Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 120820

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

.SHORT TERM...(Today and tonight)
Issued at 300 AM CDT Thu Oct 12 2017

Extensive stratus across the eastern two thirds of MN and all of WI
continues to expand slowly westward early this morning. Some pockets
of drizzle have been reported overnight, particularly over southern
MN. Temperatures are mild, ranging from the mid to upper 40s over
western MN where it is clear, to the mid 50s east under the stratus.

The stratus is confined to a shallow layer under 850 mb. Expecting
the western edges of this stratus to erode and dissipate as the
boundary layer warms and dries. The south southeast surface flow
could make this a bit difficult the further east you go, and it may
remain cloudy all day in WI. Temperatures should respond quickly
when the sun comes out, so the forecast calls for a tight
temperature gradient near the edge of the stratus mid afternoon -
likely along or just east of I-35. West of there mid 60s to lower
70s can be expected, while the lowering sun angle and extensive
cloud cover may make it hard to warm more than 5 degrees where
temperatures are now to the east.

A cold front will push through tonight. While it is expected to be
largely a dry event, there could be a few light showers or patchy
drizzle to the north and east where ample boundary layer moisture
will remain from the daytime stratus.

.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 afternoon.

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 00Z TAFS through 00Z Thursday evening)
Issued at 1025 PM CDT Wed Oct 11 2017

MVFR level cigs will blanket central and eastern sites overnight
(with the exception of KAXN and KRWF). Could also see some
light/patchy drizzle out of the low cloud deck overnight with weak
energy aloft, but coverage/impact isn`t sufficient to warrant
inclusion in the TAF. Could see occasional reduction to IFR
along/east of I-35 (KMSP-KRNH-KEAU). The low clouds gradually
erode and shift east tomorrow. Expect MN sites to scatter out by
early afternoon, and WI sites between 22z and 00z Thu. Winds will
be southeast through the period mostly around 10 knots overnight,
then increasing on Thursday at with gusts to 20-25 knots.

Cigs around or slightly below 1500 ft look to persist overnight,
with VFR arriving by 18z. Southeast winds gust to 20 knots
Thursday afternoon.

Fri...Mainly VFR. MVFR late with p.m. SHRA possible. Wind N 5-10
kts becoming NE.
Sat...Mainly VFR. MVFR late with p.m. SHRA likely. Wind ENE 5-10
Sun...Mainly VFR. MVFR early with a.m. SHRA possible. Wind NW 5-10




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