426
FXUS63 KMPX 021815
AFDMPX

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
115 PM 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 /18Z TAFS THROUGH 18Z WEDNESDAY/...
Issued at 1228 PM CDT Tue Jul 2 2024

The stratus deck is having a hard time eroding eastward
underneath filling-in high cirrus/cirrostratus clouds. The
lower ceilings are slightly above and below 1000ft, so
straddling the MVFR/IFR threshold. Ceilings will steadily rise
through this afternoon, allowing the sites under the stratus
deck to increase over the IFR level, while western MN sites have
broken away from the low stratus already and will remain,, in a
prevailing sense, within VFR. There is a chance of SHRA in
southern-eastern MN through western WI later this afternoon into
early this evening, so much so that precip mention in the TAFs
are able to be upped to TEMPOs for that timeframe. Not expecting
anything prolonged, heavy or strong, but enough that any
rainfall could be enough to drop conditions to MVFR late this
afternoon. Conditions will improve this evening through midday
tomorrow to solid VFR. Winds will generally remain 10kts or
less, but possibly a little breezier in western MN due to better
mixing with the clearing. Winds will slowly veer to SW and W
overnight through Wednesday.

KMSP...Ceiling have risen to MVFR levels, thus making IFR
ceilings no longer expected but ceilings will not rise over
2000ft until a few hours into the 02/18z TAF. Mid-level ceilings
will then prevail through this evening, but there is still the
potential for having a round or intermittent RA/TSRA late this
afternoon into this evening. Not looking for anything
strong/severe but could be just enough to nudge conditions into
MVFR through the evening push. Conditions will continue to
improve through the evening and overnight, remaining at VFR
through midday Wednesday. Winds will turn to 200-230 during the
evening push but with speeds under 10kts.

/OUTLOOK FOR KMSP/
THU...MVFR/IFR SHRA/TSRA, mainly PM. Wind SE 5-10 kts.
FRI...MVFR SHRA/TSRA likely. Wind NE 10G20 kts.
SAT...Chance MVFR/SHRA/TSRA, mainly PM. Wind W 5-10 kts.

&&

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

&&

$$

DISCUSSION...NDC
AVIATION...JPC