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441
FXUS63 KBIS 191736
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
1236 PM CDT Wed Jun 19 2024

.KEY MESSAGES...

- A slow warming trend into the weekend but seasonably cool
  temperatures continue through Saturday. Warmer Sunday and
  into early next week.

- Hit and miss showers (20 percent) today through Thursday.
  Better chances for showers and thunderstorms (30 to 75
  percent) return Thursday night through Saturday.

&&

.UPDATE...
-- Changed Discussion --
Issued at 1236 PM CDT Wed Jun 19 2024

Fair weather cumulus have begun to develop across the northwest,
so we adjusted cloud coverage in that area accordingly. Winds
have also increase slightly across the northwest as the surface
pressure gradients tightens across far eastern Montana. Some
radar returns are present in southern Saskatchewan, so we`ll
keep an eye on how far south those showers track. Otherwise, no
major changes were needed with this update.

.UPDATE...
Issued at 926 AM CDT Wed Jun 19 2024

Clear skies and calm winds cover western and central North
Dakota. Temperatures continue to rise, and as a result, the
Frost Advisory was allowed to expire at 8 AM CDT. Some low
clouds have also begun to build into the far northwestern corner
of the state, while some cirrus is currently flowing into the
southwestern corner of the state. The forecast largely remains
on track.

.UPDATE...
Issued at 625 AM CDT Wed Jun 19 2024

Mostly clear skies over much of the forecast area this morning.
Chilly in the west with downright cold temperatures southwest.
Scranton looks to be the cold spot so far with a reading of 31.
There were just a couple small patches of fog and they already
look to be diminishing so will not add any fog early this
morning. The Frost Advisory continues through 8 AM CDT or 7 AM
MDT.
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&&

.DISCUSSION...
Issued at 224 AM CDT Wed Jun 19 2024

A broad southwest upper level flow will persist across the
Northern Plains through much of the forecast period. This will
bring a series of waves across the local area but with a low
confidence in the timing and placement of resulting shower and
thunderstorm activity.

In general though it looks to be mostly dry early in the period
(today through Thursday daytime). Chances for showers and
thunderstorms then increase Thursday night through Saturday.

Within the broad southwest upper flow, one could imagine a
southern and a northern track within our local area. Today into
this evening a shortwave will lift through Wyoming and
southeast Montana and into the Dakotas. Another wave is forecast
to lift from Montana into southern Saskatchewan. As surface
high pressure over the forecast area today exits to the east, a
return flow will set up over the western Dakotas and eastern
Montana. CAMS are showing some reflectivities into southwest ND
late this afternoon/evening and northwest ND mainly this evening
and into the early overnight hours. QPF with this activity
looks minimal at best. We utilized the NBM blend for pops but
kept pops broader (3 hour duration) instead of hourly. Impacts
will be minimal with non-zero, but very low probabilities for
thunder.

On Thursday, we start the day mostly dry but we do see moisture
increasing from south to north through the day. Southern
portions of the forecast area will see more clouds and cooler
daytime highs. Low pressure from the Central Rockies moves into
the plains and we see increasing precipitation chances Thursday
evening into Friday across South Dakota and possibly into
southern portions of North Dakota. Meanwhile in the north,
temperatures will be warmer and instability higher in the
Thursday afternoon so a few thunderstorms could be found along
the International Border, but the greatest instability up here
looks to remain over Canada. It`s possible that a good portion
of the forecast area remains dry through a good portion of the
Thursday afternoon into Friday timeframe, contrary to our
current NBM guidance.

As we get into the Friday through Saturday timeframe,
we remain within the aforementioned broad southwest upper flow
but we see some rather significant differences in the
deterministic models. A DESI cluster analysis was not available,
but the WPC Day 3 cluster analysis for the 24 hour period
ending 00Z Saturday shows that the far south central into
southeast ND is, in general, the favored area for qpf
placement, but there are scenarios that would keep this area dry
as well. All scenarios also keep some light precip along or
north of the International border and this could certainly
sneak south into northern portions of the forecast area. On
Saturday there is a signal for a stronger northern wave moving
east along the International Border, which could bring a chance
of showers and thunderstorms. As for the potential for severe
storms, SPC has a general risk in the far west today, which is
covered earlier. Thursday the general risk is situated over the
southern two thirds of the state. Friday there is a marginal
risk just south of the southern James River Valley, with a
general risk pretty much statewide. There is abundant bulk shear
across the forecast area through the period. Thursday and
Friday, instability is highest just to the north and just south
of the forecast area. If we would get a stronger storm either of
these days, it would be favored along either our southern or
northern border. Although instability isn`t great, high pwats
and warm cloud depth is high indicating efficient rainers far
south central into eastern ND Friday-Friday night.

Depending on the timing/placement of the stronger wave on
Saturday, there could be a window for a stronger storm or two.
Overall the risk for strong to severe storms late Thursday
through Saturday looks to be low at this time. With the higher
temperatures Sunday and Monday we will see and increase in
instability and our broad upper level flow and high bulk shear
will remain over the area. Will need to monitor.

As for temperatures. we start out quite cool today but see a
gradual warming trend Through the weekend and into early next
week. There is a signal for some above normal temperatures
Sunday and Monday with some 90 degree readings possible in the
south on Monday. Ensemble spreads are actually not very wide
Sunday into Monday. NBM temperatures drop quite a bit after
Monday, but ensemble spreads also increase significantly, so
confidence in a warm couple of days Sunday and Monday is
pretty high, but whether we cool off significantly thereafter,
or remain warm, is murky at best.

&&

.AVIATION /18Z TAFS THROUGH 18Z THURSDAY/...
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Issued at 1236 PM CDT Wed Jun 19 2024

VFR conditions are present across all terminals, and will remain
VFR through the TAF period. Surface high pressure sits across
the area, with light winds across all sites except KXWA, and some
fair weather cumulus beginning to form in the northwest. KXWA
will see some slightly gusty southerly winds, with some gusts to
around 20 kts possible at times during the day. Lower clouds and
chances for rain begin to build into the far south near the end
of the TAF period.
-- End Changed Discussion --

&&

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

&&

$$

UPDATE...Besson
DISCUSSION...TWH
AVIATION...Besson