798
FXUS63 KMPX 180533
AFDMPX

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
1233 AM CDT Sat May 18 2024

.KEY MESSAGES...

- Chance for some isolated thunderstorms across central
  Minnesota late this afternoon into this evening.

- Low RH values Saturday afternoon could result in areas of
  elevated fire weather conditions.

- Another round of showers and thunderstorms, some possibly
  severe, in western WI Saturday afternoon and evening.

- An active pattern set to begin Sunday night. Multiple chances
  for rain, possibly heavy, and thunderstorms over the next week.

&&

.DISCUSSION...
Issued at 303 PM CDT Fri May 17 2024

Today and tomorrow... Cumulus clouds starting to build over
western Minnesota this afternoon driven by diurnal heating and
the LLJ. With inverted V soundings elevated thunderstorms could
be a risk later today across eastern Minnesota into western
Wisconsin. Some CAMs have been consistently showing this risk,
but there is a wide spread among CAMs from nothing to scattered
thunderstorms. What is confident is that with dry low level air,
heavy rain is not a threat. However, the main concerns would be
lighting and based on the soundings some isolated strong gusts.
All the cloud cover is very diurnally driven and it will clear
up as the sun sets. Then all attention turns the the cold front
moving across the Upper Midwest. This will keep Saturday cooler
than what we have seen today. It also will allow for another
round of thunderstorms in Wisconsin. It is all about timing
here. The instability should build up enough by the late
afternoon for the storms to pop. It is all about where the cold
front is located when this happens. Current CAMs suggest that it
will be near Eau Claire. Question is just west or to the east?
That is what is uncertain. Some wind and hail will be both be
possible with theses storms. More recent runs have already moved
this west as the previous discussion and earlier SPC Outlook
kept most of this risk to our east.

Sunday through Thursday...Sunday will start out dry behind
Saturday`s cold frontal passage. It won`t be long before the
next system moves in. Another system will move in from the
Rockies on Sunday with a warm front draped across the
Minnesota/Iowa border region. This system will be slow to depart
and give us multiple chances for rain Sunday through Wednesday.
This is all driven synoptically by multiple shortwave
disturbances moving along the south side of a fairly stationary
upper low over the Canadian Prairies. This will have a fair
amount of moisture available with NAEFS percentiles around the
90th during this period. As mentioned in the previous discussion
WPC has also recognized this and we are in continuous marginal
risks over this period from late Sunday into the middle of the
next week. There is also indications of a strong shear
environment on Tuesday, especially over Wisconsin. The limiting
factor here will be instability as we will be in the middle of a
wet cloudy period that could keep temperatures low and CAPE
skinny. This was recognized with a day 5 risk by SPC.

Getting past mid week the pattern continues to look busy, but the
spread among the ensembles (ENS, GEFS, and GEPS) increases. So
we could see continued rain through the end of the week or more
of a dry period. It is too soon to tell. There are however fewer
members with QPF on Thursday into early Friday before than the
previous Sunday to Wednesday period. Bottom line, it will be
cooler and wetter from late Sunday through the next week. This
should continue to help us recover from the drought and could
help restock area lakes and water tables that we weakened with
repetitive drought stress.

&&

.AVIATION /06Z TAFS THROUGH 06Z SUNDAY/...
Issued at 1222 AM CDT Sat May 18 2024

Scattered thunderstorms over central MN will continue to move
east-northeast overnight with possible brief impacts to
STC/MSP/RNH/EAU. These storms will gradually weaken over the
next 2-3 hours and TS may have a hard time reaching RNH and
EAU. Otherwise, VFR conditions tonight. The original area of
storms and showers over W WI will taper off prior to EAU. Winds
will shift from the south to west to northwest as a cold front
sweeps through. Additional thunderstorms could develop on the
cold front near EAU in the mid to late afternoon but confidence
is low-medium with a prob30 for now.

KMSP...Thunderstorms to the southwest of MSP may impact the
terminal shortly after issuance through 10Z or so. Maintained a
TEMPO with -SHRA, but may need to change that to -TSRA if they
maintain strength.

/OUTLOOK FOR KMSP/
SUN...VFR. MVFR/SHRA likely late. Wind SE 10-15kts.
MON...MVFR/-TSRA thru mrng. VFR chc SHRA aftn. Wind SE 5-10kts.
TUE...MVFR/-TSRA likely. Wind NE 10-15 kts.

&&

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

&&

$$

DISCUSSION...NDC
AVIATION...BPH