Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 082117

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
317 PM CST Thu Dec 8 2016

.SHORT TERM...(This evening through Friday)
Issued at 245 PM CST Thu Dec 8 2016

Very similar from last nights forecast with enough moisture in the
dendritic growth zone to continue scattered snow showers/flurries
through the evening for mainly the eastern half of MPX forecast
area. It could even continue for western Wisconsin on Friday as
cyclonic flow continues in the area along with the necessary
ingredient for dendrites to form. The continued cold air advection
tonight, and into Friday will lead for highs only rising into the

.LONG TERM...(Friday night through Thursday)
Issued at 245 PM CST Thu Dec 8 2016

The main concern for the longer term is the snow potential from
Saturday/Saturday night event and overall model evolution of the
trough amplification and timing of new arctic air invasion early
next week.

Initially dry conditions are expected Friday night ahead of the
next short wave. It appears the NAM is the odd model out once
again...with its farther north solution for the Saturday snow
event. Feel confident enough to drop heavier snow accumulations
mainly along and south of the MN River...which has been consistent
with most of the deterministic runs. Followed more of the GFS
solution for its evolution...which appeared to be a compromise
between the more amplified 12z NAM and the farther south 12z
ECMWF. This leaves a swath of snow in solid advisory range(3 to 5
inches accumulation) from near Morris-Willmar-Southwest Metro_and
southern Goodhue Co. with the higher amounts mainly over south
central MN close to I90. Looking at dendritic growth potential off
the GFS...shows better omega and thickness of the DGZ acrosssouth
central MN during the late morning Saturday lingering into
Saturday evening. We should see a decent burst of snow 2-3 inches
across that region of the state. Isentropic lift is strong(280K
Sfc) over the area with a solid 2 g/kg into south central MN
through 12z Sun along the MN/IA border. This could lead to a 6-7
inch total close to the border through the period.

The system shifts east rapidly into Saturday night...and should
end through 12z Sun. Models are coming more in agreement with the
secondary short wave affecting the region later Sunday into
Monday. The GFS remains farther south with it snow
development...with the other deterministic runs favoring a more
northern track and more amplified wave, We will continue with
chance pops for this feature at this time and continue to monitor
model performance in later runs.

Following this feature the timing of the arctic boundary moves
into eastern MN by late Monday afternoon. We will continue to
trend a chance of light snow/snow showers with the passage of the
front through Monday night. The coldest day appears to be Tuesday
night/Wednesday with some potential of teens below zero over the
west ...if clouds clear and winds die off. We will drop readings
a degree or two for now. Below normal temperature trends should
continue through next week.


.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
Issued at 1115 AM CST Thu Dec 8 2016

No major changes for the 18z tafs with MVFR ceilings through most
of the period, with only a small chance of VFR at times this
afternoon and evening. Any snowfall will be light and briefly
lowering visibilities to 5SM. Blowing snow is still possible at
KAXN this afternoon. Winds will remain gusty, but light winds and
backing to a more westerly direction is expected tonight.


Similar scenario with high end MVFR, or low end VFR conditions
through most of the taf period. Best chance of VFR will occur
Friday afternoon. Gusty winds this afternoon will back and drop to
around 5-8 knots by Friday.


Sat...MVFR, then IFR in SN. SE wind 5-10 kts.
Sun...IFR/MVFR in SN early. MVFR/VFR possible late. N wind 5-10 kts.
Mon...MVFR/VFR with -sn possible. WNW wind 5-10 kts.




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