Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 280946

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
346 AM CST Mon Nov 28 2016

.SHORT TERM...(Today and tonight)
Issued at 335 AM CST Mon Nov 28 2016

Early morning water vapor imagery and radar data illustrate the dry
slot centered over the forecast area, associated with the eastern
Dakotas upper low. A few spotty showers and light drizzle are being
reported, but there is a lull in the more widespread/organized

There will be two main areas of redevelopment today. The first will
be over west central MN related to the upper low, with the second
area of redevelopment anticipated along/east of Interstate 35 in
vicinity of the surface front during the late morning and afternoon
hours. While we did not see any nocturnal thunder activity locally,
the late morning and afternoon activity will have the potential for
some thunder with the surface low nearby. Non-supercell tornado
parameters (surface CAPE to 3 km and surface vorticity) peak along I-
35 (the front) this afternoon. Do not think we have enough
instability, otherwise it would be a potential tornado day.

High temperatures will be quite mild given the warm start to the
day, and expect lower 40s to lower 50s. These readings are 15-20
degrees above normal, but will likely fall short of record values
which are in the upper 50s.

Tonight precipitation will be primarily focused along the
western/northern fringes of the forecast area tied to the upper low,
and we should start to see some snow mixing in during the evening as
colder air works in.

.LONG TERM...(Tuesday through Sunday)
Issued at 340 AM CST Mon Nov 28 2016

The very highly amplified upper low will be slow to move out of
the Upper Midwest this week as a blocking type pattern develops
north across central Canada. Models have been forecasting this
scenario of the upper ridge across central Canada with a few minor
differences in the intensity and movement through Thursday.
Forecast confidence remains high as the mean upper low overhead
today will slowly fill and lift across the Great Lakes region by
the end of the week. The air mass will slowly cool overhead as
colder air rotates into the system, but nothing too extreme.
Therefore, the mixture of rain during the day and snow at night
seems likely. Any accumulations will be minor as the main lift and
deeper moisture will hold west of our region, but an inch or two
is possible in western Minnesota once colder air returns. Even if
precipitation develops or not, cloud cover will persist with
little diurnal change from nighttime lows, and daytime highs.

Next weekend remains questionable as the EC has a much different
forecast for a storm system moving out of the desert southwest,
vs. the GFS/GEM. Both the GFS/GEM continue with a more split flow
regime, with the EC more progressive, especially with the southern
jet stream. Due to these differences, forecast confidence is low
for next weekend.

Past next weekend, and how the aforementioned storm system affects
the central part of the country next weekend, a much colder flow
regime should develop the week of December 7th. This colder
outlook has been advertised enough by the longer range models to
have some support/higher confidence on a colder weather pattern
developing. Timing and how cold this air mass becomes remains the
big question. However, current models are forecasting -20 to -25C
850H temperatures behind this air mass flowing southward over the
Upper Midwest for the week of December 7th.


.AVIATION...(For the 06Z TAFS through 06Z Monday night)
Issued at 1055 PM CST Sun Nov 27 2016

The majority of the rain has lifted north of the TAF sites, but
some light drizzle and low clouds will remain overnight. There is
a slot of dry air across eastern NE and western IA that is
forecast to make its way across southwest MN overnight, so do have
VFR conditions returning by early afternoon on Monday. A few
periods of rain showers are possible as the upper level cyclone
rotates overhead.

VFR conditions should return Monday afternoon. It is possible that
they could return sooner, but confidence is too low to get to
aggressive with the clearing later tonight. A few light rain
showers are possible overnight, but for the most part the majority
of the precipitation has ended at KMSP.

Tue...MVFR/IFR. Chc -RA. Wind SW 5-10 kts.
Wed...MVFR/IFR. Chc -RA/-SN. Wind NW 5-10 kts.
Thu...MVFR/IFR. Chc -RA/-SN. Wind NW 5-10 kts.




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