Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 270948

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
348 AM CST Sun Nov 27 2016

.SHORT TERM...(Today and tonight)
Issued at 345 AM CST Sun Nov 27 2016

Concerns are twofold in the short term. First and foremost is the
widespread dense fog event that has ensued with plentiful boundary
layer moisture and light winds in place. The dense fog advisory was
expanded to included the entire forecast area. In addition to the
sub-quarter mile visibility reductions, sub-freezing temps are
likely yielding slick spots on paved surfaces (especially
bridges/overpasses). It could be awhile before visibilities improve
this morning given the low level flow and amount of moisture trapped
in the boundary layer. Will quite possibly need to extend the dense
fog advisory past its current 9 am expiration, particularly across
central MN. Given uncertainty in the areal/temporal extent to which
this would be needed, will hold off to see how things evolve this
morning. Have also gone a bit more pessimistic with cloud cover
given the potential for stratus/stratocu to linger. South/east
central and southeast MN and west central WI will have the highest
potential for sun this afternoon prior to the clouds entering from
the west, and are therefore expected to see high temps a bit warmer
(mid to upper 40s).

By 21z, Hi-res models are in pretty good agreement that the surface
low will be across southwestern SD/NE...with the precipitation
shield entering southwestern MN. Have slowed precip chances down
about 1-2 hours, but in general things look about the same, with
rain reaching the Interstate 94 corridor around 00z Monday. The 00z-
06z timeframe looks to feature the most widespread areal coverage of
rain, with indication of dry slotting moving into southwestern MN
between 06z and 12z Monday. Weak elevated instability still looks
sufficient to favor the inclusion of an isolated thunder mention
tonight as well. Most area should see one half to three quarters of
an inch rainfall by daybreak Monday.

.LONG TERM...(Monday through Saturday)
Issued at 345 AM CST Sun Nov 27 2016

The large scale pattern remains favorable for a continuation of
cloudy skies, light precipitation, and near to slightly above
normal temperatures from Monday through Wednesday. Due to these
conditions, very little diurnal temperature change is expected
with highs and lows within 5 to 10 degrees.

Models are consistent with this pattern so confidence in the
forecast from Monday through Wednesday is fairly high. One of the
main focus in the models is the strength of a large ridge building
across central Canada next week. Although models are again similar
on slowly filling and lifting a cutoff low from the Upper Midwest,
eastward across the Great Lakes by Wednesday/Thursday. The pace of
the eastward progression of this upper low is dependent on the
upper ridge location in central Canada, and the strength or
weakness as the week progresses. The cloud skies and light
precipitation could linger longer this week if the upper ridge
remains strong.

Once the upper low moves off and the upper flow becomes more
progressive, a slight warming trend is expected by next weekend.
These warmer temperatures for the first week of December will
likely be short lived as longer range models have been forecasting
a significant change in the weather pattern with much colder
conditions after December 7th. The latest EC/GFS near 240 hours
out have a very strong high pressure system building north of the
northwest territories of Canada. This air mass is progged to move
southward the week of December 7th into the the northern United
States. Although this forecast is far from perfect, trends in the
pattern change reflect a higher confidence in this air mass
affecting our region the second week of December.


.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
Issued at 1059 PM CST Sat Nov 26 2016

IFR/LIFR conditions across much of the area as fog coverage has
expanded this evening and will continue to do so overnight. Looking
ahead, low clouds will lift northward Sunday afternoon, with rain
following for Sunday evening. A few embedded thunderstorms are
possible, but at this time confidence too low to include mention
in the taf. Looking ahead, expect cloudy conditions to persist
for much of the upcoming week.

Cold see some patchy MVFR fog develop overnight, with IFR
possible. Otherwise expect VFR conditions for the morning and
early afternoon until stratus moves up from the south around 21 to
22Z. Rain will follow a few hours later, with IFR vsbys/Cigs
expected after sunset. Winds will be southeast with gusts near
20kts Sunday evening.

Mon...MVFR early with -SHRA. Wind S 10-15 kts.
Tue...MVFR/IFR. Chc -RA. Wind SW 5-10 kts.
Wed...MVFR/IFR. Chc -RA/-SN. Wind NW 5-10 kts.


WI...Dense Fog Advisory until 9 AM CST this morning for WIZ014>016-

MN...Dense Fog Advisory until 9 AM CST this morning for MNZ041>045-



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