300
FXUS63 KMPX 042316
AFDMPX

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
616 PM CDT Tue Jun 4 2024

.KEY MESSAGES...

- Strong to severe thunderstorms move east across the area
  through this evening. Small hail, isolated damaging wind gusts,
  & a tornado or two are all possible.

- Widespread rainfall amounts of 0.5-1" are expected with the
  storms tonight. Localized amounts closer to 2" could
  exacerbate ongoing flooding.

- Scattered showers & thunderstorms tomorrow afternoon. Small
  hail & gusty winds are likely with the strongest storms.

&&

.DISCUSSION...
Issued at 235 PM CDT Tue Jun 4 2024

Thunderstorms have developed on schedule across western
Minnesota, & will continue to move eastwards across Minnesota &
into Wisconsin through tonight. Instability continues to build
ahead of the front, with temperatures in the mid 80s & dew
points in the mid to upper 60s generating 1500-2000 J/kg of
MLCAPE. Instability may even increase a bit more towards this
evening as the thunderstorms approach eastern Minnesota &
western Wisconsin. Deep shear remains the limiting factor, with
the strongest forcing aloft & deep shear with this system
remaining behind the cod front. Deep shear values along the
front are only in the 20-30 kt range & oriented unidirectionally
along the front, which has caused any stronger cells to quickly
become disrupted & form a messy line of convection. As a result,
thunderstorms will likely remain sub-severe for the next hour
or two, but we may still see an increase in intensity as they
enter the more unstable environment across eastern Minnesota &
western Wisconsin. The main threat into this evening will
continue to be marginally severe hail & isolated damaging wind
gusts, but fairly high values of low-level CAPE & vorticity mean
a tornado or two can`t be ruled out if any cells are able to
remain semi-discrete. Cell-interactions within the line may
also generate enough local low-level shear & helicity to
generate a QLCS-type tornado or pockets of stronger wind within
the line. Brief heavy rain is likely with the strongest
convection along the line, but its narrow dimensions &
progressive nature should limit rainfall amounts to 0.5-1"
across the area. Locally higher amounts are still expected
wherever isolated cells are able to form ahead of the main
line, & rainfall amounts could approach 2" across these areas.
These locally higher amounts could exacerbate flooding in
sensitive areas from the heavy rain over the weekend, but
otherwise we`re not expected much in the way of flash flooding
from this event.

The thunderstorms will move clear of eastern Minnesota this
evening & western Wisconsin overnight with skies clearing out in
their wake. Very strong northwest flow & colder temperature
aloft move over the region tomorrow. While cooler & drier air
behind the front will limit surface instability, cyclonic flow &
the cooler temperatures aloft will create a classic "cold core"
setup for convection tomorrow afternoon. Widespread diurnally-
driven showers and thunderstorms are expected to develop
tomorrow afternoon, primarily along and north of I-94. While the
instability will be low, deep shear of 30-40 kts will be plenty
sufficient for the small hail and gusty winds with the
strongest storms. A lone funnel cloud or two would not be a
surprise as well. These showers and thunderstorms will wane
after sunset, with 0.1-0.25" of rain expected with any storms.

The northwest flow regime continues through the weekend, with
isolated diurnally-driven showers possible during the
afternoon, but otherwise mainly dry conditions. Models depict a
shortwave moving through the region sometime during the
Saturday-Sunday timeframe which could result in some more
widespread light rain. Temperatures will be cooler as well
through the weekend with high temperatures generally in the
upper 60s to low 70s through Sunday. Looking ahead, broad but
fairly modest ridging aloft builds over the central CONUS,
which will lead to warmer temperatures and generally dry
conditions through the end of next week.

&&

.AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/...
Issued at 611 PM CDT Tue Jun 4 2024

The line of showers and storms is pushing through early in the
period with brief periods of IFR/MVFR due to low visibility due
to rain. -SHRA is expected after the first couple hours as storm
activity diminishes as head towards 05z, at which point all
sites should be mostly dry. Cloud levels will increase behind
the departing showers with mainly high clouds after roughly
05-07z. Winds increase late in the period with gusts from
25-30kts possible around 270 after 18z.

KMSP...The wind shift has occurred at the airport over towards
230-260 with a continued shift towards 300 over the first 6
hours of the period. With only -TSRA for a couple of hours to
begin with and -SHRA afterwards, we are past the point of
needing an AWW for winds as the environment is turned over
already. Expect winds to increase after 16z tomorrow with gusts
approaching 30kts at 270. There could be a few isolated storms
tomorrow afternoon however coverage is not enough to produce
even a prob30 for now.

/OUTLOOK FOR KMSP/
THU...VFR. Wind NW 15-20G30-35kts.
FRI...VFR. Wind NW 10-15G20-25kts.
SAT...VFR. Wind NW 5-10kts.

&&

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

&&

$$

DISCUSSION...ETA
AVIATION...TDH