Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

FXUS63 KMPX 101209 AAA

Area Forecast Discussion...UPDATED
National Weather Service Twin Cities/Chanhassen MN
609 AM CST Tue Dec 10 2019

.SHORT TERM...(Today through Wednesday)
Issued at 355 AM CST Tue Dec 10 2019

Cloud cover is advancing eastward from western MN and the Dakotas 
early this morning. It has had a significant warming influence with 
temperatures rising 5 to 10 degrees as it moves overhead. The clouds 
are in association with a mid level shortwave that will swing 
through this morning. Behind this shortwave is a reinforcing shot of 
cold air and gusty winds, so temperatures won't rise much above 
zero, and they may not at all in some places in central MN. 
Scattered flurries are possible under the cloud deck. 

While the clouds have led to milder conditions overnight, the 
increasing wind behind this shortwave will bring colder wind chills 
a bit later this morning across west central MN. Extended the 
advisory there through Wednesday morning. Wind chills may remain 
around 25 below for most of the day. Clearing skies this afternoon 
will lead to good radiational cooling conditions tonight area wide. 
The exception may be across southern MN where another shortwave 
could bring increasing clouds and a chance of light snow during the 
late evening and early overnight hours. This will result in a bump 
in temperatures after a good drop early this evening. The cooling 
will resume late tonight, but temps should be warm enough and winds 
may be light enough to forgo an advisory for that area. Elsewhere, 
clear skies are expected for much of the night with decreasing winds 
as another high pressure center arrives. It's always tough to 
pinpoint where the winds will decouple and temps drop to around -20, 
but for the most part central MN and western WI will drop into the 
mid negative teens with winds remaining around 5-6 mph, giving wind 
chills of 25 to 35 below. The advisory was expanded eastward for 

The high will be centered across southern and western MN for 
Wednesday. While temps aloft begin warming, it will be tough to get 
much mixing at the surface with light winds and abundant snowpack. 
Therefore, highs tomorrow will be similar to today in the low single 
digits above and below zero.

.LONG TERM...(Wednesday night through Monday)
Issued at 355 AM CST Tue Dec 10 2019

In the longer term we'll see the large scale pattern de-amplify as
the eastern upper trough lifts to the north. There is a fair
amount of disagreement in how the synoptic flow will evolve beyond
this weekend, so there is not much impetus to go against the
consensus NBM guidance beyond Friday at this point (which results
in near to below normal temperatures and few chances for
precipitation). The main item of concern in the period is a 
system that will impact the region Wednesday night into Thursday. 
Forcing with this system will not be as strong as with yesterday's
shortwave trough, but the window of precipitation will be a bit 
longer and snow ratios could be a bit higher. At this point, 
amounts of just a dusting to 2 inches look likely, but will need 
to keep an eye on things, since it is one of those sneaky 
northwest flow features that could squeeze out 3 or 4 inches 
depending upon the strength of frontogenesis and whether we see a 
decent period of dendrites. In addition, won't be shocked if 
guidance winds up a bit south of where it currently places the 
main axis of precipitation, since that often seems to happen when 
a good arctic airmass is already in place ahead of such features.
In any event, it still looks to be far from a significant system,
but timing could be troublesome once again (with snow falling 
during the commute on Thursday). After the Wednesday 
night/Thursday system the flow becomes more progressive and we'll 
have a few shortwave troughs pass through the region, brining a 
couple chances for more light snow. 


.AVIATION...(For the 12Z TAFS through 12Z Wednesday morning)
Issued at 609 AM CST Tue Dec 10 2019

Clouds are spreading east across the region this morning, but the
back edge is already pushing across western MN. Cigs are largely
VFR with some localized MVFR and IFR levels. Clear skies expected
this afternoon and tonight. WNW winds will shift SW this evening,
then shift back to WNW later tonight.

KMSP...No additional concerns.

Wed...VFR. Wind NW 5 kts. 
Thu...VFR with MVFR/-SN likely early. Wind SSE 5 kts. 
FRI...MVFR ceilings with -SHSN possible. Wind S 5-10 kts.


WI...Wind Chill Advisory from 9 PM this evening to noon CST Wednesday 
     for WIZ014>016-023>028.

MN...Wind Chill Advisory until noon CST Wednesday for MNZ041>043-

     Wind Chill Advisory until noon CST today for MNZ044-045-051-

     Wind Chill Advisory from 9 PM this evening to noon CST Wednesday 
     for MNZ044-045-051>053-055>063-065>070.



National Weather Service Glossary of Abbreviations