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369
FXUS63 KMPX 300939
AFDMPX

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
439 AM CDT Sun Jun 30 2024

.KEY MESSAGES...

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- Soaking rain & chance for severe thunderstorms late Monday
  into Tuesday.

- Thunderstorms and locally heavy rainfall likely for the 4th of
  July.
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&&

.DISCUSSION...
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Issued at 403 AM CDT Sun Jun 30 2024

Part two of a dry & quiet weekend continues today with sunny
skies, light winds, & warmer temperatures in the low to mid 70s.
Dry conditions will continue through most of the day Monday, but
our next widespread soaking rainfall comes Monday evening into
Tuesday as a surface low along the US/Canada border slowly drags
a frontal boundary through the region. Strong southerly flow
ramps up Monday morning & advects Gulf moisture into the region,
with precipitable water values potentially exceeding 2" by late
Monday night. The precipitation with this system looks to come
in two waves, the first begins Monday afternoon over the Dakotas
but will likely take until the evening or even overnight hours
to reach much of Minnesota & Wisconsin. This wave is largely
driven by low-level forcing by the strong warm-air advection, &
some upper-level support from a shortwave along the leading edge
of an intensifying 90-100 kt jetstreak. Increasing shear and
ample instability will create a threat for strong to severe
thunderstorms with this wave, but this looks to be more likely
across the Dakotas during the afternoon. A lull in the
precipitation appears likely Tuesday morning, but another
round of thunderstorms is expected to develop Tuesday afternoon
& evening - this time along the surface frontal boundary. The
severe environment looks better across our area with this
second wave on Tuesday, especially across southern Minnesota &
western Wisconsin.

Rainfall amounts are still tricky to nail down owning
to the limitations of resolving convection at this range, but
ensemble guidance show high probabilities of at least an inch of
rain for much of the area, with the highest probabilities
across southern Minnesota & western Wisconsin. Guidance shows a
general spread between the two systems, with the Monday night
rain potentially more likely across central MN & western
Wisconsin, while the Tuesday evening rain more likely across
southern Minnesota. This scenario would likely result in a
widespread 1-2" across the entire area by Wednesday morning.
However, if both waves happen to train over the same area, which
would be most likely across southern Minnesota into western
Wisconsin, then these areas could see in excess of 2-3" of rain
with much less falling across central Minnesota. Rivers across
the have generally all crested by this weekend, but additional
rises are likely wherever the heaviest rain falls through
Tuesday.

Drier conditions develop midweek as the flow aloft weakens &
becomes more zonal, but another round of showers &
thunderstorms looks likely for the 4th of July & into Friday as
a broad shortwave trough develops & moves over the Upper
Midwest. Confidence is lower for this system following the
Monday-Tuesday wave, but locally heavy rainfall & strong severe
thunderstorms are possible, with ensemble guidance again showing
high probabilities for rainfall amounts >1" over the area. There
is still a lot of spread in timing among models, but our
highest PoPs from the NBM ensemble are centered on the evening
of the 4th. Probably a bit too early to cancel any fireworks
displays, but at least some thunderstorms on the 4th look pretty
likely at this point. A chance for showers and thunderstorms
continues over the weekend, but with not nearly as strong
a signal for heavy rain or thunderstorms.
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&&

.AVIATION /06Z TAFS THROUGH 06Z MONDAY/...
Issued at 1028 PM CDT Sat Jun 29 2024

VFR conditions expected throughout this duration with nearly no
clouds once they dissipate this evening. High pressure will
steadily slide across MN/WI through Sunday night. This will
maintain light wind speeds with varying direction and keep
skies mainly clear. The only wrinkle may be fog formation prior
to sunrise tomorrow morning at KEAU close to the river there.

KMSP...No additional concerns.

/OUTLOOK FOR KMSP/
MON...VFR. Chc MVFR/-SHRA day, MVFR/TSRA likely overnight. Wind
      SE 15G25 kts.
TUE...MVFR. Chance MVFR SHRA/TSRA. Wind SW 10-15 kts.
WED...VFR Wind WSW 15G25 kts.

&&

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

&&

$$

DISCUSSION...ETA
AVIATION...JPC