Area Forecast Discussion
Issued by NWS Bismarck, ND

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FXUS63 KBIS 191414
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
914 AM CDT Wed Jun 19 2019

.UPDATE...
Issued at 914 AM CDT Wed Jun 19 2019

The focus of this update was on increasing PoPs into the 70-100
percent range further east from Linton and Ashley to Napoleon and
LaMoure through the morning, in line with radar imagery which has
rain across that area -- east of what almost any model simulation
would suggest at this point. In contrast, radar imagery supported
reducing PoPs through the morning in northwest and north central
ND. Forcing for ascent will continue to be maximized across south
central ND today, immediately downstream of a vorticity maxima
centered over southwestern ND as of mid morning. Midlevel lapse
rates are modest and lightning production has been rather limited
thus far, though forecast soundings suggest enough bouyancy will
develop through the day for embedded storms. We will continue to
evaluate the potential for additional storm development across
southwestern ND this afternoon, where visible satellite imagery
does suggest enough cloud breaks may exist to support adequate
boundary-layer-based destabilization for initiation.

UPDATE Issued at 630 AM CDT Wed Jun 19 2019

Current satellite and water vapor imagery shows an area of
vorticity across far southwest North Dakota, which appears to be
a developing mesoscale surface low. This low will be the focus for
widespread showers and storms today, which has already begun
showing up on the radar across southern North Dakota. Expecting
showers and storms to continue to increase in coverage and congeal
into what appears to be an MCV-like system later this morning and
into the afternoon hours. This will lead to a prolonged period of
moderate rainfall with pockets of heavy rainfall across south
central North Dakota today. Some areas could see over 2 inches of
rainfall by this evening.

&&

.SHORT TERM...(Today and tonight)
Issued at 242 AM CDT Wed Jun 19 2019

Widespread showers and thunderstorms highlight the short term
forecast, with the heaviest rainfall expected across south central
North Dakota.

The 00z GFS/EURO/NAM show a rather compact, slow moving surface
low developing across the North Dakota/South Dakota border early
this morning, bringing an area of showers and storms to the
southern half of western and central North Dakota. It appears
northwest and north central North Dakota will miss out on most of
the rain from this surface low. The heaviest rainfall amounts are
expected across south central North Dakota, where the CAM models
suggest a prolonged period of moderate to heavy rainfall near the
center of the surface low. Both the GFS and the EURO give much of
south central North Dakota between 1 and 2 inches of rain from
12z Wednesday morning through 00z Wednesday evening. The WPC has
placed this area under a slight risk for excessive rainfall. This
makes sense given the very moist environment suggested by forecast
soundings, with highly anomalous precipitable water values and
very slow cloud layer winds/corfidi vectors. Although soil
moisture in this area is rather low, some minor flooding will
still be possible... mainly in flood prone urban areas.

Although it appears southwest North Dakota will not see much of a
flood threat, there is the possibility for a few strong to
marginally severe storms in this area during the afternoon and
evenings hours. This will be highly dependent on cloud cover
conditions across the southwest today, with severe storms being
much less likely if cloudy conditions prevail. If enough sunshine
and destabilization does occur, then large hail up to the size of
quarters and gusty winds will be possible with the strongest
storms.

The latest blend of model guidance suggests a secondary round of
showers and storms tonight, with more locally heavy rainfall
possible. Areas that see high rainfall amounts today may be more
prone to minor flooding tonight if another round of heavy
rainfall moves over the same locations.

.LONG TERM...(Thursday through Tuesday)
Issued at 242 AM CDT Wed Jun 19 2019

The relatively cool and wet pattern continues throughout the long
term forecast. Expect high temperatures in the 60s and 70s
Thursday through Tuesday.

A shortwave trough rotating around a rather large upper level low looks
to move through North Dakota on Thursday, with showers and storms
mainly across northern and eastern North Dakota ahead of a
frontal boundary. Some areas may see more heavy rainfall on
Thursday, mainly across the eastern third of North Dakota where
the environment will be most favorable for heavy rainfall. The WPC
has places most areas east of the Missouri River under a marginal
risk for excessive rainfall.

The aforementioned upper low looks to stall out across Montana
and western North Dakota on Thursday and Friday, with a large
surface low evident underneath the upper low. This will bring
continued clouds and cooler temperatures with more showers and
thunderstorms. Portions of western and northern North Dakota have
the best chance of receiving the most rainfall Thursday through
Friday as forcing looks to be the most favorable there. The flash
flood threat looks rather low during this time with unimpressive
precipitable water values.

Saturday through Monday are shaping up to be a bit drier as the
surface low and the upper low slowly moves northward into Canada.
With that being said, showers and storms will still be
possible... especially across northern North Dakota.

&&

.AVIATION...(For the 12Z TAFS through 12Z Thursday morning)
Issued at 914 AM CDT Wed Jun 19 2019

An area of IFR to LIFR stratus in southwestern ND will slowly
lift by afternoon. Otherwise, in general VFR to MVFR ceilings are
expected across western and central ND today. Expect widespread
showers and thunderstorms across southwest and south central North
Dakota today, affecting KBIS and KDIK. Further north, showers and
storms will be much more scattered, likely keeping KISN and KMOT
dry for most of today. Locally heavy rainfall is possible across
south central North Dakota through today, including the KBIS
terminal.

&&

.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

UPDATE...CJS
SHORT TERM...TK
LONG TERM...TK
AVIATION...TK/CJS



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