Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 121844

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
144 PM CDT Thu Oct 12 2017

.SHORT TERM...(This evening through Friday)
Issued at 138 PM CDT Thu Oct 12 2017

Surface analysis this afternoon shows a cold front extending south
from central Manitoba province through the central Dakotas to
along the CO/WY border. In advance of this front is extensive NE-
SW high pressure from central Quebec province through the Great
Lakes into the mid-Mississippi River Valley. Aloft, pronounced SW
flow is entrenched over the area between a subtropical ridge over
the Gulf Coast states and a longwave trough over the western
CONUS. While the southeastern ridge will generally hold its place
through tomorrow morning, a chunk of the trough aloft will break
off and shift east, moving into central Canada, helping nudge the
cold front across Minnesota tonight and across Wisconsin tomorrow.
Very little upper level support will accompany the front while
deepest moisture is generally south of the WFO MPX coverage area.
Therefore, aside from an increase in cloud cover for the bulk of
the coverage area, the only precip potential lies in far southern
and far eastern parts of the coverage area tonight and tomorrow
morning, mainly in the form of sprinkles/drizzle. High pressure
will fill in behind the front, bringing in cooler air for the
area. Whereas highs ranged from the upper 50s to the upper 60s
from east to west this afternoon, highs will only range from the
mid 50s in central MN/WI to the lower 60s in southern MN/WI.

.LONG TERM...(Friday through Wednesday)
Issued at 300 AM CDT Thu Oct 12 2017

The longer term concerns remain timing and extent of precipitation
coverage with Fridays front and the development of the trough over
the weekend. This evening models have trended drier with the
front at least initially as the main forcing will be directed to
the southeast as the system moves through. Should have abundant
cloud cover at least into the afternoon and cant rule out a
sprinkle if the upper jet can channel any significant
frontogenesis over the area. At this time, it appears that will
occur further to the southeast as the front departs Friday

The 00Z deterministic runs have sped up the next trough into the
region the weekend. It looks like the showers will lift northeast
across the area Saturday afternoon and should exit most of the
area through Saturday night. Increased PoPs slightly into Saturday
afternoon into the northern areas. The thunder threat appears low
and we left that out for now. We may have to expand some low
thunder probabilities at least over the southeast portion of the
area Saturday afternoon into early evening if instability
increases with the trough.

Depending on the strength of the next trough(the GFS still is a
bit deeper/colder than the ECMWF but has trended more toward the
ECMWF) we could struggle to warm into the 50s Sunday. The mean
flow becomes more zonal into early next week and we should see
temepratures warm up nicely through the 60s once again. At the
moment, the Wednesday system looks questionable with the ECMWF
bringing a pacific front through Wednesday. It looks dry and
rather warm through midweek.


.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
Issued at 138 PM CDT Thu Oct 12 2017

Low stratus is very slow trying to erode to the east but having a
hard time doing so. Will still look for ceilings to gradually rise
in eastern MN thru western WI, to a combination of low VFR and
upper-threshold MVFR. The -DZ/-SHRA looks to have dissipated so am
no longer thinking there will be any visibility restrictions.
Overnight, the low stratus will make a return, producing ceilings
in MVFR to IFR levels (IFR mainly in western WI) before skies
steadily clear out by late morning and VFR conditions will
prevail. Winds will remain from the SE today and gusty then settle
down to the 5-10 kt range overnight and shift to SW and NW thru

KMSP...Ceilings will increase to VFR levels by late this afternoon
then remain there through the evening push. A period of MVFR
ceilings is expected overnight but clearing should develop prior
to the Friday morning push, letting VFR conditions prevail. Timing
could be a little tricky.

Sat...Mainly VFR. MVFR late with p.m. SHRA likely. Wind ENE 5-10
Sun...VFR. Wind NW 5-10 kts.
Mon...VFR. Wind SW 5-10 kts.




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