Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 021119
AFDMPX

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
519 AM CST Fri Dec 2 2016

.SHORT TERM...(Today and tonight)
Issued at 330 AM CST Fri Dec 2 2016

With no precipitation expected this period, the focus is on the
cloud cover and temperatures. A large low pressure system is
centered north-northeast of the Great Lakes which is easily
discernible on water vapor satellite imagery early this morning.
This system continues to keep our area within a low level cyclonic
flow regime with plenty of low level moisture in place across the
region.

The limited precip activity came to an end last evening and we do
not expect to see any additional precipitation this period, but
rather stay locked in under stratus through today and tonight.
Given the abundant cloud cover, the blend of all the new
guidance came in with a slightly cooler trend for high
temperatures today, so adjusted down a degree or two across the
area.

Surface high pressure will continue pushing into the area today,
so wind speeds should be relatively light. And despite the high
pressure at the surface, the various models indicate saturation
below 850mb lasting throughout the period which means overcast
skies are plausible as the moisture is stubborn to move this time
of year with limited mixing depth.

.LONG TERM...(Saturday through Thursday)
Issued at 330 AM CST Fri Dec 2 2016

Saturday and Sunday...Upper level ridging for much of the day on
Saturday will give way to an incoming weak longwave trough axis
emanating from the west coast. Very little in the way of surface
reflection is evident with this upper level feature, so it can be
described as either a very minor cold front or a fairly decent
surface trough. In fact, temperatures will actually be on the
rise behind the feature due to the fact that surface flow shifts
from south to west while upper level heights rise behind the
passage of the upper trough. Scattered rain/snow showers will be
associated with these features but with little consequence. There
will be slightly better lift going into eastern portions of the
WFO MPX coverage area (specifically, western WI), so there is the
potential for up to an inch of wet snow Sunday afternoon and
evening. As for temperatures, highs will climb from the low-mid
30s on Saturday to the mid-upper 30s on Sunday while lows remain
in the mid-20s to around 30s.

Monday through Thursday...The picture is becoming clearer in the
extended and that picture shows both a noticeable cooling trend
to below normal temperatures and the avoidance of any significant
storm systems impacting the area. A large upper level low from
northwest Canada will slowly drift into the Great Lakes during
the early-middle portions of next week. As this low drops south,
forming a large longwave trough over the western 2/3 of the CONUS,
a low pressure center will develop over the northern Rockies which
will be picked up by this trough. The storm center looks to take a
track across the Dakotas into northern MN Monday night into
Tuesday, dragging a cold front through the region. Moisture will
be fairly starved with this system as the low becomes strung out
by the time it moves through NW MN. This will keep precipitation
totals low while the cold air lags behind its track. Once the
front moves through, then strong CAA within surface high pressure
and NW flow aloft will keep any significant systems away from the
area. The only feature which would bring precipitation will be the
approaching upper level low, which would mainly impact eastern
portions of the coverage area. In addition, the cold front looks
to stall out south of the area enough to possibly being light
snows to southern portions of the coverage area. Overall, the
scenario is looking for occasional periods of light snow Tuesday
through Thursday for eastern and southern portions of the coverage
area with only minimal accumulations possible. The more
significant impact will be much colder air moving into the region.
H85 temps will drop to around -20 deg C Wed through Thu, which
translated to the surface will spell lows dropping into the single
digits to lower teens with highs in the teens to lower 20s by the
middle portion of the week.

&&

.AVIATION...(For the 12Z TAFS through 12Z Saturday morning)
Issued at 514 AM CST Fri Dec 2 2016

The main point of this aviation forecast period is very little
change in the ceiling and winds gradually decreasing as surface
high pressure works in from west to east. Despite the high at the
surface, the abundant low level moisture in the 2k-3k ft layer will
not be going anywhere. It is possible that ceilings jump just
above 3k feet today during the day, so VFR could be achieved, but
kept at least 3k ft or lower in the forecast at this time as given
the very low sun angle, diabatic mixing and lifting of the cloud
base is tough this time of year.

KMSP...no change from the main discussion.

/OUTLOOK FOR KMSP/
Sat...VFR. Wind SW 5-10 kts.
Sun...MVFR. Chance -SN. Wind SW 10 kts.
Mon...VFR. Wind S 10-15 kts.

&&

.MPX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
&&

$$

SHORT TERM...SPD
LONG TERM...JPC
AVIATION...SPD



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