National Weather Service Forecast Discussion

Thornton Weather Forecast   
Today's Forecast Story   
784
FXUS65 KBOU 170907
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
307 AM MDT Tue Mar 17 2026

.KEY MESSAGES...

- Light alpine snow showers, producing a an inch or two of
  accumulation for the higher elevations through this morning.

- Significant warm and dry period ahead from today through
  Saturday. All-time new March record high temperatures a good bet
  for the plains Thursday, Friday and Saturday.

- Hot and dry weather will sustain prolonged high fire danger for
  portions of the plains today and Wednesday, then across much of
  the forecast area Thursday through Saturday.

&&

.UPDATE...
Issued at 257 AM MDT Tue Mar 17 2026

Winds have been gusting in the 50`s and 60`s across mtn and
foothill areas with a few gusts up to 70 mph.  Cross-sections
showed favorable mtn top stability with cross-barrier flow in
the 40-45 kt range. Mtn top stability should decrease by mid to
late morning so expect winds to be not quite as stg.

&&

.DISCUSSION /Through Monday/...
Issued at 1159 PM MDT Mon Mar 16 2026

Current radar shows light snow showers across the northern Front
Range mountains due to lingering mid-level moisture. Expect
scattered snow showers to continue overnight and into early Tuesday
morning, with only a couple of inches in additional accumulation.
With 700-mb winds reaching up to 50-60 kts across the high terrain,
blowing snow is likely through early morning, especially along the
high mountain passes.

Unfortunately, the ongoing mountain snow showers look to be the only
chance of precipitation for the rest of the week. A well-defined
upper level ridge in Southern California will begin to trek east
Tuesday through Saturday, with northwest flow aloft bringing warm,
dry and breezy conditions to the forecast area, along with a
prolonged period of elevated-to-critical fire weather conditions
(see fire weather discussion below).

Anomalous heat will return to the region beginning Tuesday, with
forecasted highs in the low-to-mid 70s across the plains and low
40s to upper 50s across the mountains/valleys. Expect warmer
temperatures later this week as the ridge of high pressure
continues east. Current ensemble solutions favor high temperatures
in the low- to-mid 80s Thursday through Saturday (However, the
GEFS still remains the coolest of the models, with high 70s to low
80s for later this week). With this trend, there is a good chance
we will break record high temperatures later this week. Current
high temperature records at DIA are:

March 19: 81 degrees set in 1907
March 20: 80 degrees set in 1907
March 21: 78 degrees set in 1995

By Saturday/Sunday, flow aloft should weaken and become more zonal
as guidance continues to indicate a shortwave trough trekking across
the northern United States. A cold front associated with the system
should bring cooler air mass to the region, with temperatures
moderating to the low 60s.

&&

.AVIATION /06Z TAFS through 06Z Wednesday/...
Issued at 1115 PM MDT Mon Mar 16 2026

VFR conditions thru the period. Gusty WNW winds up to 35 mph will
continue at BJC thru 08z and then should decrease by 08z. Winds
will then increase again by 15z from the WNW and continue thru Tue
aftn with gusts to 35 mph at times.

DIA will maintain a WSW wind overnight and then turn more WNW
by 16z or 17z with gusts up to 25 mph. By 19z expect a more
NW direction with gusts from 30-35 mph thru the aftn.

APA will be light drainage overnight and then go WSW by 14z.
By 16Z winds will become more westerly with gusts to 25 mph
thru 20z. After 20z expect a more WNW direction with gusts
from 30-35 mph.

By early Tue evening, winds will decrease at all three airports
with wind directions WNW or NW.

&&

.FIRE WEATHER...
Issued at 257 AM MDT Tue Mar 17 2026

Critical fire weather conditions are expected across the northern
and eastern plains today. Modeled Skew-T soundings indicate
breezy northwest winds aloft mixing down to the surface by late
morning/early afternoon. Wind gusts up to 35-45 mph are expected,
with locally higher gusts closer to the Wyoming border. Relative
humidity values will drop down to the mid-teens. A Red Flag
Warning remains in effect from 10 AM through 8 PM and have added
central and southern Weld county to the warning.

Elevated-to-critical fire weather conditions return on Wednesday for
the the northern and eastern plains. With the continued warming,
minimum relative humidity values will range between 9-15% with winds
gusting up to 25-35 mph at times. For this reason, have decided
to issue a Fire Weather Watch. South Park could see elevated fire
weather conditions as well.

For the rest of the week, elevated-to-critical fire weather
conditions are expected across the forecast area due to the
anomalous warm and dry airmass. Recent moisture along the Front
Range mountains should keep fuels from being susceptible to
combustion. However, will need to continue to monitor the next
couple of days.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning from 10 AM this morning to 8 PM MDT this
evening for COZ238-242>244-248>251.

Fire Weather Watch from Wednesday afternoon through Wednesday
evening for COZ238-242>244-248>251.

&&

$$

UPDATE...RPK
DISCUSSION...MAI
AVIATION...RPK
FIRE WEATHER...MAI/RPK

NWS BOU Office Area Forecast Discussion