550
FXUS63 KMPX 272336
AFDMPX

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
636 PM CDT Sat Apr 27 2024

.KEY MESSAGES...

- A cool & rainy day is on tap for Sunday.

- Another round of showers & thunderstorms likely on Tuesday, with a
  few stronger storms possible across S MN.

- Rest of next week looks dry with seasonable temperatures.

&&

.DISCUSSION...
Issued at 248 PM CDT Sat Apr 27 2024

Satellite imagery highlights a potent mid-level trough over the
western CONUS with a more vigorous shortwave evident over the Four
Corners region. Our sfc low is moving over Lake Superior leaving
the Upper Mississippi valley in the wake with northwest or
westerly winds and seasonable temperatures. Speaking of
temperatures, Looking back toward the southern Plains, another
developing sfc low is ejecting out of the Four Corners and will
trek into the Plains later today. Current obs reveal
temperatures in the mid to upper 50s with 10-15mph W/NW winds.
Dry conditions last into the overnight period ahead of the next
system that`ll bring another round of rain & wind on Sunday.

For Sunday, We`ve seen things continue to slow down vs previous
guidance runs. PoPs really ramp up after 12z Sunday morning so
tonight should remain dry for most of us. Our sfc low looks to
remain to our south on Sunday and this will keep us on the
cooler side. High temperatures will be rather brisk, struggling
to hit 50 outside of the I-90 corridor, with a steady rain
expected as well. As for the severe risk, SPC day 2 places I-90
and S MN into the Marginal risk category but guidance doesn`t
seem all to excited with storms in S MN. The better environment
stays off to our south and east in Iowa & Wisconsin as the warm
front really doesn`t clear our counties. An isolated storm or
two will be possible in S MN, particularly late afternoon into
Sunday evening, with a non-zero chance of becoming strong or
severe.

Looking at the week ahead, we`ll dry out and remain cooler to
start the week with high temps in the low to mid 50s on
Monday. The cooldown doesn`t last long as a warm front moves
through Monday night into Tuesday, with temperatures forecast
into the low to mid 70s Tuesday afternoon. Along with the warmer
temperatures comes another, arguably better set up for
thunderstorms Tuesday afternoon. Guidance tracks a healthy
shortwave through the Dakotas on Tuesday. NBM ramps up the PoPs
Tuesday afternoon. This system tracks the cold front through
southern & central MN Tuesday afternoon & evening. This lines up
nicely with diurnal heating maxima and should mean we`re
dealing with convection vs stratiform rain. There will be a
severe risk with a low CAPE/higher shear set up looking to play
out. Forecast soundings highlight a few 100 J/Kg of surface-
based instability and 35+ kts of effective shear & curved
hodographs. Our limiting factor will be the lack of sufficient
lapse rates and that should keep the severe threat to an
isolated strong storm or two vs many. Still, this looks to be an
environment that could support a few marginally severe storms.

Afterward Tuesday, we`ll return to cooler seasonable
temperatures (50s/60s) and a break from precipitation until
next weekend. So why does the forecast have a slight chance for
showers Thursday and Friday if guidance is mostly dry? The NBM`s
make up contains a lot of ensemble members that likely feature
timing differences or features that likely won`t impact us. This
time of year going forward 30 to 40 PoPs are pretty standard
despite no driving system in the deterministic models. So, the
NBM is actually favoring drier conditions which DOES line up
with the bulk of the ensemble guidance. In reality, seasonable
temperatures and a stretch of dry weather will wrap up the week
before next weekend. Guidance is beginning to hint at another
low pressure tracking into the Upper Midwest that would give us
yet another damp/cool weekend.

&&

.AVIATION /00Z TAFS THROUGH 00Z SUNDAY/...
Issued at 611 PM CDT Sat Apr 27 2024

Generally MVFR ceilings to start (with a few sites just 1-2
hundred feet above that level but are expected to drop below not
long after initialization), with IFR ceilings expected during
the day tomorrow as rain moves in from the south and will
overspread all TAF sites. Too much uncertainty to place CB/TS at
any given site, so while the chance is non-zero, trying to
pinpoint any convection is too problematic to include in this
set of TAFs. Northerly winds around 10kts to start will become
NE and increase to around 15G25kts shortly after daybreak
Sunday, potentially to near 20G30kts. Winds will continue to
veer to E by Sunday evening.

KMSP...Kept the dropping-ceiling trend the same from the
previous TAF set, and held off precipitation mention until after
daybreak Sunday. Still no mention of CB/TS as uncertainty is too
high, but will continue to evaluate for later mention. Main
issue may be strong NE winds which could cause crosswind
complications for the parallel runways.

/OUTLOOK FOR KMSP/
MON...MVFR/-SHRA early, then VFR. Wind WSW 15-20G30 kts.
TUE...VFR in the morning, MVFR/-TSRA likely in the
afternoon/evening. Wind SW bcmg NW 10-15 kts.
WED...VFR, chc MVFR/-SHRA. Wind light/variable.

&&

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

&&

$$

DISCUSSION...BPH
AVIATION...JPC