543
FXUS63 KMPX 172319
AFDMPX

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
Issued by National Weather Service La Crosse WI
619 PM CDT Tue Jun 17 2025

.KEY MESSAGES...

- Additional rain chances return Wednesday and last through the end
  of the forecast period.

- Increasing confidence in above normal temperatures this
  weekend with heat indices over 95F Saturday and Sunday, then
  cooler temperatures arrive early next week.

&&

.DISCUSSION...
Issued at 239 PM CDT Tue Jun 17 2025

Diurnal shower and thunderstorm chances through Friday

A much quieter day is on tap across Minnesota & western
Wisconsin as cooler and drier air has settled in behind
yesterdays frontal passage. Current observations reveal
temperatures in the 70s with light and variable wind for much
of the region. Temperatures should warm a few degrees more into
the mid 70s to lower 80s by late afternoon. It is not all clear
skies and sunshine as there is a chance for scattered
thunderstorms along the I-90 corridor this afternoon and
evening. The mesoscale environment is driven by sufficient shear
and modest instability, but we are not looking at severe
weather potential. A few storms could be capable of producing
small hail and gusty winds. A similar scenario unfolds on
Wednesday with highs in the 70s to lower 80s with non-zero
chance of pop- up thunderstorms/showers in the afternoon. The
Twin Cities metro should remain dry throughout most of the next
36 hours.

Thursday will open the door for slightly more organized showers
and thunderstorms as a weak shortwave disturbance embedded in
the northwest flow moves through N MN and W WI. Thursday is
tagged by the SPC with a Day 3 SWO Marginal risk across the
entire Upper MS valley. Forecast sounding highlights an area of
1000-2000 J/Kg CAPE and 40 to 50 knots of bulk shear that
should be adequate for a severe risk. Wind shear does appear to
be in the speed shear category vs directional shear but should
be plenty to support potential severe thunderstorms and
organized convection. This will push through and we will
briefly dry out Thursday night.

A Potential Ring of Fire Setup for Convection This Weekend into
Early Next Week

An expansive ridge begins building into the region on Friday. A
strong low level jet will set up on the western flank of the
ridge from the Gulf north to the Upper Midwest. This will
provide a continuous source of WAA and Gulf moisture advection
into the region for the weekend. The EPS mean 850mb winds will
vary between the 90th and 99th percentile when compared to the
climatology for this period. What is more impressive is that
the duration will last through Sunday and will translate to
impressive heat and humidity this weekend. There will be
potential for a sunrise surprise Friday morning as our
shortwave lifts northeast through late Thursday night/early
Friday morning. Showers and thunderstorms are likely but should
lift out of the Twin Cities region by late morning hours. High
temps warm into the mid to upper 80s by Friday afternoon.
Another round of thunderstorms is likely Friday night across
central Minnesota as an elevated warm front lifts through.
Storms should stick to near our shared CWA boundary with Grand
Forks and Duluth as there will be strong capping in place across
the southern half of Minnesota. Saturday will be the first
truly hot and humid day we have had since last year as moisture
continues to pool across the region. High temps top out in the
low 90s - but dewpoint temperatures will also be in the low to
mid 70s will push heat indices into the upper 90s to low 100s.
There are some drier solutions that keep our heat indices in the
mid to upper 90s but either way it will be humid. 12Z ECMWF
highlights 16-19C 700mb temperatures in place from Saturday
morning through Sunday evening. This should place a lid on any
potential convection forming in our area, but we will have to
keep an out to our north and west where little to no capping is
present. Barring convective debris, Sunday appears to be even
warmer with a similar Tds as Saturday. If we do not achieve the
MaxT forecast, we are still going to be very humid with the
persistent Gulf moisture LLJ. This level of heat may require a
heat headline down the road.

Uncertainty Early Next Week With Ridge Positioning

Guidance diverges Sunday night through the middle of next week.
The exact evolution of shortwaves and associated cold fronts as
well as the ridge placement and strength would support this
uncertainty. At some point a shortwave will break down the NW
edge of the ridge and a cold front will push through the Upper
Midwest. This should offer a break from the heat and humidity
but could lead to another round of thunderstorms & heavy rain.
Cooler temperatures will arrive by mid-week as the ridge should
breakdown enough/shift SE to allow cooler, more zonal flow into
the area.

&&

.AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/...
Issued at 618 PM CDT Tue Jun 17 2025

VFR conditions will be prevalent for much of the forecast period
with some low probabilites (10-30%) in recent HREF guidance for fog
development overnight resulting in category reductions to vsbys.
However, confidence was too low to include in the TAF issuance at
this time. Otherwise, showers and embedded storms persist across
portions of central MN that slowly trek southeast. Overall the
environment for these remains unfavorable with minimal instability
towards the Twin Cities so have kept the VCSH mention to KSTC and
KAXN. Additionally, showers and storms move in to the region
generally from the Twin Cities metro and south for the afternoon
tomorrow. Consequently, have included some prob30 mention for both
KMKT and KEAU. Winds will switch to the NW for tomorrow and remain
between 5-10 kts.

KMSP...VFR conditions are likely through the evening and into the
overnight with few to bkn VFR cigs. There remains a small chance (10-
30%) for some fog development overnight which may reduce vsbys
however confidence remains too low to introduce in the TAF at this
time. As we head into the afternoon on Wednesday, there remains some
small chances (15-25%) for storms, however confidence for these
remains highest southeast of the Twin Cities.

/OUTLOOK FOR KMSP/
THU...VFR, slgt chc MVFR/-TSRA. Wind W 5-10kts.
FRI...VFR, chc IFR/TSRA. Wind W 5-10kts.
SAT...VFR, slgt chc MVFR/-TSRA. Wind S 10-15 kts

&&

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

&&

$$

DISCUSSION...WFO MPX
AVIATION...WFO MPX