Sleepy Eye, Minnesota Weather Forecast Discussion

172
FXUS63 KMPX 121952
AFDMPX
Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
252 PM CDT Fri Sep 12 2025
.KEY MESSAGES...
- Scattered showers and weak thunderstorms continue this afternoon
and diminish this evening.
- Warm and humid through the next several days with temperatures in
the 80s.
- Sporadic shower and storm chances arrive on Sunday and linger
  into next week.
&&
.DISCUSSION...
Issued at 251 PM CDT Fri Sep 12 2025
A lobe of 700mb warm air advection has resulted in a large swath of
showers and thunderstorms across much of Minnesota from late morning
through early this afternoon, with a few of the storms dropping
quarter sized hail in central and northern Minnesota within the
Duluth NWS CWA. MLCAPE values of 500-1000 J/KG alongside weak bulk
shear under 30kts have kept the strength from spreading further than
a few individual storm cells. A couple of strong storms have been
moving along the northern periphery of our CWA over Mille Lacs and
northern Kanabec counties, however over the last hour or so these
storms have lost much of their strength and are primarily a heavy
rain and lightning threat at this point. Satellite also supports the
weakening trend, with cloud tops generally warming meaning shallower
storms with weaker updrafts. With the warm air advection weakening
into the evening, we will also lose our only forcing and the spread
and strength of showers and storms should diminish. If you are
planning on being outdoors this evening, remain aware of storms in
the area primarily for the risk of thunder and lightning.
Warmer temperatures are expected over the next 4 to 5 days as
further lower mid level warm air advection alongside efficient
mixing will bring 80s for highs with a shot at low 90s depending on
how well we are able to mix with potential cloud cover. The GFS has
been most aggressive in bringing stronger WAA further north, with
the ECMWF/CFS generally keeping things confined to southern
Minnesota south of the Minnesota River through Saturday and into
Sunday. A broad upper level trough digging south into the eastern
Rockies will negatively tilt later Sunday into Monday introducing a
large area of CVA which could bring another round of showers and
thunderstorms, however models still differ on the intensity and
placement of the strongest forcing with the GFS generally more
easterly with stronger showers compared to the ECMWF/CFS, with the
GFS also showing significantly warmer temperatures. The main
question is whether this is due to a warm bias leftover from the
summer or if it is a legitimate expression of the forecast, which to
this point seems like the former due to the more muted responses in
the other global models. This is further reinforced if we look at
the ensembles with the GEFS overall hotter and more bullish on
precipitation across our coverage area compared to the EPS/CFS. The
stronger signal for Sunday into Monday on the GEFS also tends to
bring the entire system wrapping around to the north by late Monday
into Tuesday, which could limit further potential as it pushes into
Canada compared to the other ensembles which keeps the forcing in
the area a bit later. Overall, there are still several forecast
scenarios that could play out depending on the strength of the
trough and positioning of the CVA such that confidence is too low to
push higher than 30-40 PoP through the period, with the caveat that
any potential showers will likely be accompanied by thunderstorms of
varying strength. With the synoptic signal still muddied with little
consensus beyond the large scale setup, we may have to wait until
the 18-30 hour period ahead of any potential storms to accurately
gauge their max intensity.
As we look a bit later in the forecast period, the low level WAA
weakens by midweek with significant differences after Wednesday as
the GFS brings a much more dramatic shift towards colder upper air
temperatures while the ECMWF/CFS keep things close to normal. Given
the potential thermal gradient over the area, we may have some
additional synoptic forcing to force further showers and
thunderstorms, however this is even less certain the later you get
beyond Wednesday. For now, expect a low confidence forecast after
Wednesday until we see some better alignment in the upper air
pattern, keeping in mind that by that point we are in the last 1/3rd
of September when we typically see our last real convective chances
for the year due to the decreasing insolation and time of day.
&&
.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...TDH
AVIATION...TDH

NWS MPX Office Area Forecast Discussion