Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 142115

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

.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 entend 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 18Z TAFS through 18Z Sunday afternoon)
Issued at |108 PM CDT Sat Oct 14 2017

The main aviation concern is the arrival of precipitation, the
predominance of that precipitation and the arrival of IFR cigs
later today along with the persistence of those ceilings through
the night. Moisture and elevated instability from Iowa surged
northward across southern mn during the mid morning hours and
extended along a narrow line from Redwood Falls to Eau Claire
around 1 PM. That line of showers will continue moving northward
affecting Kmsp by 20Z. Nothing significant expected other than -SHRA
and a rapid deterioration of the ceilings leading to IFR
conditions. A storm system located in the Southern Plains will
move to central Iowa by evening and northeast to northern Michigan
by daybreak Sunday. Moisture will continue surging into MN the
rest of the day into the evening hours. The worst conditions will
occur between 00-06z as both cigs/vsbys will remain in the
MVFR/IFR range along with very gusty winds from the
north/northwest. Between 06-10z conditions will slowly improve in
western Minnesota, with VFR/MVFR in the east. By 12Z conditions
should be VFR across MN and MVFR in western WI. Skies will be
mostly clear after 15z across the entire area.


Timing of precipitation/lower cigs is the main concern. Expect the
first batch of precipitation to affect the air field around 20z.
After that it is somewhat questionable as to the extent of
widespread precipitation until the low moves into Wi and wrap
around precipitation affects the air field. The most significant
precipitation will remain well south of KMSP. Early Sunday
morning, conditions will improve with VFR cigs likely.


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





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