611
FXUS65 KBOU 200531
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
1131 PM MDT Sun Apr 19 2026

.KEY MESSAGES...

- Dry and unseasonably warm weather continues through Wednesday.
  Highs will be nearly 20 degrees above normal Tuesday and
  Wednesday.

- Critical fire weather conditions likely on Wednesday due to
  increasing winds and very low humidity, with elevated to critical
  conditions lasting into Thursday.

- Pattern change to cooler and unsettled weather Friday through the
  upcoming weekend.

&&

.DISCUSSION /Through Sunday/...
Issued at 1028 PM MDT Sun Apr 19 2026

No significant changes were made to this forecast package, as the
general synoptic pattern remains largely unchanged. Upper-level
ridging will keep warm and dry conditions in place over the forecast
area through mid-week, with widespread critical fire weather
conditions expected for Wednesday afternoon and evening when
gusty southwest winds are expected ahead of our next upper- level
disturbance, and likely persisting into Thursday. Only subtle
differences are noted in the latest guidance outputs, keeping
higher confidence in the current forecast. While no significant
precipitation events are on the horizon, a more active pattern
looks to persist through the forecast period, with a few shots at
some mountain snow and rain for the plains.

This evening`s upper-air maps show the upper-level ridge axis is now
situated along the spine of the Rocky Mountains. This feature will
be responsible for a few days of warming temperatures and tranquil
weather across the forecast area as it remains overhead through
Tuesday. Under the ridge, warmer temperatures are expected each day
as 700 mb temperatures gradually warm by a few deg C through
Tuesday, maintaining for Wednesday afternoon, and cooling
significantly Wednesday night. Afternoon highs will warm into the
upper 70s and low 80s across the plains on Monday, with our mountain
valleys seeing highs in the 60s. Temps will be slightly warmer on
Tuesday, and max out on Wednesday as downslope winds strengthen due
to a deepening lee surface trough. Some locations will see
afternoon highs 12F to 25F above seasonal norms. A cold front is
expected on Wednesday night that will bring temperatures back to
near seasonal norms for Thursday, and the cooler temps are
expected to stick around through the weekend, likely dropping to
below seasonal norms.

By Tuesday night, southwesterly flow aloft will increase as an
upper- level trough quickly approaches the Intermountain West and
pushes the ridge to our east. This will set us up for some
significant fire weather conditions developing for Wednesday as
gusty southwest winds are expected to mix down to the surface
where very low relative humidity values will be in place.
Widespread 30 to 40 mph wind gusts are likely across the forecast
area where single digit RH is expected across the plains, and low
teens across the foothills and mountain valleys. While moisture is
expected to increase across the northern mountain valleys through
the evening, the plains and South Park won`t see any significant
RH recoveries overnight (only 30- 40%), and highlights may be
needed through late Wednesday night as winds stay elevated as
pressure gradients become tightest in the evening hours. See more
in Fire Weather Discussion below. With the poor RH recoveries
overnight, elevated to critical fire weather conditions will
likely persist into Thursday as winds remain elevated.

Light precipitation chances will be possible Wednesday night as the
trough pulls some mid-level Pacific moisture into the mountains, but
the plains will be battling downslope drying that will limit precip
to the high country. Persistent precip chances look likely into
the weekend as an upper-level low meanders about across the
northern tier, with multiple smaller scale disturbances keeping
elevated Pacific moisture flowing into Colorado.

&&

.AVIATION /06Z TAFS through 06Z Tuesday/...
Issued at 1129 PM MDT Sun Apr 19 2026

VFR conditions will continue. Drainage winds overnight will become
light and variable by 16z. Winds by 19z will become light east and
then shift to light southeast after 02z.

&&

.FIRE WEATHER...
Issued at 1028 PM MDT Sun Apr 19 2026

High confidence in significant fire weather conditions developing
Wednesday as gusty southwest winds are expected to mix down to
the surface where very low relative humidity values will be in
place. Widespread 30 to 40 mph wind gusts are likely across the
forecast area where single digit RH is expected across the plains,
and low teens across the foothills and mountain valleys. While
moisture is expected to increase across the northern mountain
valleys through the evening, the plains and South Park won`t see
any significant RH recoveries overnight (only 30- 40%), and
highlights may be needed through late Wednesday night as winds
stay elevated as pressure gradients become tightest in the evening
hours. With the poor RH recoveries overnight, elevated to
critical fire weather conditions will likely persist into Thursday
as winds remain elevated, mainly for South Park, the foothills,
and the plains where RH will range from 10 to 15% coinciding with
gusty northwest winds ranging from 30-45 mph.

&&

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

&&

$$

DISCUSSION...9
AVIATION...RPK
FIRE WEATHER...9

NWS BOU Office Area Forecast Discussion