Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 262006

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
306 PM CDT Fri May 26 2017

.SHORT TERM...(This evening through Saturday)
Issued at 306 PM CDT Fri May 26 2017

Wind shift is crawling across MN this afternoon and is expected to
be near the I-35 corridor around 4/5pm. SPC meso analysis has SBCAPE
pushing 1000 j/kg along the boundary, with a narrow line of storms
present from about Aitkin north. These storms have gone up within a
zone of PV advection ahead of a weak short wave heading for the
Arrowhead. This little bit of lift with the instability is just
enough to get storms going, down here, we lack the forcing and hence
why as of 3 pm we lack the thunderstorms. However, HRRR/HopWRF and
other CAMs have been persistent with developing convection north of
the metro in east central MN and vis satellite shows cumulus
congestus in this area, so continued to advertise chance PoPs late
this afternoon/evening working across from around Mora over to
Barron, WI.

Not much expected for tonight other than increasing clouds from the
west as the wave currently moving into WY heads across Nebraska.
Light winds are expected and we may see enough boundary layer
moisture linger in western WI to allow for some patchy fog to
develop in the river valleys and other low lying areas.

As for that WY wave, there will be a good shield of rain to its
north working across southern SD overnight within a zone of decent
h7-h6 Fgen. This area of rain will be knocking on the doorstep of SW
MN by Saturday morning. However, this area of fgen is expected to
fall apart as it moves into western MN Saturday morning as
thunderstorms start to expand in coverage across southeast Nebraska.
Latent heat release from these storms will help lead to the demise
of the northern piece of fgen as that starts lining up to our south.
The result, is we are anticipating a dry, though cloudy day across
the MPX area, with any rain coming up into south central MN during
the afternoon with more widespread/heavier rain staying down in IA.
Also have just shower mention tomorrow, with any instability looking
minimal. Finally, did cool highs Saturday a little, though it could
be cooler, especially in western MN depending how quickly/thick
clouds come in.

.LONG TERM...(Saturday night through Friday)
Issued at 306 PM CDT Fri May 26 2017

There`s not a lot to talk about in the long term period.
A digging longwave trough across the Great Lakes region Sunday
through midweek which will keep us in cool northwesterly flow with
multiple opportunities for isolated or scattered showers in deep
cyclonic flow and cold air advection.  But, any rain amounts will be
 light across the area with no real system coming through during the
period.  Sunday and Monday will see increased cloud cover and with
limited CAPE values, could see isolated Thunder.

There is decent agreement in this trough holding its course through
midweek but there are some differences toward the end of the week.
The GFS/ECMWF both indicate upper level ridging finally pushing the
trough east with a surface high dropping out of Canada near the end
of the week.  The main differences lie in the timing of this with
the EC holding on to the cooler and slower departure of the trough
when compared to the GFS.

Regardless, May will finish on a cool stretch and is likely to
finish just below normal for averages temperatures at MSP.  If this
does verify, this will break the 20 month above average streak at
MSP.  Our last month that was below normal was August, 2015.


.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
Issued at 1258 PM CDT Fri May 26 2017

Frontal boundary on the doorstep of STC and will be getting to the
I-35 corridor during peak daytime heating. Starting to get a
decent cu field forming along the boundary from STC north and
expect shra/tsra to develop from this by 19z. MSP/RNH will be the
only locations with a threat of seeing this diurnally driven
activity. Expect VFR skies throughout, with SKC overnight, but mid
level clouds will become OVC Saturday as the wave currently
working across WY heads our way.

KMSP...The hrrr has been pretty consistent with some iso/sct
shra/trsa activity in the vicinity around 22/23z. Precip chances
look better north, hence only a vcsh from 22z to 00z.

Sun...VFR. Chc -shra. Wind NW 10-15 kts.
Mon...VFR. Chance showers. Wind NW 10-15 kts.
Tue...VFR. Wind NW 10 kts.




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