National Weather Service Forecast Discussion

Thornton Weather Forecast   
Today's Forecast Story   
000
FXUS65 KBOU 190537
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
1137 PM MDT Mon Mar 18 2024

.KEY MESSAGES...

- Warmer weather, with occasional light mountain snow showers this
  upcoming week.

&&

.UPDATE...
Issued at 802 PM MDT Mon Mar 18 2024

Another clear and quiet night with no adjustments needed to
current fcst.

&&

.SHORT TERM...(This evening through Tuesday)
Issued at 257 PM MDT Mon Mar 18 2024

Quiet weather prevails this afternoon across northeast Colorado.
Surface observations show temperatures in the mid to upper 50s
across the lower elevations. Some of the deeper snowpack areas are
running a bit cooler a the lower 50s. Tonight, expect mainly clear
skies with lows in the upper 20s and 30s for the lower elevations
and teens/20s for the high country. Tomorrow will trend a bit warmer
with some warming in temperatures aloft and decreasing snowpack.
Highs rise into the 60s for the most lower elevation spots with mid
60s across the east plains. The upper level low (that once helped
bring last weeks snow) will slowly shift eastward across AZ. It will
be well south and weaker, but will support lower coverage light snow
showers across the central and southern Colorado mountains in the
afternoon.

.LONG TERM...(Tuesday night through Monday)
Issued at 257 PM MDT Mon Mar 18 2024

Wednesday, the stubborn closed low accelerates eastward through
New Mexico, but the bulk of the remnant moisture stays to our
south. Aloft, weak northwest flow will prevail, and mild
conditions with low elevation highs in the low 60`s along with dry
weather can be expected. The best opportunity for a stray shower
will be for our southern mountains in the afternoon.

Moving into Thursday, a glancing shortwave will produce a shot of
reinforced northwesterly flow and Pacific moisture. As a result, a
few light mountain snow showers should materialize, and westerly
surface winds will strengthen across the northern tier of our
mountains and foothills, when gusts may approach 50 mph for wind-
prone locations. The lower elevations will be warmer under the
effects of the downslope winds, with highs climbing into the mid
to upper 60`s. Highs on Friday will drop just a few degrees
behind the weak surface front associated with Thursday`s
shortwave, but even then temperatures look likely to remain in the
60`s.

Looking ahead at Saturday, the west coast will begin to be
impacted by a developing trough. Over Colorado, flow aloft turns
increasingly westerly with a rise in moisture advection and
increased potential for mountain snow showers, especially later in
the day. Subsidence should keep the plains and urban corridor dry,
and sustain the mild temperatures for another day.

Solutions begin to diverge more considerably for the latter half
of the weekend and particularly into early next week. There is
overall consensus among ensemble means depicting a longwave
trough pushing across the Rocky Mountain region during this
period, and good agreement on the return to unsettled weather,
with ~70-90% of ensemble members (depending on the suite in
question) pointing to some precipitation for the wider Front Range
region as early as Sunday afternoon/Sunday night. Ensemble mean
tracks still aren`t overly favorable for a higher-impact upslope
event (too far north), but the system does look to carry better
potential for colder air and some deterministic solutions such as
the GFS do depict some bifurcation in the flow, with one low
dipping farther south. In any case, the bulk of this event is just
beyond our long term forecast period, so there`s plenty of time to
iron out more details and for things to change.

&&

.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
Issued at 1137 PM MDT Mon Mar 18 2024

VFR to prevail through Tuesday. Skies will be clear through
Tuesday morning and then mid clouds will increase Tuesday
afternoon, mainly over the higher terrain at first. The clouds
then spread eastward through Tuesday evening, with ceilings above
6000 feet. Southerly drainage winds will prevail through about
15-16Z at DEN and APA, then become variable to east for Tuesday
afternoon. Winds return to a drainage direction after 00Z
Wednesday.

&&

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

$$

UPDATE...RPK
SHORT TERM...Mensch
LONG TERM...Rodriguez
AVIATION...Meier

NWS BOU Office Area Forecast Discussion