Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 101029

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

.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 06Z TAFS through 06Z Sunday night)
Issued at 1135 PM CST Sat Dec 9 2017

A frontal boundary will move through and bring northwest winds
today. Could see some MVFR ceilings, but most locations should be
VFR. Later Sunday night another quick moving system will bring
southwesterly winds back across the region and some light snow
will develop.

Did include a brief period of MVFR clouds Sunday afternoon based
on the persistent trend in the forecast soundings that show a
broken layer around 1500 to 2000 ft. There is a chance for snow
showers Sunday night into Monday morning which could bring a brief
period of MVFR or even IFR conditions.

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




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