821
FXUS63 KMPX 220042
AFDMPX

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
742 PM CDT Fri Jun 21 2024

.KEY MESSAGES...

- A flood watch remains in effect across southern Minnesota into
  western Wisconsin into Saturday due to additional rainfall
  across saturated soils.

- After the rain ends on Saturday we should see a break Sunday
  into Monday.

- River flood concerns will extend into next week, with several
  local sites forecast to reach major flood stage.

&&

.UPDATE...
Issued at 742 PM CDT Fri Jun 21 2024

Numerous thunderstorms are developing across southwest MN in
response to a strengthening LLJ and associated moisture
transport unimpeded by the lack of deep convection across
northern IA. It remains to be be seen how far north this
convection will develop, but it will be farther north than
models indicate unless thunderstorms begin developing across
northern IA in a more serious fashion. 3-hr NCRFC flash flood
guidance from earlier this afternoon is as low as 1/4-1/2 inch
from near Faribault to Mankato and St. James. It seems unlikely
now convection will miss these areas this evening. Therefore, we
are expecting the potential for serious impacts to these areas
a bit later this evening. Considerable and life-threatening
flash flooding is likely if training occurs there. Flash Flood
Warnings are likely in the coming hours.

&&

.DISCUSSION...
Issued at 303 PM CDT Fri Jun 21 2024

Rest of Today... Rainfall overnight trended farther to the
south the originally expected. This trend was noticed in this
last discussion with the decaying MCS following the better
moisture across far southern Minnesota. Heavy rainfall occurred
with this system with 2 to 5 inches measured. Additional
showers and periodic thunderstorms occurred across parts of
this same area later in the morning causing flash flooding,
areal flooding, and river flooding across southern Minnesota.
Thankfully recent model trends have continued a southern trend
with the heaviest rainfall. This is due to the expected location
of the warm front. The I-90 corridor south into Iowa now looks
like best location for thunderstorms and heavy rainfall due to
this frontal placement. There remain some model spread that
keeps this farther north, such that the watch remains in effect
to the north. This is also largely due to saturated soils such
that there would not need to be much rain for flooding too
occur. This saturation is shown by current FFG values. However
this threat remains more likely to the south as outlined in the
SPC Mesoscale Discussion and southward shift of the WPC moderate
ERO.

Saturday... The flood watch continues into Saturday as rain is
expected to continue Saturday morning into afternoon (mainly WI
for afternoon). This will be tied to the slow moving synoptic
forcing with the surface low shifting into Wisconsin on
Saturday. Rain chances should go down quickly on the western
side of the low. Light rain and drizzle could persist on the
western side of the low, but little additional rainfall is
expected.

Sunday through Thursday... Sunday into Monday is when we finally
get a dry period. This should allow some time for water to start
to receded along the smaller streams and overland. Larger,
especially mainstem rivers, will continue rises for a while as
water flows into them. There are two times that could see
another round of rain next week: a frontal passage Monday night
into Tuesday and again near the end of the week. The first
event Monday night into Tuesday should move through faster and
should not be as long of a duration event as we have recently
seen. Of course any thunderstorms could still have high rain
rates and soils would still be more sensitive than normal.
Looking ahead to the end of the were there is still to much of
a spread in the ensembles to have much confidence past saying
that the Upper Midwest will see more rain.

&&

.AVIATION /00Z TAFS THROUGH 00Z SUNDAY/...
Issued at 652 PM CDT Fri Jun 21 2024

Scattered thunderstorms are expected much of the night across
southern MN or northern IA, mostly south of the TAF locations.
However, a cluster over southwest MN will potentially impact RWF
early this evening and MKT later this evening. Cigs will slowly
deteriorate to IFR through the night.

KMSP...Cigs will hover near 1kft for the next few hours, then
showers and perhaps a couple thunderstorms will approach late
this evening. IFR likely thereafter. Showers will continue until
08-09Z overnight, then another break before the next and final
round is possible Saturday afternoon.

/OUTLOOK FOR KMSP/
SUN...VFR. Wind NW 10-15 kts.
MON...VFR. Chc-TSRA/MVFR late. Wind SE 10-15 kts.
TUE...VFR. Wind NW 5-10 kts.

&&

.HYDROLOGY...
Issued at 303 PM CDT Fri Jun 21 2024

Despite a lack of confidence in the location of highest QPF for
tonight, we`ll see enough rain in areas already having issues from
last night`s and this morning`s rain to warrant an areal flood
warning in south central MN. This warning will need to be watched
for extension to the south depending on how the precip sets up along
I-90, could also go through the night. River forecasts are mainly on
track this afternoon, paying particular attention to the Cannon
where training has occurred today, along with the mid/lower
Minnesota where lots of inflow coming from the tribs south of
Mankato.

&&

.MPX WATCHES/WARNINGS/ADVISORIES...
MN...Flood Watch through Saturday afternoon for Anoka-Blue Earth-
     Carver-Dakota-Faribault-Freeborn-Goodhue-Hennepin-Le
     Sueur-McLeod-Nicollet-Ramsey-Rice-Scott-Sibley-Steele-
     Waseca-Washington-Wright.
     Flood Watch until 7 AM CDT Saturday for Brown-Martin-Redwood-
     Renville-Watonwan-Yellow Medicine.
WI...Flood Watch through Saturday afternoon for Dunn-Eau Claire-
     Pepin-Pierce-St. Croix.

&&

$$

UPDATE...Borghoff
DISCUSSION...NDC
AVIATION...Borghoff
HYDROLOGY...CCS