194
FXUS63 KMPX 141812
AFDMPX

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
112 PM 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 /18Z TAFS THROUGH 18Z SATURDAY/...
Issued at 112 PM CDT Fri Jun 14 2024

Aviation...VFR with rainfall arriving by tomorrow morning.
Other than the diurnal cu field this afternoon, cigs will
becoming BKN to OVC tonight as our next system arrives from SW
to NE across all sites. Rainfall is most likely to pester RWF
and MKT early tomorrow morning before becoming more widespread
tomorrow afternoon. Rainfall could be heavy at times, especially
for our southern sites thus impacts to flight categories are
possible. Winds will begin NW`ly then shift to SE`ly by this
evening. Winds will increase in speed tomorrow morning once the
system arrives with gusts reaching 20-25kts.

KMSP...Not much chance in the near term for regarding the TAF. Still
expecting the NW`ly winds to shift SE`ly by 00z. Aside from few
afternoon 050 clouds, the more prevalent cloud cover develops
overnight but should remain in VFR. Rain chances increase
through the morning hence the introduction of PROB30. Rainfall
will becoming likely after 21z. Rainfall could be heavy at times
and may require MVFR vsby but was reluctant to include this
period due to heaviest rainfall timing. Winds tomorrow will
remain a SE/SSE component and becoming breezy with gusts between
20-25 kts by the afternoon.

/OUTLOOK FOR KMSP/
SUN...Mainly VFR. Slight chc TSRA/MVFR. Wind S 10-15 kts.
MON...MVFR with MVFR/TSRA possible. Wind S at 05-10G15-20 kts.
TUE...MVFR with MVFR/TSRA possible. Wind S at 10-15G25-30 kts.

&&

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

&&

$$

DISCUSSION...Borghoff
AVIATION...Dunleavy