766
FXUS63 KMPX 291158
AFDMPX

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
658 AM CDT Mon Apr 29 2024

.KEY MESSAGES...

- Slight Risk (level 2 of 5) of severe weather for south central Minnesota
  Tuesday with what will be our next round of widespread
  showers and thunderstorms.

- Pattern to remain active with rain chances every 24 to 48
  hours, with another widespread soaking rain looking likely
  Thursday and more showers possible Saturday and again early
  next week.

&&

.DISCUSSION...
Issued at 356 AM CDT Mon Apr 29 2024

At 3am, the surface low was near Redwood Falls. It will move through
the Twin Cities metro this morning, on its way to the western U.P.
of Michigan this afternoon. With this low is the primary shortwave
aloft and it`s the PV feature with this shortwave that is driving
this last batch of rain and a few thunderstorms moving north across
southern MN overnight. This area of showers will slowly clear out of
central MN through the morning and linger over northwest WI into the
afternoon. For most of us, today will be another cool and cloudy
Spring day with temperatures not moving much today, with highs in
the mid 40s (central MN) to mid 50s (west central WI).

Tonight, we`ll slowly clear the low level clouds out, but mid level
clouds will be increasing as we see WAA develop ahead of the
shortwave coming Tuesday. This continues to look like an impressive
wave, with a strong PV anomaly, a negatively tilt, and highly
diffluent mid/upper level flow. The biggest question when it comes
to our severe weather threat is what will the quality of the
moisture return be ahead of the cold front that will sweep across
our area. Right now, the HREF indicates 500-1000 j/kg of CAPE will
be possible into south central MN. Wind shear will not be an issue,
with a conducive wind field for organized severe weather with curved
and long hodographs in place ahead of the cold front. It`s just a
question of can we get enough instability to create severe
convection with those hodographs. Given the diffluence aloft,
upscale growth into a line of showers and storms is expected,
with the greatest risk for severe weather being south of Mankato
where instability has the greatest likelihood of exceeding 500
j/kg and the SPC has a Slight Risk in the Day 2 severe weather
outlook.

Outside of the severe weather, given the forcing, another widespread
round of showers and storms is expected Tuesday into Tuesday night.
This band of showers and storms will be fairly progressive, so we`re
only looking at rainfall amounts around 0.5", but LPMM QPF from the
HREF does highlight some potential for amounts closer to 1.5" near
the Iowa border where stronger convection is expected.

The next wave in the train shows up on Thursday and this will be yet
another shortwave taking on a negative tilt as it rotates around the
main upper low centered back near the ND/Manitoba/Alberta border.
This wave looks to go a bit farther south than Tuesdays, which puts
us in line for seeing more of the deformation rainfall on the cool
side of the surface low. This could be another shot for a pretty
large footprint of 1"-1.5" of QPF from south central MN into east
central MN and western WI.

Looking beyond, the ECMWF shows addition chances for rain Saturday,
Sunday night into Monday, and Tuesday into Tuesday night of next
week. Although there`s low confidence on how strong any one of these
waves will be, where they will track, or if they will even come to
fruition, what it does show is that this very active pattern is
going nowhere anytime soon.

&&

.AVIATION /12Z TAFS THROUGH 18Z TUESDAY/...
Issued at 648 AM CDT Mon Apr 29 2024

Surface low is starting out this period near New Ulm (KULM) and
will be tracking across the Twin Cities through the morning.
The worst conditions are expected in and near the surface low,
where DZ will at times bump vis down to IFR levels and CIGS
LIFR. It will be a slow improvement to the IFR cigs through the
day, but by the end of the day, most terminals should be MVFR.
Clearing will be slow to occur Monday night, though RAP
soundings do show low clouds starting to clear toward sunrise
Tuesday for MN terminals west of MSP.

KMSP...Occasional vis down to 1sm in DZ will be possible through
the morning as we work the surface low over the field. 9z RAP
forecast soundings show stratus finally clearing MSP between 12z
and 15z Tuesday with the next round of shra/tsra not impacting
MSP until closer to 00z Wed (7pm CST Tue).

/OUTLOOK FOR KMSP/
TUE...VFR. MVFR/TSRA 23-03z. Wind SE 10-15 kts.
WED...VFR. Wind W 5-10 kts.
THU...MVFR/-SHRA likely. Wind E 10-15 kts.

&&

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

&&

$$

DISCUSSION...MPG
AVIATION...MPG