259
FXUS63 KMPX 131148
AFDMPX

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
648 AM CDT Sun Jul 13 2025

.KEY MESSAGES...

- A few strong to severe storms possible this afternoon and
  evening from central into southwest MN.

- Continued bouts of Canadian wildfire smoke and poor air
  quality possible through Monday.

- Next chance for widespread rain chances will come Tuesday
  afternoon through Wednesday night. Severe storms will be
  possible Tuesday afternoon & evening, with an excessive rain
  threat existing through the whole period.

- Below normal temperatures for the end of the week into next
  weekend, with another period of unsettled weather possible
  Friday night into Saturday.

&&

.DISCUSSION...
Issued at 326 AM CDT Sun Jul 13 2025

It was another smoky night overnight, but the approach of a surface
trough and associated uptick in southwest winds will help push the
smoke northeast of the area, with both the HRRR/RAP showing surface
smoke concentrations dropping off considerably this afternoon. With
that front will also come a risk of isolated to scattered storms.
There really isn`t much mid level support, with the main source of
forcing today being convergence along the low level wind shift.
Given the favorable southwest winds, we`ll see temperatures warm
well into the 80s, with dewpoints ahead of the wind shift pooling up
to around 70. HREF shows 2000-2500 j/kg of mlCAPE developing this
afternoon ahead of the wind shift. Forecast soundings don`t show
much capping on this instability either, so we have enough
instability with the weak forcing to support the thunderstorm
threat. For the severe potential, we`ll have a northwesterly jet
streak nosing into the area, which will provide 30-40 kts of deep
layer shear. So we have the shear and instability to support some
organized convection. HREF updraft strength and updraft helicity
products support the potential for an angrier storm or two, with
some supercell structures possible as well. So we concur with the
SPC in adding the Marginal risk of severe storms for this afternoon
and evening in MN. Storms will be diurnally driven and this activity
will likely die off before reaching southeast MN and western WI
Sunday night. For Monday, we`ll see instability build again, though
this time it looks capped, with Monday really being about setting
the stage for the Tuesday through Wednesday night period. The main
potential for Monday is the RAP had HRRR both show another surge of
smoke coming in behind the wind shift Sunday evening, with both
models showing another potential day of wildfire smoke.

Tuesday through Wednesday night, we`ll have a positively tilted h5
trough slowly work across the northern CONUS, with an equally slow
front moving across the region. How quickly the cap from Monday
erodes will determine how quickly we`ll see rain move south into
central MN Tuesday afternoon. Also, the EPS continues to ratchet up
the heat on Tuesday ahead of the boundary. We stuck with the NBM
highs in the upper 80s/lower 90s, though the EPS has quite a few
members topping out in the mid 90s on Tuesday. Combine those
temperatures with dewpoints likely in the lower 70s and there will
be some potential for heat headlines in the Twin Cities metro
Tuesday. As you can imagine, all that heat and humidity will lead to
a rather unstable environment as well and it`s this instability that
will support an increasing threat for thunderstorms by the
afternoon across central Minnesota. The big limiting factor for a
big severe risk is our mid and upper flow will be weak, with the
main upper flow still up over southern Canada. So it`s likely to be
slow moving storms. With PWATs up into the 1.5-1.9" range, we`ll
have some heavy downpours mixed in there. The main limiting factor
for the heavy rain threat is we look to get our rain in several
waves given the nature of the upper level wave slowly moving across
the north central CONUS. This will mean we get some breaks between
each round of rain, with each subsequent round likely to fall
slightly farther south than the previous. All this adds up to us
getting some soaking rains, but it will likely be tough get
widespread excessive rainfall issues. From the severe perspective,
that looks best Tuesday as rain Wednesday/Wednesday night will come
when we are north of the boundary and in a bit more stable airmass,
with a more overrunning type setup taking shape.

To end the upcoming workweek, we will have cool high pressure from
Canada. This will mean highs only in the 70s, but being it`s coming
from Canada, it will bring a renewed threat for reduced air quality
with wildfire smoke. For next weekend into the following week, we`ll
see a seasonably deep h5 low setup over Hudson Bay/northern Canada.
This in turn will result in seasonably strong zonal flow along the
US/Canada border, which means we should continue to see a parade of
waves moving across the region, with no prolonged stretches of dry
weather expected anytime soon.

&&

.AVIATION /12Z TAFS THROUGH 12Z MONDAY/...
Issued at 633 AM CDT Sun Jul 13 2025

Smoke is still with us this morning with a mix if IFR/MVFR
vsbys. However, both the HRRR and RAP show that increasing
southwest winds today will be enough to mix the smoke out, with
minimal surface based smoke at all terminals by this afternoon.
Late this afternoon, a surface trough will move into western MN.
Convergence along the boundary will provide the source of lift
to drive a risk of isolated to scattered storms. Based on where
the front is progged to be at 00z, STC and RWF will have to best
chance of seeing a storm, so added PROB30s to those two
locations. Tonight will see light winds and clear skies with
radiational fog possible in western WI.

KMSP...Based on HRRR smoke concentration forecasts, VFR vsbys
are expected to return between 15z and 17z. Storms will fire
late this afternoon to the west and will likely dissipate this
evening before they can reach MSP. Monday morning, the RAP and
HRRR show another round of surface based smoke settling in, so
introduced another round of MVFR vis in FU Monday morning.

/OUTLOOK FOR KMSP/
MON...VFR. Wind SE 5 kts.
TUE...VFR, TSRA likely evening/overnight. Wind SW 10-15 kts.
WED...MVFR, chc IFR/-TSRA. Wind NE 5-10 kts.

&&

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

&&

$$

DISCUSSION...MPG
AVIATION...MPG