Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 162356

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
656 PM CDT SUN OCT 16 2016

.SHORT TERM...(This evening through Monday)
Issued at 221 PM CDT Sun Oct 16 2016

A few showers and thunderstorms will develop early this evening
across western and southern MN ahead of a low pressure system and
warm front across NE/IA. As these features move northeast tonight,
the concentration of showers and thunderstorms will increase
across eastern MN and western WI. Favorable conditions remain in
place with respect to wind shear, instability and forcing for a
few of the storms to become severe with large hail from the Twin
Cities metropolitan area on north and east. Various CAMS suggest
thunderstorm activity becoming more concentrated across eastern MN
(Twin Cities) by 03z with the activity spreading across western
WI through 07z. Likely to categorical pops remain in place with
rainfall amounts from a quarter to a half inch with the high end
amounts in west central WI.

Fog will develop across much of the FA late tonight and continue
into mid morning on Monday due to the showers moving through early
tonight and the anomalously high dew points in the upper 50s to
lower 60s advecting in. The fog threat will be exacerbated where
it rains early tonight followed by some breaks in the clouds late.
Hence, the confidence for fog, some of it dense, it highest across
east central and southeast MN as well as all of west central WI. A
dense fog advisory may be needed later tonight and Monday morning.

On Monday, we will have to deal with plenty of low clouds and fog
in the morning. A weak cool front will bisect the FA from NE-SW.
A wave of low pressure will ride northeast along the front Monday
night bringing a threat of showers and thunderstorms to the FA
during the late afternoon hours with much better chances Monday

Due to the aforementioned dew points, it will be a very mild night
across much of the FA with lows over eastern and southern areas in
the lower 60s, which is warmer than our normal high for this time
of year. Monday has the potential to be a warm day with +12 to
+14 deg C air over us at H85. However, due to the extensive
clouds and morning fog, it also has a high bust potential. For now
went with highs from the lower 60s in central MN to the lower 70s
across southern MN on east to KEAU. These highs will be about 5
degrees too cool if more sunshine develops in the afternoon and
the showers/thunderstorms hold off until evening.

.LONG TERM...(Monday night through Sunday)
Issued at 221 PM CDT Sun Oct 16 2016

The majority of the longer term looks quite quiet across the region,
with near to slightly above normal temperatures. The only period of
concern will be tomorrow night, with another period of showers and a
few thunderstorms expected. In the big picture, southwesterly upper
flow at the start of the period will give way to weak upper
troughing through midweek before the flow amplifies a bit toward the
end of the week as ridging builds to our west and a trough digs over
the eastern CONUS. By the end of the forecast period the pattern
flattens out a bit once again with fairly zonal flow across the
north central part of the country.

PoPs look to increase quickly tomorrow evening as a shortwave trough
moves through the region, and a surface low tracks across the
south/southeast portion of the area. The GFS, NAM, and ECMWF all
show fairly widespread precipitation near and north of the surface
frontal boundary. Instability looks fairly limited, general AOB 500
J/Kg, but deep layer shear is significant and AOA 45 kt for much of
the area. Given the low CAPE/high shear environment, it`s possible
that we could see a few stronger storms, and SPC has a marginal risk
for severe weather oriented WSW-ENE coincident with the frontal
boundary and instability axis. Any precipitation should move out of
the area by Tuesday morning, with cooler drier air arriving for much
of the week. The next chance of any widespread precipitation looks
to hold off until late Saturday into Sunday when return flow should
bring sufficient moisture back into the area ahead of a weak
shortwave that is progged to drop through on WNW upper level flow.


.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 643 PM CDT Sun Oct 16 2016

Even though the radar is fairly echo-free at this hour and the low
clouds are confined to SD/IA and far southwest MN, we expect a
poor aviation weather night and poor conditions through tomorrow
morning. The reason is a warm front that is expected to lift north
over the next several hours. There are large differences in
moisture across this front and we think that showers and storms
will break out late this evening and affect most of the TAF sites
before 06z - followed by the potential for IFR/LIFR fog and low
stratus with the warm front in the area through the morning.


We expect the radar to "light up" over the next few hours. The
thunder should be limited to a couple hour window late this
evening or early tonight. Most or all of the rain will be out of
the area by sunrise, however, the low clouds and fog potential is
still high late tonight and tomorrow with all of the moisture
expected to surge north out of NE/IA. The low clouds might have a
hard time clearing tomorrow as well - weak winds and little mixing
potential works against the clearing tomorrow.

Tue...VFR. Wind W 5-10kts.
Wed...VFR. Wind NW 4-8kts
Thu...VFR. Wind NW 5-10kts


.MPX Watches/Warnings/Advisories...

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