821
FXUS63 KMPX 222030
AFDMPX

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
330 PM CDT Sat Jun 22 2024

.KEY MESSAGES...

- Rain showers and embedded thunderstorms are expected this s
  afternoon. The threat for severe weather is low.

- There`s a Slight Risk (level 2 of 5) of severe storms Monday
  evening.

- Active pattern continues with another round of precipitation
  expected Thursday afternoon through Friday night.

&&

.DISCUSSION...
Issued at 329 PM CDT Sat Jun 22 2024

An area of showers and embedded thunderstorms across west central
Minnesota will continue to trek just north of due east this
afternoon. The severe threat is low, not non-zero, but the main
concern is the additional rainfall on already saturated soils and
rising area rivers/tributaries. Additional rainfall amounts of 0.25"
to 0.5" are likely, with locally up to 1 inch where embedded
thunderstorms track. We are closely watching rain rates and amounts
as this area tracks through given the potential impact to the
ongoing flooding across southern Minnesota. After this exits east
we`ll dry out for the remainder of this weekend. Temperatures will
stick in the low to mid 70s this afternoon and lows in the upper 50s
and low 60s tonight. Sunday looks to finally be a drier day for a
change and presents us an opportunity to tackle any yard work that`s
piled up over the past week or two. The next wave arrives in
northwest flow from Canada late tonight and will move across
northern Minnesota into northern lower MI on Sunday. There is a
threat for some isolated afternoon showers & storms northeast of I-
94 but instability will be minimal, around 500 j/kg, so the severe
risk Sunday is low and most of us should remain dry!

Our attention turns to Monday and the potential severe weather
threat, especially Monday evening and Monday night. SPC`s severe
weather outlook highlights much of Minnesota and NW Wisconsin under
a Slight risk (2 out of 5) for severe thunderstorms. Monday and
Tuesday will be the warmest days of the week with highs in the mid
to upper 80s and given the recent rainfall dewpoint temps will be in
the upper 60s and 70s across the region. Warm air advection ramps up
in response to a shortwave in Canada. This should lead to an
impressive build up of instability in the warm sector. How favorable
will the thermodynamic environment get? A mean of various guidance
would build in 3000 to 4000 j/kg MLCAPE values beneath steep mid
level lapse rates Monday afternoon. Forecast soundings do have
favorable curved hodographs with good low level shear and SRH that
would be capable of supporting tornadoes, damaging winds, and large
hail. Monday afternoon and evening`s severe potential is evident but
there are a few questions that we`ll need to answer first. Surface
to 3km lapse rates are forecast to range between 5.5 to 6.0 deg/km
under an appreciable cap. 700 hPa temperatures will range from 12 to
16C and likely require additional forcing mechanism for initiation
in the warm sector Monday PM. Looking aloft, the upper level support
isn`t great as the best forcing remains off to the north across
northern Minnesota and Canada.

The most likely scenario is that convection fires Monday
evening over NW MN where a weaker cap is overcome by either the
sfc cold front and/or the strengthening LLJ before growing
upscale into an MCS and tracking across central MN into NW WI.
This would still pose a severe threat across our area, but the
warm sector likely remains storm free throughout Monday
afternoon. Our environment will be capable of supporting severe
thunderstorm threat if we`re able to get thunderstorms to
initiate. There is plenty of uncertainty with what scenario will
play out. Any convection that develops will pose a heavy rain
threat with ample moisture to work with. This will support
impressive rain rates where storms track, although the isolated
to scattered coverage should help limit any additional flash
flood concerns for now.

Tuesday and Wednesday appear to offer a much needed stretch of dry
weather. High pressure will bring drier air as it settles in through
mid-week. The end of the week looks active as another system impacts
the Upper Midwest. For Thursday through Friday night, a shortwave
will trek along the international border to Lake Superior. Guidance
supports the development of a LLJ across the Dakotas and western
Minnesota Thursday night. This would support the potential for two
rounds of thunderstorms, one Thursday night with the LLJ and one
Friday afternoon and evening with the cold front passage. Given
the recent wet pattern, this system will support both potential
severe weather and excessive rainfall.

&&

.AVIATION /18Z TAFS THROUGH 18Z SUNDAY/...
Issued at 1157 AM CDT Sat Jun 22 2024

Current IFR/MVFR cigs should last at least into this evening.
Showers and thunderstorms currently over western MN will move
east through this afternoon. Visibilities will drop to IFR
within heaviest cells, though, a general downward trend in
intensity is expected as cells near our WI terminals. For most
of MN, conditions should improve MVFR/VFR during tonight as cigs
rise and skies break some. But, a reduction to MVFR is possible
Sunday morning with a chance for some patchy fog. For MKT, RNH,
and EAU, cigs should remain steady/drop into IFR overnight.
Conditions at all terminals should slowly improve during Sunday
morning. North-northeasterly winds will turn northwesterly and
slow to under 5 knots overnight before becoming west-
northwesterly at 5-10 knots Sunday morning.

KMSP...Added TEMPO from 22-00z today for periods of
thunderstorms where visibility could drop to IFR. IFR conditions
look more likely overnight with lack of cloud clearing.

/OUTLOOK FOR KMSP/
MON...VFR. Chc -TSRA/MVFR late. Wind SSE 10-15 kts.
TUE...VFR. Wind NW 10-20 kts.
WED...VFR. Wind NW 5-10 kts.

&&

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

&&

$$

DISCUSSION...BPH
AVIATION...CTG