Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 150527
AFDMPX

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
1227 AM CDT Sun Apr 15 2018

.UPDATE for 06z aviation discussion below...

&&

.SHORT TERM...(This evening through Sunday)
Issued at 420 PM CDT Sat Apr 14 2018

The winter storm across the Upper Midwest continued to dump heavy
snow from southwest Minnesota through east central Minnesota into
western Wisconsin. Forecast soundings had 40 to 50 knots at 3500 ft,
and some of this momentum was able to reach the surface as the
heavier bands of precipitation moved through. The combination of 2
in/hr snowfall rates, together with 25 to 30 kt winds prompted the
expansion of the blizzard warning in to the Twin Cities metro area
and far west central Wisconsin.

The power and impact potential of this system has been advertised
for several days, and the sensible weather of roads closed,
thundersnow, and zero visibility certainly met expectations. This
storm is occluded to the primary area of heavy precipitation is tied
to the upper level vorticity maxima. Over the next 24 hours this
will slowly slide to the east so expect the heaviest snowfall in the
TROWAL area of this storm to shift from central MN towards central
Wisconsin.

Winds should gradually decrease this evening and overnight as the
surface low fills. On Sunday still expect some wrap-around moisture
and positive vorticity advection to lead to some lingering light
snow. Did increase pops on Sunday since the dendritic growth zone
extends from roughly 925mb up through 500mb so should have
efficient crystal growth. The warmest temperatures on Sunday will be
across the northwest CWA, with most locations remaining below
freezing. If that happens at MSP, it would break the lowest maximum
temperature for April 15, which was 32 in 1951.

.LONG TERM...(Sunday night through Saturday)
Issued at 420 PM CDT Sat Apr 14 2018

Light snow will likely be continuing into Monday morning across
eastern Minnesota and western Wisconsin with the cyclonic flow
remaining in place. Accumulations shouldn`t be too impressive,
especially considering what is going on right now, but the ECMWF
does bring potential for another 2 to 3 inches Sunday night and
Monday morning. Increased PoPs into the likely range through
Sunday night, and then tapered them down through Monday.

Quieter weather will return later Monday and Tuesday as a surface
ridge passes overhead. Temperatures will be cooler due to a deep
snowpack and lows Monday night as skies clear and winds subside
could be back into the teens.

The next system has the potential to bring several more inches of
snow. This one is more compact, but the low is potent and has
plenty of moisture to work with. Models have been fairly
consistent for it being several days out, but the track of the
low is still most uncertain. Both the GFS and ECMWF and their
ensembles impact much of the CWA with some degree of snow. The
best area at this time looks to be across southern MN, but that
can certainty change in the coming days. The synoptic set up and
dynamics with this system could bring warning criteria snows yet
again.

A trough follows that system through late week. There continue to
be indications of another large system developing over the central
Plains next weekend, which could spread heavy precipitation
northward toward the Upper Midwest. By then the atmosphere looks
warm enough for more rain than snow, but system dynamics will
play the ultimate role in determining that as time goes on.

&&

.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
Issued at 1220 AM CDT Sun Apr 15 2018

Expect MVFR with periods of IFR conditions to prevail through
much of the forecast period. Improving conditions to VFR first at
KAXN and later toward KSTC-KRNH as the system lifts out. Snow is
expected to continue across the area through the day ending first
western sites and before 06z Mon to the east. NE-N winds will
remain gusty into Sunday before relaxing from west to east into
Sunday night.

KMSP...MVFR with OCNL IFR will continue through much of the
forecast period. We could see brief heavier snow periods one in
the morning 14z/17z and again during the afternoon before ending
by 06z Sunday. Cigs expected to erode to VFR after 08z. Continue
gusty NE-N wind during the period.

/OUTLOOK FOR KMSP/
Mon Night...VFR. Wind NW 5-10 kts.
Tue...Mainly VFR. MVFR ceilings possible late. Wind E 5-10 kts.
Wed...MVFR conditions likely in -RA/-SN. Wind NE 5-10 kts becoming
NW.

&&

.MPX WATCHES/WARNINGS/ADVISORIES...
WI...Blizzard Warning until 7 AM CDT this morning for WIZ023-024.

     Winter Storm Warning until 7 PM CDT this evening for WIZ014>016-
     025>028.

MN...Blizzard Warning until 7 AM CDT this morning for MNZ054-056>070-
     073>078-082>085-091>093.

     Winter Weather Advisory until 1 AM CDT early this morning for
     MNZ048-049-055.

     Winter Weather Advisory until 1 PM CDT this afternoon for
     MNZ043>045-050.

     Winter Storm Warning until 7 PM CDT this evening for MNZ051>053.

&&

$$

SHORT TERM...JRB
LONG TERM...BORGHOFF
AVIATION...DWE



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