Area Forecast Discussion
Issued by NWS Twin Cities, MN

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453
FXUS63 KMPX 101800
AFDMPX

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
1200 PM CST Sun Dec 10 2017

.updated for 18z taf discussion below...

.SHORT TERM...(Today and tonight)
Issued at 417 AM CST Sun Dec 10 2017

A weak north-south warm front has been inching eastward most of
the night but has stalled west of I-35. Temperatures west of the
front have risen into the upper 20s to mid 30s, but light winds
and clear skies to the east of it have allowed temperatures to
drop into the teens. Winds will turn more northerly this morning
so we may be nearing highs for the day already in the warm sector.
Clouds will also be increasing and they are widespread across
northern MN into most of WI. This should keep many areas from
reaching the 30s today.

Dry weather will prevail until this evening when a clipper system
begins to move in. Models still don`t seem to have a solid handle
on it yet with lingering uncertainty of where the band of snow is
going to set up. This is likely due to how elongated the mid
level wave is and the placement of the surface low is thus prone
to bounce around a bit. The mid level wave overall is quite potent
and lapse rates above 850 mb are impressive. This should sustain
a solid band of snow along and north of I-94 overnight with
potential for it to overachieve in places. Still maintaining a
forecast of 1 to 2 inches for now.

Another thing to watch is whether freezing drizzle can develop in
the warm sector (western and southern MN) as ice is lost aloft
with the dry slot and/or temps aloft warm above freezing. Forecast
soundings aren`t too helpful with poor consistency of moist
layers from hour to hour and forcing is weak outside of the snow
band so am not confident in much precipitation in those areas.

.LONG TERM...(Monday through Saturday)
Issued at 417 AM CST Sun Dec 10 2017

The steady WAA band of snow will push east by Monday morning, but
wrap around snow showers will continue through the morning hours.
We may be able to squeeze another couple tenths of an inch of
accumulation before dry air filters in during the afternoon.

The active northwest flow will continue through the period. At
this point none of the short waves passing through have much
potential for producing meaningful snow accumulation. PoPs may be
underdone, however, mid to late week. Cyclonic flow Wednesday
through Friday will likely produce snow showers or flurries at
times. The good news is the boundary layer is warmer than the DGZ,
which is actually quite high at 800 mb or above. Thus, we are
lacking instability from steep low level lapse rates through that
layer which should limit the extent/intensity of snow showers and
accumulation potential.

&&

.AVIATION...(For the 18Z TAFS through 18Z Monday afternoon)
Issued at 1155 AM CST Sun Dec 10 2017

MVFR cigs over the eastern portion of the cwa expected to move
little during the afternoon. We may see some erosion to the
northeast and southwest during the afternoon, with KMKT on the
western fringe. Otherwise will mainly MVFR trend to IFR
overnight as area of snow moves east over the eastern areas. Some
threat of fzdz/-fzra over the western taf sites - mainly KAXN
this evening and toward KSTC/KMSP after 06z. Will maintain snow
trend for now. Still looks like accumulations of 1-2 inches over
the eastern RAF sites into Monday morning. Cold front exits to the
south during the morning with at least MVFR cigs remaining and
possible sct shsn. nw winds becoming sly overnight ahead of
clipper and gusty nw with fropa in the wake of the system.

KMSP...MVFR cigs are likely to continue through the period.
Still expect some -sn moving in after 04z with some -fzdz possible
08z-12z or so in lull as precipitation/snow area moves east.
Still MVFR cigs through much of Monday with sct -shsn possible
into the early afternoon. NW wind becoming sly into the evening
and then NW and gusty late Monday morning.

/OUTLOOK FOR KMSP/
Mon...MFVR with chc IFR/-SHSN early. Wind NW 15G25 kts.
Tue...VFR. Wind NW 10 kts.
Wed...MVFR with -SN. Wind SE at 10 kts.

&&

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

$$

SHORT TERM...BORGHOFF
LONG TERM...BORGHOFF
AVIATION...DWE



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