141
FXUS63 KMPX 141923
AFDMPX

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
223 PM CDT Wed May 14 2025

.KEY MESSAGES...

- Slight (Level 2 of 5) Risk for severe weather tonight into
  tomorrow morning across Southwest Minnesota with large hail
  and damaging winds as the main threats.

- Enhanced (Level 3 of 5) Risk for severe weather from eastern
  Minnesota across most of Wisconsin tomorrow afternoon into
  evening with all threats possible: large hail, damaging
  winds, and a few tornadoes.

- Behind this period of more active weather we will enter into a
  cooler, below normal temperatures, and wetter period.

&&

.DISCUSSION...
Issued at 223 PM CDT Wed May 14 2025

Rest of today into tomorrow morning... Afternoon satellite
imagery shows widespread fair weather cumulus with a few
isolated thunderstorms in western Wisconsin. Based on 0 hour CAM
soundings there is instability present across the broader
region. The vertical moisture profiles are in three main areas
western Minnesota, eastern Minnesota, and western Wisconsin.
Western Minnesota is the driest profile with little chance for
anything outside of the current cumulus development. Western
Wisconsin has the highest dew points and greatest moisture
present which has allowed the development of thunderstorms.
Eastern Minnesota is in between these in moisture and therefore
has a chance for an isolated thunderstorm or two. These
isolated storm chances continue until the evening when the
surface starts to cool. At that point attention turns to the
west as a potential MCS could be moving into western Minnesota.
This is what the SPC Slight Risk was issued for. Along and ahead of
a frontal boundary across the Dakotas into Nebraska storms will
form this evening. Upscale growth is expected as they head to
the east. By the time they reach Minnesota it may even develop
into a full MCS. There are still two main camps in the CAMs: a
north route and a south route. The northerly route takes it into
central Minnesota and is based more on the overall atmospheric
flow. The southerly options remains near the Iowa border and is
rooted more along the CAPE gradient. Regardless of the path
CAMs are maintaining it as thunderstorms across Minnesota. What
is less certain is how severe it could be. Instability looks to
be strong for the morning, but not high. Shear looks sufficient
as well, so these storms could maintain themselves well.

Tomorrow evening and night... As we approach late morning into
early afternoon the next round of storm chances will start, so
there will be little or no break between these rounds across
Minnesota. There will be a break at specific locations, so there
should be time for some atmospheric recovery. Moisture will
continue to advect into the Upper Midwest in advance of the
frontal passage behind this next round of storms. Also as this
will be ahead of the frontal passage this will still be in the
warm sector. So plenty of frontogenesis in this setup for lift
with warm, moist air over us and cooler air moving in. That
combined with a stacked low throughout the troposphere means
there will be no shortage of lift. The warm and moist air at the
surface and low levels of the atmosphere combined with cooler
air aloft will provide ample instability. Forecast hodographs
and the associated shear are the big differentiators between the
different SPC Risk categories for tomorrow. Father east in the
Enhanced, there is much more impressive low level shear and
therefore a higher tornado threat than to the west over the
Slight and Marginal risk areas. Overall with the available
moisture, strong forcing, and low level shear this event seems
primed for a severe threat. We always have to ask though what
could make this not happen? For this event I`d say the first
round in the morning is a complicating factor. If that round is
stronger or more widespread than expected that could deplete
some of CAPE for later and limit the later environment. This is
a concern anytime you have two rounds so close together. For
this reason the best chances will be in western Wisconsin and
nearby parts of eastern Minnesota, as they are less likely to
see impacts from the first round of storms. As for severe risks
all are possible. Steep lapse rates, ample instability, strong
low level shear, and moisture rich flow means that supercells
are possible. Supercells would favor all modes of severe: wind,
hail, and tornado. However with a linear forcing mechanism
these storms could grow upscale making wind more of a favored
threat. SPC in their 1230 PM discussion today commented on this
storm mode concern mentioning that the orthogonal low level flow
flow with respect to surface boundaries favors discrete
supercells for mode. However they did also note trend towards
bowing and upscale growth that could shift to more of a wind
threat. In summary all severe modes are possible tomorrow, with
higher chances in east central Minnesota into western Wisconsin.

Friday into next week... The low behind all of the severe action
will be overhead on Friday. This brings with it more rain
chances and cooler temperatures with highs in the mid 50s to mid
60s. Saturday could see some remaining wrap around showers, but
overall lower rain chances. Cooler as well on Saturday with the
cooler flow behind the low putting highs in the mid to upper
50s for most, outside of some lower 60s possible in parts of
southern Minnesota. Sunday will be the one day largely dominated
by high pressure and see some sun. This will allow for some
warming in temperatures up into the 60s. Another deep low is
forecast for early to mid next week. There remains significant
spread not just in the ensembles, but the global deterministic
models about the timing and track of the low. What is consistent
is a low tracking across the Midwest and providing a chance for
substantial rainfall. After our recent hot and dry stretch,
this would be much appreciated rain to help make our fuels less
vulnerable for fire weather on hot and dry days later this
spring into the summer.

&&

.AVIATION /18Z TAFS THROUGH 18Z THURSDAY/...
Issued at 1239 PM CDT Wed May 14 2025

VFR conditions expected throughout most of this TAF set, with
scattered thunderstorms moving in near the end. A large cumulus
field is likely across all of central-southern MN into western
WI. Some scattered SHRA/TSRA are likely in western WI late
afternoon, as current radar reflects. This convection should
stay far enough east and not impact any terminals other than RNH
and EAU. Precipitation mention has been added to all terminals,
with a complex advancing east from the Dakotas overnight.
Thunder is possible with any rain, but tried to narrow down
those timeframes slightly in the TAFs. Winds will remain
generally SE, with speeds increasing on Thursday.

KMSP...Non-zero chance for a few showers this afternoon
remains, higher likelihood for precip reaching MSP arrives
Thursday morning around 9AM. Scattered thunderstorms are
possible all day, but for TAF purposes, limited thunder threat
to 9am-12pm and 2-5pm.

/OUTLOOK FOR KMSP/
FRI...MVFR/-SHRA likely. Wind WSW 20-25G30-35 kts.
SAT...MVFR mrng cigs likely. Wind NW 10-15G20-25 kts.
SUN...VFR. Wind N 10 kts.

&&

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

&&

$$

DISCUSSION...NDC
AVIATION...PV