Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 280436
AFDMPX

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
1136 PM CDT Fri May 27 2022

.DISCUSSION...(This evening through Friday)
Issued at 320 PM CDT Fri May 27 2022

KEY MESSAGES:

- Multiple rounds of thunderstorms expected tonight through Tuesday.
  Occasional severe weather is likely with any thunderstorm activity
  Saturday night through Monday night. The highest severe weather
  risks are Sunday and Monday.

- Very warm and humid this holiday weekend, then turning cooler
  again later next week.

Today through Saturday night...

We have nearly perfect weather across the area today, but that will
begin to change tonight as the shortwave currently over Montana heads
into MN by Saturday morning. This shortwave will bring with it a
warm front in the h85-h7 on the leading edge of a very warm EML that
will be with us this weekend. Best forcing, in terms of vorticity
advection ahead of the shortwave, is forecast by most models to be
directed toward northern MN, but the strongest h85 winds and highest
elevated instability will be down here. Showers and storms tonight
into Saturday morning for northern MN are looking most likely given
the track of the shortwave, with the main question being how far
south does activity build along that elevated frontal boundary. The
ECMWF continues to show a complex of showers and thunderstorms
working across the MPX area late tonight through Saturday morning and
you see some flavor of this with the NAMnest, NSSLwrf, and HRRR.
Favored our PoP forecast this direction, with likely PoPs to start
the day on Saturday along I-35 corridor that push across WI through
the morning. This activity will be elevated and the higher
instability doesn`t really show up until Saturday night, so the
severe threat looks pretty low, but some thunderstorms could
certainly impact any morning plans you have for Saturday.

Behind this wave of precip comes the EML and strong capping.
Saturday looks dry and with a thermal ridge poking up into southwest
MN, we`ll see temperatures really respond behind the morning
clouds/convection, with a 90 or two possible down toward Fairmont
and Redwood Falls, with 80s pretty common everywhere else. Trend for
precip chances Saturday night came down some with this update, but
the most likely scenario for storms Saturday night is that we`ll see
storms develop over north central Neb Saturday evening, with that
activity working northeast toward northwest MN through the night,
leaving western MN with the best chance at seeing storms late
Saturday night. Given the questions about how much this activity
will hold together through the night, the Marginal Risk on the Day
2 SPC convective outlook covers our conditional severe threat well
at this time.

Sunday and Monday...

Low pressure over the western United States will deepen over the
Colorado Rockies and become stalled Sunday. This delay in forward
progression will open the door for warmer temperatures and dewpoints
to advect into our region. Thus, increasing our likelihood of
observing precipitation for portions of the Memorial Day Holiday
weekend. The SPC currently has our area under an enhanced risk for
western MN counties while the rest of our region is under a slight
risk for Sunday. Currently, guidance is suggesting that the
aforementioned precipitation on Saturday will contain an EML. Below
the EML, a strong capping inversion will develop during this period
and will require a modest amount of forcing before we see any kind of
convection. If any type of lifting mechanism can erode into that
cap, a volatile airmass (3000-4500 J/Kg MLCAPE) and strong veering
winds would become available for development. If storms initiate, the
primary threats would support supercells capable of producing large
hail, damaging wind gusts, and a few tornadoes. The timing for the
heaviest rainfall is expected to be Sunday night into Monday morning
for the first wave of storms. A second wave of storms is anticipated
Monday night into Tuesday. Like the first wave of storms, a similar
capping inversion scenario is possible. The inversion is anticipated
for Monday`s daytime hours, however later on the proximity of the
front advancing through the Dakota`s, coupled with the warm moist
airmass would elevate the storm intensity for our region. The SPC
currently has Monday under a 15% Day 4 convective outlook risk.
Temperatures will be well above average this period. Highs in the mid
80`s Sunday and upper 80`s to lower 90`s Monday.

Tuesday though Saturday...

The low pressure system will be making its exit from our region
northward Tuesday. Given its track, windy conditions are anticipated
provided by the wrap-around segment of the departing system. Surface
temperatures along with dewpoints are expected to return to more
seasonable and comfortable levels. Even cooler than normal Wednesday
and Thursday with highs in the upper 60`s then return to normal
temperatures by the weekend. Lows through this period will be in the
low 50`s. The only notable precipitation during this time is a weak
shortwave possibly developing to our north Thursday night which
could support some showers but keeping PoPs low in the interim due
to confidence on coverage and intensity.

&&

.AVIATION...(For the 06Z TAFS through 06Z Saturday night)
Issued at 1133 PM CDT Fri May 27 2022

A band of showers and thunderstorms will enter western Minnesota by
the start of the period, and move eastwards through the overnight
hours and into the morning. CAMs have shown an upward trend in the
threat for thunder over the last few hours. Still believe the threat
will be sporadic and short-lived enough to warrant a TEMPO mention,
but amendments may be needed if this trend continues. The
precipitation is expected to weaken towards sunrise as the rain
moves through eastern Minnesota and western Wisconsin, so did not
include a thunder mention at RNH and EAU. Dry conditions are
expected the rest of the period after the precipitation moves
through, with sct/bkn stratocumulus expected. Winds will start out
light and variable but gradually become southeasterly by morning.
Wind speeds increase to 10-15 kts by morning with gusts of 20-25 kts
likely during the day. Winds drop below 10 kts during the afternoon,
and become easterly tomorrow evening.

KMSP

At least scattered showers still look likely between 4-8 AM, with
the best chance for rain expected between 4-6 AM. Thunder looks most
likely between 4-6 AM as well, with MVFR conditions likely at times.

/OUTLOOK FOR KMSP/

Sun...Chance MVFR/TSRA. Wind S 10-15G25 kts.
Mon...Chance MVFR/TSRA. Wind S 10-15G25 kts.
Tue...Chance MVFR/-SHRA. Wind SSW 5-10kts becoming W 5-10g20kts

&&

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

$$

DISCUSSION...MPG/WFO MPX
AVIATION...ETA/JLT


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