504
FXUS63 KMPX 101809
AFDMPX

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
109 PM CDT Mon Jun 10 2024

.KEY MESSAGES...

- Showers and a few thunderstorms expected tonight into Tuesday morning.
  Redevelopment of a few strong thunderstorms possible in
  eastern MN/WI Tuesday afternoon.

- Warm and muggy Wednesday with strong to severe thunderstorms
  possible in the afternoon and evening.

- Seasonable temperatures to end the week with precip chances returning
  next weekend.

&&

.DISCUSSION...
Issued at 316 AM CDT Mon Jun 10 2024

Apart from slower winds compared to yesterday, another beautiful day
will be in store for Monday. Sunny skies, light/variable winds, and
highs in the low to mid 70s will provide no excuse to not be outside
for at least some of the day. Clouds will build in from the west
this evening as an incoming shortwave brings our next good chance of
rain tonight into Tuesday. Showers and thunderstorms will develop
over the Dakotas along a cold front and travel east, likely reaching
western MN just after midnight, the MN/WI border by around 7 AM, and
then exiting our WI counties by early Tuesday afternoon. While the
original precip from the Dakotas will be decaying once it reaches
western MN, CAMs do suggest some redevelopment is likely along the
front over south-central MN with the strengthening of the LLJ.
Guidance mostly favors a widespread 0.1-0.2" of QPF from this
activity, with a few localized streaks of up to 0.5" possible. CAMs
also suggest that a 2nd round of isolated to scattered thunderstorms
may form over eastern MN later in the afternoon. This convection
would then travel east into WI by Tuesday evening. If cloud cover in
the wake of the morning precip can break apart enough to allow some
daytime heating, the environment should have 500-1000 J/kg of CAPE
amid 30-40 knots of bulk shear. For this reason, SPC has given
eastern MN/western WI a Marginal risk for damaging winds and large
hail Tuesday afternoon. The main uncertainty being if enough heating
can occur to offset the expected nearly moist adiabatic lapse rates.
A dry, seasonable Tuesday night is expected afterwards.

Wednesday is when the forecast turns even more interesting. A
strong, low-level thermal ridge will advance into the Northern
Plains ahead of a zonal jetstreak along the US/Canadian border.
Highs Wednesday afternoon will be the warmest we`ve seen in awhile.
80s are expected across the area, with southwestern MN making a run
at 90. Meanwhile, guidance forecasts ample low-level moisture being
advected north by the low-level southerly ageostrophic flow in the
exit region of the upper-level jet. Mid to upper 60s dewpoints seem
likely for most of MN by Wednesday afternoon, with guidance
suggesting lower 70s in western MN! With moderately steep lapse
rates in place, 2000-3000 J/kg of MLCAPE should result across the
much of our area. This along with bulk shear values of 40-50 knots
would allow for an environment supportive of strong to severe
thunderstorms. SPC has put nearly the entire MPX CWA in a Slight
risk for Wednesday. Current thinking is that large (to potentially
very large) hail will be the initial concern as supercells form from
western to central MN along the frontal boundary. These storms would
then travel east/southeast growing upscale into a mesoscale
convective system, transitioning the main severe threat to damaging
winds. However, there is one factor casting uncertainty on this
event: Does elevated morning convection develop across the risk area
due to the strong moisture advection? Forecast soundings in
southwest MN do show elevated instability growing during Wednesday
morning with strong convergence occurring at the nose of an LLJ. If
this precip does occur, it will be crucial to see how much it
affects the afternoon environment. Heavy rain will also be likely
with any thunderstorms as PWATs will be 1.5-1.8". While significant
flash flooding doesn`t appear likely due to strong steering winds,
small stream and urban flooding could occur if an area experiences
repeated storms.

The convection should exit to the southeast by Thursday morning,
giving most of the area a break in precip to end the work week.
However, a few showers and storms may develop in southern MN
Thursday afternoon ahead of a trailing cold front. This front will
also finally push southeast of our area by Thursday night.
Seasonable temperatures should follow into next weekend, but
precipitation chances look to return Saturday into Sunday. A short-
lived "ring of fire" setup on the periphery of a thermal ridge is
favored by guidance Saturday, followed by an incoming shortwave
during the Sunday timeframe. Thus, if you have outdoor plans for
next weekend, you may want to already consider bringing an
umbrella.

&&

.AVIATION /18Z TAFS THROUGH 18Z TUESDAY/...
Issued at 1232 PM CDT Mon Jun 10 2024

VFR to start for all TAF sites with generally light/variable
winds. Winds will eventually become SE later this afternoon with
speeds close to 10kts. Winds will continue to steadily veer to S
overnight then to SW during the day Tuesday with speeds
increasing to near 15G20kts. Clouds will increase late this
afternoon, with upper level ceilings developing this evening
that will lower to the mid-levels overnight. Rain will develop
over western MN overnight and press eastward over eastern MN
around or shortly after daybreak then spread into western WI.
Very little in the way of CB/TS expected overnight into tomorrow
thus have kept its mention out of this TAF set. Once the morning
rain ends, additional scattered convection looks to develop
Tuesday afternoon so some isolated/scattered CB/TS is possible
then. At this point, have only gone the "chance" route with MSP.
With the rain tonight into tomorrow, MVFR conditions are likely
during and shortly after until partial afternoon clearing.

KMSP...Light/variable winds will persist into late afternoon,
then winds pick up from the SE this evening through tonight in
the 5-10kts range. Winds then continue veering to SW during the
day tomorrow with speeds nudging up to 10-15kts. Showers move
into the area prior to daybreak, with best timing of rain at MSP
right around sunrise and continuing through late morning. Some
heavier batches of rain look to bring visibility into MVFR range
late morning. After this morning rain diminishes, scattered
SHRA/TSRA will develop in the afternoon, which could impact MSP
later on Tuesday. Uncertainty as to the timing/placement forces
just a PROB30 mention at this point so this will be adjusted in
later TAFs.

/OUTLOOK FOR KMSP/
WED...Mainly VFR. MVFR/-TSRA likely late. Wind SW 10 kts.
THU...Mainly VFR. Slight chance MVFR/-SHRA. Wind NW 5-10 kts.
FRI...VFR. Wind N 5-10 kts.

&&

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

&&

$$

DISCUSSION...CTG
AVIATION...JPC