545
FXUS63 KMPX 151159
AFDMPX

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
659 AM CDT Tue Jul 15 2025

.KEY MESSAGES...

- Hot & humid today with heat index values approaching 100  degrees.

- Numerous rounds of showers & thunderstorms this afternoon
  into Wednesday. Locally heavy rainfall in excess of 3-4" is
  likely, along with a few severe storms this evening.

- Well-below normal temperatures Wednesday, with below normal
  temperatures into the weekend.

&&

.DISCUSSION...
Issued at 245 AM CDT Tue Jul 15 2025

It`s a very warm night with sustained southerly flow & warming
temperatures aloft keeping temperatures from cooling off much
overnight, highlighted by MSP still maintaining 80 degrees at 3
AM. Some robust thunderstorms have taken advantage of the 3000+
J/kg of CAPE overnight across South Dakota, & the question for
the rest of the night becomes how long could convection continue
across central Minnesota? There`s little deep shear to work
with & 700 mb temperatures will continue to warm above 10 C
through the early morning, so it`s unlikely that the ongoing
severe cell over the SD/ND/MN border would continue for much
longer - but, the lack of shear hasn`t kept it from maintaining
it`s intensity for several hours now. A thunderstorm threat
looks plausible for Morris, Alexandria, & far-west central
Minnesota over the next hour or two, but the storm should
dissipate beyond that given it`s entering a more capped
environment.

With that uncertainty stated, we get into the thunderstorm chances
for today. Strong capping is expected to persist into much of the
afternoon across central & southern Minnesota, however a few high-
resolution models attempt to initiate a round of scattered
thunderstorms as early as late morning over central Minnesota. This
is a result of strengthening ascent in the right entrance region of
a strengthening jet over northern Minnesota, which could weaken the
capping enough for storms to initiate given the very unstable
atmosphere already in place. Think these morning solutions are a bit
too early & strong with the strengthening of the jet, but we should
see thunderstorm chances increase through the afternoon across
central Minnesota, and by the evening across southern Minnesota &
west-central Wisconsin. Assuming we don`t get the earlier round of
precipitation, & we clear out the cloud debris from overnight,
temperatures should be able to warm into the low to mid 90s ahead of
the slowly advancing cold front, with head index values approaching
100 degrees this afternoon.

A threat for severe storms exists with the initial rounds of
thunderstorms to develop this afternoon & evening, owing to surface-
based CAPE values of 2500-3000 J/kg & deep shear values increasing
to around 30 kts with the strengthening jet aloft. The severe
threat looks to mainly be from damaging wind gusts & large hail
from a few clusters of storms, primarily across central
Minnesota & northwest Wisconsin where the shear values will be
greatest & storms will initiate during the most unstable part of
the day. The severe threat will wane through Tuesday night, but
multiple rounds of thunderstorms are expected to continue
developing through the night & overnight hours as the forcing
aloft continues along the slowly moving cold front. Locally
heavy rainfall becomes the main threat Tuesday night into
Wednesday morning as storms will be efficient rainfall makers
with precipitable water values approaching 2" along the front
along with slow storm motions. Several high-resolution models
depict localized amounts in excess of 3-4", generally somewhere
across east-central Minnesota & northwest Wisconsin.The good
news is that these heavy rainfall amounts come mainly from
multiple waves of thunderstorms through Wednesday morning, as
opposed to thunderstorms training over the same location, which
should mitigate the flash flooding potential as water from each
wave should have some time to soak into the ground. Outside of
these locally excessive amounts, generally expect widespread
rainfall totals of 1-2" across central Minnesota & western
Wisconsin, tapering down to 0.5-1" across southern Minnesota.

Precipitation will likely linger into Wednesday afternoon, but
generally as light rain showers as we`ll be in the much cooler
air on the back side of the cold front & surface low. This will
create a nice reprieve from today`s heat in areas where it rains
& stays cloudy for most of the day, with afternoon highs
remaining in the 60s. Temperatures will still warm well into
the 70s across southeast Minnesota & western Wisconsin where the
front won`t pass until the afternoon. Temperatures remain cool
Thursday & Friday as well as Canadian high pressure slides over
the region, but we`ll have to see how much smoke accompanies the
high before calling them a few top 10 weather days. More
seasonable weather returns over the weekend & into next week,
along with a few chances for rain as a number of shortwaves pass
over the Upper Midwest. Models vary with the timing of these
waves, but Friday night-Saturday morning & Monday into Tuesday
looks to be the main timing windows. the active pattern
continues through next week, as very strong ridge develops over
the central plains & mid-Mississippi valley, placing our area
under a classic "Ring of Fire" pattern on the northern periphery
of the ridge. A few severe thunderstorm complexes look possible
somewhere across the Upper Midwest late next week, along with
very warm & muggy conditions.

&&

.AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/...
Issued at 645 AM CDT Tue Jul 15 2025

A cold front sagging into central MN this afternoon, then
slowly south toward southern MN through tonight will be the
source of many a headache for the aviation community. There
continues to be uncertainty with how quickly storms initiate on
the boundary (as early as 16-18z or as late as 20-22z) and with
how quickly this activity pushes south through the night (the
HRRR keeps MKT dry this whole period). Current TAFs tried to
keep some continuity with the going TAFs while also nudging
timing toward the HRRR. Behind the cold front, it looks likely
that we will see MVFR/IFR cigs move in to end this period.

KMSP...HREF shows multiple potential bouts of -shra/-tsra from
late this afternoon through Wednesday morning as the boundary
slowly sags south across the area. Given the strength of the
capping did delay things a little, but basically from 3z tonight
through Wednesday morning, we`ll be in and out of showers and
storms. Finally, for Wednesday morning, confidence is high will
have IFR/low MVFR stratus over the field.

/OUTLOOK FOR KMSP/
WED...MVFR, chc IFR. -SHRA likely, chc -TSRA. Wind NE 10-15
kts. THU...VFR. Wind NE 5-10 kts. FRI...VFR. Chc -TSRA after
dark. Wind SE 5-10 kts.

&&

.MPX WATCHES/WARNINGS/ADVISORIES...
MN...Heat Advisory from noon today to 8 PM CDT this evening for
     Anoka-Carver-Dakota-Hennepin-Ramsey-Scott-Washington.
WI...None.

&&

$$

DISCUSSION...ETA
AVIATION...MPG