National Weather Service Twin Cities Area Forecast Discussion

Data Provided by the National Weather Service

000
FXUS63 KMPX 010129
AFDMPX

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
829 PM CDT Wed May 31 2023

.UPDATE...
Issued at 745 PM CDT Wed May 31 2023

Updated to include 00z aviation discussion below.

&&

.DISCUSSION...(This evening through Wednesday)
Issued at 321 PM CDT Wed May 31 2023

KEY MESSAGES:

- Near record highs Thursday through Saturday.

- Scattered storms this afternoon through Friday, with coverage of
  storms gradually decreasing daily this weekend.

- Above normal temperatures and generally drier conditions expected
  to persist into next week.

Today has been another very warm day across the Upper Mississippi
River Vally. Most locations have warmed into the upper 80s with
several spots in the low 90s. We`ll see this weather pattern persist
through the next week or so as an upper high centered over the
eastern Great Lakes slowly retrogrades west across the upper MS
Valley over the weekend. Like a broken record, we continue to
utilize the NBM 50th percentile for forecast highs as the
deterministic NBM bias correction keeps temperatures at or below the
25th percentile. This results in near records highs for the first
through the third of June with records in the low 90s. Otherwise,
June 1st marks the first day of Meteorological Summer and it`ll feel
very much like Summer over the next week!

With little to large scale forcing present over the next several
days. Any precipitation will be driven by diurnal heating and any
potential remnant MCVs. Best chances for storms today look to be
from western MN to central to northeast MN. Western to central MN
has seen instability build into the 2000 to 2500 j/kg range while
the influence of a weak MCV left over from Neb/SD convection Tuesday
evening has spawned a line of strong to severe thunderstorms along
the MN/SD border. This line should continue to the pulse up and down
over the next few hours before weakening after sunset. For Thursday,
afternoon highs in the upper 80s to low 90s, with dewpoints in the
lower 60s will promote the development of scattered thunderstorms
area wide with broad brushed 40s/50s PoPs for Thursday afternoon.
Friday, the NBM has likely PoPs for almost our entire area which
remains overdone. In collaboration with neighboring WFOs we`ve used
a CONSALL blend to lower PoPs in the slgt/chc categories vs likelies
that the NBM populated with. Still, Friday should have the best
coverage of storms over the week as this is when our PWATs are
forecast to peak at around 1.5". For the weekend into next week, our
low level flow will become more easterly, then northeasterly. This
will usher in a drier air mass that should lead to a decrease in
afternoon convection. The primary thunderstorm hazard through the
weekend will be from localized heavy downpours. Most of us will not
see meaningful rainfall, but a few winners could see locally heavy
amounts over 2". The severe threat looks low as very high freezing
levels will limit the hail potential, while the lack of shear will
limit storm organization. So typical garden variety convection will
reign supreme with "the storm of the day" flirting with severe
status. Next week, ridging shifts to the east and sets the Upper
Midwest in a more northerly or northwesterly flow regime that will
lead to the lack of any organized systems and cooler temperatures.

&&

.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 745 PM CDT Wed May 31 2023

Very few changes made to the inherited 18z TAFs for this current 00z
duration. Still may have some CB/TS impact western MN TAF sites into
the early evening hours but as the north-south oriented outflow
boundary (which shows up nicely on MPX radar) continues to outrace
the ongoing convection, loss of diurnal heating and loss of forcing
will allow convection to gradually cease through the evening hours. A
few straggling showers are possible into the early morning hours but
a mainly dry overnight through Thursday morning is expected. The main
impact from the progressing outflow boundary is a short-lived wind
shift to westerly before a more prevailing SE direction resumes.
Additional convection is possible late Thursday afternoon but
confidence is overall too low to include mention at this point.

KMSP...CB/TS not expected to reach MSP this evening but have
maintained its mention for Thu afternoon as chances are a bit better
per multiple short-term models.

/OUTLOOK FOR KMSP/
FRI...VFR. Chc aftn/eve TSRA. Wind SE 10-15kts.
SAT...VFR. Chc aftn/eve TSRA. Wind SE 5-10kts.
SUN...VFR. Chc aftn/eve TSRA. Wind SE 5-10kts.

&&

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

$$

UPDATE...JPC
DISCUSSION...BPH
AVIATION...JPC

NWS MPX Office Area Forecast Discussion