FXUS63 KBIS 250603

Area Forecast Discussion
National Weather Service Bismarck ND
103 AM CDT Sun Aug 25 2019

Issued at 1233 AM CDT Sun Aug 25 2019

Lines of thunderstroms with heavy rain across the north central
this past evening are decreasing fairly rapidly in intensity now,
coincident with the NAM/GFS models CAPE and Shear forecast. With
this trend ongoing trimmed the POPs early this morning north and
east. Also lowered the min temperatures for Sunday morning.

UPDATE Issued at 924 PM CDT Sat Aug 24 2019

Scattered thunderstorms are slowly moving northeast through
portions of western North Dakota. The strongest of these are
currently in Mountrail and Ward Counties. Expecting the threat of
severe weather to taper off throughout the night as instability
decreases before a better chance tomorrow. Updated precipitation
chances and winds, but the overall forecast remains steady.

UPDATE Issued at 640 PM CDT Sat Aug 24 2019

Strong to severe thunderstorms are possible throughout the
evening, with northwest ND the current area of activity. Plenty of
instability helping with vertical growth, but lack of shear is
leading to storms being vertically stacked and collapsing on
themselves not long after they form, except for one storm moving
through Mountrail County. Mesoanalysis shows the best shear is in
central North Dakota so if convection makes it that far, could
start to see some longer- lived storms in the next few hours. Main
updates have been pops and sky cover in line with radar/satellite


.SHORT TERM...(This evening through Sunday)
Issued at 216 PM CDT Sat Aug 24 2019

A slow moving surface frontal system and upper level trough will
track slowly across the Dakotas tonight and tomorrow. A very
moist boundary layer is in place ahead of these features. Showers
and thunderstorms are likely late this afternoon/evening across a
good portion of western and central North Dakota. Some severe
storms are possible with 2000+ J/KG CAPE in place, but the main
limiting factors today in whether more robust storms develop will
be relatively weak shear and whether or not storms will be
elevated or rooted in the boundary layer. Therefore, there is
only a marginal risk of severe storms today/tonight.

Sunday we will see the slow moving cold front in central North
Dakota become the focus for thunderstorm initiation, and as the
day progresses, CAPE and shear will increase. The latest 12 UTC
model runs differ widely as to how much a cap could be in place
tomorrow and therefore the coverage and intensity of storms. Flow
across the cold front could support upscale growth into a linear
MCS with strong winds later Sunday evening. A very moist boundary
layer and high precipitable water values mean any storms that do
form will likely produce very heavy rain.

.LONG TERM...(Sunday night through Saturday)
Issued at 216 PM CDT Sat Aug 24 2019

Sunday night, the main complex of thunderstorms will depart the
region, with scattered leftover showers and thunderstorms east and

On Monday, breezy northwest flow will bring in some cooler air,
but scattered showers and thunderstorms remain possible as an
embedded short wave trough moves through. Highs Monday will be in
the upper 60s and lower 70s.

The remainder of the week we will be firmly entrenched in the
cooler northwest flow, keeping temperatures in the 60s and lower


.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
Issued at 1233 AM CDT Sun Aug 25 2019

Low pressure and an associated cold front in eastern Montana will
move east today. The front will be the focus for thunderstorms as
it moves east across the state. A line of thunderstorms is
forecast to form this afternoon and move into eastern North
Dakota by late this evening. The best chances for thunderstorms
will be from KBIS-KJMS between 22 and 06z. MVFR ceilings are
expected at KJMS until 22z. VFR elsewhere.




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