Area Forecast Discussion
Issued by NWS Bismarck, ND

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FXUS63 KBIS 290452

Area Forecast Discussion
National Weather Service Bismarck ND
1152 PM CDT Sun May 28 2017

Issued at 1152 PM CDT Sun May 28 2017

Latest suite of satellite imagery/high resolution model guidance
along with local/regional and the Canadian radar, all indicate
that a few showers will continue to propagate from north to south
overnight. Per 03z RAP13 and 00z GFS, two distinct shortwaves
currently located in southern Saskatchewan, embedded within the
cyclonic/northwest flow aloft, will slide south through 12z Monday.
Marginal mid level lapse rates of 6.5C/km and weak vertical motion
will likely keep some spotty showers going through sunrise. Thus
will continue with a slight chance of showers for most of central ND.

UPDATE Issued at 924 PM CDT Sun May 28 2017

Latest radar analysis shows showers diminishing in coverage and
intensity across western and central ND this evening. However show
activity does extend well into southern Saskatchewan and Manitoba.
With vorticity translating through cyclonic flow aloft, a small
threat of showers will likely persist through the night,
especially over eastern portions of central ND. Have adjusted
pops accordingly, trimming from the west through the remainder of
the evening and keeping at least a slight chance pop over portions
of the east through the night. No significant qpf amounts
expected. Winds continue to slowly diminish, but have dropped
significantly from early this evening. Did lower pops again over
the far southwest where skies should remain clear with light winds
toward morning.

UPDATE Issued at 642 PM CDT Sun May 28 2017

Vorticity lobe swinging southeast from eastern North Dakota into
west central MN sparked a line of showers and thunderstorms from
northern Minnesota and across the Dakotas. Showers and storms have
now exited ND and continue to track south through SD. Additional
shortwave energy rotating around the upper low will spread another
round of showers and isolated thunder quickly southeast across
western and central ND this evening. Latest mesoscale models are
not as widespread with the convection dropping through this
evening and this looks reasonable so lowered pops a bit. Think
activity will also wane as we lose daytime heating. Pressure fall
rise couplet tracked south through the forecast area today. Mainly
pressure rises across the forecast area early this evening. With
the passage of the couplet and expected decoupling of winds this
evening, gusts with the shower/tstorm activity this evening will
not be as high as this afternoon. However a local gust to around
55 mph can not be ruled out over the next hour or so.

Updated text products will be sent shortly.

UPDATE Issued at 521 PM CDT Sun May 28 2017

Gusty northwest winds will continue into early this evening. An
area of thunderstorms is now just exiting the southern James River
Valley. Pea to dime sized hail were reported with some of the
stronger storms. Thunderstorms and even showers have been
producing locally gusty winds to 50 mph. As noted in previous
discussion, environment is favorable for gusty winds today. Even a
few reports of low visibilities in blowing dust this afternoon.

Another area of showers and thunderstorms is pushing into the
northwest and north central portion of the state at this time, and
will continue to move southeast through mid evening. Atmosphere
here is more stable and the threat for severe storms is even lower
than with the first wave of convection. However, we will still
have the potential for locally gusty winds these small cells as
well, some which could gust over 50 mph.

Made some adjustments to pops/sky cover based on latest radar and
satellite imagery.


.SHORT TERM...(This afternoon through Monday)
Issued at 201 PM CDT Sun May 28 2017

Convection this afternoon and evening highlights the short term

Just like Saturday, high based convection with strong and deep
unidirectional environmental wind profiles and inverted-v
thermodynamic profiles are supporting effective momentum transfer
and parcel acceleration to the surface with wind gusts in excess
of 40kts being observed with showers and thunderstorms. This will
continue through the early evening central, reinvigorated by a
shortwave that will propagate southeast out of Saskatchewan. With
MUCAPE between 500-1000 j/kg and effective deep layer shear around
25-30kts, small/sub-severe hail is possible, with unidirectional
shear profiles limiting storm organization.

Memorial Day Monday will be similar to Saturday and Sunday under
continued cyclonic flow aloft. This means another windy day with
diurnal convection.

.LONG TERM...(Monday night through Sunday)
Issued at 201 PM CDT Sun May 28 2017

A potential warming trend for mid to late week highlights the
extended forecast.

The 12 UTC global suites are in agreement on cyclonic flow across
the Northern Plains potentially being replaced by shortwave
ridging by Thursday. This would favor a possible warm up Wednesday
into Friday, with highs in the 80s favored for Thursday.
After Friday, model certainty begins to break down. However, there
is some signal for much needed precipitation on Friday into
Saturday as the upper level ridge begins to break down.


.AVIATION...(For the 06Z TAFS through 06Z Monday night)
Issued at 1152 PM CDT Sun May 28 2017

Low vfr/mvfr cigs covering most of eastern Saskatchewan and
Manitoba, continue to advance south into north central ND as of
this writing. Expecting cigs deteriorating to mvfr at KMOT
(09z-13z Monday) and at KJMS (09z-17z Monday). KBIS will be on
the western fringes for mvfr cigs, but for now have opted to
maintain vfr with cigs at 3500feet agl. Scattered showers will be
favored at KJMS Monday, whereas isolated showers will extend back
into KMOT/KBIS. Another round of gusty northwest winds of between
20kt and 30kt can be anticipated Monday afternoon.




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