233
FXUS63 KMPX 141059
AFDMPX

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
559 AM CDT Fri Jun 14 2024

.KEY MESSAGES...

- More widespread showers and thunderstorms likely Saturday and
  Saturday night 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 the potential for
  severe weather and heavy rainfall.

&&

.DISCUSSION...
Issued at 347 AM CDT Fri Jun 14 2024

Clear skies this morning will set the stage for a beautiful day
with warm temperatures and low humidity. The dry conditions
will prevail through tonight. A shortwave will eject northeast
from the Four Corners region late tonight and could begin
spreading showers to southern MN by early Saturday. A 40 kt LLJ
and pwats as high as 2.0 inches are likely to accompany the
shortwave across the area Saturday/Saturday night. While lapse
rates will remain poor and instability limited initially,
strong moisture flux should allow for a moderate to heavy round
of showers and scattered 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 should easily fall. The amount of
moisture progged with this system has increased over the last
24 hours, and efficient rainfall processes may result in greater
than 2 inches in some locations, particularly those with
multiple thunderstorms. There is a Slight Risk of excessive
rainfall for those areas. Steep mid level lapse rates will
follow closely behind the shortwave and elevated instability is
expected to increase significantly late Saturday night. Some
more vigorous thunderstorm development may occur behind the
widespread shower activity and could pose a hail threat. These
storms could also bring a heightened flood risk following the
soaking rain from earlier.

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 just ahead of the front. Dew points pooling in the lower
70s will send heat indices into the 95-100 degree range, leading
to the first elevated heat concern of the season. The front
should reach at least southwestern MN and northwest WI 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 as early
as Sunday afternoon. The front will stall Sunday evening and
begin to lift back north late Sunday night. A strengthening LLJ
impinging on the front will be the better forcing mechanism for
convective development overnight. However, the EML will be
shifting off to the northeast and elevated instability should
thus be decreasing overnight which could limit severe
potential. SPC Day 3 Marginal risk looks good. The nearly
stationary front combined with pwats near or just above 1.75
inches and the 50 kt LLJ may bring training convection near and
north of the front, leading to more flood concerns.

Where the front is positioned Monday and beyond is the main
source of uncertainty for the rest of the forecast period.
Convection each period will also impact where it sets up to some
degree. By Monday or Tuesday, a trough over the Rockies should
lift it 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 remains 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 modified moisture up the front and into the Upper
Midwest. Rounds of thunderstorms, potentially severe, and very
heavy rainfall are possible throughout next week. Flooding will
become an increasing concern, and it`s appearing more and more
likely some areas will exceed 5 inches by this time next week.

&&

.AVIATION /12Z TAFS THROUGH 12Z SATURDAY/...
Issued at 549 AM CDT Fri Jun 14 2024

VFR conditions continue this morning with no weather-related
concerns. Northwest winds have decreased overnight and will
remain light through tomorrow morning, eventually becoming
east/southeast this evening. High level clouds will begin to
invade from the west heading into tonight, ahead of the
approaching system tomorrow. There are some lingering clouds
around 5k-8k ft over northern Wisconsin which could impact EAU
and RNH this morning.

KMSP...Winds will start to increase to 10-15kts heading into
tomorrow morning, likely gusting up to 20-25kts. Rain chances
also start to increase late tomorrow morning, but current trends
have slowed the system down so we have kept mention out of the
TAFs for now.

/OUTLOOK FOR KMSP/
SAT PM...RA/TSRA/MVFR likely, IFR possible. Wind SE 10-15G25kts.
SUN...Mainly VFR. Slight chc TSRA/MVFR. Wind S 10-15 kts.
MON...MVFR with MVFR/TSRA possible. Wind S at 05-10 kts.

&&

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

&&

$$

DISCUSSION...Borghoff
AVIATION...BED