Special Weather Statement, NWS Omaha, NE

Area Forecast Discussion
National Weather Service Omaha/Valley NE
312 PM CDT Fri Aug 27 2021

...Updated Forecast Discussion...

.DISCUSSION...
Issued at 312 PM CDT Fri Aug 27 2021

Early afternoon analysis showed a weak surface low pushing
northeastward through eastern Nebraska with an associated (and
convectively reinforced) surface boundary extending southwestward.
Not a super strong wind shift along the boundary, but at least
some weak convergence was leading to some cumulus development in a
few spots. For the most part, however, cloud cover was generally
on a downward trend along the boundary, suggesting it was in the
process of being washed out, so not sure how much forcing it will
provide for potential storms later. That said, it doesn't seem
like it would take much to get things to go, as the OAX 12Z
sounding showed a convective temperature of 97 and early afternoon
readings showed low 90s at many spots. In fact, LNK had a
temperature of 97 as of 2 PM, which was identical to their reading
yesterday at that time when they eventually topped out at 100
degrees. Therefore, do think we'll see at least some spotty shower
and storm development along what's left of the boundary by mid to
late afternoon and into this evening. With guidance suggesting
2500+ J/kg of SBCAPE and increasing shear in at least the low
levels into this evening, there seems to be at least an outside
shot for some severe storms, but given overall lack of forcing,
greater threat appears to be northeast of the area, closer to the
aforementioned surface low.

Saturday looks to be another warm, muggy day, though somewhat
breezy which should help a bit in terms of heat. Said strong winds
will continue to usher in warm, moist air ahead of a surface
boundary which will bring our next chance for severe weather. At
this time, the greatest threat for the forecast area looks to
arrive by late afternoon early evening and progress southeastward
through the evening and overnight, with some storms perhaps
lingering into Sunday morning. Strongest deep layer shear once
again looks to be behind the boundary, but still could see some
overlap with greatest instability and strongest low level shear
right along the boundary. As such, all severe weather hazards
would be possible, but given presumed upscale growth along the
boundary along with an overall warm environment, expect mainly a
damaging wind threat.

Expect some relief from the heat Sunday and Monday, with highs
across the area generally in the lower half of the 80s. Storm
chances return Sunday night through Monday as a surface boundary
looks to stall across the area and some shortwave energy slides
through. Through the remainder of the week, temperatures are
expected to warm at least a little bit as upper level ridging
gradually builds in. Various weak bits of shortwave energy also
slide through providing additional shower and storm chances, but
confidence in timing of any of those remains on the lower side.
Wednesday looks like it would have the best potential to see a
completely dry day with guidance suggesting the surface ridge axis
would be directly over the forecast area, but again, confidence
is low this far out.

&&

.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
Issued at 1203 PM CDT Fri Aug 27 2021

VFR conditions are expected for much of the period. There is a
remote possibility of a few scattered showers and thunderstorms,
but think much of the area should remain dry at the TAFS. Low-
level windshear is possible again overnight at all sites. Surface
winds should remain out of the south with some gusts at KLNK up to
30kts this afternoon.

&&

.OAX WATCHES/WARNINGS/ADVISORIES...
NE...None.
IA...None.
&&

DISCUSSION...CA
AVIATION...Kern

Hazardous Weather Outlook
National Weather Service Omaha/Valley NE
332 PM CDT Fri Aug 27 2021

IAZ043-055-056-069-079-080-090-091-NEZ011-012-015>018-030>034-
042>045-050>053-065>068-078-088>093-281200-
Monona-Harrison-Shelby-Pottawattamie-Mills-Montgomery-Fremont-
Page-Knox-Cedar-Thurston-Antelope-Pierce-Wayne-Boone-Madison-
Stanton-Cuming-Burt-Platte-Colfax-Dodge-Washington-Butler-
Saunders-Douglas-Sarpy-Seward-Lancaster-Cass-Otoe-Saline-
Jefferson-Gage-Johnson-Nemaha-Pawnee-Richardson-
332 PM CDT Fri Aug 27 2021

This Hazardous Weather Outlook is for portions of southwest
Iowa...west central Iowa...east central Nebraska...northeast
Nebraska and southeast Nebraska.

.DAY ONE...Tonight and Saturday

There will be chances for thunderstorms in the area tonight,
mainly across southeast Nebraska into southwest Iowa. There is a
small chance that one or two of these storms could become strong
or severe, if they do develop.

Heat index values over 100 are expected in parts of southeast
Nebraska and southwest Iowa Saturday afternoon.

.DAYS TWO THROUGH SEVEN...Saturday night through Friday

There is a higher chance for storms Saturday night. A few of
these storms could be strong to severe. There will also be storm
chances Sunday night into Monday night.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not anticipated, but any severe storm
reports are appreciated.

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Special Weather Statement
National Weather Service Omaha/Valley Nebraska
455 PM CDT Fri Aug 27 2021

NEZ088-272245-
Jefferson NE-
455 PM CDT Fri Aug 27 2021

...A strong thunderstorm will impact portions of Jefferson County
through 545 PM CDT...

At 453 PM CDT, Doppler radar was tracking a strong thunderstorm over
Mahaska, or 17 miles northeast of Belleville, moving northeast at 20
mph. Other storms were south of Endicott and north of Harbine.

HAZARD...Wind gusts of 50 to 55 mph and penny size hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor damage to outdoor objects is
         possible.

Locations impacted include...
  Fairbury.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

&&

LAT...LON 4000 9737 4010 9737 4035 9693 4002 9692
      4000 9701
TIME...MOT...LOC 2153Z 235DEG 16KT 3999 9739

MAX HAIL SIZE...0.75 IN
MAX WIND GUST...55 MPH

Dergan