Special Weather Statement, NWS Twin Cities, MN

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
331 PM CDT Fri Apr 13 2018

.SHORT TERM...(This evening through Saturday)
Issued at 330 PM CDT Fri Apr 13 2018

A very powerful winter storm will bring over a foot of snow to some
locations in Minnesota and Wisconsin. This storm has a lot of
moisture, with strong forcing for ascent with subfreezing
temperatures. What that in mind, it is certainly reasonable that a
few locations in southwest Minnesota will get near 18 inches of
snow. In addition, strong northeast wind will cause blizzard
conditions.

This set up for this cyclone is textbook with a strong low level
temperature gradient, amplified upper level trough, and deep
reservoir of potential vorticity. The heaviest snow will fall where
these three ingredients work together in southwest Minnesota.
Meanwhile, areas in central MN and western WI will see two round of
precipitation which is nicely depicted by the HiRes models. The
first round is tied to the warm air advection and Fgen. As of 3 pm,
this band was starting to take shape along I-94.

There should be a brief break in the precipitation tonight as it
changes to mainly a wintry mix and snow, but then expect another
band of heavy snow to lift up from the south on Saturday. This band
of snow is tied to the positive vorticity advection associated with
the Upper Level shortwave. These lobes of vorticity are difficult to
time, but the HiRes models continue to reflect the message of the
synoptic scale models and have 1-2"/hr snow bands moving through on
Saturday afternoon and evening. Meanwhile a well-defined TROWAL will
keep the highest snowfall amounts tied to this upper level wave.

Forecast models have trended a bit light with winds, and further
south with the precipitation. Tried to reflect this in the forecast,
so have lesser amounts of snow to the north. This centers the
snowband from Redwood Falls through the Twin Cities and Eau Claire.
The 19Z RAP13 and 18Z Nam continue this southern shift, so that will
be the main concern going forward and if the trend continues will
likely see the heavy snow axis shift south.

.LONG TERM...(Saturday night through Friday)
Issued at 330 PM CDT Fri Apr 13 2018

If you're hoping for a huge warmup during the latter portion of the
forecast period, there isn't much good news for you. The upper flow
will become fairly progressive, but without any prolonged
significant ridging in our area. So, although temperatures may be a
bit warmer than the past week or two, they still look to remain
below normal. The main weather feature of interest/concern is a
shortwave trough and associated surface low that will move through
the region Tuesday night and Wednesday. The model guidance is
actually in fairly good agreement on the evolution of this feature,
and unfortunately (if you're looking for Spring) precipitation type
with it looks to partially if not mostly snow. Forcing looks to be
compact and focused with the upper wave, but there will be decent
moisture in place, so the 0.25-0.50" inches of precipitation most of
the guidance suggests seems reasonable. So, could be another
accumulating snow event for portions of the area. Other than that
system, the Monday through Friday time frame will be dry with the
aforementioned below normal temperatures.

&&

.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
Issued at 157 PM CDT Fri Apr 13 2018

VFR/MVFR conditions will deteriorate to IFR/LIFR as snow develop
and wind increase. The potential for freezing rain has diminished.
There could be some sleet mixed in at times as the rain changes
over to snow. Taf sites north of I-94 will see less snow, while
areas in the southwest will have more snow and stronger winds.

KMSP...
VFR/MVFR conditions will deteriorate to IFR/LIFR as snow develop
and wind increase. The potential for freezing rain has diminished.
There could be some sleet mixed in at times as the rain changes
over to snow. It looks like there will be two rounds of heavier
precip. The first will be this evening through 06Z, and then there
should be a break as the snow band sags south before lifting
north again on Saturday late morning.

/OUTLOOK FOR KMSP/
Sun...IFR/MVFR with lingering snow. Wind N at 15G20 kts.
Mon...VFR. Wind NW 5-10 kts.
Tue...MVFR this -DZ possible. Wind SE at 10 kts.

&&

.MPX WATCHES/WARNINGS/ADVISORIES...
WI...Winter Storm Warning from 1 AM Saturday to 1 AM CDT Sunday for
     WIZ024-026-028.

     Winter Storm Warning from 7 PM this evening to 1 AM CDT Sunday
     for WIZ014>016.

     Winter Storm Warning from 10 PM this evening to 1 AM CDT Sunday
     for WIZ023-025-027.

MN...Winter Storm Warning from 1 AM Saturday to 1 AM CDT Sunday for
     MNZ076>078-083>085-092-093.

     Winter Storm Warning from 7 PM this evening to 1 AM CDT Sunday
     for MNZ049>053-058-059-061.

     Winter Weather Advisory from 1 PM Saturday to 7 AM CDT Sunday
     for MNZ043>045.

     Winter Storm Warning from 10 PM this evening to 1 AM CDT Sunday
     for MNZ060-062-063-066>070-075.

     Blizzard Warning from 7 PM this evening to 1 AM CDT Sunday for
     MNZ047-048-054>057-064-065-073.

     Blizzard Warning from 10 PM this evening to 1 AM CDT Sunday for
     MNZ074-082-091.

