Area Forecast Discussion
Issued by NWS Twin Cities, MN

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000
FXUS63 KMPX 101747
AFDMPX

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
1247 PM CDT Tue Oct 10 2017

.Updated for 18Z Aviation Discussion...
Issued at 1240 PM CDT Tue Oct 10 2017

&&

.SHORT TERM...(Today and tonight)
Issued at 300 AM CDT Tue Oct 10 2017

Surface analysis early this morning shows a wavy cold front
extending southwestward from Lake Huron into central Illinois and
Missouri then into eastern Texas. Broad high pressure centered
over the Rockies extends northeast into Minnesota and Wisconsin
and west over much of the western third of the lower 48. Aloft,
generalized zonal flow is maintaining itself along the Canadian
border while a southern stream compact upper level low pivots east
over the central Plains. This upper low is expected to move into
the northern Ohio River Valley region by daybreak Wednesday,
helping organize a low pressure center near the small
Oklahoma/Missouri border and push it northeast along the cold
front to the IN/KY/OH triple point for tomorrow. Moisture
associated with this system will not have much of a northward
extent, mainly an eastward extent, but isentropic lift from the
low will increase just far enough north within the deeper moisture
to produce isolated to scattered rain showers over far southern
MN and into southern portions of west-central WI this afternoon
and evening. Only a few hundredths of an inch of rainfall is
expected, at best. Southern MN and western WI will also be where
most cloud cover will be concentrated. Along those lines, the lack
of cloud cover early this morning along with light winds and
ample cold air advection is contributing to lows dropping to the
upper 20s to middle 30s for much of the WFO MPX coverage area. As
such, no changes are planned to the frost advisory and freeze
warning in place. These cold temperatures this morning will then
be followed by highs in the lower to middle 50s, the latter of
which will be accompanied by a lack of cloud cover. Another cold
night is expected for tonight with the high pressure area placing
itself over the central CONUS. Lows tonight will range from the
lower 30s in central MN to around 40 near the Iowa border.

.LONG TERM...(Wednesday through Monday)
Issued at 300 AM CDT Tue Oct 10 2017

The forecast concern remains the evolution of the western CONUS
trough and timing of any short waves lifting to the east
affecting our region.

In the wake of the Wednesday upper trough to the south, low level
moisture begins to lift back north in the increasing southerly
flow. Most deterministic models have been advertising this the
last few runs and the SREF has shown increasing probability of at
least MVFR cigs developing later Wednesday into Thursday. We did
increase sky cover during this period. Also, at least a low end
PoP is warranted Wednesday night into Thursday as this moisture
arrives. We should at least see the possibility of
sprinkles/drizzle depending on the overall depth of the lower
cloud layer.

Then some warming out ahead of a cold front into Thursday with
the front moving across the region Friday. PoPs continued to
increase to likely to the east as this system moved through.
Then development and movement of the trough through the area over
the weekend is the main concern. The 00Z ECMWF amplified the
trough and developed a deeper cutoff circulation over the Great
Lakes region into Sunday. This is slower than the more progressive
GFS and GEM this model run and ultimately colder as the system
occludes over the western Great Lakes. This could become cold
enough for at least a rain/snow mix over a portion of the cwa
later Saturday night, especially if the ECMWF verifies. We did
cool max temps a degree both Saturday and SUnday as this system
should provide ample cloud over and a good chance of precipitation
as it moves across.

Following this system, models drive a more zonal type flow
pattern over the high plains. This should provide generally dry
and warmer conditions into midweek.

&&

.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
Issued at 1240 PM CDT Tue Oct 10 2017

VFR conditions throughout with light winds. Area of precipitation
should remain south and east of the taf sites. Light wind will
take on a southeasterly direction Wednesday morning.

KMSP...

Northeast wind gusts should subside late this afternoon as mixing
decreases and clouds move overhead. Winds will be light
overnight, and take on a southeasterly direction on Wednesday. VFR
stratus should develop around mid-day tomorrow based on the
forecast soundings.

/OUTLOOK FOR KMSP/
Thu...VFR. Wind S 10 kts.
Fri...Mainly VFR. MVFR late with SHRA likely. Wind NW 5 kts becoming
NE.
Sat...Mainly VFR. MVFR late with SHRA expected. Wind NE 5 kts.

&&

.MPX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
&&

$$

SHORT TERM...JPC
LONG TERM...DWE
AVIATION...JRB



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