475
FXUS63 KMPX 011825
AFDMPX

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
125 PM CDT Mon Jul 1 2024

.KEY MESSAGES...

- Widespread showers and thunderstorms this evening through
  Tuesday. Locally heavy rainfall possible, primarily across
  southern Minnesota & western Wisconsin.

- Thunderstorms and locally heavy rainfall likely for the 4th
  of July.

&&

.DISCUSSION...
Issued at 419 AM CDT Mon Jul 1 2024

The main forecast challenge today will be how early showers and
thunderstorms develop across the area with a wide spread in
timing still present among both high-resolution & synoptic-scale
models. Everything is in agreement with the most widespread
thunderstorms & heaviest rains occurring tonight & overnight,
with the uncertainty being how much precipitation develops this
afternoon on the nose of the strengthening low-level jet.
Strong southerly flow ramps up Monday morning & advects Gulf
moisture into the region, with precipitable water values
potentially exceeding 2" by late Monday night. This morning,
most guidance initiates a narrow band of sowers & thunderstorms
along a weak upper-level boundary across the eastern Dakotas.
Some solutions keep this convection going into western &
central Minnesota through late morning & into the afternoon.
More likely, however, is that this convection decays as it heads
east, with perhaps some light precip across far-western
Minnesota early this afternoon. More widespread showers &
thunderstorms will hold off until this evening when WAA from the
low-level jet is strongest & better forcing aloft arrives from
an approaching jetstreak. Precipitation will overspread the area
fro west to east through the night, with the most widespread
thunderstorm coverage & best chance for locally heavy rainfall
looking most likely from south-central Minnesota through
western Wisconsin. In general, rainfall amounts up to 0.5" are
expected across western & central Minnesota, with amounts in
excess of 1-2" more likely across eastern Minnesota & western
Wisconsin through Tuesday morning. Hi-res models do indicate
some swaths of 3-4" where the heaviest thunderstorms from
south-central Minnesota through western Wisconsin, so locally
higher amounts are likely and could lead to some flash flooding
concerns. Isolated hail and strong wind gusts can`t be ruled out
with the strongest storms tonight, but the severe chances look
higher across the Dakotas where the shear & instability are
higher.

A lull in the precipitation appears likely Tuesday morning with
a second wave of showers and thunderstorms expected during eh
afternoon & evening along the surface frontal boundary. Trends
over the last 24 hours have progressed this front through the
area quicker, with the best chances for thunderstorms shifting
southeastwards into southeast MN/northeast IA/southwest WI. Some
showers and thunderstorms still look likely from south-central
Minnesota through west-central Wisconsin, but the heaviest rain
and strongest thunderstorms does appear to stay south and east
of our area Tuesday. Rainfall amounts only look to be on the
order of a few tenths across our area, but will be over an inch
wherever the main band of thunderstorms develops.

Drier conditions develop midweek as the flow aloft weakens &
becomes more zonal, but another round of showers &
thunderstorms looks likely for the 4th of July & into Friday as
a broad shortwave trough develops & moves over the Upper
Midwest. It looks very likely that most of the are will see rain
Thursday, with some uncertainty still present with how much
rain & where the heaviest rain will occur. Ensemble guidance
continues to show high probabilities for rainfall amounts >1".
Our highest PoPs from the NBM ensemble continue to be centered
on the evening of the 4th, with some indications that at least
morning events could stay dry. A chance for showers and
thunderstorms continues over the weekend, but with not nearly as
strong a signal for heavy rain or strong thunderstorms.

&&

.AVIATION /18Z TAFS THROUGH 18Z TUESDAY/...
Issued at 123 PM CDT Mon Jul 1 2024

VFR with MVFR/IFR SHRA/TSRA likely late this evening into
tonight through tomorrow morning. Scattered to broken ceilings
are beginning to make their way into western MN this afternoon
out ahead of our next system that will provide SHRA/TSRA across
all terminals tonight from west to east. Breezy SSE`ly winds
will range between 20- 30kts this afternoon before weakening
some to 15-25kts overnight. IFR stratus is likely along with
trailing scattered -SHRA in wake of the passing system. Winds
will shift to SW and not as strong between 10- 15kts tomorrow
morning although cigs reluctant to budge out of IFR categories
for the remainder of the TAF period.

KMSP...VFR to start then transitioning to MVFR to IFR categories overnight as
-SHRA/TSRA arrive. Current hi-res guidance looks to have SHRA
 encroach on MSP as early as 2z with storms likely between 4 to
 8z. Scattered SHRA is possible in wake of the system passing
 until about 12z. Low MVFR/IFR cigs will remain in place through
 the rest of the period. SSE`ly winds remaining breezy this
 afternoon with gusts nearing 30kts but should begin to decrease
 after sunset to near 20kts. Winds shift and decrease between
 10-15kts out of the SW late tomorrow morning. A slight chance
 for -TSRA was hinted in the guidance late afternoon hence the
 PROB30 from 22/24z.

/OUTLOOK FOR KMSP/
WED...VFR.Wind WSW M10-15G20 kts.
THU...VFR. PM MVFR SHRA/TSRA.Wind SE 5-10 kts
FRI...MVFR SHRA/TSRA lkly. Wind NE 5-10 G15-20

&&

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

&&

$$

DISCUSSION...ETA
AVIATION...Dunleavy