589
FXUS63 KMPX 170458
AFDMPX

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
1158 PM CDT Mon Sep 16 2024

.KEY MESSAGES...

- Highs in the 80s continue through Thursday.

- A more active pattern is expected for the second half of next
  week into next weekend with the best chance for rain right
  now is Wednesday night through Thursday evening with lots of
  spread continuing on when a weekend round arrives.

- Heavy rain is currently the greatest potential hazard, though
  a severe potential is slowly starting to emerge for the two
  active periods as well. &&

.DISCUSSION...
Issued at 318 PM CDT Mon Sep 16 2024

It`s another day of summer thanks to the blocking high that remains
entrenched over the Great Lakes. MSP has been knocking on the door
of 90 this afternoon. We have 150 years in our record book for
September 16th, and we`ve only gone into the 90s 5 times, so
although this heat is not unprecedented, it is pretty uncommon. Like
yesterday, mlCAPE is over 1000 j/kg and we have a cu field out there
as a result, but we lack the forcing (like they`re seeing up near
the Canadian border) to get thunderstorms going. We look to be stuck
in this pattern through Wednesday where we look to remain dry, but
we`ll be in this southerly, warm advective flow where you can`t rule
out seeing some isolated showers during the afternoons with peak
heating and again during the late night/early morning hours with LLJ
activity. There`s little agreement in the models on when/where any
of this activity may develop through Wednesday, so we stuck with the
NBM through Wednesday, which is a mainly dry forecast for the MPX
area, though we may be playing a bit of whack-a-mole if activity
tries to develop.

Wednesday night through Thursday night. This is what looks to be our
first period of active weather during the next 7 days. Models have
shifted a bit with this system, as what had been looking like
Thursday night for being our most likely period for rain is now more
up at the Wednesday night/Thursday time frame. What hasn`t changed
is that we`ll have a cold front coming at us Thursday that will be
becoming increasingly displaced from its surface low and upper
forcing. Given the weakly forced nature of the front, it`s no
surprise to see the variability in the models we continue to see
with QPF generation, but as mentioned yesterday, along the cold
front Thursday afternoon, there will be sufficient shear and
instability to support an at least small severe risk, it`s just a
question of where that front will be during peak heating.

Friday through next weekend. The one period where we are seeing
increased agreement is that high pressure will result in dry weather
to end the week on Friday. In addition, the west winds that we`ll
see that day will also finally break our run of highs in the 80s as
we start to see temperatures trend back toward our normal mid-
September levels. For next weekend, there`s basically a 40% chance
of rain the whole time, but that reflects the large spread we
continue to see with how, and more importantly when, our next system
will unfold. The idea of an h5 low coming out of the 4-corners at
the end of the week, going into the Great Lakes early next week
remains, but spread remains large with the track the h5 low will
take into the Great Lakes and with how long it will take to get
there. But, the potential remains for a good soaking rain to the
north/east of the eventual low track.

&&

.AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/...
Issued at 1157 PM CDT Mon Sep 16 2024

VFR. Southerly winds will continue to remain elevated in speed
through the pre-dawn hours and then increase gusts to 20-25kts
after 16z. Diurnal Cu is expected to develop this afternoon once
again and could develop a stray isolated shower. However, given
the lack of confidence within the CAMs, was reluctant to include
any mentions of precip during this TAF period.

KMSP...No additional concerns.

/OUTLOOK FOR KMSP/
WED...VFR, chc MVFR/-TSRA late. Wind SE 10-20 kts.
THU...VFR. Evening SHRA/TSRA. Wind S 15G25 kts.
FRI...VFR. Chc -SHRA/-TSRA. Wind S 5-10kts.

&&

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

&&

$$

DISCUSSION...MPG
AVIATION...BPH/Dunleavy