Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 122329
AFDMPX

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
529 PM CST Fri Jan 12 2018

.UPDATE...
Issued at 525 PM CST Fri Jan 12 2018

Updated to include 00z aviation discussion below.

&&

.SHORT TERM...(This evening through Saturday)
Issued at 308 PM CST Fri Jan 12 2018

Cold and dry for the next 36 hours. Early afternoon satellite
imagery with Rap13 surface analysis showed clear skies across the
Upper Midwest with northerly winds around 10 mph.

High pressure was centered over North Dakota, and over the next 24
hours this high pressure will slowly slide southeast. This means
decreasing winds overnight, setting the stage for very cold
temperatures. Although winds will be light, did issue a wind chill
advisory across the entire area since air temps will be near 15
to 20 below zero, and any amount of wind will push wind chills
below advisory threshold. No precipitation is expected between now
and Sunday morning.

.LONG TERM...(Saturday night through Friday)
Issued at 308 PM CST Fri Jan 12 2018

Confidence remains high on light snow Sunday afternoon and evening
for most location in the forecast area. The heaviest snow will be
in eastern Minnesota and western Wisconsin, where around 2 to 3
inches is expected. Thermal profiles show a deep dendritic layer,
but the lift is not very strong, so should get ratios in the 20 to
25:1 range.

Cold air advection will spill across the region on the back side
of this clipper. This is a classic set up for a ground blizzard,
but the forecast soundings only show wind speeds of around 30 kts
at the top of the boundary layer. Contrast that to the 40-50 kt
gusts from past ground blizzard cases, and one can draw the
conclusion that a whiteout conditions are unlikely for Sunday
night and Monday. However, did increase winds a bit above guidance
since the model blend often underdoes cold air advection cases,
and did add blowing snow to the forecast for Sunday night and
Monday.

Looking ahead, there are no significant system in the extended.
Arctic air in the wake of Sunday`s snow will stick around through
the middle of the week. A pattern change from northwest flow to more
zonal and eventually southwesterly will bring more mild air and a
chance for some precipitation toward the latter half of next week.

&&

.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 525 PM CST Fri Jan 12 2018

Solid VFR conditions through the next 24-30 hours with arctic high
pressure sliding atop the region. Except for upper level clouds
over SW MN tonight, SKC conditions will prevail at all TAF
locations. NW winds around 5 knots tonight through tomorrow will
generally become light and variable tomorrow afternoon and
evening.

KMSP...Other than wind chills dropping to around -25 degrees F
overnight through daybreak Saturday morning, no significant
weather impacts expected.

/OUTLOOK FOR KMSP/
Sun...MVFR with afternoon IFR/SN likely. Wind S 5-10 kts.
Mon...VFR with MVFR possible. Wind NW 15G20 kts.
Tue...VFR with MVFR possible. Wind NW at 10-15 kts.

&&

.MPX WATCHES/WARNINGS/ADVISORIES...
WI...Wind Chill Advisory from 9 PM this evening to 9 AM CST Saturday
     for WIZ014>016-023>028.

MN...Wind Chill Advisory from 9 PM this evening to 9 AM CST Saturday
     for MNZ041>045-047>070-073>078-082>085-091>093.

&&

$$

UPDATE...JPC
SHORT TERM...JRB
LONG TERM...JRB
AVIATION...JPC



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