Flash Flood Warning 16, NWS Omaha, NE

Area Forecast Discussion
National Weather Service Omaha/Valley NE
650 AM CDT Wed Aug 2 2023

...Updated Aviation Forecast Discussion...

.DISCUSSION...
Issued at 419 AM CDT Wed Aug 2 2023

Key Messages:

 - Heavy rain potential will continue through Wednesday morning,
   primarily focused across east central NE and southwest IA.

 - Potential for strong to severe storms across the region
   Saturday afternoon/night.

 - Cooler/dryer conditions expected for the end of this
   weekend/early next week.

...Today and Tonight...

Ongoing morning convection across western Iowa and east central
Nebraska is expected to continue through the morning hours. An MCS
is also expected to move through southeast/east central
Nebraska in this same time frame. Both regions of convection will
produce regions of heavy rain with a risk for flash flooding,
with the primary flooding risk across portions of southwestern
Iowa. There is also the potential for strong to marginally severe
wind gusts with the MCS, primarily before sun rise. These storms
are in association with a weak midlevel disturbance that moved
into the central Plains yesterday evening. As this system moves to
the east over the course today, rain chances will shift to the
east and move out of the region by this evening. While the highest
risk for thunderstorms and heavy rain will be in the morning,
lingering cloud cover and showers still appears likely through the
afternoon today. There are no strong frontal boundaries
associated with this system, so temperatures will remain slightly
below average with highs in the low to mid 80s and humidity will
remain high with dew points region wide in the low to mid 70s.

... Tomorrow and Tomorrow Night...

Warm and humid conditions are expected to persist across the
region through the day tomorrow. By late tomorrow night, another
round of showers and thunderstorms appears possible as a weakening
complex of storms should move into the region from the
west/northwest. The biggest potential for rain should be after
midnight and west of US-77. These storms are not expected to be
severe.

...Friday through Tuesday...

A shortwave trough is expected to eject into the northern Plains
Friday night into Saturday and approach the region from the
northwest. As such, there will be chances for storms across the
region Friday night and Saturday evening/night. Thunderstorm
coverage and intensity is expected to be higher for Saturday as
this is when the surface low pressure associate with the upper
level disturbance and its surface fronts are forecast to move
through eastern NE/western IA. Storms are not anticipated to be
severe Friday night, however the potential exists for strong to
severe thunderstorms across the region Saturday evening/night. At
this time, specific details on severe mode, intensity and timing
are unclear.

Behind the cold front that should pass through the area Saturday
night, conditions should be cooler and drier with high
temperatures in the upper 70s/low 80s and dew points in the mid
50s to lower 60s.

&&

.AVIATION...(For the 12Z TAFS through 12Z Thursday morning)
Issued at 646 AM CDT Wed Aug 2 2023

Rain and storms will be at/near TAF sites for the next few hours
along with low ceilings. The low ceilings should lift to MVFR by
mid morning if not sooner, but could see additional TS development
by 18Z, particularly near OFK. Aside from storms, otherwise
should improve to VFR through the afternoon at all sites. Late
tonight, after 08Z, could see some fog development with main
uncertainty surrounding the location and density of any fog. Have
included most likely timing in TAFs at all sites.

&&

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

DISCUSSION...Darrah
AVIATION...Barjenbruch

Hazardous Weather Outlook
National Weather Service Omaha/Valley NE
431 AM CDT Wed Aug 2 2023

IAZ043-055-056-069-079-080-090-091-NEZ011-012-015>018-030>034-
042>045-050>053-065>068-078-088>093-022345-
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-
431 AM CDT Wed Aug 2 2023

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

.DAY ONE...Today and Tonight

Widespread thunderstorms are expected across portions of east
central Nebraska and southwest Iowa before noon today. The
strongest storms have the risk of small hail and gusty winds.
There is also a risk for localized flash flooding.

.DAYS TWO THROUGH SEVEN...Thursday through Tuesday

There are nightly chances for thunderstorms through Saturday night.
The overall threat for severe weather is low Thursday and Friday
night, but a few storms could contain small hail, gusty winds, or
localized heavy rainfall. There is a higher potential for strong
to severe thunderstorms across the region Saturday evening/night.
It's recommended to periodically check the forecast for updates.

.SPOTTER INFORMATION STATEMENT...

Spotters should not be needed tonight.

Special Weather Statement
National Weather Service Omaha/Valley Nebraska
204 AM CDT Wed Aug 2 2023

IAZ069-020715-
Pottawattamie IA-
204 AM CDT Wed Aug 2 2023

...A STRONG THUNDERSTORM WILL IMPACT NORTH CENTRAL POTTAWATTAMIE
COUNTY THROUGH 215 AM CDT...

At 203 AM CDT, Doppler radar was tracking a strong thunderstorm near
Minden, or 18 miles southwest of Harlan, moving east at 25 mph.

HAZARD...Winds in excess of 30 mph and nickel size hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down small tree branches and blow
         around unsecured objects. Minor hail damage to vegetation
         is possible.

Locations impacted include...
Neola, Shelby, Minden, and Arrowhead Park.

This includes Interstate 80 in Iowa between mile markers 20 and 34.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

&&

LAT...LON 4137 9564 4150 9565 4150 9540 4137 9540
TIME...MOT...LOC 0703Z 264DEG 20KT 4143 9554

MAX HAIL SIZE...0.88 IN
MAX WIND GUST...30 MPH

DeWald

Special Weather Statement
National Weather Service Omaha/Valley Nebraska
206 AM CDT Wed Aug 2 2023

IAZ055-069-NEZ045-020715-
Pottawattamie IA-Harrison IA-Washington NE-
206 AM CDT Wed Aug 2 2023

...A STRONG THUNDERSTORM WILL IMPACT NORTHWESTERN POTTAWATTAMIE...
SOUTHWESTERN HARRISON AND SOUTHEASTERN WASHINGTON COUNTIES THROUGH
215 AM CDT...

At 206 AM CDT, Doppler radar was tracking a strong thunderstorm 3
miles southwest of Missouri Valley, or 9 miles east of Blair, moving
southeast at 25 mph.

HAZARD...Winds in excess of 30 mph and nickel size hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down small tree branches and blow
         around unsecured objects. Minor hail damage to vegetation
         is possible.

Locations impacted include...
Missouri Valley, Fort Calhoun, Modale, Desoto Bend National Wildlife
Refuge, Wilson Island State Park, and Historical Village Welcome
Center.

This includes Interstate 29 between mile markers 68 and 79.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

&&

LAT...LON 4145 9607 4162 9606 4161 9578 4144 9579
TIME...MOT...LOC 0706Z 294DEG 20KT 4153 9595

MAX HAIL SIZE...0.88 IN
MAX WIND GUST...30 MPH

DeWald

Preliminary Local Storm Report
National Weather Service Omaha/Valley NE
619 AM CDT Wed Aug 2 2023

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0610 AM     Tstm Wnd Gst     3 SSW Norfolk           41.99N 97.44W
08/02/2023  M71 MPH          Madison            NE   ASOS

&&

BLB

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