797
FXUS63 KMPX 251806
AFDMPX

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
106 PM CDT Wed Jun 25 2025

.KEY MESSAGES...

- Widespread rainfall amounts today and Thursday of 2" to 4" are
  expected. Locally higher amounts are possible which could lead
  to localized flash flooding.

- It is still unclear where the highest amounts will fall and
  could occur anywhere across the southern half of MN and
  western WI.

- Hot and humid this weekend with more storms possible.

&&

.UPDATE...
Issued at 1139 AM CDT Wed Jun 25 2025

Areas of heavy rain will continue today, so have issued a Flash
Flood Watch through 7am Wednesday morning for much of the area. In
addition, the Storm Prediction Center has lifted the slight risk for
today farther north, with the main threat being a brief tornado or
damaging wind.

For the flash flood watch, this tropical airmass is producing storms
with rainfall rates in excess of 2 inches per hour, and areas near
Renville MN had two locations measure over 5 inches of rain from the
late night/morning storms. These two factors, together with the
overall set up, increased confidence enough to issue a flash flood
watch for much of the area today. HiRes models continue to indicate
pockets of 4 to 6 inches, and if those were to fall over a town or
some terrain, there would be some flooding issues.

Meanwhile, a warm front is becoming more defined across southern
Minnesota. Instability will continue to build south of this warm
front. LCLs are very low to the ground, and forecast soundings show
a veered wind profile with nearly 200 m2/s2 of storm relative
helicity. Instability in excess of 1000 J/kg should be enough for
storms with rotating updrafts, which could lead to a few tornadoes
across southern Minnesota.

&&

.DISCUSSION...
Issued at 312 AM CDT Wed Jun 25 2025

Rain is moving into western MN early this morning and will
quickly overspread the entire forecast area throughout the day.
This activity is being fed by deep moisture transport ahead of a
deep trough over the Rockies and enhanced by a strengthening
low-level jet across the Central Plains. A steady stream of
upper level lift, superimposed onto a slowly northward-
advancing low-level boundary will mean steady periods of rain
and occasional storms throughout the day across much of the
region. There may be a relative lull in precipitation overnight
before another focused round of rain and storms moves through on
Thursday in response to a slightly more pronounced upper wave.

This prolonged rainfall will lead to widespread 1" to 2"
amounts through today and into this evening, followed by
possibly another 1" to 2" on Thursday. Current ground moisture
levels can generally handle a general 2 to 4 inches spread over
a 48-hour period, aside from some swollen creeks and a few
rivers approaching minor flood stage. However, parameters are
favorable for a few spots of higher rain amounts, possibly in
excess of 5 inches, particularly later this afternoon and this
evening when storm motion and low-level jet vectors become more
favorable for back building storms. This combined with moisture
profiles that are highly favorable for tropical-like rain rates
could result in a few training storms capable of very heavy rain
and flash flooding. There is still very little to grab onto
regarding where exactly the highest flash flood potential could
be with models continuing to be highly variable. These solutions
keep bouncing around with their heavy rainfall axes suggesting
it could be anywhere from central Minnesota into northern Iowa
and into much of Wisconsin and anywhere in between. Given the
difficulty of pinpointing where flash flood potential could
occur, and since this threat is expected to stay fairly
localized, decided against a large scale flood watch for now.

Rain will taper off Thursday evening leading to a much drier day
on Friday. Temperatures on Friday will be fairly pleasant with
highs ranging from the middle 70s to lower 80s. This fair
weather will be short-lived however as heat and humidity rapidly
return on Saturday. Highs on Saturday will be pushing 90 across
much of the region along with dewpoints surging into the lower
to middle 70s. This hot and humid airmass will result in strong
to extreme instability by Saturday afternoon, which could set
the stage for a convective complex moving across the region some
time late Saturday or Sunday when an upper wave tracks across
the Dakotas. While models are coming into agreement on this
solution, they still disagree on timing which could have a big
impact on how strong these storms end up becoming. Regardless,
the degree of instability alone suggests that strong to severe
storms are a possibility at some point this weekend across much
of the area.

&&

.AVIATION /18Z TAFS THROUGH 18Z THURSDAY/...
Issued at 1250 PM CDT Wed Jun 25 2025

The heaviest band of rain has lifted northward of all of our
terminals early this afternoon. Still, most sites are MVFR/IFR
which will continue through the period. Additional rain is
expected this afternoon with a few thunderstorms possible for
KMKT/KMSP/KEAU. IFR/LIFR conditions are possible with the
heaviest showers and storms. There will likely be a brief break
in the precip overnight before another round arrives early
Thursday morning. Cigs will remain IFR overnight and through
much of tomorrow morning.

KMSP...Thunderstorm chances are highest to the south of the
terminal due to the placement of the warm front, but a few
storms are still possible late this afternoon. Have opted to
change the TEMPO to PROB30. Otherwise, mainly IFR conditions
through the period with easterly winds becoming northeast
tomorrow morning.

/OUTLOOK FOR KMSP/
FRI...VFR. Wind variable 5 kts.
SAT...VFR. Chc TSRA/MVFR late. Wind S 5-10 kts.
SUN...MVFR/RA likely, chc TSRA/IFR. Wind W to NW 5-10 kts.

&&

.MPX WATCHES/WARNINGS/ADVISORIES...
MN...Flood Watch through Thursday morning for Anoka-Benton-Blue
     Earth-Carver-Chippewa-Chisago-Dakota-Faribault-Freeborn-
     Goodhue-Hennepin-Isanti-Kandiyohi-Le Sueur-McLeod-Meeker-
     Nicollet-Pope-Ramsey-Renville-Rice-Scott-Sherburne-Sibley-
     Stearns-Steele-Swift-Waseca-Washington-Wright.
WI...Flood Watch through Thursday morning for Barron-Chippewa-Dunn-
     Eau Claire-Pepin-Pierce-Polk-Rusk-St. Croix.

&&

$$

UPDATE...JRB
DISCUSSION...DPH
AVIATION...Dye