Area Forecast Discussion
Issued by NWS Twin Cities, MN

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291
FXUS63 KMPX 031839 AAB
AFDMPX

Area Forecast Discussion...UPDATED
National Weather Service Twin Cities/Chanhassen MN
1239 PM CST Sat Dec 3 2016

.SHORT TERM...(Today and tonight)
Issued at 430 AM CST Sat Dec 3 2016

Early this morning, a subtle 700mb wave was moving through the
area producing a few areas of flurries or very light snow
despite high pressure at the surface. As expected the cloud cover
has held firm, but there is some erosion to the cloud deck across
portions of South Dakota. But, the last few satellite scans show
new stratus forming in northwest Iowa and expanding. So, we are
holding firm to the forecast for continued cloud cover this
period.

Early this morning, a mid level shortwave trough axis was apparent
on water vapor imagery pushing into the Dakotas from
Montana/Wyoming. This shortwave is expected to continue east
through the Dakotas this morning and begin spreading light snow
into western Minnesota this afternoon/evening. As the wave becomes
more negatively tilted and the PV feature pushes through late
tonight, isentropic lift (albeit not impressive) will coincide
with deeper moisture and produce up to an inch of snowfall across
far eastern MN and into west central WI by tomorrow morning.

Temperatures will continue to only vary by 5-10 degrees through as
skies remain mostly cloudy. We could see some brief breaks in the
clouds later today before the shortwave reaches us, but clouds
will fill back in tonight.

.LONG TERM...(Sunday through Friday)
Issued at 430 AM CST Sat Dec 3 2016

Sunday through Tuesday...The day will commence with a cold front
swinging through the region in conjunction with a modest longwave
trough axis. Light snow will likely be ongoing in far eastern MN
into western WI, and likely will continue in western WI through
much of the day. Its fast progression and far proximity from the
parent low (in south-central Canada) will mitigate any appreciable
snow accumulations so will only look for 1-2 inches in western WI
with less than an inch going into eastern MN. Some mixture with
-RA is possible in southeast MN as cold air advection will not
kick in until the start of the week, particularly with H5 heights
actually rising slightly on the backside of the departing ridge
for Monday. Highs will increase from the low-mid 30s on Sunday to
the mid 30s to lower 40s on Monday, even with plenty of cloud
cover still in place. A more potent but drier cold front will
swing through the region Monday night into early Tuesday and this
front will be the leading edge of a prolonged surge of colder air
which will last through the rest of the week. While some snow
showers are possible across the area, very limited moisture look
to keep accumulations minimal at worst, potentially an inch or
less. The main impact will be H85 temps in the -20 to -25 deg C
range starting to make their way down from northwestern Canada
atop dense high pressure oozing its way southeast. H5 heights
will also drop, shifting to a more west to northwest flow. As
such, highs are expected to only range 20-30 degrees.

Wednesday through Friday...Much colder temperatures will be the
main story with only minor spurts of -SN throughout the second
half of the week. The dense cold high pressure and deep northwest
flow will prevent any significant systems from impacting the
region, making for the first strong cold spell of the season. An
upper level trough will drop southeast through the region late
Wednesday into early Thursday, bringing some snow showers for
mainly northern and eastern portions of the WFO MPX coverage area
but with little to no snow accumulation. As alluded to,
temperatures will go on a very noticeable plunge to below normal
levels and this is even without any upstream snow cover to help
modify or enhance the colder air. Highs are expected to drop to
the teens while lows hit the single digits. Winds will also
increase in the mid-to-late week timeframe, which means wind
chills from Wednesday on through the rest of the week will
commonly run from zero to ten degrees below zero Fahrenheit.

&&

.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
Issued at 1239 PM CST Sat Dec 3 2016

MVFR cigs are beginning to break up from west central to south
central MN early this afternoon and this clearing will continue to
push eastward for the rest of the day. A period of VFR conditions
are likely this evening before snow advances eastward across the
region tonight. IFR cigs and visibilities are expected with the
snow and accumulations will range from a half inch to as much as 3
inches across western WI.

KMSP...MVFR cigs still persist at taf issuance time but they are
beginning to erode quickly just to the south and west. Another
narrow band of stratus behind some of this clearing may move back
in during the next couple hours, so not confident in VFR
conditions until mid afternoon. Snow looks to arrive during the
late evening and IFR conditions are expected for much of the
overnight with some improvement Sunday morning.

/OUTLOOK FOR KMSP/
Mon...VFR. Wind SE 10-15kts.
Tue...MVFR. Chc -SN early. Wind WNW 10-20kts.
Wed...MVFR. Wind WNW 15-25kts.

&&

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

$$

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



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