Hail in Iowa, October 20, 2021

AREA FORECAST DISCUSSION
National Weather Service Sioux Falls SD
558 AM CDT Wed Oct 20 2021

.SHORT TERM...(Today and Tonight)
Issued at 347 AM CDT Wed Oct 20 2021

A strong system will wrap up and drift northeast today. Early this
morning warm/moist advection roughly around 925 mb was producing an
area of showers and isolated thunderstorms. While shear would
support isolated severe storms so far the instability is too low to
allow for any sustained updrafts. However, shortly after sunrise
through late morning the upper level dry slot will wrap north into
the area and should increase mid level lapse rates. This may push
CAPE values in far southeast SD, northwest IA and possibly
southwest MN to around 1000 J/kg. With moderately strong shear
isolated severe storms will be possible. The main threat will be
hail to quarters but some wind will be possible but less likely.
Patchy heavy rain will also be possible as the activity lifts
northeast this morning. By afternoon we appear to get more into a
trowal wrap around set up with the better chance for a more
persistent stratiform rainfall across central and eastern SD.
Overall rainfall amounts will likely be less than a half an inch
south of Interstate 29 and a half an inch to an inch to the north.
Some higher amounts are likely in southwest MN with some dependency
upon how convection develops and moves this morning. Otherwise it
will be a chilly day with nearly steady temperatures in the 40s and
50s.

The trowal continues to wrap into the area tonight with any real
drying not taking place until late tonight. The more persistent
forcing will shift east through the night however so the better
chances should be mainly east of the area after midnight. Winds will
gradually diminish over central SD late tonight which should allow
temperatures to fall into the lower 30s, possibly allowing for a
little frost.

Thursday will be a cool day but winds will be on the lighter side.
Other than some high clouds a decent amount of sunshine is expected.
Highs generally lower 50s along and north of Interstate 90 and mid
50s to the south.

.LONG TERM...(Thursday through Tuesday)
Issued at 347 AM CDT Wed Oct 20 2021

Thursday night into Friday morning will see high pressure settle
into the area and drift east. A pretty good chance to see some frost
and possibly freezing temperatures. The models are indicating a
somewhat strong northwest oriented upper level jet moving into the
area Thursday evening which should bring an increase to mid and high
level cloudiness. If this moves in soon enough it will limit the
amount of radiational cooling and lows may end up a touch less cold.
Main point is frost and freeze Friday morning not a guarantee.
Friday night into Saturday morning will see a chance, albeit smaller
chance, for frost and freezing temperatures. If the pattern holds
the better chance would be east of Interstate 29. After this the
chance for frost and freezing temperatures will be very low. Highs
both Friday and Saturday should be in the 50s, maybe some lower 60s
near the Missouri River. Winds will be a bit stronger from the
southeast on Saturday as the next wave approaches. On Saturday night
warm advection increases and the chances for showers will also
increase. Some question whether or not we will see any thunder but
for now will leave that out.

Forecast confidence is quite low heading into Sunday as all model
solutions diverge quite a bit. The GFS and Canadian are somewhat
on the same page an upper trough swinging through the northern
plains. The Euro on the other hand, has a closed low passing south
of the area. Given a saturated atmosphere, rain appears possible,
most likely occurring in the morning as of this current time.
Have left 20- 30% PoPs to account for the uncertainty. Weak
ridging builds aloft by Monday afternoon and continues into
Tuesday. All models are in a bit more agreement about an upper
wave moving into the region Tuesday afternoon. However, strength,
location, and tilt could not be more different. WAA should be in
place ahead of the incoming wave, resulting in above average
temperatures. Thinking high temperatures will be in the 60s to 70s
across the CWA. Gusty winds also appear possible due to an
intensifying surface pressure gradient ahead of a cold front. Rain
may be possible along the front, but confidence is far too low to
talk about and specifics or amounts. A dry Wednesday with cooler
temperatures looks to be in store for next week.

&&

.AVIATION...(For the 12Z TAFS through 12Z Thursday morning)
Issued at 555 AM CDT Wed Oct 20 2021

Occasional showers and isolated thunderstorms will continue
through the morning. By afternoon much of the convection will have
diminished, but a more stratiform rain will develop, especially
west of Interstate 29. This rain will gradually work from wets to
east throgh the evening, before coming to an end by tonight.
Ceilings are expected to lower through the morning as well with
fairly widespread IFR conditions expected. By late tonight
ceilings should begin to improve from west to east.

&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&

SHORT TERM...08
LONG TERM...08/MM
AVIATION...08

Hazardous Weather Outlook
National Weather Service Sioux Falls SD
336 AM CDT Wed Oct 20 2021

IAZ001>003-012>014-020>022-031-032-MNZ071-072-080-081-089-090-097-
098-NEZ013-014-SDZ040-055-056-061-062-066-067-069>071-210845-
Lyon-Osceola-Dickinson-Sioux-O'Brien-Clay-Plymouth-Cherokee-
Buena Vista-Woodbury-Ida-Lincoln-Murray-Cottonwood-Nobles-Jackson-
Pipestone-Rock-Dixon-Dakota-Brookings-Lake-Moody-McCook-Minnehaha-
Turner-Yankton-Union-
336 AM CDT Wed Oct 20 2021

This Hazardous Weather Outlook is for portions of northwest Iowa,
west central Iowa, southwest Minnesota, northeast Nebraska, east
central South Dakota, and southeast South Dakota.

.DAY ONE...Today and Tonight

A few strong to severe thunderstorms will be possible this morning.
Hail up to the size of quarters is possible with the strongest
storms. Some localized heavier rain will also be possible with
around two inches possible in the heavier areas. The better chance
for heavy rain should be across parts of southwest Minnesota.

.DAYS TWO THROUGH SEVEN...Thursday through Tuesday

No hazardous weather is expected at this time.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not expected at this time.

SDZ038-039-050-052>054-057>060-063>065-068-210845-
Beadle-Kingsbury-Gregory-Jerauld-Sanborn-Miner-Brule-Aurora-
Davison-Hanson-Charles Mix-Douglas-Hutchinson-Bon Homme-
336 AM CDT Wed Oct 20 2021

This Hazardous Weather Outlook is for portions of central South
Dakota, east central South Dakota, south central South Dakota,
and southeast South Dakota.

.DAY ONE...Today and Tonight

No hazardous weather is expected at this time.

.DAYS TWO THROUGH SEVEN...Thursday through Tuesday

No hazardous weather is expected at this time.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not expected at this time.