Afton Alps

000
FXUS63 KMPX 301721
AFDMPX

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
1221 PM CDT Fri Oct 30 2026

.KEY MESSAGES...

- Dry today with a few hit and miss showers for Saturday, but
  the weather shouldn't dampen any Halloween plans you have too
  much.

- A slow moving low with a minimum pressure in the 990s will
  move across MN Monday into Tuesday. This system will have near
  record high PWATs for November, with a widespread soaking 
  rain expected.

&&

.DISCUSSION...
Issued at 337 AM CDT Fri Oct 30 2026

Today through the weekend... The evolution of the weather pattern 
this weekend will be interesting. There will be troughs digging in 
the Pac NW and New England. The atmospheric response to these 
coastal troughs will be building heights and ridging across the 
north central CONUS into the Canadian Prairie provinces. Getting 
thrown into this ridge mix is the upper trough currently seen on 
water vapor imagery coming out of Mexico into western TX and New 
Mexico. As we go through the weekend, this upper energy to our 
southwest will drift northeast into our ridge. What won't be lacking 
is moisture, with PWATs expected to build to over 200% of normal. 
What is lacking is forcing with the building heights locally. The 
net result is models (CAMs, deterministic, and machine learning) 
show smatterings of light QPF moving north across the area Friday 
night through Saturday. Given the scattered nature of activity we're 
seeing with the CAMs, we did reduce PoPs from the NBM to hold PoPs 
down in the chance category. What this upper energy coming up from 
the south will do is provide us with a mild and cloudy weekend. For 
the 35th year in a row, we will not repeat the Halloween of 1991, 
but you may encounter some damp conditions.

Monday and Tuesday... This is the portion of the forecast that looks 
intriguing. We will see the west coast trough from this weekend move 
out across the Plains. At the surface, we'll have a slow moving low 
with MSLP values in the 990s move across the center of the country. 
Guidance has continued to drift north toward where the AIFS has been 
the last few days with a surface low working across MN Monday into 
Tuesday. This low will be a powerhouse when it comes to rainfall 
potential. PWATs this weekend that will be 200-250% of normal will 
surge to near 400% of normal early next week, or over 4.5 standard 
deviations above normal. There will be two phases of forcing with 
this system. Monday will feature strong isentropic lift, with a 
broad band of moderate rain expected to move north across the area 
with this isentropic lift. Monday night into Tuesday, we transition 
to deformation precipitation within the cold conveyer and warm 
sector showers (and probably a few storms) ahead of the cold front. 
Locations that end up north of the surface low track will double dip 
on the isentropic and deformation rainfall. Much of the guidance out 
there has a band of over 2" QPF north of where that model tracks the 
surface low. In fact, when looking at the 00z EPS members at MSP, 
the 90th percentile for QPF is over 3", so this lends some 
confidence in a high end rainfall event for November standards 
occurring with this system early next week. In fact, the EPS has a 
70-90% chance of QPF exceeding 1" across the entire MPX area. From a 
climatology perspective, MSP averages 1.61" of liquid for the entire 
month of November. The greatest calendar day liquid precipitation on 
record in the Twin Cities for the month of November was 2.52" on 
November 11, 1940, which of course was the great Armistice Day 
Blizzard. You may have noticed we never mentioned anything other 
than rain with this system next week and that's because there's 
absolutely no cold air for this low to tap into, so it's all rain 
and a storm that will easily fall into the "waste of a good winter 
storm" category.

Finally something else to keep any eye on with this system will be 
how the warm sector evolves. With h85 winds forecast to be up over 
50 kts, we will have strongly curved hodographs in the warm sector. 
If we can somehow manage to get some instability up here (which 
isn't an outlandish proposition with dewpoints likely to surge into 
the lower 60s), then we'll have a pretty classic low CAPE/high shear 
severe weather setup. Right now, it looks cloudy with saturated 
profiles that greatly limit our instability potential, but given the 
degree of shear we'll have, we'll have to keep a close eye on the 
instability potential.

Wednesday and beyond... After Tuesday, there's a lot of spread with 
how long we'll remain in moist cyclonic flow behind the early week 
low. In general, we like the idea of the NBM with PoPs slowly 
decreasing Wednesday into Thursday as this system slowly pushes east 
across the Great Lakes. The end of this forecast also looks to be 
the beginning of a rather blah period of weather as split flow 
develops across North America, with a weak northern stream well to 
our north in northern Canada and a dominate southern stream down 
near the Gulf coast (a rather classic El Nino weather pattern). This 
will keep storm systems away from us and leave us with a mild 
airmass in place. In fact, it looks unlikely for MSP to see sub 
freezing temperatures into the middle of November. We may end up 
making a run at November 18, 2016 for the latest first freeze on 
record for the Twin Cities.

&&

.AVIATION /18Z TAFS THROUGH 00Z SUNDAY/...
Issued at 1206 PM CDT Fri Oct 30 2026

VFR conditions continue, though ceilings are already beginning
to lower across northern Iowa and southern Minnesota. These 
MVFR cigs will push north through the period, covering much of 
the region by tomorrow morning. As this system moves through, 
light, scattered showers are expected. The primary impact will 
be with lowering cigs, likely dropping to IFR during the mid-
late morning for areas that see rain. Showers likely become 
isolated by Saturday evening, though ceilings will remain 
MVFR/IFR. Winds will remain light, generally below 10 kts, out 
of the E/SE.

KMSP...High clouds have begun to clear out this afternoon, 
however another deck of mid-high level clouds are approaching 
from the south already. Expect ceilings to lower through the 
period, eventually dropping to MVFR between 07-10z. On and off 
rain showers are expected tomorrow morning, with ceilings 
dropping to IFR at times as the heavier rain moves through. 
Visibility is expected to stay MVFR or better.

/OUTLOOK FOR KMSP/
SUN...VFR. Wind SE 5-10 kts. 
MON...MVFR/IFR. SHRA. Wind SE 10-15G30 kts.
TUE...MVFR. -SHRA. Wind SE to NW 10-15G20 kts.

&&

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

&&

$$

DISCUSSION...MPG
AVIATION...BED