686
FXUS63 KMPX 041727
AFDMPX

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
1227 PM CDT Tue Jun 4 2024

.KEY MESSAGES...

- Today...A line of thunderstorms will move through the area
  this afternoon & evening. Damaging winds and large hail are
  the primary threats, with a tornado or two are possible across
  mainly central/eastern Minnesota & western Wisconsin.
  Widespread rainfall amounts of 0.5-1" could exacerbate ongoing
  flooding, especially where locally higher amounts occur.

- Rest of the week...Breezy northwest wind gusts 25 to 35 mph
  Wednesday, Thursday, and Friday along with drier conditions.

- Looking ahead, the drier trend continues into next week.

&&

.DISCUSSION...
Issued at 320 AM CDT Tue Jun 4 2024

TODAY...No major changes from the previous forecast. Confidence
remains high that storms will develop late morning or early
afternoon across west central Minnesota, and move eastward
across the region. This should be a solid area of showers and
thunderstorms, so pretty much everyone will see rain. Amounts
will range from less than a half inch across western Minnesota,
to likely near an inch across eastern MN and western WI. The 00Z
HREF local probability matched mean showers a few pockets of
around 2 inches, which seems reasonable if multiple storms track
across the same area. Overall, the heavy rain threat with this
system is less than the previous system given the progressive
nature of the line.

The severe weather risk remains nearly unchanged across the
region. There is a noteworthy elevated mixed layer above a weak
capping inversion, and that should hold off convection until
the stronger forcing arrive, allowing surface instability to
build with MLCAPE values near 2000 J/kg by the afternoon. As
mentioned in the previous discussion, the wind profile can be
characterized as linear and mostly parallel to the north/south
line of storms. For that reason, expect storms to form a line,
with the main severe threat tied to storms shortly after
initiation, or any storms that manage to develop ahead of the
line. 0-3km shear profiles could be sufficient for developing
QLCS mesovortices if any segment of the line manages to get an
west-to-east surge or bow.

WEDNESDAY THROUGH TUESDAY...Overall drier conditions are
expected from Wednesday into next week. Northwest flow will
bring cooler and drier air across the region. In this cold air
advection regime, expect clear skies in the morning, with
afternoon cumulus building and potential for scattered showers
and thunderstorms during the afternoon and evening. Any
shortwave trough embedded in the northwest flow that rotates
across the region will aid in the shower/thunderstorm
development. However, these will not produce heavy rain, but
could manage to drop some small hail and gusty winds. Speaking
of winds, forecast soundings show deep mixing during the day, so
expect wind gusts of 25 to 35 mph for Wednesday through Friday
during the late morning into the early evening. These winds will
drop off after sunset, but should remain fairly steady
overnight. Temperatures will be just on the cool side for early
June, with highs in the 70s and lows in the 50s. No significant
rainfall is expected into next week as the persistent northwest
flow keeps the summer moisture well to the south.

&&

.AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/...
Issued at 1218 PM CDT Tue Jun 4 2024

Compared to the 12z TAF, the 18z is very similar with slight
differences in timing of incoming showers and storms being the
main highlight. CAM guidance has generally slowed the onset of
stronger thunders 30 to 60 minutes later than the previous
forecast, thus many FM groups have been pushed back slightly.
Otherwise we remain on track to see a period of SHRA into TSRA
beginning 20-21z at AXN and spreading eastwards through the rest
of the sites by 00z, with activity ending by 03-04z. As the
showers and storms move through, expect a quick wind switch from
the current 150-180 over to 300-330 before a slower shift closer
to 240-270 by period`s end. Speeds decrease behind the front
generally below 10kts, before showers and storms arrive expect
some gusts up to 20-25kts.

KMSP...The timing of TSRA is the main concern, with an
approximate start time from 2230-2300z with a 2-3 hour window
it weakens into lingering SHRA. The 21z AMD will continue to
refine the timing as we should have a solid idea of the start
time of the event.

/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...JRB
AVIATION...TDH