Area Forecast Discussion
Issued by NWS Twin Cities, MN

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383
FXUS63 KMPX 281807
AFDMPX

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
107 PM CDT SAT MAY 28 2016

.SHORT TERM...(Today and tonight)
Issued at 333 AM CDT Sat May 28 2016

The short term concern remains the extent of shower/thunder threat
today and tonight.

Water vapor imagery showing negatively tilted upper trough lifting
slowly northeast. Moisture feed continues into southern MN ahead of
the trough.  Various short term hires models continue to show slug
of showers/isolated thunder moving through Iowa into southern MN
will continue its northward trek through the morning. Will
continue high pop trend through the day...as upper trough continues
to lift northeast. Surface boundary is rather diffuse and appears
to be moving into far southern MN early this morning.  Remnants of
yesterdays boundary appears to be weakening further into west
central WI.  Here some fog developed as dewpoints remain high.
This is expected to dissipate as showers lifts into the area later
this morning. Thunder threat will lift north during the morning as
well...though should remain rather limited.

This afternoon...a weak surface low will develop along the boundary
in southern MN and will be the focus of more concentrated thunder
threat.  Appears some threat of isolated severe with large
hail/strong wind gusts associated with he stronger storms mainly
across southern third of MN into west central WI. Some NST/brief
weak tornado concern as well...depending on how much heating and
destabilization takes place. The namwrf showed best chance of this
occurring was south central MN during the afternoon/early evening as
the surface low moves east along with the front.  Will have to
monitor radar trends closely into the afternoon. Temperatures will be
held down in the 60s once again over the northwest cwa as cloud cover
remains over the area. some lower and possible mid 70s into western
Wisconsin if modest breaks develop.

The trough swings east tonight and should take most of the
shower/thunder threat with it.  We will trail pops off to the west
during the night along with ending any thunder threat after
midnight.

.LONG TERM...(Sunday through Friday)
Issued at 333 AM CDT Sat May 28 2016

The balance of the holiday weekend is not looking too bad as a
drying trend ensues on Sunday in the wake of the upper low headed
our way this morning from the central plains. Memorial Day is
pretty much dry across the entire forecast area. The main concern
with Monday is how fast will showers and thunderstorms return
across west central through south central Minnesota. The GFS is
dry in these areas until Monday evening. This is even drier than
the 27.18z run. The ECMWF on the other hand remains a fast
outlier with some activity possible in the aforementioned areas
Monday afternoon. The 28.00z run is even faster than the 27.12z
run. Hence, the two models are going in opposite directions. The
GEM is more of the middle ground with some precipitation seen.
This speed difference between the ECMWF and GFS is tied to a
vigorous upper low/short wave moving our way from the northern
Rockies on Monday. The ECMWF is a little faster aloft and the
height fields are much more negatively tilted over those on the
GFS. In the end, allowed from some small pops to develop in the
afternoon from west central through south central MN. Highs/lows
both days will be some 5 to 8 degrees above normal.

The wave approaching from the northern Rockies on Monday will
take until late Thursday to clear the Upper Mississippi Valley
region. Tuesday and Tuesday night will be a wet period with
numerous showers and scattered thunderstorms. A surface low and
associated cold front will be moving slowly across Minnesota
Tuesday afternoon and evening which may result in some of the
convection being strong to severe if sufficient breaks in the
cloud cover occur allowing for destabilization. Rain amounts from
Monday night through Tuesday night will likely fall into the 0.50
to 1.5 inch range with the heavier amounts tied to the convection.

The balance of the long term (Wednesday through Friday) will see
increasing northerly flow across the region as a strong ridge
builds in the western United States. This will bring our temperatures
back closer to seasonal levels with highs in the upper 60s to
lower 70s common. A few instability showers can`t be ruled out as
well across mainly the eastern half of the forecast area due to
the cold air aloft.

&&

.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
Issued at 107 PM CDT Sat May 28 2016

Thunderstorms are most likely over southern Minnesota into Wisconsin
this afternoon and early evening. Upper low in eastern Nebraska
was moving slowly northeast into Minnesota. Areas along and north
of the track should see mostly steady rain and frequent mvfr
ceilings. Thus have kept krwf, kaxn, and kstc in low clouds
through the taf period. There may be a bit a respite at krwf late
this afternoon, but for now, have only brought ceilings there up
to 2500 feet agl.

South of this track, there is a threat of storms this afternoon
and early evening from south central MN into WI, where there will
be some breaks in the clouds. Air mass is rather unstable but
lapse rates become somewhat poor later. Therefore have limited
mention of storms to about three hours during late afternoon. Once
low goes by later tonight, mvfr ceilings will move in.

KMSP...
Airfield is along a weak boundary where surface low will be
tracking later this afternoon and evening. Therefore winds will be
quite variable into the evening. Will limit thunder threat to 21z-
24z although it is possible some thunder might develop around 19z.
Right now it appears the stronger precip during 18z-21z will remain
west and southwest of kmsp but confidence is only average on this
timing. MVFR conditions will move in late tonight once the low
passes by.

/OUTLOOK FOR KMSP/
Sunday night and Monday...VFR. Variable wind less than 10 knots.
Monday night and Tuesday...MVFR ceilings and visibilities expected
with a chance of showers and thunderstorms. Southeast wind 10 to
15 knots.

&&

.MPX Watches/Warnings/Advisories...
WI...None.
MN...None.
&&

$$

SHORT TERM...DWE
LONG TERM...RAH
AVIATION...TDK



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