Sedan, Minnesota Weather Forecast Discussion

793
FXUS63 KMPX 182325
AFDMPX
Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
625 PM CDT Thu Sep 18 2025
.KEY MESSAGES...
- On and off chances for rain continue through the weekend.
  Most widespread activity this evening through Friday.
- Drying out next week, with temperatures remaining near normal
  this period.
&&
.DISCUSSION...
Issued at 321 PM CDT Thu Sep 18 2025
Water vapor imagery this afternoon shows our very sluggish upper low
still spinning over the Dakotas. Given how far west it and its
associated vorticity has remained, we`ve been stuck in a zone of
moisture, but limited forcing for precip, hence why for much of us,
we`re still waiting on it to actually rain in this supposedly active
pattern. The good news is we`re finally seeing signs of the more
active pattern moving into southern MN! The culprit is a shortwave
down by KC and a surge of moisture out ahead of it in Iowa. The
combination of this wave moving north and the Dakotas low moving
into western MN will all conspire to bring more widespread rainfall
chances this evening through the day on Friday. Definitely not a
washout, but something where you`ll want to keep an umbrella handy.
Through all of this, lapse rates will remain weak, which will
translate into limited instability and weaker updrafts. Add in
almost no deep layer shear and the severe risk will remain low.
However, with the surface low and remnant frontal boundary moving
across southern MN Friday, we will have to keep an eye out for
potential non-supercell tornado (NST) funny business, though it may
only end up being a funnel cloud festival wherever we can get some
low-level instability to line up with a boundary on Friday.
For the weekend, the upper low will be filling in as it crawls
across the upper MS valley. This will mean the highest PoPs on
Saturday will be found east of I-35, with the main moisture feed
shifting east of the MPX area for Sunday, tough with the trough
overhead, we`ll still be developing scattered diurnal activity on
Sunday. When all is said and done, most of the MPX area will have
seen a half to one inch of rain by the end of the weekend, with some
pockets of 2+ inches given the anomalous moisture (PWATs around
1.5"), slow movement of storms, and potential for multiple rounds.
However, high rainfall amounts like that will be quite isolated, so
hydro threats will be pretty minimal as well.
Next week, our blocky pattern will remain, with the northern stream
remaining well to the north across Canada. Within the broad ridging
over the CONUS, we`ll continue to see h5 lows get left wandering in
weak flow. Trends from the models for next week is for the next cut-
off h5 low to be south of the MPX area, which trends us toward drier
weather, with temperatures running a little above normal. In other
words, very pleasant conditions. Looking at the ensembles, there are
no signs of any cold air for the next 2 weeks, with the weather
remaining pretty quite for the rest of September once we get past
this more active period that will last into early next week.
&&
.AVIATION /00Z TAFS THROUGH 00Z FRIDAY/...
Issued at 625 PM CDT Thu Sep 18 2025
Scattered clusters of thunder storms this evening. These storms
will continue through the evening, but with the loss of daytime
heating they should become less in coverage the later we get.
Rain will not come to an end as more widespread rain showers are
expected to develop overnight. MVFR likely and IFR possible with
the low ceilings rather than a visibility reduction. Showers
continue into tomorrow with another round of thunderstorms
possible in the afternoon. Winds will remain southeasterly,
light overnight and around 10 knots during the daytime.
KMSP...Thunderstorms in the vicinity of MSP to start this
period. These storms should reduce in coverage later in the
evening. Then tonight more widespread rain is expected to
develop. More of a continued MVFR impact with this with maybe a
brief period of IFR possible in the morning during the coolest
part of the day. Another round of thunderstorms possible in the
afternoon tomorrow.
/OUTLOOK FOR KMSP/
SAT...Chc MVFR/-TSRA. Wind S 5-10 kts.
SUN...Chc MVFR/-TSRA. Wind SW 5-10 kts.
MON...Chc MVFR/-SHRA. Wind S bcmg N 5-10 kts.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...None.
WI...None.
&&
$$
DISCUSSION...MPG
AVIATION...NDC

NWS MPX Office Area Forecast Discussion