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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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