394
FXUS63 KMPX 220524
AFDMPX

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
1224 AM CDT Tue Jul 22 2025

.KEY MESSAGES...

- An active weather pattern will start Tuesday and last through
  Thursday with multiple chances for showers/thunderstorms, with
  the potential for strong/severe storms and heavy rainfall.

- Warm and very humid conditions Tuesday and Wednesday,
  including heat index values rising to the upper 90s to low
  100s.

&&

.DISCUSSION...
Issued at 353 PM CDT Mon Jul 21 2025

Things have quieted down this afternoon following the early
morning decaying MCS and early afternoon isolated hailer.
Should continue to be a relatively quiet evening ahead of an
active pattern setting up tomorrow.

Heat continues to build overnight, with yet again another chance
for early morning convection. CAMs generally produce some form
of an MCS in the western Dakotas late tonight, which then
progresses eastward along the instability gradient into tomorrow
morning. Outside of the NAMnest, the latest hi res models track
this particular system more across the northern half of
Minnesota. Typically we do see somewhat of a southward turn as
these systems "ride the ridge," but in this case we`ll have the
ridge building north. To that end, if the frontal boundary
situates any further south OR we see the initial convection
form a little more south (closer to the Black Hills), we could
see that convection take a path closer to the I-94 corridor.
Neither forcing nor shear are all that impressive, so the main
drivers are the 3000+ J/kg MUCAPE and 1.75"+ PWATs. The most
likely scenario is that parts of central MN and western WI see
the southern edge of a line of storms tomorrow morning into the
early afternoon.

Heat-wise, southwest Minnesota will likely see the worst
conditions on Tuesday... temperatures in the low 90s and dew
points in the upper 70s could lead to heat indices over 100F
during the afternoon. Confidence is low to medium, with
uncertainties surrounding how the convection plays out tonight
and tomorrow morning. Heat headlines are possible should
confidence increase that the line of storms overnight stays
north, and we receive enough daytime sunshine.

The fun continues tomorrow evening as another area of
convective initiation looks likely near the MN/Dakotas border.
Increasing instability and moisture could lead to some trouble,
particularly with a heavy rain threat if storms begin to train
or quickly form along outflow boundaries. There are some
noteworthy QPF totals coming out of the CAMs... widespread
amounts of 1-2" with pockets of 6"+. Much of this stays in the
northern half of Minnesota and Wisconsin, but it will not take
much for it to creep south where areas like St Cloud, MN or St
Croix Falls, WI are in the axis of heaviest rainfall. A lot of
this will depend on what happens with the MCS tonight... if it
moves through further south, and then the boundary sets up
further south, higher confidence in a convectively driven Flood
Watch may be warranted.

The heat shifts west on Wednesday, with heat indices in the
upper 90s possible for parts of SE MN into western WI. A final
round of storms Wednesday evening into Thursday morning will be
the last push of this pattern. We "cool off" to end the week,
with highs in the low 80s and lows into the 60s. Ridging returns
this weekend, with heat and daily storm chances to start next
week.

&&

.AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/...
Issued at 1216 AM CDT Tue Jul 22 2025

Low level stratus will build this morning with a few spots
seeing IFR/LIFR due to sporadic BR also creeping in. The
trickiest part of the forecast is how to handle -TSRA chances
today, with AXN/STC seeing a chance that is most likely to stay
north of the terminals, with all sites seeing prob30 type
chances after 21z through the end of the period. Model guidance
is still fairly spread on both intensity and placement of -TSRA,
so elected to broad brush with prob30 groups for now. If we can
get some better consensus, the timing will be refined in future
TAF issuance. CIGS that fall to IFR/MVFR will improve slowly
with VFR CIGS by 21z aside from the convective potential. Winds
will also increase towards 10-15G20kts by the final 12 hours of
the period.

KMSP...After a dip into IFR this morning, expecting to see
gradual improvement back to VFR by around 19-20z. The prob30
group will see some refinement in timing as we get closer.

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


&&

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

&&

$$

DISCUSSION...BED
AVIATION...TDH