077
FXUS63 KBIS 050237
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
937 PM CDT Thu Jul 4 2024

.KEY MESSAGES...

- Scattered showers and isolated thunderstorms will continue to
  diminish through this evening.

- The story will be much of the same Friday through Sunday with
  daily chances (30 to 60 percent) of showers and scattered
  thunderstorms. The entire day will not be a washout for most,
  as much of the activity will be of the "hit or miss" variety.

- A gradual warming and drying trend is expected to begin next
  week.

&&

.UPDATE...
Issued at 937 PM CDT Thu Jul 4 2024

Convection continues to diminish this evening, although we still
have a few areas with persistent lightning, primarily in the
Ward and McHenry County areas. There are some showers moving
south towards the Bismarck/Mandan area, but hoping those
continue to dissipate, and worst case only bring some light rain
in the next hour or two. Latest trends and high- res guidance
indicate showers and isolated thunderstorms should be completely
done across the forecast area by 7 or 8 UTC, although by
midnight most locations will not be seeing any additional rain.
Freshened up POPs through tonight based on this, and also used
latest blended guidance for POPs through the day Friday, with
additional hit and miss showers and thunderstorms expected
through the day.

UPDATE
Issued at 643 PM CDT Thu Jul 4 2024

Scattered showers and thunderstorms continue on the northwest
side of a deep upper low analyzed in central Minnesota early
this evening. The good news is that over the past hour or so,
radar returns have begun to noticeably diminish as we lose our
diurnal heating. We did update POPs but it is a bit tricky since
although there are upstream storms in the southern Canadian
Prairies, we aren`t expecting them to last too much longer once
they cross into northern North Dakota. Tried to broad brush
precipitation chances with the potential trending down through
the evening, and especially once we get past midnight.

We continue to monitor any localized flooding potential, with
multiple reports of heavy rain rates with these storms (at least half
an inch of rain in 10 to 15 minutes, for example). The
combination of slow-moving storms from limited flow aloft, and
occasional areas of training, have caused some concern across
areas in the south central as well as northeast of Williston.
The expectation is that as the current showers and storms
diminish, any remaining flood potential will end across the
area.

&&

.DISCUSSION...
Issued at 200 PM CDT Thu Jul 4 2024

Western and central North Dakota currently sits under the
influence of a broad upper low overhead and an expansive
amplified ridge to our west. Cyclonic flow will maintain
numerous showers and scattered thunderstorms through the
afternoon and into the evening across most of western and
central North Dakota. These storms will be your typical
popcorn/hit or miss summertime thunderstorms with a skinny CAPE
profile and very low shear. However, we have started to notice
a bit of a training trend, especially along the line from just
southeast of Harvey, down to near Moffit. MRMS estimates we`ve
seen anywhere from an inch to 2.5 inches of rain along this line
of storms in the past couple of hours. There may be some small
hail contamination with a few storms but reports suggest these
are efficient rain producers with some rainfall rates of 1 to 3
inches or greater an hour. If sufficient training can maintain
itself, a localized flooding environment here could end up
materializing through the afternoon. Thus far, MRMS Crest Unit
Streamflow has only shown minimal response.

Showers and storms will last into the early evening but should
start to diminish with the loss of diurnal heating. Lows tonight
will be in the 50s under a partly to mostly cloudy sky.

The upper low kicks out to the east by Friday morning and low
amplitude ridging moves quickly across the state through the
first part of the day. A subtle shortwave embedded within the
larger western US ridge will approach in the afternoon hours,
leading to another thunderstorm environment similar to today
with some decent instability but little to no shear. Coverage
will be similar, very hit or miss with popcorn convection. Rinse
and repeat on Saturday as another compact upper low rides down
the western ridge and brings us yet another round of popcorn
convection.

The western ridge then finally starts to nudge closer to us on
Sunday, shifting the best chances of scattered showers and
storms to the eastern half of the forecast area. Highs will be
in the 70s through Sunday.

By Monday, we start to dry out as the ridge continues to
approach. This will also help warm temperatures through the
week. We start off with highs in the mid 70s to lower 80s on
Monday, warming into the 80s and possibly even some lower 90s by
mid to late week. NBM temperature spread is very low
considering the time frame so it seems like ensembles are in
fairly good agreement that this western ridge will be a main
driver for our weather pattern next week.

&&

.AVIATION /00Z TAFS THROUGH 00Z SATURDAY/...
Issued at 643 PM CDT Thu Jul 4 2024

Hit or miss thunderstorms will slowly diminish through the
evening, expecting to end by around 06Z at all terminals.
Severe storms are not expected but the strongest storms may
produce locally heavy rainfall and small hail. If a heavier
storm moves overhead, brief MVFR to IFR visibilities will be
possible. Ceilings are generally VFR at all terminals, although
can`t rule out a brief period of MVFR ceilings, especially in
areas of precipitation. Winds may become gusty and erratic in and
around any thunderstorms. Chances for precipitation return
Friday afternoon, and we did include VCTS at KDIK/KXWA during
this time with this update. However, precipitation
chances/timing late in the TAF period will be similar to today,
where it will be scattered hit or miss showers and
thunderstorms with low predictability.

&&

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

&&

$$

UPDATE...Jones
DISCUSSION...ZH
AVIATION...Jones