National Weather Service Forecast Discussion

Thornton Weather Forecast   
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909
FXUS65 KBOU 142331
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
531 PM MDT Wed Oct 14 2026

.KEY MESSAGES...

- Cool, cloudy, and drizzly through tonight.

- Rain and mountain snow becoming widespread tonight, before
  winding down on Thursday.

- Several inches (4-12") of snow expected for the mountains
  above9,000 to 10,000 feet with travel impacts tonight and
  intoThursday morning. Lighter snow and at least a dusting into
  the mountain valleys and higher foothills.

- First freeze of the season expected over most of the plains
  lateThursday night into early Friday morning.

- Drier and warmer again for the weekend and early next week.

&&

.DISCUSSION /Through Wednesday/...
Issued at 111 PM MDT Wed Oct 14 2026

Water vapor satelliteimagery shows the upper level low near the
Four Corners at this time. It is still forecast to track northeast
across Colorado, but models favor a slightlymore northerly track
than earlier advertised. We nudged precipitation amounts down
slightly because of this track shift.Easterly low level flow
continues to produce widespread low clouds and drizzle east to the
Continental Divide. This easterly flow is a downslope component
west of the divideand satellite imagerycurrently shows mostly
sunny skies at this time. As the upper level low nears, ridge top
winds turn more southerly, which should cut off the downslope
flow. The next batch of lift and precipitation is over south
central Colorado and will lift northeast, bringing rain and
mountain snow late this afternoon and evening. Then overnight as
the low shifts over northeast Colorado, northwest flow (more
typical) is expected to leadto orographic lift in addition to the
deformation zone. Meanwhile, eastern Colorado is expected to see
a lull in precipitation, except for continued drizzle. The
deformation zone shifts east over northeast Colorado bringing rain
showers. The heaviest rainfall amounts and best chance for rain
will be over the northern part of the state. If the more northerly
low trend continues, areas along and south of I-70 may see very
little additional precipitation Thursday. Rain and mountain snow
will end Thursday afternoon as the upper level low weakens and
moves east of the area.

The remnants of the upper level low will be northeast of the
State by Thursday evening. Much drier air will move into the area
leading to clearing skies during the evening. This will lead to
good radiational cooling and a chilly overnight period Thursday
night/Friday morning. Most locations are expected to see a frost
or hard freeze therefore, we have issued a freeze watch for
Thursday night and into Friday morning. We maintain a northwest
flow aloft on Friday as a ridge develops to our west and a trough
to our east. Surface high pressure over Colorado will lead to a
sunny day with light winds and cool temperatures for Friday. Highs
will be slightly below normal with readings in the mid to upper
50s.

The ridge to the west moves over Colorado Saturday and we see
ridging continue through Monday. A weak trough passes through the
ridge on Sunday. There`s enough moisture for clouds, but not
enough for precipitation. So we may see a slight dip in
temperatures Sunday with the increase in cloud cover. Highs are
expected to be in the 70s Saturday through Monday, with some upper
60s possible Sunday if cloud cover persists for much of the day.
Southwest flow aloft is expected for Tuesday and Wednesday as a
strengthening trough along the west coast pushes the ridge east of
the region.Temperatures will continue to run above normal under
this pattern with dry conditions persisting. This trough along the
west coast is the next system to watch for precipitation
acrossour area late next week.

&&

.AVIATION /00Z TAFS through 00Z Friday/...
Issued at 516 PM MDT Wed Oct 14 2026

Showers will be likely (70 percent) thru 05z with visibility down
to 2-5sm with the heavier rain. Ceilings will remain generally
blo 1000 ft. From 05z thru 11z expect periods of ceilings below
500 ft with areas of fog and drizzle with visibility if 1-3sm.
There is a chance (30 percent) of lower visibility down to 1/2sm
in fog, especially at BJC for a few hours.

Winds early this evening will be east at DIA with NE winds at BJC
and variable directions at APA. Eventually winds will become more
N/NNE by 05z which will continue overnight.

On Thu, there will be a period of rain between 14z and 18z with
visibility down to 5sm at times times. Ceilings will be in the
1200 to 1500 ft range with and may drop below 1000 ft for a few
hours. After 18z rain chances should gradually decrease. By 22z or
23z ceilings should gradually sct out.

As far as winds, they will be from the north and gradually
increase by 14z with gusts up to 30 mph through the aftn. Winds
should gradually decrease by 23z.


&&

.BOU WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until 6 AM MDT Thursday for COZ031-033-
034.

Freeze Watch from late Thursday night through Friday morning for
COZ038>051.

&&

$$

DISCUSSION...BM
AVIATION...RPK

NWS BOU Office Area Forecast Discussion