Special Weather Statement, NWS Omaha, NE

Area Forecast Discussion
National Weather Service Omaha/Valley NE
641 PM CDT Sun Sep 19 2021

...Updated Aviation Forecast Discussion...

.DISCUSSION...
Issued at 248 PM CDT Sun Sep 19 2021

.Tonight and Monday:

A vigorous short-wave trough currently over the Pacific Northwest
is forecast to broaden/amplify while progressing into the
northern and central Plains on Monday. Meanwhile, an associated
cold front will continue through the northern Plains this
afternoon and evening, before sweeping through the mid-MO Valley
on Monday.

Increasing height falls/dynamic cooling ahead of the approaching
mid-level trough will combine with a marginally unstable air mass
to foster widely scattered showers and thunderstorms late tonight,
especially across northeast NE. Forecast soundings in that area
indicate that parcel buoyancy will be relegated to the mid-levels
with a notably dry sub-cloud layer. That thermodynamic
configuration could promote a few strong downdrafts and resulting
gusty surface winds near the SD border.

The cold front is expected to move into the northwest part of our
area between 6 and 7 AM on Monday, before reaching the Lincoln and
Omaha areas between noon and 1 PM. The front should then exit our
area between 3 and 4 PM. The pre-frontal convective regime
mentioned in the previous paragraph is forecast to shift
east/northeast of the area by mid morning, with some uncertainty
in the extent of subsequent shower and storm development along the
cold front through the remainder of the day. Latest CAM data
suggest the best chance will exist over far southeast NE and
extreme southwest IA by mid afternoon with any strong to severe
storm potential likely materializing east of our area.

There should be a fairly substantial temperature gradient across
the front with afternoon readings ranging from the mid 60s over
northeast NE to mid 80s in far southeast NE.

.Monday night through Tuesday night:

A cooler, Canadian air mass will overspread the region in tandem
with a broad surface high, which will build from the High Plains
into the mid/lower-MO Valley. We will continue to undercut much of
model guidance on Tuesday night's lows with some upper 30s
possible over portions of west-central IA into northeast NE.

.Wednesday into next weekend:

The 12z global models suggest that mid-level heights will
temporarily build ahead of a short-wave trough tracking from
south-central Canada into the upper-MS Valley and Great Lakes on
Thursday night into Friday. That system will be accompanied by a
cold front, which would move through the mid-MO Valley during that
same time. Under that scenario, Thursday would be the warmest day
with highs in the upper 70s to around 80. Otherwise, it appears
temperatures will be mainly in the lower to mid 70s with minimal
precipitation chances.

&&

.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 639 PM CDT Sun Sep 19 2021

VFR conditions will prevail through the forecast period with
gusty south winds through the night. Low-level wind shear is a
concern overnight as well as low level winds, just above the
surface, ramp up. Isolated showers and thunderstorms are possible
along and ahead of a cold front, which will move into the area on
Monday morning.

&&

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

DISCUSSION...Mead
AVIATION...Pearson

Hazardous Weather Outlook
National Weather Service Omaha/Valley NE
322 PM CDT Sun Sep 19 2021

IAZ043-055-056-069-079-080-090-091-NEZ011-012-015>018-030>034-
042>045-050>053-065>068-078-088>093-201030-
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-
322 PM CDT Sun Sep 19 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 Monday

Widely scattered thunderstorms are possible tonight, a few of
which could produce gusty winds of 40 to 50 mph, especially near
the South Dakota border. Additional storms may materialize on
Monday afternoon along a cold front moving through the area. The
best potential for a strong storm or two will be in the Falls
City and Clarinda, IA areas in the 2 to 4 PM timeframe. Gusty
winds and small hail will be the main hazards.

.DAYS TWO THROUGH SEVEN...Monday night through Sunday

No Hazardous Weather is expected at this time.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not expected.

Special Weather Statement
National Weather Service Omaha/Valley Nebraska
1057 PM CDT Sun Sep 19 2021

NEZ016-017-031-200430-
Madison NE-Pierce NE-Antelope NE-
1057 PM CDT Sun Sep 19 2021

...A strong thunderstorm will impact portions of northwestern
Madison, southwestern Pierce and southeastern Antelope Counties
through 1130 PM CDT...

At 1056 PM CDT, Doppler radar was tracking a strong thunderstorm over
Oakdale, or 31 miles west of Norfolk, moving northeast at 35 mph.

HAZARD...Winds in excess of 40 mph and half inch hail.

SOURCE...Radar indicated.

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

This strong thunderstorm will be near...
  Oakdale around 1100 PM CDT.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

This storm may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.

&&

LAT...LON 4194 9801 4211 9817 4239 9781 4215 9755
TIME...MOT...LOC 0356Z 235DEG 28KT 4208 9802

MAX HAIL SIZE...0.50 IN
MAX WIND GUST...40 MPH

Kern

Special Weather Statement
National Weather Service Omaha/Valley Nebraska
1139 PM CDT Sun Sep 19 2021

NEZ011-012-016-200515-
Cedar NE-Knox NE-Antelope NE-
1139 PM CDT Sun Sep 19 2021

...A strong thunderstorm will impact portions of northeastern
Antelope, eastern Knox and northern Cedar Counties through 1215 AM
CDT...

At 1138 PM CDT, Doppler radar was tracking a strong thunderstorm 5
miles north of Creighton, or 28 miles southwest of Lewis And Clark
State Recreation Area, moving northeast at 40 mph.

HAZARD...Winds in excess of 40 mph and nickel 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.

This strong thunderstorm will be near...
  Bloomfield around 1155 PM CDT.

Other locations in the path of this storm include Yankton.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

&&

LAT...LON 4285 9729 4285 9722 4281 9721 4280 9716
      4277 9713 4277 9706 4240 9790 4259 9805
      4286 9763 4285 9744 4287 9742 4287 9738
      4285 9736 4287 9731
TIME...MOT...LOC 0438Z 224DEG 42KT 4254 9787

MAX HAIL SIZE...0.88 IN
MAX WIND GUST...40 MPH

Kern