Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 291715

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
1215 PM CDT SUN MAY 29 2016

Issued at 1215 PM CDT Sun May 29 2016

Updated to include 18Z aviation discussion below.


.SHORT TERM...(Today and tonight)
Issued at 330 AM CDT Sun May 29 2016

Confidence is low with the forecast this morning with regards to
precipitation chances. We currently have an upper low over central
Minnesota that is moving very slowly east. Cloud top cooling has
been occurring around the low since midnight with showers increasing
in coverage and intensity across portions of central Minnesota as
well as southeast Minnesota and west central Wisconsin. It`s the
showers in central Minnesota that are troubling. The CAMS are having
a tough time with the showers with several indicating them too far
north. Others that use a hot start fade the showers in 1 to 2 hours
which has not been the case. Therefore, opted to drive scattered
showers all the way southeast through the Twin Cities early this
morning before allowing things to diminish some off to the east.

This then feeds into what happens from late morning onward as more
showers are shown in the CAMS developing from Alexandria all the way
down to the Iowa border and then back northeast across west central
Wisconsin. Feel a little more confident about these showers given
the steep lapse rates seen from the SFC-700 mb along with a skinny
CAPE profile. The showers shouldn`t be too widespread with isolated
wording used in the forecast. The showers will fade early this
evening will the loss of daytime heating and ridging aloft spreading
in from the west.

It will be dry from late evening onward. A concern overnight is the
potential for fog development, especially from central Minnesota
through west central Wisconsin. These areas have the lowest temp/dew
point spreads under weak high pressure. You also have the damp
ground from the recent rains. Indicated areas of fog developing
after midnight for the aforementioned areas.

Highs forecast for today remain on the high side of most guidance.
The forecast is closer to the NAM then anything else given some
breaks in the cloudiness during the afternoon along with the cold
trough at 850 mb moving east of the area. Little change to the lows
forecast for tonight with around 50 in the central Minnesota to the
upper 50s in the Twin Cities on southward.

.LONG TERM...(Monday through Saturday)
Issued at 330 AM CDT Sun May 29 2016

The longer term concerns are the development and movement of the
next closed low moving through the northern stream Tuesday
through wednesday night.

initially on monday...waa/theta-e advection lifts northeast
across the southwest portion of the cwa by Monday evening. We
will likely see at least some elevated thunder develop perhaps as
early as Monday morning over the far southwest per latest trend
of the NAM WRF and ECMWF which both paint some light qpf into
southwest MN before 18z. Instability increases with the surface
warm front lifting northeast into southwest MN monday night. This
should generate more widespread activity along with some threat
large hail and wind gusts into Monday night.

On Tuesday...CIPS Analog guidance is indicating at least a chance
of severe weather as the trough swings east along with a surface
cold front. The 00z gfs was showing moderate instability
developing and increasing shear as the trough approaches. Only
real limiting factor will be cloud cover/heating concerns with
possible morning activity lingering. This shifts east tuesday
night and should take any significant thunder threat with it.
Rainfall for the Monday night through Tuesday night period
approaches the 1 inch mark for most of the cwa. With PW`s
increasing to 1.5 inches...this looks feasible considering the
amount of forcing indicated. As the trough exits the area
wednesday...we still could see some showers/perhaps some isolated
thunder as it moves through into Wednesday night.

The warmest day of the upcoming forecast looks to be Memorial Day
with some lower 80s indicated. We should see plenty of sunshine at
least early in the day...with increasing mid/high level clouds
from the west during the afternoon. After that...we trend to
below normal through Thursday with the passage of the trough.
Then warmer conditions develop with increasing sunshine. Some
chance of showers/thunder returning to the area next Friday night
into Saturday as both the GFS and ECMWF bring in a frontal system


.AVIATION...(For the 18Z TAFS through 18Z Monday afternoon)
Issued at 1215 PM CDT Sun May 29 2016

We`ll continue to see ceilings at most locations through the
afternoon with a fairly extensive cu field across the region in
the lingering cyclonic flow and decent lapse rates. A few SHRA will
likely develop, but tough to say where/when, so kept things VCSH
for now, and can amend if/when things develop and look likely to
impact a location. Thunder isn`t out of the question given the
lapse rates and MLCAPE values above 1000 J/kg over a portion of
the area, although the better forcing is generally north/east of
the better instability. Otherwise, we should see things clear out
tonight, and things will then be quiet through the remainder of
the period.

KMSP...TAF reflects expected conditions with fairly good
confidence overall. Main uncertainty is with any precipitation
that may occur this afternoon, and at this point VCSH seems to be
the best way to handle things, with amendments possible if/when
things materialize.

Monday night...MVFR ceilings and visibilities possible with a
chance of showers and thunderstorms. Southeast wind 5 to 15 knots.
Tuesday...MVFR ceilings and visibilities possible with a
chance of showers and thunderstorms. Southwest wind 5 to 15
Tuesday night...VFR. West wind 5 to 10 knots.
Wednesday and Wednesday night...MVFR ceilings and visibilities
possible with a chance of showers and thunderstorms. West wind 10
to 20 knots.
Thursday...VFR. Northwest wind 10 to 20 knots.


.MPX Watches/Warnings/Advisories...


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