578
FXUS63 KMPX 161736
AFDMPX

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
1236 PM CDT Sun Jun 16 2024

.KEY MESSAGES...

- Showers and thunderstorms will diminish early this morning. Hot
  and very humid today with heat indices peaking near 100
  across eastern/southern MN into WI. A Heat Advisory remains in
  effect for the Twin Cities metro.

- A front will stall across southern Minnesota tonight, focusing
  the next round of heavy showers and thunderstorms along it
  through Monday. A few more inches of rain may fall in places,
  posing a flash flood threat. Isolated severe storms are
  possible.

- Front lifts north Monday night with the main heavy rain
  threat area refocusing across northern and central Minnesota.
  A Moderate Risk of flash flooding remains in this area.

- Additional showers and storms will develop along a cold front
  Tuesday. A few severe storms and more heavy rain will
  accompany this round.

&&

.UPDATE...
Issued at 1147 AM CDT Sun Jun 16 2024

Moisture advection has helped boundary layer moisture such that
we have seen greater cloud cover than previously forecast. For
this reason the max temperatures for today are now in the 80s
with upper 80s in the metro/heat advisory area. This drop
brings heat index values down from around 100 in the metro down to
around 95. It will still be hot and humid today so the heat
advisory will remain in place.

&&

.DISCUSSION...
Issued at 359 AM CDT Sun Jun 16 2024

An MCV northeast of the Twin Cities is heading east early this
morning. Showers and thunderstorms are gradually diminishing
from west to east and cloud tops are warming quickly. The
ongoing convection across southern MN is more disorganized than
it was earlier, but still poses a low risk for flooding for the
next hour or so due to 1 to 2 inch per hour rates. Clouds are
clearing across western MN and eastern SD, setting the stage for
a hot and very humid day. A warm front will lift north this
morning and thermal ridging will build up ahead of a cold front
set to move in this afternoon. 925 mb temps of +25 to +27 still
suggest highs near 90 across southern/eastern MN into WI. Dew
point pooling will occur as the front approaches this afternoon,
aided by the last 24 hours of rain. Readings could reach the mid
70s. Combined with temperatures near 90, heat indices will peak
around 100 and thus a Heat Advisory remains in effect for the
Twin Cities metro this afternoon. Despite the high dew points,
the atmosphere will remain capped today due to a stout elevated
mixed layer, so convective redevelopment today is unlikely.

The cold front will stall near the IA/MN border tonight and
remain there through Monday. Steep lapse rates will remain
through much of the night and the atmosphere will remain capped.
However, an increasing LLJ across the Plains will spark
elevated thunderstorm development first over SD and Neb this
evening, then as some veering of the jet occurs overnight into
western IA, activity will spread across MN. Some large hail
could accompany storms. The larger threat though will be another
round of heavy rain. The LLJ won`t be particularly strong, but
continued development and training of convection north of the
stalled front, very high pwats around 2 inches, and primed soil
from yesterday`s activity, will enhance the threat for flash
flooding. It`s a little peculiar CAMs and global models aren`t a
little more robust with QPF given the set up, although the 06Z
HRRR does have some 2 to 4 inch totals across west central MN. A
Flood Watch may eventually be needed once confidence in spatial
placement of the heaviest QPF with tonight`s round increases.

The front won`t move much or at all most of Monday. Continued
development of thunderstorms should occur in much of the same
areas as tonight. As the trough begins to head northeast across
the Plains later in the day, the LLJ will strengthen and
moisture transport will maximize. This will allow more robust
development to occur across central MN with another 2 or 3
inches possible in spots. Some large hail could also accompany
the stronger cores. Despite the widespread precip north of the
front, the ejection of the system northward and very strong WAA
will push the warm front, and thus the zone of heavy rainfall,
north quickly Monday night. After a coolish day, the passage of
the warm front will send temperatures into the mid 70s Monday
night.

By Tuesday, the trailing cold front will push through. Strong
forcing along the front and a very moist and unstable airmass
ahead of it will produce a band of showers and thunderstorms
along it. A relatively slow progression will lead to yet another
threat for strong/severe storms, and heavy rain and flooding
through Tuesday evening.

The front will stall Wednesday southeast of the area, but it may
be near enough for additional showers across southern MN into
parts of central and western WI. A return of it northward
Thursday and Friday with the approach of the next system will
bring increased chances for more storms.

By the time we reach late week, most of the area will likely see
an additional 3 to 5 inches of rain. Some localized areas will
be heavier, of course. The risk for river flooding is still
being assessed and will depend on each round going forward, but
it`s safe to say increases can be expected and several locations
will likely rise to flood stage in the coming days.

&&

.AVIATION /18Z TAFS THROUGH 18Z MONDAY/...
Issued at 1228 PM CDT Sun Jun 16 2024

SCT/BKN clouds continue for the first 6-12 hours of the period
ahead of another round of SHRA/TSRA arriving after 06z and more
likely by 09-11z. Kept the timing of precipitation simple within
the current TAF as more uncertainty is present towards the end
of the period depending on how quickly the early morning round
moves through. There will be breaks during the day and after the
end of the period on Monday, but the timing has yet to be fully
resolved. Winds are a bit gusty to start the period but should
be on a downwards trend outside of any gusts with -TSRA.

KMSP...Confidence in showers/storms arriving by 09-10z is fairly
high at this point, with the main uncertainty being how quickly
this round moves through the area. The period between roughly
15-00z tomorrow will have gaps and breaks in -SHRA/-TSRA,
however confidence is too low to pinpoint for now. Expect
greater detail to hopefully arrive by the 06z TAF regarding
better timing during the day tomorrow.

/OUTLOOK FOR KMSP/
TUE...VFR/MVFR, TSRA/SHRA likely, chc IFR. Wind S
15-20G30-35kts.
WED...VFR/MVFR, chc -TSRA/-SHRA. Wind N 5-10kts.
THU...VFR/MVFR, chc -TSRA/-SHRA. Wind NE 5-10kts.


&&

.MPX WATCHES/WARNINGS/ADVISORIES...
MN...Heat Advisory until 7 PM CDT this evening for Anoka-Carver-
     Dakota-Hennepin-Ramsey-Scott-Washington.
WI...None.

&&

$$

UPDATE...NDC
DISCUSSION...Borghoff
AVIATION...TDH