Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 120003

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
703 PM CDT Wed Oct 11 2017

.UPDATE...For 00Z Aviation discussion below


.SHORT TERM...(This evening through Thursday)
Issued at 417 PM CDT Wed Oct 11 2017

Swath of low clouds has been streaming northward across eastern MN
and western WI today. There are some breaks, but not enough to
merit seeing the clouds disappear tonight. Short term models do
indicate these will stay overnight, so have beefed up the sky
cover grids for tonight. A weak short wave will also arrive late
tonight, and this is when there will be a chance of some drizzle.
There just isn`t enough mid to high level moisture for much more
than that. Temps in this area will be above normal, maybe
remaining above 50 degrees in the metro or some parts of southern
MN or western WI.

Meanwhile, low pressure in Saskatchewan will move east, and the
gradient will strengthen across western MN. With winds staying
around 10 mph, western MN should have relatively balmy lows in
the mid and upper 40s.

Once the next wave goes by late tonight, Thursday should be
relatively quiet. Fastest upper flow will be to the west and
northwest, from Manitoba to Utah and beyond, so MN/WI will be on
the dry side of this. Thus temps will be a few degrees above
normal, generally in the 60s.

.LONG TERM...(Thursday night through Wednesday)
Issued at 417 PM CDT Wed Oct 11 2017

The mean flow in the upper atmosphere will remain progressive in the
lower 48 contiguous states as a fast west to east jet stream
dominates the extended period. This type of pattern is relatively
warm but not necessarily active for the Upper Midwest. The strength
of these system will be determined by the upper jet core, frontal
boundary, and available moisture. The first cold front will move
across the area Friday morning. Moisture is lacking and forcing is
weak. Therefore, most of the precipitation will occur southeast of
the Upper Midwest (anafront), with only low chance pops expected.
This weekend a frontal boundary does have more upper level
support as the 50H short wave is fairly strong leading to better
lift. Moisture return is the main concern, but models do show some
support of increasing moisture depth by Saturday. This will lead
to much better chances of precipitation. This system will be
followed by another cool down for a day or so. However, once again
the upper level pattern will lead to milder temperatures
returning by the middle of next week.

One change in the upper level pattern, especially for temperatures,
is the transfer of much colder temperatures across northern Canada,
to Alaska, and eastern Asia. Usually this pattern shift will lead to
much above normal temperatures for the Upper Midwest and current CPC
models are forecasting this trend. As for precipitation, there is no
definite clear signal of a wetter or drier pattern. However, both
the EC/GFS does show a split flow regime by late next week. This
type of split flow pattern is relevant to precipitation chances. If
the southern stream in more active, our weather is drier. However,
if the northern stream is more active, our weather is wetter.


.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 704 PM CDT Wed Oct 11 2017

MVFR level cigs will creep north across the area this evening, and
remain entrenched at sites overnight (with the exception of KAXN
and KRWF). Followed the SREF cig prob for trends overnight. Could
also see some light/patchy drizzle out of the cloud deck overnight
with weak energy aloft, but coverage/impact isn`t sufficient to
warrant inclusion in the TAF. The area to watch for potential
reduction to IFR will be along/east of I-35 (KMSP-KRNH-KEAU). The
low clouds 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 above 10
knots, with gusts to around 25 knots.

Expecting primarily MVFR cigs overnight (circa 1500 ft), mainly
after 05z. Best estimate on scattering is around/after 18z.
Southeast winds through the period, gusting to 20 knots beginning
at 18z.

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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