  Finally, last thing to deal with is
freezing temps across the plains late tonight into Wed morning.
Overall, confidence isn`t high as to how widespread overage will be
and duration of freezing temps.  DESI yields the highest threat
across the Palmer Divide so will upgrade this area to a warning.
Across the rest of the plains will leave the watch in place.

&&

.LONG TERM /Wednesday through Monday/...
Issued at 312 AM MDT Tue May 7 2024

The models show a pretty strong upper closed low/upper trough, east-
west oriented, to our immediate north and northwest on Wednesday at
12Z.  Models show this feature to sag slowly southward and over the
northern half of Colorado through Wednesday and Wednesday night. By
Thursday, weak east-west oriented troughing is still over the
state with a closed circulation over the southern Great Basin. The
synoptic scale energy with all this is nothing great for our CWA.
The main effects will be quite a bit of cloudiness from Wednesday
afternoon through Thursday night with cooler than normal
temperatures and a chance of precipitation especially over the
northern half of the CWA. In fact, showers will be likely along
the northern border areas of the alpine zones. At this time, total
snowfall amounts are not significant. The showers should be snow
above 7,000 feet. Instability is lacking on Wednesday with limited
instability over the western CWA by Thursday afternoon. Will
leave the "slight chances" for thunderstorms in. For temperatures,
Wednesday`s highs will mainly be in the 50s over the plains and
20s-30s in the mountains. Thursday`s highs are bit colder over the
plains and tad warmer in the mountains.

For the later days, Friday through Monday, models keep the weak
upper trough across Colorado with the upper closed low still over
the southern Great Basin on Friday. The upper trough moves well
east by Saturday, however, some weak upper circulation remnants
are still progged over the Desert Southwest Saturday and over
Utah on Sunday, then over Colorado on Monday. The airmass warms up
through the four day period. There is weak synoptic scale energy
in place much of the time. The afternoon instability gets better
as well, which is reflected in the QPF fields. Models show late
day convection along with thunderstorms with the best chances
on Monday.

&&

.AVIATION /12Z TAFS through 12Z Wednesday/...
Issued at 512 AM MDT Tue May 7 2024

Winds have been gusty from the west all night. By 15z
they may trend more WNW and continue that way thru
early evening. Wind gusts to 40 mph may occur from
18z through 01z. Winds should gradually decrease
in the evening and eventually become more more WSW
by 07z.  VFR conditions still expected today, however,
a few high based showers may move across in the aftn
with ceilings down to 10000 ft or so.

&&

.FIRE WEATHER...
Issued at 250 AM MDT Tue May 7 2024

Critical fire conditions will be in place this afternoon into
the early evening across southeastern Elbert and southern
Lincoln counties due to very windy conditions and low humidity.
Across the rest of the plains there will be elevated fire
conditions.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until 6 PM MDT this evening for COZ031-
033-034.

Freeze Watch from late tonight through Wednesday morning for
COZ038>040-042>049.

Freeze Warning from midnight tonight to 8 AM MDT Wednesday for
COZ041.

Red Flag Warning from 11 AM this morning to 7 PM MDT this
evening for COZ247.

&&

$$

SHORT TERM.....RPK
LONG TERM......RJK
AVIATION...RPK
FIRE WEATHER...RPK