Porter, Minnesota Weather Forecast Discussion

687
FXUS63 KMPX 081114
AFDMPX
Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
614 AM CDT Mon Sep 8 2025
.KEY MESSAGES...
- After a cool start to the month, normal temperatures with
  highs in the 70s this week.
- Multiple chances for showers and thunderstorms, with the best
  chances tonight into tomorrow.
&&
.DISCUSSION...
Issued at 259 AM CDT Mon Sep 8 2025
Today and Tomorrow... After a prolonged period of cold air
advection to start the month we have now moved into a warm air
advection regime. This will help to limit the cooling this
morning, with temperatures not as frosty as they were yesterday
morning. Despite this, with clear to mostly clear skies we are
still radiating out amd have temperature falling into the 40s.
This could cause some of the more frequent fog spots (like
valley and near bodies of water) to have fog this morning as
they reach saturation. Once the sun comes out temperatures will
warm into the 70s today, with a chance to break 80 in western
Minnesota. As this is largely advecting in aloft around 850 mb,
a substantial warm nose is expected to develop today. This will
largely inhibit convective chances for much of the day. Even
when convection might form later today into tonight an elevated
storm is more likely than a surface based storm. Precipitation
timing will favor late as the LLJ will provide the best support
tonight. The areas with the best chance for storms will be along
the nose of this LLJ. Current high resolution guidance has this
favoring to our north more into the arrowhead of Minnesota.
There will however be a trailing boundary to the southwest of
this area where lapse rates are expected to be better. The
overall PoP is lower here, but if an updraft can come together
there is a better chance for severe weather in this area of
central Minnesota where SPC has placed a marginal risk. Overall
this marginal risk area is very conditional and more likely than
not will not occur, but if deep convection can initiate the
conditions would allow for it to become severe with the forecast
shear profile. This setup will continue into tomorrow morning
until the warm front lifts through the region or the LLJ
dissipates.
Another boundary is expected to pass through in the
afternoon/evening tomorrow. Along this weaker, more cold
frontal boundary another round of storms are possible. Once
again elevated storms would be favored based on forecast
soundings which favor high LCLs. There is more uncertainty when
it comes to tomorrow afternoon and evening. More instability
could come together, but getting an overlap with the better
shear is what may not occur. Overall uncertainty in how all the
pieces line up has kept us in just general thunder for day 2.
Wednesday through the Weekend... Looking ahead to the rest of
the week we are still expected a ridge to build in for the
middle of the week. This will provide for a period of drier
weather in the middle of the week. Later in the week a trough
looks likely to build in the western CONUS in global guidance.
What has more spread though is out to the east over the eastern
Canada/Great Lakes region. The different global models take the
upper low on different paths. How this side of the larger scale
pattern evolves will be one the keys in how active the weather
is later in the week into the weekend. If it sets up more as a
blocking pattern the warmer and dry weather will continue. For
this reason NBM PoPs in the late week remain in the slight
chance category due to the spread in global ensemble systems.
&&
.AVIATION /12Z TAFS THROUGH 12Z TUESDAY/...
Issued at 613 AM CDT Mon Sep 8 2025
Winds will pick up this morning as we warm up with southerly
winds gusting 20 to 30 knots. Winds will get less gusty this
evening into tonight, but will still be sustained around 10
knots. Storm chances will increase late afternoon into tonight,
with the best chances tonight. Added in some PROB30 groups for
when the thunderstorms are most likely. Rain chances will
continue into early Tuesday, with an after this TAF period
afternoon chance possible as well.
KMSP...Some isolated thunderstorms possible late
tonight/tomorrow morning. Another round also possible tomorrow
afternoon, after this TAF period.
/OUTLOOK FOR KMSP/
TUE PM...VFR. Chc -TSRA/MVFR. Wind SE 5-10 kts.
WED...VFR. Wind E 5-10 kts.
THU...VFR. Wind SE 5-15 kts.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...None.
WI...None.
&&
$$
DISCUSSION...NDC
AVIATION...NDC

NWS MPX Office Area Forecast Discussion