Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 201818

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
1218 PM CST Wed Feb 20 2019

.SHORT TERM...(Today through Thursday)
Issued at 330 AM CST Wed Feb 20 2019

Latest water vapor satellite imagery showing upper trough lifting
northeast across the Mississippi River Valley. A couple of
vorticity maxima lifting through the area. One moving into
southeast South Dakota which has enhanced snowfall rates to 2
inches an hour near Sioux Falls area. The other is lifting
through the Missouri area. Models continue to trend strong
forcing lifting northeast across the entire CWA today. We still
should see a widespread 6 to 10 inch accumulation across the
area. Snowfall rates will likely continue in the 1 to 2 inch an
hour range through the morning as the trough lifts northeast.
Expect decent dendrites as well with SLR`s averaging around
15-17:1 during the peak of the event. Headlines were updated to
include the Winter Storm Warning for the entire cwa.

The upper trough will lift to the northeast CWA by late afternoon.
Could still see some light accumulation there into the early
evening so expiration times were left as is for now.

Clouds should break some to the west overnight with high pressure
ridge building across for Thursday. Temperatures are expected to
remain in the teens to the west and lower to mid 20s to the east

.LONG TERM...(Thursday night through Tuesday)
Issued at 351 AM CST Wed Feb 20 2019

A period of tranquil weather will occur Thursday into early
Friday while the beginnings of the next winter storm will be
taking shape over the southwestern U.S. The main wave won`t be
impacting the area until later Saturday. However, there`s another
wave expected to ripple northeast in the southwest flow Friday and
Friday night. This round will impact primarily western and
central MN as isentropic lift begins to increase and the snow
focuses along a stationary front from the western high Plains up
through northeastern MN. There could be a few inches with this
round before the wave moves off and snow dissipates late Friday
night into early Saturday. Dry mid level air could allow for
patchy freezing drizzle during this period, but the more likely
scenario is a cessation of precipitation.

The potent longwave trough over the desert southwest will
eventually kick out across the southern Rockies and reach the
central Plains Saturday, rapidly becoming negatively tilted as it
does so. This is a great precursor for significant deepening of
the surface low and this one will be no different. Various
guidance continues to show a near bomb cyclone as it tracks across
the Midwest.

There are several things to watch with this one. First, the track
is still uncertain and models continue shifting around with each
run. The overnight runs have shifted a tad further south,
including the EPS mean. GEFS remains a bullish northern solution,
impacting southwest to east central MN and northern WI hardest.
Deterministic track guidance is pretty consistent taking the low
across northern MO into southeastern WI. Usually this is a bit
south of the ideal track for heavy snow locally and the forecast
overnight has trended in that direction. It should be noted that
highly negatively- tilted systems and strong cyclones tend to
migrate northward as time closes in. Second, the amount of
moisture with this system will be quite high and moisture
advection is expected to be impressive given the wind field.
Therefore, we may have to contend with mixed precip or rain across
portions of the area depending how far north the system tracks.
And third, we should have wind and blowing snow issues to contend
with given the deepening trend of the cyclone. Blizzard conditions
are probable in some sections of the CWA. Between the system
today and the one this weekend which itself could bring a foot or
more, we may crush the February record by 10 to 15 inches in some
areas by early next week.

There are signs of another system impacting the region next week,
but consistency at that range is poor. What is certain is much
below normal temperatures will continue into early March.


.AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon)
Issued at 1217 PM CST Wed Feb 20 2019

Snow has begun to taper off across southern Minnesota with
visibilities improving to IFR, but moderate to heavy snowfall
with LIFR visibilities is still expected to continue through mid-
afternoon across central Minnesota and west-central Wisconsin.
Snowfall will continue to diminish through the afternoon, and is
expected to end by mid- afternoon at MKT/RWF and by evening at
all other terminals. Ceilings will remain fairly through tonight,
with mainly low-end MVFR expected but can`t rule out a few
instances of IFR. Ceilings may break out overnight at RWF/MKT, but
otherwise expect them to hold through the period.
Easterly/southeasterly winds become westerly as the snow ends,
with speeds generally at or below 10 kts.

KMSP...The heaviest snowfall has ended, with lighter snowfall and
borderline LIFR/IFR visibilities expected through mid-afternoon.
Light snowfall with IFR visibilities will continue through
afternoon, with snowfall most likely ending by 6 PM. Can`t totally
rule out MVFR ceilings clearing out overnight, but believe they
will hold until tomorrow afternoon.

Thu night...MVFR cigs possible. Wind WSW 5 kts.
Fri...MVFR cigs. -SN/IFR likely late. Wind SE 5-10 kts.
Sat...Afternoon SN/IFR likely. Wind NE 5 kts becoming NW

WI...Winter Storm Warning until 9 PM CST this evening for WIZ014-

     Winter Storm Warning until midnight CST tonight for WIZ015-016-

MN...Winter Storm Warning until 6 PM CST this evening for MNZ041-042-

     Winter Storm Warning until 9 PM CST this evening for MNZ043>045-



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