Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 231004
AFDMPX

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
404 AM CST Thu Feb 23 2017

.SHORT TERM...(Today)
Issued at 400 AM CST Thu Feb 23 2017

Satellite imagery this morning and short term weather models
continued to depict the much drier air advecting southward across
Minnesota. The drier air will have a major impact on the timing of
the precipitation this afternoon which will be limited to far
southern Minnesota where the depth of the moisture will be more
apparent. Temepratures will be much cooler than yesterday, but
still above normal with readings in the 30s, to lower 40s.

.LONG TERM...(Tonight through Wednesday)
Issued at 400 AM CST Thu Feb 23 2017

We`ll start with the highlights for the Friday winter storm.  We
updated the forecast to reflect a blend of the 00z runs of the
GFS/ECMWF along with the WPC QPF guidance. The result of this was a
nearly 50% reduction in the snowfall forecast from Marshall through
much of the Twin Cities metro to Rice Lake, WI and points north. The
heaviest snow in the form of 12-15" with amounts up to 18" not
unreasonable is still in the forecast, but is now forecast along and
south of a Fairmont to Eau Claire line with a much tighter gradient
in place to the northwest of where the heaviest snow band is
expected. These adjustments to the snowfall forecast, along with
increased confidence on where the heaviest snow will fall resulted
in upgrades to a blizzard warning in south central MN, with a winter
storm warning to the northeast into Chippewa county in WI, with a
buffer of watches left in place around the warnings. We also trimmed
the northwest tier of counties out of the watch.

Main change seen with the guidance overnight was an overall
convergence toward what the ECMWF has been showing the past few
days. The NAM and several of the hi-res models lie northwest of the
preferred GFS/ECMWF blend, but even these models have been trending
southeast toward the preferred blend with each successive run. The
current forecast has fairly robust agreement within the GEFS as well
and we have fairly high confidence in the current forecast, at least
for where the heaviest band of snow will fall (Fairmont up toward
Eau Claire). There is less confidence northwest of the main band,
though the gradient in the end may end up being even tighter than
what we currently have. This gradient makes county based warnings
somewhat difficult, which is displayed best by Washington county,
where we currently have about 9 inches forecast down by Cottage
Grove and Afton, with totals closer to 3 inches up by Forest Lake.

Models continue to show a weak upper wave moving across the area
Sunday, with low pops in for that. In addition, our temperatures
after Friday will be strongly tied to our expected change in snow
cover and did move high temperature forecasts Saturday through
Monday toward the ECMWF, which shows considerably warmer
temperatures across western and central MN, where bare ground
is expected to be maintained.

Next potential system of significance comes Tuesday/Wednesday.
The Canadian continues to look unreasonably strong with this
system, the GFS continues to struggle to get anything of
significance going, while the ECMWF continues to have another
decent little precip event for us. Given the spread, we only have
chance pops at best. This looks to be a warmer system as well,
with a rain/snow mix expected.

&&

.AVIATION...(For the 06Z TAFS through 06Z Thursday night)
Issued at 1152 PM CST Wed Feb 22 2017

MVFR cigs are clearing across central MN as drier air rapidly
dives south. Expecting low level clearing at all the TAF sites
late tonight or early Thursday with high clouds remaining. Then,
snow will advance northward Thursday evening, but models have
shifted the heavy snow potential considerably south and it`s
possible RWF, MSP, and RNH will be on the edge of the steady snow.

KMSP...Biggest concern will be timing the MVFR cigs out and the
snow for Thursday night. Current timing appears to be between
10-11Z but it could be earlier if holes begin breaking up the
overcast as is the case near STC. As for the snow, it looks like
MSP is on the northwest fringe of the heavy snow now and it may be
the case most of it remains south.

/OUTLOOK FOR KMSP/
Fri...IFR/-SN likely early. Wind N 20G35kt.
Sat...VFR. Wind NW 10-15 kts.
Sun...VFR. Chc MVFR/-SN. Wind light and variable.


&&

.MPX WATCHES/WARNINGS/ADVISORIES...
WI...Winter Storm Warning from 6 PM this evening to 6 AM CST Saturday
     for WIZ023>028.

     Winter Storm Watch from this evening through late Friday night
     for WIZ014>016.

MN...Winter Storm Warning from 6 PM this evening to 6 AM CST Saturday
     for MNZ063-069-070-077-078.

     Winter Storm Watch from this evening through late Friday night
     for MNZ051>053-059>062-068.

     Blizzard Watch from this evening through late Friday night for
     MNZ065>067-073.

     Blizzard Warning from 6 PM this evening to 6 AM CST Saturday for
     MNZ074>076-082>085-091>093.

&&

$$

SHORT TERM...JLT
LONG TERM...MPG
AVIATION...BORGHOFF


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