121
FXUS63 KMPX 090329
AFDMPX

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
1029 PM CDT Fri Aug 8 2025

.KEY MESSAGES...

- Elevated heat and humidity of today becomes noticeably less so
  starting Saturday, continuing into next week.

- A round of thunderstorms is likely late this evening into
  early Saturday morning, with a few storms possibly strong to
  severe.

- Much more tranquil weather conditions from late Saturday
  through much of next week.

&&

.UPDATE...
Issued at 1016 PM CDT Fri Aug 8 2025

Thunderstorms are beginning to develop across western Minnesota
along a frontal boundary. The 09.00z MPX sounding shows a strong
cap (~24C at 800mb), but the profile out of ABR is more
favorable with considerably cooler temperatures aloft. The
convection that has managed to develop near KAXN has overcome
what capping does exist (although it`s been slow to intensify),
but appears that it`s becoming more organized. Anticipating
this line to fill in to the south over the next couple of hours
and continue to move to the northeast through early morning. A
Severe Thunderstorm Watch has been issued, with the main threats
being large hail initially before transitioning to more of a
damaging wind threat.

&&

.DISCUSSION...
Issued at 317 PM CDT Fri Aug 8 2025

A fairly extensive stratocumulus deck has lingered across
central-southern MN and western WI throughout the day in the
wake of early morning convection. In addition, this cloud cover
has generally remained north of a warm front wobbling over the
MN/IA border which has had a hard time pushing northward through
the day today. This has not only kept instability from rising
higher than expected but has also kept temps/dewpoints/heat
index values lower than expected. The first result of this has
been the early cancellation of all heat advisory headlines
across the WFO MPX coverage area. The next result has been lower
CAPE/higher CINH across the area, evidenced by showers trying
to move into southern MN from the FSD area that has been
weakening while shifting eastward and racing away from the
nearly north-south oriented cold front over the far eastern
Dakotas.

Nevertheless, there is still sufficient instability in advance
of the cold front per SPC analysis, including MUCAPE in the
4000-5000 j/kg range, over the southern 1/3 of MN that
additional storms could take advantage of later this evening
into the overnight hours should deep layer shear better align
with the progression of the surface cold front. There is still
plenty of uncertainty as to whether thunderstorms that develop
this evening over the eastern Dakotas and progress eastward
across central-southern MN can become surface based to tap into
the high instability. So while there is little doubt that
thunderstorms will develop this evening, thus having PoPs into
the Likely category, it is a matter of the storm strength and
them being elevated vs surface-based, which if surface-based,
they could then tap into the low-level MUCAPE and the strong
low-level jetting and bulk shear. So, overall a conditional and
uncertain scenario for severe weather is expected tonight. The
main hazard still looks to be damaging wind gusts, but large
hail and a few tornadoes cannot be ruled out.

The precipitation will have pushed through the bulk of the
coverage area by daybreak Saturday morning with only a few
generic (non- severe) thunderstorms possible by that point as
the cold front makes continued progress eastward through the day
Saturday. This will drop the precip chances across the area
from west to east and also make for cooler and less humid
conditions across the coverage area. Highs will only range from
the upper 70s to mid 80s on Saturday.

For next week, very similar day-to-day conditions are expected
with very few chances for precipitation. In fact, many
locations may well experience no precipitation for the entire
week. This is due to generally high pressure prevailing at the
surface, even despite the arrival of a frontal boundary midweek
that looks mainly dry, and weak ridging aloft to keep
appreciable trough axes away from the area. Highs will remain in
the upper 70s to mid 80s range with tolerable humidity levels.

&&

.AVIATION /00Z TAFS THROUGH 00Z SUNDAY/...
Issued at 635 PM CDT Fri Aug 8 2025

Low-range VFR for all TAF sites at initialization but the
expectation is still there to have convection late this evening
through early morning Saturday at all sites. A complex of
thunderstorms is expected to develop over the eastern Dakotas
late this evening then steadily shift eastward over central-
southern MN and western WI through the overnight hours. VFR-
worthy rain showers will likely precede and follow the main
batch of storms, but the TSRA itself will likely drop conditions
to MVFR, with IFR visibility possible should the heavier showers
move directly across the terminals. Precipitation will end from
wet to east around daybreak onward, with the precip lingering
longest at EAU. Breezy S winds at the start will shift to a more
W direction behind the precip, with the stronger storms possibly
producing strong variable wind gusts.

KMSP...Have nudged the best timing for TSRA slightly later in
this TAF set, looking for it to move across MSP in the 07z-10z
timeframe. Gusty winds and heavy rain look to be the main
hazards, but some hail cannot be ruled out. Ceilings and
visibility will likely drop to MVFR during the time of TSRA,
with IFR visibility possible. Otherwise, VFR conditions are
expected through this evening, and once again from around
sunrise onward behind the precipitation.

/OUTLOOK FOR KMSP/
SUN...VFR. Wind SW 5-10 kts.
MON...VFR. Wind W 5-10 kts.
TUE...VFR. Wind SW 5-10 kts.

&&

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

&&

$$

UPDATE...Dye
DISCUSSION...JPC
AVIATION...JPC