Corcoran, Minnesota Weather Forecast Discussion

112
FXUS63 KMPX 121716
AFDMPX
Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
1216 PM CDT Fri Sep 12 2025
.KEY MESSAGES...
- Very warm and humid for the next several days. Highs in the
  upper 80s to lower 90s this weekend.
- Chance of thunderstorms this afternoon and evening with
  additional chances next week.
&&
.DISCUSSION...
Issued at 324 AM CDT Fri Sep 12 2025
It`s a quiet and mild morning with scattered high clouds
streaming east across the region. Some patchy fog and low clouds
have developed in Wisconsin, but the most widespread fog remains
to the east. Any fog will burn off quickly after dawn. An Omega
pattern remains in place across the country with the ridge axis
stretching from Texas to Minnesota. A weak disturbance will lift
north across the Plains, then turn east and crest the ridge this
afternoon and evening across the southern half of Minnesota and
Wisconsin. Steep lapse rates greater than 7.5 C/km, pwats in
the range of 1.5 to 1.75 inches, MUCAPE of 500-1000 J/kg, a
persistent weak LLJ, and a stalled frontal boundary draping
northern IA or southern MN will all aid in the potential for
thunderstorm development this afternoon and evening. The
boundary layer will remain dry, however, and some CIN is
expected to remain. Many CAMs show some scattered thunderstorms
by early afternoon across western Minnesota, progressing east
through the rest of the day and into the early evening.
Introduced 30-50% PoPs across the whole area.
The surface front is expected to lift north into southern
Minnesota Saturday. A hot airmass to the south characterized by
925 mb temps exceeding +27C will send highs into the low to mid
90s. Cooler air to the north and southeast flow will keep highs
elsewhere in the mid 80s. Winds shift more southerly area wide
Sunday, and while the intensity of warm air aloft will ease a
bit, a larger portion of the region will reach the upper 80s to
lower 90s. Combined with dew points around 70, heat indices will
likely top off in the mid 90s.
The ridge shifts slightly east Sunday, and by afternoon an upper
trough will advance toward the Upper Midwest. It will become a
bit negatively tilted Sunday evening and spread a 40-50 kt mid
level jet into western Minnesota. Lapse rates will remain weak,
but an uncapped atmosphere and stronger forcing arriving should
allow storms to develop in the afternoon and evening. SPC
highlights western Minnesota in a day 3 marginal risk. PoPs
will likely need to be increased in later forecasts.
Sunday`s upper trough will lift north Monday and ridging will
build back in its wake. However, additional short wave troughs
embedded in the gyre of a parent trough over the northern
Rockies will keep the forecast unsettled for much of next week.
&&
.AVIATION /18Z TAFS THROUGH 18Z SATURDAY/...
Issued at 1210 PM CDT Fri Sep 12 2025
Clusters of -TSRA in western/central MN will likely affect most
of the TAF sites throughout the first 6-8 hours of the period,
present at the beginning at AXN/RWF and pushing eastwards
through 00z. Significant wind gusts are not currently expected
with -TSRA, with the main impacts stemming from VIS reductions
and lightning. Timing wise, AWIPS time of arrival tool on the
storms currently in western MN would have them pushing towards
STC by 19-20z, MSP/MKT by around 20z, and RNH/EAU by 21-22z.
Duration looks to be a few hours at most, on the order of 2-3
for most locations at the current pace. CAMs are performing
extremely poor with this entire setup, thus the ongoing -TSRA
will be tracked based on movement rather than modeling through
the next few hours. After -TSRA move through, winds weaken below
08kts generally from 100-130 as skies SCT200-250 by the end of
the period.
KMSP...Model guidance showed little -TSRA which is why the
prob30 was removed with the 15z AMD, however given current
activity a TEMPO has been introduced from 20-22z based on the
movement of what is currently in Renville County. -TSRA may
arrive 10-15 minutes prior to 20z if further cu develops ahead
of what is present. The window for -TSRA should be fairly tight,
with little persisting beyond 22z as it moves over western WI.
/OUTLOOK FOR KMSP/
SUN...VFR, chc MVFR/-TSRA late. Wind SE 5-10kts.
MON...VFR, chc MVFR/-TSRA. Wind S 5-10kts.
TUE...VFR, chc MVFR/-TSRA pm. Wind S 5-10kts.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...None.
WI...None.
&&
$$
DISCUSSION...Borghoff
AVIATION...TDH

NWS MPX Office Area Forecast Discussion