Area Forecast Discussion
Issued by NWS Bismarck, ND

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FXUS63 KBIS 170948

Area Forecast Discussion
National Weather Service Bismarck ND
448 AM CDT Thu May 17 2018

.SHORT TERM...(Today and tonight)
Issued at 358 AM CDT Thu May 17 2018

A quasi-stationary frontal boundary across northern North dakota
will be the focus for showers and thunderstorms today.

Mid 50s dewpoints are slowly working their way into North Dakota
this morning. By this afternoon instability should approach the
2,000-3,000 J/KG range. This, combined with the nearby front and
upper level wave should produce all the required ingredients for
severe thunderstorms.

Most models depict around 30-40 knots of 0-6 km shear parallel to
the front. This should be sufficient to produce rotating
updrafts. Initially, some discrete storms may develop across
southwest or central North Dakota. If this occurs these discrete
storms have the potential of producing all types of severe
weather...including a few tornadoes. A veering wind profile and
the presence of a nearby boundary, combined with relatively low
LCLs could lead to an initial tornado threat. SPC has placed most
of southwest and south central North Dakota in a slight risk with
a 4% tor probability. However, discrete storms should be
relatively short- lived as they will likely remain rooted to and
train along the boundary. This would favor a quick transition to
convective line segments. Therefore, the severe threat should
diminish somewhat by the evening and favor more of a hail/wind
focus. Very heavy rain is likely in any thunderstorm that develops
with PWAT values around 1.4 inches.

.LONG TERM...(Friday through Wednesday)
Issued at 358 AM CDT Thu May 17 2018

Numerous showers and scattered thunderstorms are expected into
Friday. Depending on how far south the boundary pushes by Friday
afternoon will determine whether or not southeast North Dakota has
much of a severe storm threat. The heaviest rainfall should fall
across south central North Dakota through the James River Valley.
In total 1-2 inches seems plausible. Some isolated locations could
see upwards of 2 inches.

Cooler weather will then be seen for the weekend and scattered
light frost will be a threat both Saturday morning north central
and Sunday morning southwest.

The remainder of the forecast period will see a gradual warming
trend with generally dry weather until Tuesday and wednesday with
scattered showers and thunderstorms.


.AVIATION...(For the 06Z TAFS through 06Z Thursday night)
Issued at 1220 AM CDT Thu May 17 2018

Isolated thunderstorms are possible across western and central
North Dakota tonight into Thursday morning. However, impacts to
any one terminal tonight into Thursday morning are highly
uncertain. Thunderstorm chances slowly increase through the day
Thursday across the area. Numerous thunderstorms are possible
beginning late Thursday afternoon into Thursday night. A few
thunderstorms could be severe across the southwest and south
central. IFR conditions in thunderstorms are likely. MVFR ceilings
will develop across northern North Dakota Thursday afternoon and




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