Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 221114

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
514 AM CST Wed Nov 22 2017

.updated for 12z aviation discussion below...

.SHORT TERM...(Today and tonight)
Issued at 257 AM CST Wed Nov 22 2017

The main forecast concern in the short term will be timing and
extent of light snow event this afternoon/evening.

Few residual stratocumulus exiting the far eastern cwa. Meanwhile,
a large area of Pacific moisture is spilling over the western CONUS
ridge across the Dakotas. Expect this trend to continue through the
morning with increasing mid/high level clouds expected to move east.
Mostly cloudy conditions by noon over the MN portion of the
cwa. This should put an end to much temperature recovery, with the
exception to the lee of the Buffalo Ridge to the southwest, where
some downsloping will occur. Isentropic lift increases over the
northern cwa this afternoon and spreads east into west central WI
for the evening. We do saturate to at least 4K feet in best area
of lift so we should be able to generate some light snow, even
with the rather dry start this morning. It will take much of the
day to saturate and will continue to carry a slight chance PoP as
far south and west as the metro this afternoon into the evening.
More than likely a few flurries will be the result here with
perhaps around one half inch along the northeast periphery of the
cwa, along the Highway 8 corridor in west central Wisconsin.

We expect a general clearing trend again from west to east during
the night as the weak wave moves through.

.LONG TERM...(Thursday through Tuesday)
Issued at 257 AM CST Wed Nov 22 2017

Not much of a change expected in the weather pattern during the long
term period, with relatively fast flow expected across the CONUS that
will send systems across the area every couple of days.  We will be
under the influence of mainly a mild Pacific airmass though will
continue to see brief one or two day cool downs in the wake of each
system. There are no systems of significance through the weekend, but
the GFS/ECMWF have a potential trouble maker for us Tuesday/Tuesday
night next week, but as will be explained to come, it`s a bit early
to get overly excited about that system yet.

Not much has changed with the forecast Thursday and Friday. Friday
still looks to offer a chance of showers as a cold front associated
with another surface low tracking across southern Canada moves
across MN and western WI during the afternoon. Greatest precip
potential looks to be from northern MN into northern WI, closer to
the surface low and better PV advection from the shortwave forcing
that low. The Canadian and even SREF keep precip north of the MPX
area, but plenty of other guidance shows a line of showers
developing along the eastward advancing cold front from central MN
into west central WI, which is where the highest pops continue to be
centered. Still a bit of uncertainty with highs on Friday and the
wild card here is the cloud cover. Most guidance pushes highs above
the 50 mark up to about the I-94 corridor, but the NAM is painting a
different story.  The NAM brings dense stratus up into the area
Friday night, which is certainly possible with surface dewpoints
increasing into the low 40s. With dense stratus around all day, the
NAM is a good 10 degrees colder than us and the rest of the guidance
suite. This possibility is the one thing that that makes us hesitant
to say MSP will finally crack that 50 degree mark this month on

Behind this front we will again see blustery northwest winds, though
winds do not look as strong as what was seen early Tuesday morning.
The one change noted over the last few model runs for this weekend
is they are considerably warmer. Gone are the -8c to -12c h85 temps
for Saturday, which are now forecast to be 0c to -8c, with h85 temps
surging above 0c by Sunday. The result, is our cold day Saturday is
still looking to have highs in the mid 30s to low 40s as opposed to
upper 20s to mid 30s like we were seeing a couple of days ago.
Sunday is even more dramatic, with most of the area looking to
finish off the holiday weekend with highs back into the 40s.

Next week is when things look potentially interesting, at least from
the operational runs of the GFS and ECMWF. As the ridge bringing
record warmth to the southwest for Thanksgiving begins to breakdown
and slide into TX, models show a trough coming into the west coast
Sunday/Sunday night. This through will emerge from the Rockies
Monday night, with a surface cyclone likely developing over the
Plains and heading our direction Tuesday. Though the ECMWF/GFS are
in pretty good agreement with each other for this far out, GEFS QPF
plumes for Alexandria show that the operational GFS only has one
other GEFS member showing a similar forecast. In this pattern over
the last couple weeks, the models really have not started to settle
in on a forecast and ensembles begin to show limited spread until we
have hit the day4 potion of the forecast. So although the GFS and
ECMWF are showing a decent snow storm next week for western and
central MN, it`s probably too early to start getting excited about
details until we get to models run Friday night or Saturday, though
it is encouraging to see that at this point, the models are not
sending yet another surface low across southern Canada and have this
one at least closer to home. Behind this wave though we look to
quickly return to a mild Pacific airmass, with winter looking to
still tease us at this point as opposed to setting up shop for an
extended period of time.


.AVIATION...(For the 12Z TAFS through 12Z Thursday morning)
Issued at 515 AM CST Wed Nov 22 2017

VFR conditions expected with area of light snow developing mainly
north of KSTC to KEAU this afternoon and exiting to the east this
evening. Cigs will lower to 4K feet over the north and east as
frontal system moves east late afternoon/evening. Winds becoming
nw with fropa.

VFR conditions with winds becoming southerly 6 to 11 kts this
morning. Expect cigs to lower to 4-5k ft by 20z. May see some
virga but believe main light snow area will develop east of the
area. Clearing overnight with wind becoming nw late.

Thu...VFR. Winds NW 5 kts.
Fri...VFR with MVFR/-SHRA likely late. Winds SW 10 kts turning NW
with PM FROPA and increasing to 15-20 kts.
Sat...VFR. Winds NW 10G20 kts.




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