Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 240550

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
1250 AM CDT Sun Jun 24 2018

.Updated for 06Z Aviation Discussion...
Issued at 244 AM CDT Sun Jun 24 2018


.SHORT TERM...(This evening through Sunday)
Issued at 239 PM CDT Sat Jun 23 2018

RAP h85 analysis has been depicting a pool of slightly higher
theta-e air across central MN, which is where we have seen some
isolated showers develop. The HRRR has has been showing this
activity much of the day and that combined with RAP h85 theta-e
forecasts supports this isolated activity continuing into the
evening, so have some low pops across central MN through 6z to
account for that.

Satellite and radar imagery both easily depict a shortwave over
central SoDak this afternoon. This feature will slide into western
MN and slowly shear out across southern MN Sunday. Precip has been
slow to develop to the east of this feature, so have really
slowed down the progression of PoPs into southwest MN tonight.
Tied arrival of chance pops on the movement a weak h5 vorticity
max the RAP brings out of SoDak and into western MN. The NMM,
though slow, probably is the CAM that is closest to what we are
currently thinking for precip evolution tonight.

Sunday, dewpoints will be a tick higher, with forecasting
soundings from the NAM/GFS showing 1000-1500 j/kg of largely
uncapped CAPE developing. Forcing wise, there is not much there,
so this looks to result in unorganized scattered convection. Like
today, Sunday will feature little shear and little in the way of a
severe threat. But, slow storm motion will result in some very
localized heavier precip amounts.

.LONG TERM...(Sunday night through Saturday)
Issued at 239 PM CDT Sat Jun 23 2018

The remainder of the week will see some progression of the large
scale upper air pattern during the first half of the week before
it gets bottled up toward the end of the period. The medium range
guidance is in fairly good agreement on the overall evolution of
the longwave features through the end of the week, with a bit more
disagreement by the end of next weekend. The somewhat split flow
currently over the central CONUS will become more phased by
midweek after we see a shortwave trough move through our area on
Tuesday and another passes by to our north Wednesday into early
Thursday. After that the western side of a very broad sub-tropic
ridge over the eastern US and western Atlantic will get pumped up
over the central US with troughing over the western US. This will
put us into what looks to be a potentially very busy period of
weather from late in the week into the first part of the July 4th
week. We should wind up hot and humid and will have forcing in
place just to our west in association with the upper trough. So,
could easily see a period of periodic MCSs moving through the
region as the surface frontal boundary and cooler/drier air
struggles to push east into the stubborn upper ridge.

We`ll have a good chance for some showers/thunderstorms across the
west Sunday night into early Monday, then eastward across the
remainder of the area Monday night through Tuesday as the
aforementioned southern stream shortwave trough moves through the
region and surface low moves northeast from the central Plains
across southern Minnesota. Widespread severe weather doesn`t
appear likely, but there may be enough instability and shear for a
few severe storms later Monday into Tuesday, particularly over
the southern and southeastern portion of the area. We should see a
break in precipitation chances Tuesday night and Wednesday as a
weak surface ridge builds into the area. The northern stream
shortwave trough moving by to our north later Wednesday and
Wednesday night could produce some precipitation in the northern
portion of the area, but most areas look to stay dry. After that,
we look to have recurring chances for showers/thunderstorms with
MCS passages from Thursday night through the remainder of the
forecast period as activity develops to our west and moves east
around the periphery of the upper ridge. At this point, it`s tough
to pin point too much for completely dry periods, but better than
one might expect at days 5-7 given better than typical agreement
in the guidance.


.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
Issued at 1244 AM CDT Sun Jun 24 2018

VFR conditions throughout, but there are increasing chances for
showers and thunderstorms across western Minnesota.At this point
it looks like there could be a round diminishing this morning, and
then another one developing in the later afternoon. Did not
include thunder in the Tafs for this issuance. Winds will be

VFR conditions throughout. Could get a passing shower or
thunderstorm, but at this point it appears the best chances will
be west of KMSP. Winds will be southeast throughout.

Tue...MVFR/-SHRA/-TSRA likely. Wind SE bcmg NW 5-10 kts.
Wed...VFR. Winds NW 5-10 kts.
Thu...VFR. Winds SE 5-10 kts.




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