&&

SHORT TERM...JRB
LONG TERM...
AVIATION...JRB

Hazardous Weather Outlook...UPDATED
National Weather Service Twin Cities/Chanhassen MN
350 PM CDT Fri Apr 13 2018

MNZ041>045-047>070-073>078-082>085-091>093-WIZ014>016-023>028-
142100-
Douglas-Todd-Morrison-Mille Lacs-Kanabec-Stevens-Pope-Stearns-
Benton-Sherburne-Isanti-Chisago-Lac Qui Parle-Swift-Chippewa-
Kandiyohi-Meeker-Wright-Hennepin-Anoka-Ramsey-Washington-
Yellow Medicine-Renville-McLeod-Sibley-Carver-Scott-Dakota-
Redwood-Brown-Nicollet-Le Sueur-Rice-Goodhue-Watonwan-Blue Earth-
Waseca-Steele-Martin-Faribault-Freeborn-Polk-Barron-Rusk-
St. Croix-Pierce-Dunn-Pepin-Eau Claire-
350 PM CDT Fri Apr 13 2018

This Hazardous Weather Outlook is for portions of central and
southern Minnesota...and west central Wisconsin.

.DAY ONE...Tonight

Rain will change over to snow this evening. Areas of blowing snow
are expected overnight across western Minnesota. Winter Storm
Warnings and Blizzard Warnings are in effect.

There is a chance of thunderstorms across southern Minnesota,
mainly this evening. Some storms may be strong with small hail.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday

Winter Storm Warnings and Blizzard Warnings continue through
Saturday evening. Please consult the winter hazard message for
more information.

There is a chance of thunderstorms Saturday afternoon and evening.

The combination of additional snow and rainfall over frozen soil
will increase flood potential over the weekend into next week.
Some area rivers may reach bankfull by Sunday and minor flood
stage by midweek.

.SPOTTER INFORMATION STATEMENT...

Spotters and snowfall observers are urged to report snowfall
amounts to the National Weather Service.

Borghoff

Special Weather Statement
National Weather Service Twin Cities/Chanhassen MN
1236 PM CDT FRI APR 13 2018

MNZ064-131815-
Yellow Medicine-
1236 PM CDT FRI APR 13 2018

...A STRONG THUNDERSTORM WILL AFFECT SOUTHERN YELLOW MEDICINE
COUNTY...

At 1235 PM CDT, a strong thunderstorm was located near Hendricks, or
20 miles southeast of Clear Lake, moving northeast at 50 mph.

Winds in excess of 30 mph and half inch hail are possible with this
storm.

Locations impacted include...
Granite Falls, Canby, Clarkfield, Porter, Spring Creek, Hazel Run,
Burr and St. Leo.

This includes the following highways...
 U.S. Highway 212 near mile marker 48.
 U.S. Highway 59 between mile markers 92 and 98.

LAT...LON 4480 9638 4481 9556 4463 9595 4463 9645
      4468 9646
TIME...MOT...LOC 1735Z 227DEG 43KT 4456 9636

Special Weather Statement
National Weather Service Twin Cities/Chanhassen MN
121 PM CDT FRI APR 13 2018

MNZ064-073-131845-
Yellow Medicine-Redwood-
121 PM CDT FRI APR 13 2018

...A STRONG THUNDERSTORM WILL AFFECT NORTHWESTERN REDWOOD AND
SOUTHEASTERN YELLOW MEDICINE COUNTIES...

At 121 PM CDT, a strong thunderstorm was located near Milroy, or 15
miles east of Marshall, moving northeast at 55 mph.

Nickel size hail is possible with this storm.

Locations impacted include...
Echo, Belview, Vesta, Milroy, Lucan and Seaforth.

LAT...LON 4474 9544 4473 9541 4470 9538 4469 9532
      4466 9529 4467 9525 4464 9521 4438 9542
      4443 9560 4445 9560
TIME...MOT...LOC 1821Z 204DEG 47KT 4446 9548

ETA

Special Weather Statement
National Weather Service Twin Cities/Chanhassen MN
320 PM CDT FRI APR 13 2018

MNZ084-085-093-132045-
Steele-Waseca-Freeborn-
320 PM CDT FRI APR 13 2018

...A STRONG THUNDERSTORM WILL AFFECT NORTHWESTERN FREEBORN...SOUTHERN
STEELE AND SOUTHEASTERN WASECA COUNTIES...

At 320 PM CDT, a strong thunderstorm was located over Hartland, or 13
miles northwest of Albert Lea, moving northeast at 40 mph.

Nickel size hail is possible with this storm.

Locations impacted include...
New Richland, Ellendale, Hartland, Lemond, Hope and Steele Center.

This includes the following highways...
 Interstate 35 between mile markers 25 and 35.
 U.S. Highway 14 between mile markers 166 and 167.

LAT...LON 4374 9350 4381 9361 4407 9339 4393 9311
TIME...MOT...LOC 2020Z 205DEG 34KT 4382 9350

ETA

Special Weather Statement
National Weather Service Twin Cities/Chanhassen MN
357 PM CDT FRI APR 13 2018

MNZ093-132130-
Freeborn-
357 PM CDT FRI APR 13 2018

...A STRONG THUNDERSTORM WILL AFFECT NORTHWESTERN FREEBORN COUNTY...

At 356 PM CDT, a strong thunderstorm was located over Alden, or 10
miles west of Albert Lea, moving north at 25 mph.

Nickel size hail is possible with this storm.

Locations impacted include...
Alden, Hartland, Freeborn and Manchester.

This includes Interstate 90 between mile markers 143 and 151.

LAT...LON 4365 9365 4375 9365 4385 9363 4385 9336
      4384 9335 4362 9351
TIME...MOT...LOC 2056Z 195DEG 23KT 4368 9357

ETA

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