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fxus63 kfsd 170355 

Area forecast discussion
National Weather Service Sioux Falls South Dakota
1055 PM CDT sun Jun 16 2019

Short term...(this evening through monday)
issued at 430 PM CDT sun Jun 16 2019

Elongated upper level low with several impulses shearing through
the flow was located along the international border at mid-afternoon.
A secondary frontal boundary was pushing slowing southeast from
northwest Minnesota into northeast SD, likely nearing khon based on
satellite, but hard to define otherwise with only subtle changes in
the wind field across South Dakota. Has heated out nicely after the morning
lower clouds/fog, with most areas upper 70s to lower 80s, and
despite mixing out some of the moisture, still suggestions in
modified hrrr/RUC profiles that there could be a little MLCAPE of
300-500j/kg. Have yet to see much more than an angering of the
cumulus field in some areas, but starting to see a few pre-shower
returns near the front near khon. Still possible to see a few
showers or even a rogue rumble of thunder near/east of the Buffalo
Ridge and into northwest Iowa through very early evening, but ending
before sunset.

Other showers and storms developing out in western South Dakota this
afternoon, and will progress east working against the ending of the
diurnal cycle, but should bring some showers or thunder to a few
spots west of the James River before weakening. The main
precipitation is likely to develop later in the night as right
entrance of jet with the northern wave begins to interact with the
slowly progressing frontal boundary. Elevated instability tonight
and Monday is fairly meager, and just a bit better as one moves
toward the south across the County Warning Area. Therefore, have limited coverage of
thunder to isolated north and scattered south, as pops gradually
increase to as high as likely south of I-90 and west of kfsd by
daybreak Monday. The rainfall chances will continue at times
through much of Monday, mainly near/south of I-90 tracking along.
With the lower to mid-level frontal forcing and upper jet entrance.
As a result of the increased clouds and areas of precip, temps will
be quite a bit cooler most hours, but should sneak up into the mid

Long term...(monday night through sunday)
issued at 430 PM CDT sun Jun 16 2019

Another wave moving through the northern trough will rotate through
the area on Monday night, but with the boundary settling southward,
highest rainfall chances continue progressively south of I-90
through Tuesday morning. GFS seems to have a north bias to
precipitation by Tuesday/Tuesday night, and have dried out
progressively from north to south through Tuesday and Tuesday night.
Much of Wednesday could also remain dry, especially I-29 eastward,
as approaching wave has to fight the drying effects of low-level
ridging through Minnesota and takes much of the day for warm advection to
build in from the west. Main synoptic boundary will tie up a goodly
share of the moisture in the Southern Plains, so instability remains
a limited quantity, while shear does improve as low-level jet
returns Wednesday night/Thursday ahead of advancing cold front.
Depending on timing, there could be a window for a few severe storms
if all pieces could come together. The flow does look to continue
to amplify toward a western trough/eastern ridge toward the weekend,
but with differences in details between operational solutions and
within the ensembles. A stronger wave looks to move in toward Friday
night/Saturday, and this could provide a more significant severe
weather/heavy rainfall threat, again largely dependent on details
and timing.

In general, the blended approach for initialization grids is
resulting in far too much in terms of precipitation chances, but no
consensus on timing to remove. Thus, the takeaway is that despite
the consistently wet forecast, there will be drier periods during
the mid to late week, and temps will generally remain a bit below


Aviation...(for the 06z tafs through 06z Monday night)
issued at 1051 PM CDT sun Jun 16 2019

Weak shower activity will be possible through 17z Monday south of
I-90. Potential for scattered thunderstorms Monday afternoon as
daytime heating interacts with a weak boundary inching southward.
As showers and thunderstorms become more numerous, ceilings may
build towards MVFR conditions after 00z Tuesday.


Fsd watches/warnings/advisories...
South Dakota...none.


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