271
FXUS63 KMPX 290346
AFDMPX

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
1046 PM CDT Fri Jun 28 2024

.KEY MESSAGES...

- Showers and storms end this evening over/near southeast MN
  with a dry and seasonably cool weekend to follow.

- Unsettled weather expected Monday into Tuesday, with heavy
  rain and some severe storms possible.

- Next potential active weather period is the 4th into the 5th, though
  model spread remains high (and forecast confidence low)
  during this timeframe.

&&

.DISCUSSION...
Issued at 335 PM CDT Fri Jun 28 2024

Surface analysis this afternoon shows a surface low up between
Bemidji and International Falls, with a cold front trailing to the
south from the low down to about Fairmont at 230pm. We`ve seen
extensive cloud cover through the day, which has held down
temperatures, but a plume of 70+ degree dewpoints has managed to
crawl its way along the front up to just west of the metro. This
moisture has allowed mlCAPE values to build to over 1000 j/kg along
the front from about Litchfield on south into Iowa. Along this
instability axis, we`ve see a weak line of storms develop along
the I-90 corridor down into Iowa. Over the next few hours, this line
of storms will continue to slide east toward La Crosse, with limited
expansion to the north expected. The strongest h85 winds are off to
the east of our area, so we have limited low level shear. Still, mid-
upper level winds will be strong enough to support 40-50 kts of deep
layer shear, so enough deep shear is present to support a low end
severe risk. From the 1630z Day 1 outlook, where the SPC has a 2%
tornado probability up into southeast MN captures where the greatest
likelihood of seeing some stronger storms will be through the
evening.

As we go through tonight, the cold front will push off to our east,
but that does not end our precipitation chances. This afternoon,
there`s an h5 low moving into wrn NoDak and as this moves east
through the night, we`ll see the threat for scattered showers and
maybe an isolated thunderstorms across central Minnesota. For the
rest of the weekend it should be mainly dry, but you can`t
completely rule out some isolated showers on Saturday as the last
piece of upper level energy moves through. Surface temperatures will
be cool and the atmo drying out, so we continue to keep PoPs below
15% (which keeps a precip mention out of our point-and-click
forecasts), but if things end up as robust as the 18z HRRR shows, we
may need to add in some -SHRA mention to the forecast for Saturday.
Big thing for Sunday is with the high overhead and the cooler highs
on Saturday, lows Sunday morning will fall into the 40s for all but
the urban core of the Twin Cities metro.

Next up on the weather system merry-go-round comes Monday into
Tuesday. Meso scale difference remain, but on the large scale, we
see the models bringing two shortwaves across the area. The first
goes from the Dakotas into northwest Ontario Monday/Monday night,
with the main trough swinging through the upper MS Valley on
Tuesday. It`s the first one that will likely pose the greatest
issues hazardous weather wise as it will send a 50-60 kt LLJ across
the area Monday night. Upstream of this LLJ, we`ll see 1000-1500
j/kg of MUCAPE feeding into this LLJ, which will result in another
heavy rain threat Monday night. The severe threat Monday is a
little more questionable given the threat for extensive cloud cover
and WAA rain to limit surface based instability, but if we see
surface features progress as far east as the ECMWF has them Monday
afternoon, then a severe risk extending a little farther east than
what the SPC Day 4 outlook has will be possible. Going ahead to
Tuesday, another round of showers and storms looks likely ahead of
the main trough, but where surface features are at that point will
determine where the greatest severe/heavy rain risk will be, but we
are seeing the potential for one more round of showers Tuesday
afternoon before this system departs to the east. Where the second
round of precip ends up will help determine what final rainfall
amounts look like, but the EPS mean QPF does have near 2" of rain
over southeast MN. When looking at the individual members at RST,
you do see a handful of EPS members with over 3" of rain early next
week, so the heavy rain threat will have to be watched.

As has been the case, the break in the weather looks to be short-
lived (Wednesday), but we are seeing signs for more unsettled
weather from the 4th into the 5th. Model spread during this period
remains quite large, so PoPs in the 30s and 40s from the NBM makes
sense, but we`re still a couple of days out before we can have much
confidence in saying whether or not your holiday festivities will be
impacted by weather.

Beyond this system, there is some hope that things may start to
settle down a little bit as upper ridge starts building farther
north and the upper jet begins to nudge north and weaken some, but
we`ll see if this hyper-active pattern can actually settle down.

&&

.AVIATION /06Z TAFS THROUGH 06Z SUNDAY/...
Issued at 1045 PM CDT Fri Jun 28 2024

Mostly VFR conditions are expected the rest of tonight, though
IFR will linger at KEAU. A cold front will drop southward,
reaching west central MN around daybreak. It will bring MVFR
ceilings that will spread toward the southeast, reaching western
WI by mid morning. Northwest winds are expected to increase to
15-20 kts with gusts in the 20s by late Saturday morning.

KMSP...Timing of the increase in northwest winds is the main
item for this forecast. Have targeted 15Z for gusts around 25
knots but that may vary by an hour or so. Few other concerns.

/OUTLOOK FOR KMSP/
SUN...VFR. Wind N bcmg E 5-10 kts.
MON...VFR/MVFR, RA likely, chc -TSRA. Wind SE 10-15G25 kts.
TUE...VFR/MVFR, chc RA. Wind W 5-10 kts.

&&

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

&&

$$

DISCUSSION...MPG
AVIATION...TDK