383
FXUS63 KMPX 161808
AFDMPX

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
108 PM CDT Wed Apr 16 2025

.KEY MESSAGES...

- Elevated fire weather risk this afternoon.

- Showers and a few storms likely Thursday/Thursday night. Level
  2 out of 5 severe weather risk across southern Minnesota,
  mainly for large hail.

- Next chance (30%-50%) for showers comes Sunday into Monday,
  but high uncertainty in this forecast.

&&

.DISCUSSION...
Issued at 251 AM CDT Wed Apr 16 2025

TODAY...Early morning satellite imagery and surface obs showed
mostly clear skies across the region with southeast winds
developing as the surface high moved off toward the Great Lakes.
The air was pretty dry, with dewpoints only in the mid 20s
across the region. These southeast wind and the dry air will set
the stage for elevated fire weather conditions later this
afternoon. Forecast winds and humidity will be right near the
Red Flag Warning threshold. We opted to issue a Special Weather
Statement, but there is a chance that if high clouds don`t
develop as currently forecast, then the humdities could be
lower and a Red Flag Warning may be needed.

THURSDAY...Confidence has increased in the potential for strong
to severe thunderstorms across southern Minnesota. The main
threat with these storms will be large hail, but some wind and
an isolated tornado can not be completely ruled out.

One thing that is unfavorable for wind or hail is the CIN in the
lowest level of the forecast soundings. This indicates that
elevated convection will be more likely, rooted above the
boundary layer. Currently expecting low clouds most of Thursday,
but if there are a few breaks and we manage to get some diurnal
instability to develop, that could erode the CIN and introduce
the potential for some surface-based storms.

As mentioned in the previous discussion, mid-level lapse rates
of 7.5 to 8 C/km, along with a favorable deep layer shear
profile with the increasing winds aloft are the two main drivers
that would support organized convection, and the potential for
some hail. The Storm Prediction Center has expanded the Marginal
Risk northward, and introduced a Slight Risk to the south along
I-90. Most locations should see rain, but since this is
convection, the potential is that some areas may get missed,
especially west of I-35. In addition to severe weather, a few
storms could produce heavy rain, with the HREF supporting
isolated 1 to 2 inch amounts. The storms will track eastward
Thursday evening, but some lingering rain showers are possible
Thursday night.

FRIDAY THROUGH TUESDAY...Chances for rain showers linger into
Friday as the cold front associated with our inverted surface
trough is slow to push through the region. Eventually northwest
winds will bring cooler and drier air across the area. Cool air
will remain in place for Saturday with dry conditions.

Sunday and beyond have high uncertainty in the forecast. And
upper level wave over the 4-corners region at the base of a
positively tilted upper level trough is forecast to eject over
the central CONUS. However, the exact position of this wave
varies considerably among the guidance. There are equally
plausible solutions that a large precipitation shield with a
develop cyclone will lift northward and bring widespread rain
across the region, or that the system will track south and the
region will remain dry. For now, continued with the blended
guidance, which has generally 30 to 50 percent rain chances
across the region.

&&

.AVIATION /18Z TAFS THROUGH 18Z THURSDAY/...
Issued at 1245 PM CDT Wed Apr 16 2025

Not much happening this period until Thursday morning. One trend
we`ve seen with the 12z models is a lack of activity within the
warm advection Thursday morning, with most models holding off on
storms until the afternoon along the cold front. The one
exception is up in central MN, where several CAMs show activity
developing during the late morning hours. Otherwise, fairly
widespread convection is expected Thursday afternoon across
central and eastern MN ahead of the cold front that will be
moving across western MN during peak heating on Thursday. Given
the timing, only the end of the 30 hour TAF period at MSP has a
TS threat worthy of mentioning this period. For CIGS, went the
route of the RAP, which shows low cigs likely holding off until
after the fropa, so no widespread warm sector IFR/MVFR cigs like
we`re seeing with the LAV, with all TAFs remaining VFR this
period, though this is something we`ll continue to reassess
through the night.

KMSP...HREF shows TS probabilities of over 80% at MSP Thursday
afternoon, so jumped out beyond a prob30 for that threat with
the prevailing shra & tempo TS Thursday afternoon. It`s thunder,
so there`s still plenty of time for the placement of TS to
change, though the 12z HREF would say it could be a very active
afternoon on Thursday, with upwards of 2" of rain possible.

/OUTLOOK FOR KMSP/
FRI...MVFR/-SHRA early, then VFR. Wind NW 10-15 kts.
SAT...VFR. Wind NW 10-15 kts.
SUN...Chc MVFR/-SHRA. Wind E 10-15 kts.

&&

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

&&

$$

DISCUSSION...JRB
AVIATION...MPG