863
FXUS65 KBOU 202019
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
219 PM MDT Fri Mar 20 2026

.KEY MESSAGES...

- All-time March record high temperatures broken on Thursday will
  almost certainly be broken one or two more times through
  Saturday.

- Heat peaks on Saturday with all time March records being broken
  by several degrees! A few locations may see 90F Saturday
  afternoon.

- Prolonged elevated to critical fire weather conditions due to
  record heat and extremely low humidity levels. Saturday is still
  shaping up to be the most widespread critical day as winds
  increase.

- Brief drop to near normal temperatures Sunday.

- Return of unseasonable warmth, potential record heat (>70%
  chance), and more fire weather concerns again by Tuesday and
  Wednesday.


&&

.DISCUSSION /Through Friday/...
Issued at 145 PM MDT Fri Mar 20 2026

There`s only so much we can write about with the ongoing pattern.
A relentless upper level ridge continues to sit over the desert
southwest, but will start to flatten later today into Saturday.
High temperatures will end up near all-time record highs for
March (and, in some cases would be record highs for April!)
through Saturday.

The flattening upper level ridge will lead to increasing zonal
flow aloft... leading to an added downslope component to the
low/mid-level flow as those winds mix down late Saturday morning
into Saturday afternoon. Mid-level temperatures are expected to
warm another ~2C (near +14-15C), which would translate to high
temperatures about 5F warmer than yesterday/today. Exactly how
much wind mixes down Saturday will determine if we do see a
couple >90F temperatures across the plains, and will also have
implications for fire weather concerns across the lower
elevations. Unfortunately, there isn`t a well-defined signal for
this across today`s guidance. The HRRR/RRFS solutions are
generally favored in this period... where winds may be slow to
develop across the plains but do pick up enough by the mid-
afternoon for at least a few 90s across the Denver metro.

We`ll see some relief from the heat Saturday night as a cold front
pushes across the plains, leading to a more mild (but still above
normal) temperature forecast for Sunday. Highs are expected to
remain in the upper 60s to low 70s. Guidance has generally backed
off on the amount of moisture to work with, with little (if any)
precipitation expected across the higher elevations.

Ridging will start to build back across the southwestern CONUS
by early next week, with Colorado remaining on the
north/northeastern periphery of the thermal ridge. Modest west-
northwest flow aloft should allow for at least a little added
warming from downslope winds... with highs in the 70s on Monday,
near 80F Tuesday, and potentially as warm as the mid/upper 80s on
Wednesday. NBM probabilistic/percentile data appears to be,
somewhat inexplicably, far warmer than the deterministic NBM and
most of the available 12z ensemble members. Our forecast lies on
the cool side of the NBM forecast, but is probably a little
warmer than it should be.

There are mixed signals by later in the week. Another shortwave
does attempt to impinge on the ridge by Thursday or Friday, with
most guidance attempting to push another cold front in Thursday.
However, there appears to be a gradual trend to hold onto the
above normal temperatures through Thursday. That shortwave may
have enough moisture associated with it for a few scattered
rain/snow showers across the higher elevations, but ensemble
guidance continues to look rather dry through the end of the
month.

&&

.AVIATION /18Z TAFS through 18Z Saturday/...
Issued at 1155 AM MDT Fri Mar 20 2026

VFR conditions expected for the TAF period. Light winds will turn
to the north or northeast this afternoon at DEN and APA. Light
winds will continue tonight with drainage flow overnight. Winds
will be weak and out of the wst for the majority of the day on
Saturday. By the mid to late afternoon, gusty westerly winds will
develop at all terminals. Gusts could reach 25 knots at APA and
DEN and 30 knots at BJC.

&&

.FIRE WEATHER...
Issued at 145 PM MDT Fri Mar 20 2026

Elevated to critical fire weather conditions will continue through
this evening, and become more widespread on Saturday. Red Flag
Conditions have been observed at the Buckeye RAWS and at the AWOS
sites located around the Pawnee Grasslands, and this should
continue through the rest of the afternoon hours.

As zonal flow increases on Saturday, widespread critical fire
weather conditions are expected to develop. Winds will first start
to mix down to the surface across the high mountain valleys and
Front Range foothills by mid/late morning, before spreading
eastward into the I-25 corridor and plains by early/mid afternoon.
There is some question as to how far east winds manage to spread,
with the I-76 corridor serving as the general cutoff point for Red
Flag conditions.

A cold front should bring a brief period of improved conditions
Saturday night and Sunday, but well above normal (potentially
record high) temperatures are expected to redevelop next week.
Elevated to critical fire weather conditions will be possible each
afternoon, depending on how much wind spreads across the forecast
area.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning from 11 AM to 10 PM MDT Saturday for COZ211-
213>216.

Red Flag Warning until 7 PM MDT this evening for COZ238-242.

Red Flag Warning from 2 PM to 10 PM MDT Saturday for COZ238>245-
248-250.

&&

$$

DISCUSSION...Hiris
AVIATION...Danielson
FIRE WEATHER...Hiris

NWS BOU Office Area Forecast Discussion