262
FXUS63 KMPX 130835
AFDMPX

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
335 AM CDT Thu Jun 13 2024

.KEY MESSAGES...

- Showers across southern Minnesota this morning, then drying
  out until early Saturday.

- More widespread showers and thunderstorms likely Saturday with
  locally heavy rainfall possible.

- An intense heat wave will build across the eastern third of
  the country next week with the Upper Midwest on its western
  periphery. This will mean periods of hot and humid conditions
  and multiple rounds of thunderstorms with heavy rainfall.

&&

.DISCUSSION...
Issued at 335 AM CDT Thu Jun 13 2024

Storms have finally exited to the southeast early this morning.
A front is trying to make its way eastward across central and
southwestern MN, but surface winds have become light or calm and
for now it has stalled. West of the front dew points have
dropped into the upper 40s to mid 50s while remaining in the 60s
east. Areas of fog are developing along the front and some
locally dense fog is possible, especially where heavy rain fell
last evening. Mid level clouds across SD will spread east early
this morning and a band of showers will likely develop across
western and southern MN just after sunrise. The development of
these showers is almost certain, but CAMs are inconsistent with
the spatial details so for now kept 50-60 PoPs for this area.
Once development occurs, PoPs will likely need to be increased
further for some areas. Showers will exit to the southeast early
this afternoon and clearing will follow for the rest of the day.
Despite early day rain, highs in the low 80s are expected area
wide.

Dry conditions will prevail through most of Friday night, but a
shortwave will eject northeast from the Four Corners region and
could begin spreading showers to southern MN by early Saturday.
A 40 kt LLJ and pwats as high as 1.75 inches are likely to
accompany the shortwave across the area Saturday/Saturday night.
While lapse rates will remain poor and instability limited,
relatively strong moisture flux should allow for a moderate to
heavy round of showers and isolated storms to bring more healthy
rainfall totals. The track of the center of the disturbance
across IA will place southern/eastern MN and WI in the heaviest
swath of rain, where 1-2 inches may fall. There is a Slight Risk
of excessive rainfall for those areas.

The disturbance will exit early Sunday and upper ridging will
quickly follow. A surface cold front will approach from the
northwest Sunday afternoon. Thermal ridging will work up the
front and 925 mb temps of +25 to +27C suggest highs in the lower
90s. Dew points around 70 will send heat indices into the mid to
upper 90s, leading to the first elevated heat concern of the
season. The front should reach at least central MN by Sunday
evening. An EML with mid level lapse rates greater than 8 C/km
should cap the atmosphere and prevent convective development,
but if forcing along the front can overcome the cap, there will
be a conditional risk of severe weather through Sunday evening.

How far south the front sags Monday before returning northward
will depend on the strength of the synoptic system well to the
north in Canada and the building ridge across the east. By late
Monday or Tuesday, a trough over the Rockies should lift it back
north and allow it to become a southwest-northeast oriented
quasi-stationary boundary through at least midweek. Intense
heat and humidity will overspread the Great Lakes and Ohio
Valley throughout this time, and depending on the surface
frontal position and related convective activity, may
occasionally make an appearance this far west. The ensemble
spread for temperature is quite large next week due to spatial
differences with the front. One thing is near certain, there
will be a tremendous amount of moisture over the Gulf, marked by
pwats greater than 2.75 inches. The strength of the ridge
across the east and a 50 kt LLJ across the Plains will funnel
some of this moisture up the front and into the Upper Midwest.
Rounds of thunderstorms, potentially severe, and very heavy
rainfall are possible throughout next week. Flooding may become
an increasing concern over the next several days.

&&

.AVIATION /06Z TAFS THROUGH 06Z FRIDAY/...
Issued at 1212 AM CDT Thu Jun 13 2024

Scattered thunderstorms from south-central MN into west-central
WI will continue moving southeast, exiting all of our terminals
within the next couple of hours. During this time, periodic
visibility reductions to MVFR/IFR are expected with any of the
stronger storms that pass over a terminal. Afterwards, VFR
conditions are expected through the rest of the period with cigs
remaining above 10000 feet. A band of light rain showers seems
likely across southern MN late Thursday morning but impacts
should be minimal. Southwesterly winds will turn northwesterly
during Thursday morning, increasing to above 10 knots (with
gusts to 20 knots) before slowing to around 5 knots Thursday
evening.

KMSP...Thunderstorms will be in the vicinity of MSP before
moving southeast by 07Z. Northwesterly winds could gust to 20
knots during Thursday afternoon.

/OUTLOOK FOR KMSP/
FRI...VFR. Wind N at 5 kts.
SAT...RA/TSRA/MVFR likely, IFR possible. Wind SE 10-15G25kts.
SUN...Mainly VFR. Slight chc TSRA/MVFR. Wind SW 10-15 kts.

&&

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

&&

$$

DISCUSSION...Borghoff
AVIATION...CTG