900
FXUS63 KMPX 020820
AFDMPX

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
320 AM CDT Tue Jul 2 2024

.KEY MESSAGES...

- Another round of rain possible this afternoon, best chances
  for heavy rain and thunderstorms from south central MN to
  western WI.

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

&&

.DISCUSSION...
Issued at 320 AM CDT Tue Jul 2 2024

Today and Tonight...Continued warm air and moist air advection
into the Upper Midwest will continue to provide for additional
rain chances. NAEFS suggests that precipitable water values over
1.75" remain possible. These values are well into the 99th
percentile, so the environment is primed for heavy rain. So far
for this first round of rain the heaviest rain has remained to
the south over Iowa into parts of southeast Minnesota. This
activity took up much of the moisture present such that the QPF
farther north was not as high as expected. This first round of
rain, early this morning, was largely tied to the system over
Canada. Another system is expected to move through today more
so over Iowa. This will keep southern Minnesota into western
Wisconsin as the main areas of interest. Forecast model
soundings in this area of interest show saturated soundings with
high precipitable water values, but limited instability. Should
still be enough for some thunderstorms to form, but would be
hard to see much chance for strong to severe storms. So this
looks to be more of a heavy rain risk than anything else.

Wednesday...High pressure returns, briefly, on Wednesday with a
warmer and sunnier day expected. This should allow for high
temperatures to reach into the lower to mid 80s. A few ensemble
members do provide a chance for some light rain Wednesday
afternoon, so kept some low PoPs in the forecast.

Thursday and Friday...Unfortunately it does continue to look
like a trough will move into the Upper Midwest on Thursday for
the holiday. This forcing is well agreed upon between the main
deterministic models. Looking towards to the ensembles, the
variance here is more tied to timing rather than rain occurring
or not. Start times vary between members, but overall it is the
afternoon of July 4th into the following morning that has the
most members in agreement. On the severe front the timing will
be important. If we avoid much early day rain than we could
build more instability and have a greater severe risk. This
uncertainty is why SPC has placed us in a marginal risk for
Thursday. The surface low associated with this rain will move
into the Great Lakes on Friday providing for more rain chances
on Friday

The Weekend... Our active pattern continues into the weekend
with more rain chances late Saturday into Sunday as a shortwave
moves in from Canada. A lot more spread of course looking this
far out, so details remain uncertain. What is clear however is
that you will have to look past this weekend for a prolonged dry
period.

&&

.AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/...
Issued at 1041 PM CDT Mon Jul 1 2024

Rain shield continues to blossom this evening across MN/WI such
that all sites are not only reporting precip but also seeing
most already down to MVFR range for ceilings. Confidence high
enough to maintain prevailing -SHRA/-RA at all terminals, not so
much for TSRA so have maintained CB/TS generally in TEMPO
groups. Precip will move out of the area prior to daybreak for
the MN sites, lasting a little longer for the WI sites, but
ceilings will gradually drop through the duration of the
rainfall. MVFR ceilings will likely drop to IFR levels closer to
the end of the rainfall. Conditions will gradually improve
during the day Tuesday with VFR conditions being realized mid-
to- late day. That said, there is a mentionable chance for late
afternoon SHRA/TSRA over southern-eastern MN into western WI so
it warrants keeping that PROB30 going late tomorrow afternoon.
Winds will remain breezy from the SE through the overnight
hours, then diminish and veer to SW behind the swath of
rainfall.

KMSP...Best timing for any TS into MSP still looks to be through
08z, with the timing for rainfall ending altogether around
11z-12z. Will still expect ceilings under 2 kft for the Tuesday
morning push, potentially into IFR range after sunrise and
through at least midday. Ceilings may return to MVFR range for
the afternoon push but still likely below 2 kft. There is still
a mentionable chance for late Tuesday afternoon SHRA/TSRA
reaching MSP so it warrants keeping that PROB30 going late
tomorrow afternoon. Winds will still be breezy throughout the
overnight hours and beyond sunrise, generally in the 150-170
direction. Stronger winds may be found at the 1-2 kft levels
into the early morning hours, not quite meeting the LLWS
definition but with a vector difference as those winds will be
more S to SW, there is a bit of low level turbulence that may be
experienced overnight through the pre-dawn hours.

/OUTLOOK FOR KMSP/
WED...VFR.Wind WSW M10-15G20 kts.
THU...VFR. PM MVFR SHRA/TSRA.Wind SE 5-10 kts
FRI...MVFR SHRA/TSRA likely. Wind NE 5-10 G15-20

&&

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

&&

$$

DISCUSSION...NDC
AVIATION...JPC