284
FXUS63 KMPX 301736
AFDMPX

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
1236 PM CDT Thu May 30 2024

.KEY MESSAGES...

- Today and Tonight...Rain and thunderstorms will move into
  western Minnesota later today and slowly push eastward into
  Friday morning. The risk for damaging wind, hail, and heavy
  rain is low, but non- zero.

- Friday...A narrow area of thunderstorms with heavy rain is
  possible Friday afternoon/evening, mainly along and east of
  I-35.

- Next Week...Two stronger systems will bring widespread
  thunderstorm chances on 1) Sunday evening/night, and 2)
  Tuesday/Night. These are several days away, but will need to
  be monitored for severe weather and heavy rain potential.

&&

.DISCUSSION...
Issued at 246 AM CDT Thu May 30 2024

Today and Tonight...Early morning satellite and radar showed an
area of showers and thunderstorms across the Dakotas slowly
moving east. A few high clouds were spreading out ahead of
these, and this will lead to filtered sunshine today. Areas in
western Minnesota will see some scattered showers and
thunderstorms develop later today as warm air advection moves
across the region. A more widespread area of precipitation will
arrive when the aforementioned convection in the Dakotas makes
its way east this evening and overnight. This will be a slow-
moving system, and most locations should see some rainfall. For
that reason, did increase the hourly precip chances above the
blended guidance where confidence was highest in rain. The
timing may be off a bit, as alluded too in the previous
discussion, but wanted to advertise the higher likelihood of
seeing some rain as this system slowly passes across the region
later today and into Friday morning. There are marginal risks
for both wind/hail across southwest MN, and also excessive rain
across central and western MN. However the lack of instability,
together with the steady eastward advancement of the storms,
should limit concerns for severe weather or flooding.

On Friday...this boundary will eventually stall out across the
region, and then slowly shift northward a couple counties as a
warm front. This stall, and then change in direction could lead
to heavy rain threat from training thunderstorms over a narrow
area. WPC has issued a marginal risk of heavy rain across
central/eastern MN and western WI. Although the risk outlooks
are the same, the synoptic set up is more favorable for heavy
rain on Friday afternoon/evening as compared to today/tonight.
While confidence is higher in the heavy rain potential tomorrow,
there is more uncertainty on where the storms will track. Some
of the guidance has the boundary hanging up across the Twin
Cities, while others have it making it down to near I-90. Given
the lack of heavy convection with a cold pool from tonight`s
storms, the northern solution seems more likely, but can`t rule
out the southern solution (as shown in the 06Z HRRR) either.

On Saturday, most locations should be dry. But, there could be a
boundary in place, and weak warm air advection will linger
across the region. While your location likely won`t see any
rain, there is a small chance (20 to 30%) that it could catch a
stray shower or thunderstorm, so did increase pops above the
blended guidance to at least represent this potential.

Sunday through Thursday...Confidence continues to increase in
the chance for storms late Sunday into Sunday night, and also
again Tuesday into Tuesday night. On Sunday, the thermodynamic
set up is about the best we`ve had all year, with mid level
lapse rates forecast to be near 8C/km, and surface temps in the
low 80s with dewpoints in the lower 60s. MUCAPE values near 2000
J/kg are possible, with a favorable shear profile of southerly
925 winds of 20 to 30 kts, and due westerly winds above 500 mb.
While the shortwave trough does have a lower amplitude, it will
be moving pretty quickly, and becoming more amplified. If things
come together just right, that could lead to organized
convection with severe weather potential late Sunday and Sunday
night.

A second system, will follow quickly for Tuesday. There is more
uncertainty in the timing and placement of this upper level
shortwave. The deep layer shear profile does appear favorable
for severe weather, but the CAPE potential is still variable. At
the very least, both these systems will be monitored over the
next few days.

&&

.AVIATION /18Z TAFS THROUGH 18Z FRIDAY/...
Issued at 1225 PM CDT Thu May 30 2024

A difficult TAF period ahead with increasing clouds and shower
chances increasing after 00z as they spread eastwards overnight.
AXN/RWF are already seeing -SHRA/-TSRA approaching the sites by
20-21z, with increasing chances by 00z. As we get past 02-03z,
-TSRA should transition to mostly -SHRA as the line pushes
 towards the rest of the sites. Winds initially at 150-180 at
 10-15kts gust up to 25kts through this afternoon before
 decreasing as the -SHRA arrives. Chances for -TS once again
 pick up towards the end of the period roughly 18-21z tomorrow.

KMSP...The main consideration within the TAF is whether or not
to include TS mention overnight, which has been omitted in favor
of -SHRA for now. There is still a roughly 10-20 percent chance
for lightning from 06z to 13z which is the primary time frame
for -SHRA, however the confidence is still fairly low as the
environment remains unfavorable until tomorrow afternoon.

/OUTLOOK FOR KMSP/
SAT...VFR/MVFR, chc -TSRA. Wind SW 10-15kts.
SUN...VFR, likely MVFR/-TSRA late. Wind S 10-15kts.
MON...MVFR/-TSRA early, then VFR. Wind W to NW 10kts.

&&

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

&&

$$

DISCUSSION...JRB
AVIATION...TDH