745
FXUS63 KMPX 212003
AFDMPX

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
303 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.

&&

.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 /18Z TAFS THROUGH 18Z SATURDAY/...
Issued at 1233 PM CDT Fri Jun 21 2024

This remains a low confidence TAF set as the models have
continued to struggle with handling this convective
environment. I was able to reduce the hours of prevailing TS
mention and drop TS from some terminals entirely. The warm
front is just north of I-90 with widespread showers along and to
the south of it. Immediate impacts will be to MKT/EAU with
fringe impacts to RWF/MSP. Our current thoughts are that
greatest chance for TS development this afternoon will be along
and south of that boundary. This highlights MKT being most at
risk for see TS development. Tonight, precip coverage will
expand as the LLJ intensifies in response to a shortwave moving
across Neb. Guidance has the heaviest rainfall occurring along
and south of the I-90 corridor in southern Minnesota and
northern Iowa. Given the southern MN focus for forcing, did
keep AXN/STC dry during this TAF period. With this warm front
just making it past I-90, the MPX terminals (with the possible
exception of MKT) will remain north of the warm front this
period, which means persistent MVFR/IFR cigs can be expected.

KMSP... Higher confidence on warm front placement has allowed us
to drop TS mentions this evening/tonight. -SHRA is still
forecast overnight into Saturday AM.

/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 through Saturday morning for Brown-Martin-Redwood-
     Renville-Watonwan-Yellow Medicine.
WI...Flood Watch through Saturday afternoon for Dunn-Eau Claire-
     Pepin-Pierce-St. Croix.

&&

$$

DISCUSSION...NDC
AVIATION...BPH
HYDROLOGY...CCS