516
FXUS63 KBIS 181432
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
932 AM CDT Tue Jun 18 2024

.KEY MESSAGES...

- Widespread showers with isolated to scattered thunderstorms
  today.

- Below normal temperatures today and tonight, with frost
  possible tonight. Some temperatures below freezing can not be
  be ruled out in southwest North Dakota. Seasonably cool
  temperatures continue through Saturday.

- Mostly dry Wednesday, then chances for showers and
  thunderstorms return late Thursday through Saturday.

&&

.UPDATE...
Issued at 926 AM CDT Tue Jun 18 2024

Random areas of fog have developed with visibilities jumping all
around, so we just covered the whole area with a mention of
patchy fog through the late morning. With the Minot radar down,
it has been a challenge to have a good handle on the rain
falling in the northern half of the state. PoPs have been
continuously updated.

UPDATE
Issued at 633 AM CDT Tue Jun 18 2024

Scattered showers lingering over the James River Valley with
Light rain over the far west and north central. Overall though,
precipitation has diminished substantially over the past few
hours. The threat for thunder also looks to have diminished as
well. Do expect shower activity to increase today over western
and into central ND with the approach of the upper low over
eastern Montana. Updated text products will be transmitted
shortly.

&&

.DISCUSSION...
Issued at 316 AM CDT Tue Jun 18 2024

Strong convection has exited the southern James River Valley and
the thunderstorm watch has been cancelled. A large area of
stratiform rain with some embedded thunder, extends west into
south central ND, west of the Missouri River, with some strong
northeast winds. This precipitation is expected to exit the area
this morning. However, with upper level low pressure situated
over eastern Montana shower activity will linger through the
day.

High pressure will build over the area tonight bringing clearing
skies. By 12 UTC Wednesday, surface high pressure is situated
over the western Dakotas. Currently the NBM is depicting low
temperatures in the mid 30s to upper across a good portion of
western North Dakota, most notably over southwest ND. MOS based
temperatures support this with mid 30s indicated at both
Dickinson and Hettinger. The NAEFS SA table indicates a high
probability of very dry air over the Mondak region Wednesday
morning. The ECMWF SA page indicates a high probability of cold
temperatures over all of western ND Wednesday morning. The NBM
is currently depicting a rather large area of patchy frost early
Wednesday morning over the southwest, with patchy frost also
extending into portions of the northwest and south central, west
of the River. There is some uncertainty as to the potential for
low level moisture and possible fog/stratus Wednesday morning so
will let the day shift make the call, but would expect a Frost
Advisory, with the potential of some freezing temperatures over
or normally cool areas south and west of the Missouri river and
Lake Sakakawea, and possibly into the northwest as well.

Besides the cold temperatures Wednesday morning, this mid-week
period should be pretty quiet with, maybe a hit or miss shower,
but overall mostly dry conditions Wednesday morning through the
daytime Thursday.

Another upper level shortwave will track from the West Coast,
across the Rockies and into the Northern Plains region late in
the work week and into the weekend. This will bring increasing
chances for showers and thunderstorms late Thursday through
Saturday.

&&

.AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/...
Issued at 633 AM CDT Tue Jun 18 2024

Widespread MVFR to IFR ceilings are expected today across
western and central North Dakota. Isolated shower activity this
morning will increase later this morning and this afternoon
especially west and north central. Thunder can`t be completely
ruled out, but uncertainty is high enough that we will not
include it in any TAF today. MVFR-IFR conditions should begin to
improve to VFR this afternoon into this evening but KBIS and
especially KJMS could see MVFR cigs lingering beyond 06Z.

Breezy northerly winds this morning are expected to gradually
diminish this afternoon and shift more westerly. Winds should
become light by this evening.

&&

.BIS WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$

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