Area Forecast Discussion
Issued by NWS Twin Cities, MN

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048
FXUS63 KMPX 142355
AFDMPX

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
555 PM CST Thu Dec 14 2017

.UPDATE...
Issued at 538 PM CST Thu Dec 14 2017

Updated to include 00z aviation discussion below.

&&

.SHORT TERM...(This evening through Friday)
Issued at 1228 PM CST Thu Dec 14 2017

We remain under large scale cyclonic flow with a strong ridge in
place across the western CONUS and the parade of clipper systems
moving through the Upper Midwest. Currently, one such clipper is
sliding through the Dakotas toward Nebraska. Tonight, another wave
will move into northeastern MN and head east through the Great
Lakes.

This leaves us out of any measurable precip chance for the rest of
today and tonight. Instead, we will see cloudy skies with flurries
possible from the low stratus across the entire area. Thinking
the clouds mostly stay in place, but any scattering would once
again lead to temperatures dipping colder than advertised.

For tomorrow, the ridge shifts east and the baroclinic zone will
end up moving through our area ultimately setting up in a NW to SE
oriented fashion. This acitivity will be ahead of another wave up
in Canada. As theta-e advection increases in the morning, could
see light snow start to develop across west central MN and expand
eastward through the remainder of the day. Very little
accumulation is expected during the day. As we head into tomorrow
night, the best chance for an inch or so of snow will be from
northwestern MN through northwestern WI, so a glancing blow for
central MN and western WI.

.LONG TERM...(Friday night through Thursday)
Issued at 1228 PM CST Thu Dec 14 2017

Snow will be ongoing at the start of the period thanks to the
aforementioned baroclinic zone across eastern MN and wester WI by
tomorrow night. Overall expect up to 1-2" of snow by Saturday
morning for part of western WI and northwest toward central MN.

The remainder of the weekend looks dry and it still looks like we
will warm above freezing both Monday and Tuesday. Overall pretty
quiet weather from Saturday through midweek.

The most interesting part of the long term is about a week away.
The ECMWF and GFS both develop a low pressure system out ahead of
a deep trough across the southwestern CONUS. We will have to keep
an eye on where that system will trend in the guidance. The 12Z
run of the ECMWF shifted it south a probably 200 miles, which
demonstrates the degree of uncertainty when run to run changes are
so large. Regardless of the track of this system, it does look to
cool down below normal after it passes.

&&

.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 538 PM CST Thu Dec 14 2017

Cold northwest flow with embedded weak shortwaves will continue
through tomorrow which will mainly spell MVFR ceilings with
occasional rounds of flurries and snow showers. Not looking for
any accumulation with any rounds of snow that come through nor any
reduction in visibility but it is enough to warrant mention,
mainly this evening and again midday Friday. NW winds this evening
will settle into the 5-10 kt range then back to SW tomorrow and
diminish to around 5 kt.

KMSP...Ceilings are expected to remain above 1700ft through the
Friday morning push, and there are some indications that a brief
period of VFR ceilings are possible overnight so have advertised
as such. However, would not be surprised if ceilings remain in
MVFR range throughout this TAF set. Best timing of another round
of -SHSN looks to come midday tomorrow through tomorrow afternoon
with ceilings dropping below 1700ft at that point, but ceilings
may also remain close to 2000ft so it again looks close.

/OUTLOOK FOR KMSP/
Sat...Chc MVFR. Wind E 5 kts.
Sun...VFR. Wind NW 5 kts.
Mon...VFR. Wind SW 10-15 kts.

&&

.MPX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
&&

$$

UPDATE...JPC
SHORT TERM...SPD
LONG TERM...SPD
AVIATION...JPC



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