281
FXUS63 KMPX 150746
AFDMPX

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
246 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 approach 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 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 thew
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 /06Z TAFS THROUGH 06Z WEDNESDAY/...
Issued at 1035 PM CDT Mon Jul 14 2025

VFR at initialization and through sunrise tomorrow morning.
Clouds will be on the increase through the day, with chances for
SHRA/TSRA ramping up late Tuesday afternoon into Tuesday night.
Have kept PROB30 mention to allow for some wiggle room in the
start time, with prevailing wording from around 00z thru the
remainder of this TAF duration. S winds through tonight will
become SW during the day tomorrow with speeds near or slightly
under 10kts, then winds will undergo appreciable wind shifts as
the east-west oriented surface front responsible for the
precipitation slowly drops south across southern MN/WI.

KMSP...Dry thru mid-afternoon, then chances for SHRA/TSRA ramp
up from about 22z onward, with precipitation likely/prevailing
from about 00z onward. TSRA likely mainly between 00z-08z
Wednesday then diminishing to showers by daybreak Wednesday
morning. MVFR conditions likely but cannot rule out IFR
conditions due to visibility under heavier bouts of rain.

/OUTLOOK FOR KMSP/
WED...MVFR, chc IFR/-TSRA. Wind NE 5-10 kts.
THU...MVFR early, then VFR. Wind NE 5-10 kts.
FRI...VFR. 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...JPC