Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 141735
AFDMPX

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
1135 AM CST Thu Dec 14 2017

.UPDATE...
Issued at 1123 AM CST Thu Dec 14 2017

Updated for the 18Z aviation discussion below.

&&

.SHORT TERM...(Today and tonight)
Issued at 338 AM CST Thu Dec 14 2017

Quick moving clipper moving into northeast MN this afternoon is
still on track to drop south along the MN/WI border this evening,
with maybe 1.5" of snow coming down for Ladysmith down to Eau
Claire. Models have remained fairly consistent with the handling of
this wave and only change made to the existing forecast for this
snow was to delay its arrival by a couple of hours.

Beside the snow, there also looks to be a 3 or 4 hour period behind
this systems cold front where winds could get a bit strong,
especially for western into south central MN. CAA in the wake of the
front will result in steep lapse rates with a mixed layer getting up
to between 850 and 800 mb. NAM shows top of the channel winds
immediately behind the front getting into the mid 40 kts, so did
boost winds above blended guidance, with some 40+ mph wind gusts
not out of the question. Beside the winds, forecast soundings also
show any post frontal stratus being located directly within the
dendritic growth zone, so it shouldn`t be tough developing
flurries/light snow through the night.

Big question for Saturday is how quickly do we loose the low clouds.
Even if we do lose the clouds though, we will be placed squarely
within the temperature gradient between the cold trough to the east
and warm ridge to the west, so any way you slice it, our Saturday
will have more clouds than sun. Not much spread in guidance for
highs tomorrow, so stuck pretty close to a mean of blended guidance.

.LONG TERM...(Friday through Wednesday)
Issued at 338 AM CST Thu Dec 14 2017

An upper low over northwest Ontario will drive a stream of weak
shortwave energy across the area Friday into Saturday. The best
forcing looks to occur along and north of Interstate 94, where
30-40 POPs have been included.

On Saturday night and Sunday another wave follows on its heels,
as an inverted surface trough noses into central Wisconsin. Could
see some light snow over west central Wisconsin.

The first half of the upcoming week looks dry with mid level
ridging dominating locally. By the end of next week the western
shortwave trough looks to kick out and reach the area late in the
week. Large scale features and timing are still uncertain with
GFS/ECMWF models currently pointing toward higher snowfall
chances/amounts north/east of the area.

Overall high temperatures will run above normal, with the
exception of over west Central WI where more clouds and cyclonic
flow will keep temps slightly below normal. Meanwhile, low
temperatures will average 5 to 15 degrees above normal.

&&

.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
Issued at 1123 AM CST Thu Dec 14 2017

Continued cool cyclonic flow will reinforce stratus across the
region, but the guidance does indicate a few hour period this
evening through tonight of cigs rising to VFR levels. And given
this pattern and the shortwave dropping through the Dakotas, snow
flurries and sporadic snow showers will continue to move through
as well. Winds will behave quite well, generally from the
northwest around 10 knots or less. The next main wave shows up
right at the end of the TAF period and looks to mainly impact
northern MN and western WI will reduced vsbys in snow, but some of
those conditions could graze the I-94 corridor in Minnesota as
well.

KMSP...no accumulation expected from flurries and snow showers.

/OUTLOOK FOR KMSP/
Sat...Chc MVFR. Wind E 5 kts.
Sun...VFR. Wind NW 5 kts.
Mon...VFR. Wind SW 10-15 kts.

&&

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

$$

UPDATE...SPD
SHORT TERM...MPG
LONG TERM...LS
AVIATION...SPD


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