Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 141101

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

.SHORT TERM...(Today and tonight)
Issued at 352 AM CDT Sat Oct 14 2017

Today`s forecast is associated with two different lifting mechanisms
as precipitation begins to develop across far southern Minnesota
this morning, and western Minnesota this afternoon.

Initial shower activity across eastern Nebraska is related to strong
forcing along an elevated frontal boundary over the central plains.
This area of showers will spread northeast and begin to affect far
southern Minnesota between 9 am and noon. Model CAMS indicate that
this activity will be more scattered through the morning/early
afternoon as it lifts northward across southern Minnesota.

An area of stratus across central Iowa has already begun to
develop/spread northward over northern Iowa during the pre dawn
hours. This area of lower clouds will spread rapidly northward as
winds in the boundary layer begin to increase from the southeast.

The second lifting mechanism is associated with a strong short wave
over western Wyoming. This system will move eastward and enhance the
overall lift across South Dakota by noon. As it begins to interact
with the deeper moisture surging northward across southern
Minnesota, a larger area of precipitation should develop across
western Minnesota during the afternoon. As the storm system begins
to intensify by the late afternoon, bands of showers will develop,
especially along and north of the elevated frontal boundary. This
frontal boundary will be key as to where the heaviest and steadier
precipitation develops this evening. Currently, the main area will
be across west central/central Minnesota during the evening, then
this translates eastward during the overnight hours across eastern
Minnesota and western Wisconsin. Any slight deviation from this
elevated frontal boundary and jet core moving overhead, will
determine where these bands of showers develop. Another aspect to
this system is the rapid intensification this evening which will
lead to increasing wind speeds overnight. Wind gusts of 30 to 40 mph
will likely occur in western/southern Minnesota after midnight as
the storm moves eastward over the western Great Lakes. Much colder
air will wrap into this system which could lead to some light snow
in western/central Minnesota before the precipitation ends. But no
accumulations are expected.

.LONG TERM...(Sunday through Friday)
Issued at 352 AM CDT Sat Oct 14 2017

Showers will quickly end across WI Sunday morning as the system
races across the Great Lakes. Clearing will also take place,
marking the beginning of a dry period for all of next week. Sunday
will be the coolest day of the week with highs in the upper 40s to
mid 50s.

An expansive ridge encompassing much of the central CONUS will
build in Sunday night and remain in place into next weekend. A few
impulses will ridge along the northern periphery of the ridge
across Canada, which may drop cold fronts into the Upper Midwest.
These will do little other than to delay the arrival of the most
aggressive warming. That will take place late week as the ridge
builds eastward and centers itself over the southeastern U.S. 925
mb temps of +14 to +16C Tuesday-Thursday will become +17 to +20C
by Friday and Saturday, when high temperatures could rise well
into the 70s and possibly the low 80s. Records Friday and Saturday
are in the mid to upper 80s, which would be a little tough to get
but record warm minimums in the upper 50s/low 60s are within
reach. PoPs remain near zero Sunday night through Friday.


.AVIATION...(For the 12Z TAFS through 12Z Sunday morning)
Issued at 600 AM CDT Sat Oct 14 2017

The main aviation concern is timing of MVFR/IFR cigs this morning
or before 18z as moisture from Iowa surges northward across the
area. Between 18-21z conditions will deteriorate rapidly across
southern Minnesota with MVFR/IFR cigs/vsbys likely in SHRA.
Conditions will likely deteriorate in central/west central
Minnesota between 21-00z as the storm system moves closer to the
region. The worst conditions will occur between 00-06z as both
cigs/vsbys will remain in the MVFR/IFR range along with increasing
winds from the north/northwest. Between 06-12z conditions will
slowly improve in western Minnesota, with VFR/MVFR in the east.


Timing of precipitation/lower cigs will be the main concern after
18z with MVFR/IFR cigs/vsbys likely developing in the afternoon,
and continuing in the evening. Later tafs can use tempo periods as
heavier precipitation develops. Late tonight/Sunday morning,
conditions will improve with VFR cigs likely.


Sun aftn...VFR. Wind NW 5-10 kts.
Mon-Thu...VFR. Wind SW 5-10 kts.




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