949
FXUS63 KBIS 202307
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
607 PM CDT Mon Jul 20 2026

.KEY MESSAGES...

- Windy today, with near-critical to critical fire weather
  conditions across much of southwest and south central North
  Dakota.

- A few strong thunderstorms could develop in central North
  Dakota late this afternoon and evening, but severe weather is
  not expected.

- Cooler on Tuesday, then a warming trend commences with very
  hot conditions returning this weekend with high temperatures
  and heat index values potentially above 100 degrees.

&&

.UPDATE...
Issued at 558 PM CDT Mon Jul 20 2026

Isolated thunderstorms continue to drop southeast from Canada
into the northwest and north central portion of the state.
Around 700-900 J/KG of Cape available and moving into some
better bulk shear as cells move south. Could be a stronger cell
with small hail and locally gust winds. Will continue to
monitor. Winds will diminish this evening, with another night of
comfortable temperatures, mainly in the 50s to lower 60s.

&&

.DISCUSSION...
Issued at 200 PM CDT Mon Jul 20 2026

Currently a large upper level high is in the Central Plains
with a ridge building in the Pacific Northwest. In the Northern
Plains quasi-zonal flow with a slight northwest tilt is present.
A small upper level low is about to dig through the Lake
Superior region, with a trailing cold front in southern Canada
to its west. At the surface this cold is present too, currently
nearing the North Dakota border. Ahead of the front is low
cumulus clouds in northern North Dakota, and breezy northwest
winds across the state from the cold front last night. This
evening that cold front might kick off scattered showers and
maybe a thunderstorm in the north and central. With almost no
CAPE but 40kts of shear, a brief strong storm is possible with
small hail.

Tuesday will be the coolest day of the forecast period with
highs slightly below normal in the 70s and 80s as the flow turns
more northwest before the incoming ridge. The rest of this week
however the strong warming trend will start once again. The
current ridge in the Pacific Northwest will slide east to the
Northern Plains with the ridge axis ending up over the western
part of the state on Saturday. A strong thermal ridge will
follow with temperatures at 850mb nearing 100 degrees over the
state on Saturday, with the compressional heating of that air
mixing down, the current NBM highs this upcoming weekend around
105 in the southwest and south central. Looking at the NBM
percentiles, these deterministic values are actually only the
50th percentile. The 90th temperatures are close to 110 in the
south. It is very possible that the NBM currently has a warm
bias because we have been so far above normal in the last few
weeks, and this incoming ridge actually looks a little weaker
and less humid than the last one. Only time will tell on what
high temperatures actually happen. Saturday the ridge breaks
down back to near zonal flow, leading to slight chances for
showers and thunderstorms Saturday with the flow off the
mountains. The rest of the weekend will continue to be very
warm. Heat products will likely be needed again.

&&

.AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/...
Issued at 558 PM CDT Mon Jul 20 2026

High pressure will build over the forecast area through the 00Z
TAF period. Mostly VFR conditions are expected but there will be
scattered low VFR to possibly MVFR clouds around tonight into
Tuesday morning, with a local MVFR ceiling not out of the
question, but uncertainty is too high attim to include in any
TAF site. Strong northwest winds early this evening will
diminish by mid evening, then generally a light northerly flow
through the remainder of the TAF period.

&&

.BIS WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning until 9 PM CDT /8 PM MDT/ this evening for
NDZ034-042-045-046.

&&

$$

UPDATE...TWH
DISCUSSION...Smith
AVIATION...TWH