Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 231105

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
505 AM CST Thu Nov 23 2017

.updated for 12z aviation discussion below...

.SHORT TERM...(Today and tonight)
Issued at 400 AM CST Thu Nov 23 2017

The main forecast concern in the short term is the extent of
high clouds during the day and if that will limit heating

Satellite showing abundant cirrus dropping southeast across
Minnesota this morning. Associated with the weak short wave/vort max
over eastern North Dakota/northwest Minnesota. Will have to carry
this throughout at least the morning and perhaps some thinning out
this afternoon before the next high level Pacific moisture surges

At the surface, there remains a weak surface low moving across
southwest MN and is forecast to exit to the southeast this morning.
This will leave weak high pressure over the eastern cwa with a
developing surface warm front to the west. This pacific warm front
may work into southwest MN this afternoon and with some southerly
wind should be able to downslope some lower 50s to the lee of the
Buffalo Ridge in the southwest. Otherwise temperature are forecast
to remain in the 30s to east and lower to mid 40s over much of MN
portion of the cwa.

Tonight the Pacific front moves east and we expect perhaps an
evening low with steady or slowly rising temperatures over much of
the cwa. Mid/high clouds are expected to be abundant again as the
next frontal system approaches.

.LONG TERM...(Friday through Wednesday)
Issued at 400 AM CST Thu Nov 23 2017

A potent storm system will propagate across southern Canada
Thursday night into Saturday, dragging a cold front through
Friday. This front looks mostly dry with the best forcing to the
north and a lack of deep moisture to the south. The best chance of
any showers appears to be north of I-94, and especially across
northern MN and the U.P. of Michigan. Some mid level cloud cover
may accompany the front midday, but these should clear behind it
while warm temperatures aloft remain and deeper mixing arrives
Friday afternoon. This should allow temperatures to rise into the
50s across much of the region and even MOS is showing a strong
potential of this.

A shot of cooler air will arrive for Saturday ahead of another
surface ridge set to park itself over the western Atlantic and mid
Atlantic states early next week. Sunday and particularly Monday
will be mild. In fact, if we mix to 925 mb given any of the
deterministic guidance for Monday, highs would reach the mid 60s
to lower 70s across southern and western MN. Record highs are in
the upper 50s to mid 60s. GFS is fastest with the cold front and
brings it through during the afternoon, but the slower GEM and
ECMWF would allow maximum warming potential keeping the front
north through evening. Kept temps about 10 degrees cooler than
the mix down technique given the risk of mid level cloud cover.
However, the official high temperature forecasts are several
degrees above the standard blend due to the included cold
bias corrected grids. Oddly enough MOS and raw model surface
temps are handling this anomalous event well, which leaves me
wondering that maybe temperatures will indeed be in the 60s given
their propensity to underplay these setups. Mechanical mixing
with gusty southwest winds may make up for some of the cloud

Models have dropped the idea of a large scale storm system early
next week by keeping a split flow in place with progressive cold
fronts. Decided to drop all PoPs in the extended period beyond
Friday given trends and only small scale features embedded in the
fast west northwest flow. These features are not predictable more
than a couple days in advance. The yo-yoing of temperatures will
likely continue into early December, along with drier than normal


.AVIATION...(For the 12Z TAFS through 12Z Friday morning)
Issued at 510 AM CST Thu Nov 23 2017

VFR conditions throughout. Light winds will becoming sw-s through
the day and into tonight, increasing west later tonight. Varying
degree of mid/high level clouds increasing tonight.

VFR conditions throughout. Light winds will becoming sw-s this
afternoon and tonight. Varying degree of mid/high level clouds
becoming bkn100 by 15z Fri.

Fri night...VFR. Winds SW 10 kts turning NW with FROPA and
increasing to 10-15 kts.
Sat...VFR. Winds NW 10-15 kts.
Sun...VFR.Winds S 5-15 kts.




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