Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 221854

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
154 PM CDT WED JUN 22 2016

.SHORT TERM...(Today and tonight)
Issued at 500 AM CDT Wed Jun 22 2016

50+ kt LLJ that kicked off thunderstorms from SW MN down into eastern
IA veered over to the east quickly last night, with the heavy rain
threat already well southeast of the mpx cwa. For the morning, its
remnants of convection that moved across the Dakotas last night that
will bring light rain to many areas along and south of the I-94
corridor this morning. This far northeast, the instability is
considerably weaker than what they have been dealing with in South
Dakota, so not expecting much of a severe threat, just an area of
showers with embedded thunderstorms running down the elevated
instability gradient from west central toward southeast MN. We will
see a break in activity during the late morning into the early
afternoon, but expect showers and thunderstorms to bubble up again
at the nose of an inverted surface trough that will slowly work
across central MN this afternoon and western WI tonight. Extensive
cloud cover will limit instability, so only looking at a few hundred
j/kg of MLCAPE feeding this activity, so not anticipating anything
severe with coverage scattered at best. Would not be at all
surprised if the first update to the Day 1 convective outlook from
the SPC quickly removes the slight risk from southeast MN.

Tonight, any precip chances will be tied to locations out ahead of
the slowly moving inverted trough. Convergence along this boundary
is weak and instability disappears tonight, so we could be entirely
overdone on the chance PoPs we have in western WI, could very well
end up being nothing more than a cloudy and hazy morning Thursday
across eastern MN and western WI.

Only minor tweaks were made to temperatures today and tonight. Those
were to limit how far east we bring highs in the 80s today, with
cloud cover looking to be slower to clear western and southwest MN
this afternoon. For tonight, cloud cover was increased from what we
had going, so increased lows a few degrees to account for that.

.LONG TERM...(Thursday through Tuesday)
Issued at 500 AM CDT Wed Jun 22 2016

The main focus in the long term remains on Saturday with the
incoming trough and the potential for severe weather.

By Thursday, the aforementioned weak surface trough will be east
of the forecast area and high pressure will be building in across
the Upper Mississippi River Valley. While the GFS and NAM continue
to spit out light QPF near the central MN/WI border, there just
isn`t much to support this. There is little to no forcing and the
moisture is confined to the lowest 8000ft of the atmosphere.
Overall, Thursday looks pleasant with mild temperatures and low
humidity. The warmth and moisture builds on Friday with an upper
ridge moving overhead and a surface low developing in the High
Plains in response to a trough moving into the Northern Rockies.
This wave will begin to initiate thunderstorms across North Dakota
Friday evening/night that should lift north into Canada Saturday
morning. The deepening surface low will lift north and occlude by
Saturday evening. This puts most of Minnesota and western
Wisconsin in the warm sector with ample instability for convection
and a strong trigger with the approaching upper trough and cold
front on Saturday. The deep layer shear is marginal with the
upper jet lagging behind the cold front in the Northern Plains.
Most of the shear is in the lowest 1km, which does increase the
wind/tornado threat in eastern MN and western WI where the surface
winds are forecast to be close to true south and there is good
cyclonic curvature to the hodographs. Given the strong forcing,
there is a good chance for widespread convection and perhaps even
a solid line by 00z, which would suggest a wind /possible hail/
threat. Interesting to note, the top CIPS analog for the past
three runs of the GFS has been June 17, 2010 - Minnesota`s record
tornado outbreak. This is due to the strength of the incoming
trough FRI/SAT and strong momentum fields. The speed shear doesn`t
match June 17th, but there are similarities in other ingredients
and in the overall pattern obviously. Cooler weather returns
behind the front SUN-MON.


.AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon)
Issued at 141 PM CDT Wed Jun 22 2016

Main concerns are thunder potential this afternoon and the
potential for MVFR ceilings overnight, which mainly look to affect
the eastern half of the area. Keeping an eye on a mid level
shortwave dropping southeast across northwestern MN toward
northern WI this afternoon and tonight. Still expect scattered
showers and thunderstorms to possibly get going this afternoon
along the southern periphery of this wave. How far south the
precip extends is the question that is beginning to look like it
may not be as far south as we once thought. Still included VCTS at
a few sites but may be able to remove that depending on what we
see develop as the afternoon goes on.

KMSP...Have included VCTS in the TAF this afternoon because there
is a possibility of thunder. However, hi-res CAMs are initializing
too far south so far, which may indicate their solutions push
storms too far south along the inverted trough. Will continue to
monitor and update as needed.

FRI...VFR. Winds SSE 5-10 kts.
SAT...VFR. Chc MVFR TSRA in the aftn/eve. Winds S-SW 10 kts.
SUN...VFR. Winds W 10-20kts.


.MPX Watches/Warnings/Advisories...


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