524
FXUS63 KBIS 012225
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
525 PM CDT Mon Jul 1 2024

.KEY MESSAGES...

- There is a Marginal Risk (level 1 of 5) to Slight Risk (level
  2 of 5) for severe thunderstorms through this evening for much
  of western and central North Dakota, excluding some
  northwestern portions. The main hazards are hail up to ping
  pong ball size and wind gusts up to 60 mph.

- Isolated to scattered thunderstorms possible Tuesday and
  Wednesday. An isolated severe thunderstorm is possible
  Wednesday, mainly in the southwest.

- The chance for showers and thunderstorms on Independence Day
  is 60 to 80 percent across all of western and central North
  Dakota.

&&

.MESOSCALE...
Issued at 525 PM CDT Mon Jul 1 2024

Around 445 PM CDT, multiple reports of funnel clouds were
received north and east of Minot. Even though there is a risk
of severe storms, these funnel clouds were not associated with
that threat. Rather, they formed from developing showers/weak
thunderstorms along a vorticity-rich surface boundary that is
trackable on KMBX radar. These funnel clouds are very unlikely
to reach the ground and cause any damage. The risk for funnel
clouds will translate eastward into western McHenry County. A
Special Weather Statement has been issued to address the funnel
clouds.

Thunderstorms farther to the south are not intensifying as expected.
The 20Z special RAOB from Bismarck only sampled -10 J/kg SBCIN, but
since then, low clouds have expanded, and the temperature at
Bismarck has fallen around 3-5 degrees Fahrenheit. So far, there
have been no notable reports of any winds or hail whatsoever,
although dual-polarization radar data has suggested smaller, rain-
coated hail at times. We have also seen bowing segments with
favorable 0-3 km shear vector orientation fail to produce even 40
mph gusts. So it appears that the stable boundary layer has greatly
limited the severe potential thus far.

At 515 PM CDT, a line of semi-discrete storms was building northeast
over Lake Oahe into Emmons County. These storms show some mid-level
rotation on radar, and shear vector orientation orthogonal to
the boundary could promote a continuation of the semi-discrete
mode. The downstream environment does contain increasing low
level SRH, but is also likely more stable per SPC mesoanalysis
and satellite imagery inference.

So far, storms have been progressive. But rainfall rates as high as
1 to 1.5 inches per hour have been reported, and the 20Z Bismarck
RAOB sampled 1.62" precipitable water. Any areas that receive
multiple rounds of storms this evening will have a localized risk
for flash flooding.

&&

.DISCUSSION...
Issued at 314 PM CDT Mon Jul 1 2024

Cold front is still expected to bring showers and thunderstorms
through this evening. Isolated to scattered severe thunderstorms
are still expected. Main threats will be hail up to ping pong
ball size and wind up to 60 MPH. These threats could be high if
storm mode takes on more discrete characteristics. For the
latest breakdown on the environment see the mesoscale
discussion. Timing wise look for these stronger storms to get
going mid to late afternoon then pushing eastward through the
evening. Some breezy southerly winds are possible through this
evening ahead of this front, although winds have generally
trended lower than previous forecast today. Most of the severe
weather will exit or dissipate tonight. A broad trough lingering
in the north could bring an isolated shower or perhaps
thunderstorm in these areas tonight, with a low threat for
severe weather. Low temperatures tonight will generally be in
the 50s.

This broad trough then looks to linger across the state on
Tuesday, and perhaps bring a secondary cold front Tuesday
afternoon through the evening. The result will be isolated to
scattered thunderstorm chances through the day, with higher
chances in the north. Instability and shear are limited for
Tuesday, thus severe weather is not expected at this time. Look
for temperatures in the 70s. Breezy northwest winds are also
possible for Tuesday. The upper level winds are not
particularly strong, and ECMWF EFI values are fairly low. Thus
advisory level winds are not expected at this time. A quiet
night with lows in the 50s are then expected for Tuesday night.
Another broad trough still looks to push across the state on
Wednesday. This could bring more scattered chances for showers
and thunderstorms. Instability still looks somewhat limited
although shear is increased on this day. Perhaps an isolated
stronger storm is possible, especially in the south. SPC
currently has a Marginal Risk in the southwest. High
temperatures on Wednesday will warm slightly in the mid 70s to
mid 80s.

The broad trough could still develop a cutoff low across the
region on Independence Day. This could still bring widespread
showers and thunderstorms. Of note that some clusters have this
low further south which would bring less rain to the are. This
southern solution equates to about a 40% chance of occurring,
with a 60% chance of the low maintaining a similar track that
has been forecasted. Either solution would bring cooler
temperatures to the area in the low to mid 70s. Clusters then
show northwest flow through the Holiday weekend, although a
building ridge in the west could attempt to push more eastward
later in the weekend. Temperatures could warm to near normal as
a result, and perhaps slightly warm if the ridge can build
further inland. Chances for showers and thunderstorms will be
found each day, with the potential for waves to traverse through
this northwest flow. CSU-MLP pops for severe weather are low
for severe weather during this time period.

&&

.AVIATION /18Z TAFS THROUGH 18Z TUESDAY/...
Issued at 110 PM CDT Mon Jul 1 2024

Chances for showers and thunderstorms will increase this
afternoon and linger through this evening. MVFR to perhaps brief
IFR conditions will be possible with these storms. Some MVFR
ceilings may also be possible this afternoon ahead of these
storms. Strong winds and large hail will also be possible with
any stronger storm. Thunderstorms then push eastward tonight,
with VFR conditions generally returning. There could however be
some lingering MVFR ceilings through the night and into Tuesday
morning. An isolated shower or thunderstorms is also possible
tonight into Tuesday morning across the north, although
confidence is not high enough to include at this time. Breezy
northwest winds are also expected to return on Tuesday.

&&

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

&&

$$

MESOSCALE...Hollan
DISCUSSION...Anglin
AVIATION...Anglin