Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 100418

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
1118 PM CDT Wed Aug 9 2017

.SHORT TERM...(This evening through Thursday)
Issued at 425 PM CDT Wed Aug 9 2017

Showers from this morning have primarily moved east of I-35 & will
continue to drift into Wisconsin as the evening progresses. The
next round of precipitation is already developing, primarily along
a cold front across the eastern Dakotas. This activity will
become more widespread & spread further east this evening as the
cold front approaches. A few isolated cells have developed across
far western MN ahead of the front & where skies have cleared since
this morning. 1000-1500 J/Kg of MLCAPE has already developed
across western MN where the strongest thunderstorm activity is
expected. Effective-layer bulk shear in this region is only on the
order of 20-30 kts so widespread organized convection is not
expected, but a few of the strongest clusters may be able to
produce a few instances of small hail & gusty winds. Only
expecting a few hundred J/Kg of CAPE to persist into central &
eastern MN so expect activity this evening to be mostly showery,
with a few rumbles of thunder.

Showers & thunderstorms tonight should move out of the area before
sunrise, with some localized patchy fog possible in areas that
receive the most rainfall tonight. A cool & cloudy day is expected
tomorrow behind the cold front with temperatures on the order of
10 degrees below normal. Steepening mid-level lapse rates behind
the front should result in just enough instability to kick off
some widely scattered showers/thunderstorms tomorrow afternoon.
Best chances for this precipitation will be along & east of I-94.

.LONG TERM...(Thursday night through Wednesday)
Issued at 425 PM CDT Wed Aug 9 2017

Very quiet long term period, with limited precip chances and
continued cooler than normal weather. Do not anticipate severe
weather in the long term period.

By tomorrow night, the shortwave trough will be off to our east
moving through the Great Lakes.  Wrap-around showers will be coming
to an end across western MN by that time.  High pressure will build
in behind this activity and setup Friday to be a very nice day.  The
dry weather looks to continue into Saturday, but could see some
showers and isolated thunderstorms develop Saturday afternoon as
another upper level shortwave moves in from our west. The forcing
with this feature looks to primarily move across southwest
Minnesota into Iowa, with the best chance of precip coming on
Sunday morning across far southern Minnesota. This looks to be our
only real shot at measurable rain through the long term period.

The longwave trough will remain in place and continue to provide
northwesterly flow aloft and temperatures will continue to be below
normal.  And with the remainder of the forecast relatively dry,
there aren`t any hazards to be concerned with early next week.


.AVIATION...(For the 06Z TAFS through 06Z Thursday night)
Issued at 1115 PM CDT Wed Aug 9 2017

A complex of TSRA/SHRA in a band 30-50 miles wide west of the Twin
Cities, will continue to move eastward across far eastern
Minnesota, and into west central Wisconsin before 9z. Otherwise,
MVFR/IFR cigs will develop in west central/central Minnesota and
expand south/southwest in the pre dawn hours, and likely continue
through the morning before lifting to VFR Thursday afternoon. A
few SHRA are possible by mid/late morning as the main storm system
rotates across central Minnesota. An isolated TSRA is also
possible, but not likely.


The complex of SHRA/TSRA west of the airport as of 415z, will move
across the airport between 5-7z with a period of 2-3SM in +SHRA.
This area of precipitation will move out by 7z, with MVFR,
possibly IFR cigs during during the pre dawn hours. Confidence
remains low on these cigs, but enough to continue the trend in the
TAF. These cigs will begin to lift and become VFR by the
afternoon. A few SHRA are also possible during the
morning/afternoon time frame. Winds will become west/northwest
Thursday morning, and more north Thursday afternoon.


Fri...VFR. Wind N 5-10 kts.
Sat...VFR. Wind NE 5 kts.
Sun...VFR. Slight Chc SHRA/TSRA afternoon. Wind ESE 5 kts.




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