Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 150337

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
1037 PM CDT Sat Oct 14 2017

.UPDATE...For 06z Aviation discussion below


.SHORT TERM...(This evening through Sunday)
Issued at 415 PM CDT Sat Oct 14 2017

The main focus of the short term will be precipitation and how
widespread this precipitation is through the late afternoon and into
the overnight hours. Current radar is not overly impressive in terms
of echoes moving up from sw MN, reinforcing the idea that the
best coverage and more significant qpf amounts will be on the
western and northwestern fringes of our forecast area. Line of
showers extending from Mankato into central WI will continue
moving to the north. No significant shower activity is moving up
from IA. Radar trends reinforce what some of the high res models
are suggesting and that is more of an off and on sprinkles to
light showers weather event through the early evening hours before
the low pressure area currently in the central plains moves
northeast and wraps around precipitation moves in. By Sunday
morning the low will be in northern MI and all precipitation will
be out of the MN area with a few lingering showers in western WI.
Although latest model runs are indicating a faster departure of
precipitation. Skies clear rapidly Sunday morning with northeast

.LONG TERM...(Sunday night through Saturday)
Issued at 415 PM CDT Sat Oct 14 2017

The main story in the long term is the extended period of dry and
mild weather Monday through Friday. High temps in the 70s are
certainly plausible, especially in western MN beginning Tuesday,
reaching western Wisconsin by Friday. Humidity will also be on the
increase late this week.

Until then, Sunday night will be a cool night, with frost possible
across much of the region. Did mention frost for those areas
where it has not yet frosted out. Surface high will be in the
southern plains, but a ridge will extend northward into MN/WI.
There will be some gradient wind, but not much, with southwest
winds less than 5 mph.

After that, the northern jet stream will be across southern Canada
for a few days, with short waves sideswiping our area Monday night
and Wednesday. Pacific fronts with mild westerly flow will
accompany these, with surface winds generally shifting between
south and west. It is likely that the first wave will only bring
some high level clouds, but the second wave Wednesday will have a
bit more mid level moisture, enough for some mid level clouds.

The upper pattern does change somewhat during the middle and
latter part of the week. Upper level low pressure in the Canadian
High Arctic retrogrades while a strong system moves through the
Gulf of Alaska Tuesday and Wednesday. This will eventually result
in a deep trough along the west coast, while upper high pressure
builds over the central states. Models are in fairly good
agreement about this. Therefore broad southwest flow will develop
over MN/WI, and southerly winds will transport higher humidity
into the area. We could well see dew points in the mid 50s by
Friday in addition to max temps in the 70-75 range. As this
unfolds, the next chance of precip will be next Saturday. Just out
of curiosity, took a look at the GFS precipitable water, which
reaches to 1 inch Friday evening and increases to 1.5 inches
Saturday evening. ECMWF shows some decent theta-e and specific
humidity at that point as well.


.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
Issued at 1038 PM CDT Sat Oct 14 2017

The deformation band of light rain will swing across the area
from west to east overnight. Attendant ceilings will mostly be in
the 1500-2500ft range, with pockets of IFR. Visibilities
attendant with the rain will generally be in the 3-5sm range.
North/northwest winds will gust to between 20 and 25 knots
overnight, then subside on Sunday morning and gradually back to
west/southwest. Scattered to broken mid/high clouds will filter
across the area on Sunday, but VFR conditions are expected.

Expect cigs to be around/below 1500 feet overnight, then scatter
out and rise to 2000ft around 13z, with VFR developing by 17z.

Mon-Thu...VFR. Wind SW 5-10 kts.




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