094
FXUS63 KMPX 181142
AFDMPX

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
642 AM CDT Tue Aug 18 2026

.KEY MESSAGES...

- Another round of showers and weak storms will affect primarily
  southern MN this morning. Isolated showers with some rumbles
  of thunder remain possible during the day.

- Another chance for rain arrives Thursday into Friday, with a
  few strong storms possible.

- Quiet weather returns after Friday, with seasonal temperatures
  and only hit or miss chances for rain.

&&

.DISCUSSION...
Issued at 301 AM CDT Tue Aug 18 2026

The initial round of showers and storms that was expected as
this mid level shortwave coupled with a surface front push
through the area, and round two is the cluster of showers and
storms over eastern South Dakota. This second round is expected
to move across southern Minnesota this morning, arriving in our
coverage area closer to 5-6am and affecting the area along and
south of the Minnesota River, with the best chance for more than
showers being on the southern edge of the line that is more
likely to be in Iowa. All this to say, we do not expect to see
significant or widespread impacts from the second round,
primarily some showers and maybe rumbles of thunder that exits
the area later this morning. The CAMs all have some form of cold
air northwest flow isolated showers lingering throughout the
day, and with a bit of mixed layer CAPE we could see a few
rumbles of thunder from any activity as well, although with
unidirectional northwest flow, it is unlikely that anything more
than a rumble or two results from it. The front will fully pass
through during the day and leave us with weak high pressure by
this time tomorrow morning, resulting in quiet weather through
Thursday when our next chance for showers and storms arrives.
Temperatures today and tomorrow will be in the 70s thanks to the
weak subsidence from the weak high pressure as well as the
meager CAA from the northwest flow, returning to the 80s on
Thursday as our next system arrives.

Speaking of, our next chance for rain will arrive on Thursday as
a broad area of weak forcing stretches south of a weak surface
low in central Canada, with northwesterly flow aloft
continuing. The surface low looks to move southeast towards the
northern tip of Lake Superior by 12z Friday, and as it does our
area finds itself between the weak leading warm front and
sagging cold front, resulting in chance for scattered showers
and storms starting late Thursday morning and continuing until
the cold front moves through by midday Friday. The setup is
rather interesting with a narrow upper level jet streak left
exit region arriving Friday morning coupled with a low level
jet, with the low level jet also within northwest flow which is
a rather unique setup as typical nocturnal low level jet
features tend to favor southerly flow. One would think we will
struggle with moisture with this kind of setup, which is
certainly a consideration, however most of the guidance shows
dew points in the low to mid 60s with the ECMWF even suggesting
upper 60s by Thursday evening. As long as our low level
advection does not contain significant dry air, we should have
enough moisture to force showers and storms. I would expect the
forecast trend as we approach to gradually favor increasing PoPs
and QPF, with ensemble probabilities showing above 80%
likelihood for at least a tenth of an inch across most of the
MPX coverage area by 7am Friday. The percentages get lower than
30% for a half inch or more, which seems realistic given the
pattern. As the cold front arrives on Friday, one last push of
precipitation will make way for more seasonal temperatures and
weak high pressure to round out the 7 day period into early next
week. The longer range pattern continues to favor northwest
flow aloft as the ridge slides westwards, giving us potential
for shortwaves to produce precipitation, however also favoring a
relatively low confidence forecast at this time scale.

&&

.AVIATION /12Z TAFS THROUGH 18Z WEDNESDAY/...
Issued at 631 AM CDT Tue Aug 18 2026

Widely scattered SHRA and isolated TSRA continues at the start
of the period. A lot of this morning`s precipitation has been
short-lived over any given area, and we expect that bubbly
nature to continue. Rain will gradually clear out this morning,
but redevelopment is expected this afternoon. The best chance
for any afternoon storms will be along a line from MKT to EAU
and south. Winds will primarily be out of the N/NW today, but
become light and variable overnight.

KMSP...Showers have developed across the west and north metro
this morning, but they have been weakening and may struggle to
reach KMSP. They are tied to a boundary that will move through
the south metro though, and additional pop up showers will be
possible until around 13z as the boundary moves through. It is
possible that KMSP remains dry. There are more showers to the
north which could reach the terminal by late morning, but
confidence is low that they would persist that long.

/OUTLOOK FOR KMSP/
WED...VFR. Wind NW 5-10 kts.
THU...VFR, chc PM MVFR/-SHRA. Wind SW 10-15 kts.
FRI...VFR, chc -TSRA/MVFR. Wind W 10-15kts.

&&

.MPX WATCHES/WARNINGS/ADVISORIES...
MN...None.
WI...None.

&&

$$

DISCUSSION...TDH
AVIATION...BED