627
FXUS63 KBIS 190929
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
429 AM CDT Wed Jun 19 2024

.KEY MESSAGES...

- Frost Advisory for western and portions of south central North
  Dakota early this morning.

- 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.

&&

.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 appears
to remain over Canada. It`s possible that a good portion of the
forecast area remains dry Thursday afternoon into Friday,
contrary to our current NBM guidance.

As we get into the Friday through Saturday timeframe,
confidence continues to diminish as 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 the
general favorite for qpf placement, but there are scenarios that
would keep this area dry as well. All scenarios also keep some
light precip right along 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. 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
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 /06Z TAFS THROUGH 06Z THURSDAY/...
Issued at 1211 AM CDT Wed Jun 19 2024

Low pressure over the Great Lakes Region will continue to lift
northeast as high pressure builds over western and central ND
tonight.

Low VFR ceilings to begin the 06Z TAF period will clear from
west to east overnight. A few areas of MVFR cigs could be
possible over central ND, as well as some patchy fog in the west
as clouds clear. However at this time confidence is to low to
mention. West to northwest flow to begin the TAF period will
transition to a southeast flow this afternoon/early evening.

&&

.BIS WATCHES/WARNINGS/ADVISORIES...
Frost Advisory until 8 AM CDT /7 AM MDT/ this morning for
NDZ001-002-009-010-017>020-031>034-040>044.

&&

$$

DISCUSSION...TWH
AVIATION...TWH