846
FXUS63 KMPX 152342
AFDMPX

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
642 PM CDT Wed May 15 2024

.KEY MESSAGES...

- Brief funnel clouds possible across southwestern Minnesota this
  afternoon.

- A band of showers with a few rumbles of thunder will gradually drift
  from western Minnesota into western Wisconsin this afternoon
  through Thursday morning. Rainfall amounts of 0.25" or less
  expected.

- Dry to end the work week, followed by the chance for scattered
  showers and storms on Saturday.

&&

.DISCUSSION...
Issued at 155 PM CDT Wed May 15 2024

Early afternoon satellite imagery illustrates clouds expanding to
the east across the region, tied to the advance of a surface low
spinning through eastern South Dakota. MPX Radar imagery captured an
initial band of echoes across western Minnesota earlier today, but
surface observations reveal that little if any precipitation was
able to reach the surface given notable dry air throughout the
column. Better support for precipitation will arrive this afternoon,
as a shortwave located within the upper flow advances across the
Upper Midwest. The forcing associated with this wave will be
recognized by way of a cold front, which is forecast to slowly move
across Minnesota and western Wisconsin starting this afternoon and
continuing into tomorrow morning. Regional MRMS picture depicts the
first showers developing along the South Dakota/Minnesota state
border at this hour. CAMs are in fairly solid agreement with the
timing of the narrow band of rain showers, such that our PoP timing
reflects the highest PoPs (80-90%) across western Minnesota this
afternoon, moving across I-35/Twin Cities Metro by late evening, and
eventually wrapping up across western Wisconsin by mid-morning
Thursday. We can`t rule out some thunder, especially across
southwest Minnesota where a few hundred joules of CAPE are present
on forecast soundings. Additionally, we will have to watch for the
potential for funnel clouds/perhaps a quick spin-up with the initial
convection this afternoon, given ample surface vorticity co-located
with an axis of 0-3km CAPE per SPC mesoanalysis. Rainfall amounts of
0.25" or less are expected for most locations, with slight chance
that a few spots observe higher amounts due to convective nature of
the rainfall.

The last of the showers will depart western Wisconsin by midday
tomorrow, which will open the door for a dry end to the work week.
Little change in the airmass will allow for highs to climb into the
low 70s tomorrow afternoon. Our focus will shift back to the
northwest on Friday, as an upper low is forecast to take shape
across southern Canada. Synoptic scale warm advection will increase
across the Upper Midwest ahead of this system, which will warm
temperatures well above normal heading into the weekend. Friday`s
highs are forecast to climb into the to a developing upper low
across southern Canada low to mid 80s for much of the region and
it`s conceivable that locations in western Minnesota make a run
towards 90 degrees. As the upper low transitions east Saturday, a
cold front will swoop across the region. Scattered showers and a few
thunderstorms appear possible with this frontal passage. Forecast
soundings show a capping inversion present across south/west
portions of the area Saturday morning, with less capping (later in
the diurnal curve) across eastern Minnesota and western Wisconsin
during the afternoon and evening. For this reason, the highest PoPs
(40-60%) exist for locations along and east of I-35. Temperatures
will cool back to the 70s following the passage of this storm system.

As mentioned by the midnight shift, the pattern from early next week
onward will be dominated broad southwest flow aloft, such that the
main storm track appears to setup south of Minnesota/Wisconsin. We
have maintained slight chance PoPs for several days next week, as
it is possible that portions of the area (mainly south) may be
"brushed" by the passing disturbances. Global ensembles feature a
northward shift in the general storm track by the end of next week,
which may result in the return of more widespread rain chances
towards the end of the extended forecast.

&&

.AVIATION /00Z TAFS THROUGH 00Z FRIDAY/...
Issued at 634 PM CDT Wed May 15 2024

Cloudy skies to prevail this evening through midday Thursday,
including ceilings dropping to MVFR and potentially IFR with and
behind a swath of showers to slide across MN/WI this evening
into early morning Thursday. Rainfall is becoming weaker this
evening, leaving little chances that visibilities will drop to
less than 6SM, thus have left flight category changes to solely
ceilings. In addition, the precipitation band is running into
drier and more stable air, thus have eliminated CB/TS mention.
Weak showers will drift through, then ceilings will drop to MVFR
range overnight through late Thursday morning before improving
to VFR and scattering out. Winds will shift from SE to SW
through the early morning hours then turn westerly during the
day Thursday. Speeds will run generally around 10kts, though
breezy speeds in western MN at initialization will settle down
later this evening.

KMSP...Kept much of what was inherited from the 15/18z TAF set,
with the main window of rainfall between 03z-08z, and no mention
of CB/TS. Ceilings will drop to MVFR prior to the Thursday
morning push and remain within MVFR throughout Thursday morning,
including some sub-1700ft ceilings. Conditions will then quickly
improve to VFR late Thursday morning.

/OUTLOOK FOR KMSP/
FRI...VFR. Wind SE 10-15kts.
SAT...VFR, chc MVFR/-TSRA. Winds SE becoming W 15-20G30kts.
SUN...VFR. Wind SW 10kts.

&&

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

&&

$$

DISCUSSION...Strus
AVIATION...JPC