Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 210952

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
352 AM CST Wed Feb 21 2018

.SHORT TERM...(Today and tonight)
Issued at 315 AM CST Wed Feb 21 2018

Very benign short-term portion of the forecast with arctic high
pressure moving across the region and upper level flow transitions
from zonal to slightly southwesterly with a much drier atmosphere.

Surface analysis shows the center of high pressure over the Dakotas
and this high pressure airmass is expected to shift easterly over
southern Minnesota and into the Great Lakes through Thursday
morning. Nearly all of the moisture associated with the previous
frontal system has also moved well off to the east, leaving clear
skies in place for today. Despite full sunshine, the cold air
advection behind the front will result in highs only reaching the
mid-teens to lower 20s.

While the high pressure area shifts off to the east tonight, a weak
cold front will drop in from the northwest. In addition, a fairly
impressive upper level wave over the Deep South will move northwest
within the digging southwest flow aloft, bringing another surge of
moisture well into the north-central CONUS tonight. This will result
in an increase in clouds overnight through daybreak Tuesday.
However, with the GFS being the fastest among the models to bring in
precipitation prior to 12z, am considering this an outlier and have
gone with consensus to keep precipitation out of the area prior to

Lows early Thursday morning will be relatively milder than what is
being reported this morning. While lows this morning will range from
-10F to +5F, lows this time tomorrow will run between 0F-10F.

.LONG TERM...(Thursday through Tuesday)
Issued at 330 AM CST Wed Feb 21 2018

Longer term concerns are overall model trends for the snow event
Thursday/Thursday night and the possibility of a more significant
storm Saturday/Saturday night.

Models a fairly consistent on lifting the next short wave across
the area Thursday. Forcing/isentropic lift moves int rapidly
Thursday morning and across much of the cwa through 00z Fri.
Strongest forcing moves across the area Thursday night with fairly
widespread QPF over 0.20 inch then. Snow amounts look to range
from 2 to 4 inches over most of the cwa. If more significant QPF
arrives with the trough, it could drop a little higher snow
amounts with a headline possible. The blended model tries to
remove ice in the dendritic layer fairly quickly, with the GFS
trend much slower. This makes good sense as greatest lift moves
through and we are pretty much saturated in the dendritic layer
per the GFS. The GEFS P-type probability plots indicate snow over
the area as do the SREF plumes. Will trend the loss of ice lifting
north through 12z Friday. This did give some small chance for
freezing drizzle on the tail end of the system.

This system exits the area early Friday leaving another lull in
the overall weather through Friday night. The latest model
guidance continues to show development of a rather potent storm
system over the Oklahoma panhandle region to the southwest late
Friday night. It lifts northeast and deepens to 989mb toward
southeast MN/northeast IA region by Saturday evening. This would
draw warm air ahead other system and we could see mixed rain
changing to snow over the far eastern portion Saturday. From what
I was able to see of the 00z ECMWF, it looked to be similar to
timing with the GFS as well with rather high QPF and snow
potential associated with it. If this trend continues, this could
be a significant snow maker for much of the cwa.

Weak riding aloft develops in the wake of this system with dry and
mild conditions into Tuesday. The GFS reloads the western trough
and lifts some moisture northeast toward the cwa late in the
forecast period. This too will have to monitored for yet another
possible storm affecting the wester Great Lakes later next week. A
more active pattern developing as we head toward Spring over the

Temperatures appear to be trending closer to normal with reading
a little above normal possible into next week.


.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
Issued at 1056 PM CST Tue Feb 20 2018

We will be VFR with mainly clear skies by daybreak this period
with a 5-10 kt west wind as we get a breather Wednesday before
snowfall returns Thursday.

KMSP...No additional concerns.

Thu...VFR in mrng, MVFR or lower in aftn with -SN. Chc IFR late.
      Wind SE 5-10 kts.
Fri...MVFR. Chc VFR by aftn. Wind W 5 kts.
Sat...VFR in mrng, MVFR or lower in aftn. Chc IFR/-SN late. Wind E
      5 kts.




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