Alert archive / Iowa / Severe Thunderstorm Warnings in 2019

Severe Thunderstorm Warning 88, NWS Sioux Falls, SD

July 20, 20195 counties in Iowa

NWS Sioux Falls, SD issued this severe thunderstorm warning at Jul 20, 2019, 9:37 AM CDT for 5 counties in Iowa. It was in force for 38 min. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued: Jul 20, 2019, 9:37 AM CDT (14:37 UTC)
Expired: Jul 20, 2019, 10:15 AM CDT
In force: 38 min
Issued by: NWS Sioux Falls, SD
Area: Storm-based polygon
Hail: 0.75 in
Wind: 60.0 mph

Counties Buena Vista County, IA, Cherokee County, IA, Clay County, IA, O'Brien County, IA, Plymouth County, IA

The radar

The Sioux Falls radar (KFSD), 152 km from the middle of the area, began a volume at 14:41 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

Did it verify

Not verified. The Iowa Environmental Mesonet's Cow found no qualifying storm report inside this severe thunderstorm warning while it was in force. That is not proof nothing happened: reports are thin where few people live.

Cow counts a report within 15 km of the polygon while the warning was in force: a tornado for a tornado warning; hail of 1 inch or more, a gust of 58 mph or more or wind damage for a severe thunderstorm warning; a flash flood report for a flash flood warning.

The watch it was issued in

The SPC watch in force over the same counties when this warning went out.

Issued	Product	Office	Lasted
Jul 20, 5:51 AM CDT	Severe Thunderstorm Watch	SPC	5 hr

The nearest sounding before it

Omaha, NE (KOAX), launched 12:00Z, 2.6 hours before the alert went out and 180 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.

Skew-T log-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.

Mixed-layer CAPE: 854 J/kg
Mixed-layer CIN: -500 J/kg
Mixed-layer LCL: 2014 m above ground
0-6 km bulk shear: 10 kt
0-1 km storm-relative helicity: 57 m²/s²
0-3 km storm-relative helicity: 83 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

112 
WUUS53 KFSD 201437
SVRFSD
IAC021-035-041-141-149-201515-
/O.NEW.KFSD.SV.W.0088.190720T1437Z-190720T1515Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Sioux Falls SD
937 AM CDT Sat Jul 20 2019

The National Weather Service in Sioux Falls has issued a

* Severe Thunderstorm Warning for...
  Cherokee County in northwestern Iowa...
  East central Plymouth County in northwestern Iowa...
  Buena Vista County in northwestern Iowa...
  Southern Clay County in northwestern Iowa...
  Southeastern O'Brien County in northwestern Iowa...

* Until 1015 AM CDT.

* At 937 AM CDT, a severe thunderstorm was located over Cleghorn, or
  10 miles northwest of Cherokee, moving east at 45 mph.

  HAZARD...60 mph wind gusts.

  SOURCE...Radar indicated.

  IMPACT...Expect damage to roofs, siding, and trees.

* This severe thunderstorm will be near...
  Cherokee and Larrabee around 950 AM CDT.
  Aurelia around 1000 AM CDT.
  Alta around 1010 AM CDT.
  Storm Lake, Lakeside and Truesdale around 1015 AM CDT.

Other locations impacted by this severe thunderstorm include Calumet,
Meriden and Rembrandt.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

For your protection move to an interior room on the lowest floor of a
building.

Torrential rainfall is occurring with this storm, and may lead to
flash flooding. Do not drive your vehicle through flooded roadways.

&&

LAT...LON 4256 9507 4276 9597 4297 9578 4292 9491
      4256 9492
TIME...MOT...LOC 1437Z 288DEG 39KT 4285 9570 

HAIL...<.75IN
WIND...60MPH
 
$$

SG

2 follow-up statements

331 
WWUS53 KFSD 201458
SVSFSD

Severe Weather Statement
National Weather Service Sioux Falls SD
958 AM CDT Sat Jul 20 2019

IAC149-201508-
/O.CAN.KFSD.SV.W.0088.000000T0000Z-190720T1515Z/
Plymouth IA-
958 AM CDT Sat Jul 20 2019

...THE SEVERE THUNDERSTORM WARNING FOR EAST CENTRAL PLYMOUTH COUNTY
IS CANCELLED...
    
The severe thunderstorm which prompted the warning has moved out of 
the warned area. Therefore, the warning has been cancelled.

A Severe Thunderstorm Watch remains in effect until 1100 AM CDT for
northwestern Iowa.

LAT...LON 4271 9574 4296 9554 4292 9491 4256 9492
      4256 9507
TIME...MOT...LOC 1458Z 288DEG 39KT 4278 9540 

$$

IAC021-035-041-141-201515-
/O.CON.KFSD.SV.W.0088.000000T0000Z-190720T1515Z/
Cherokee IA-Buena Vista IA-Clay IA-O'Brien IA-
958 AM CDT Sat Jul 20 2019

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 1015 AM CDT
FOR NORTHEASTERN CHEROKEE...BUENA VISTA...SOUTHERN CLAY AND
SOUTHEASTERN O'BRIEN COUNTIES...

At 958 AM CDT, a severe thunderstorm was located near Aurelia, or 7
miles east of Cherokee, moving east at 45 mph.

HAZARD...60 mph wind gusts.

SOURCE...Radar indicated.

IMPACT...Expect damage to roofs, siding, and trees.

This severe storm will be near...
  Alta around 1010 AM CDT.
  Storm Lake, Lakeside and Truesdale around 1015 AM CDT.

Other locations impacted by this severe thunderstorm include Calumet,
Meriden and Rembrandt.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

For your protection move to an interior room on the lowest floor of a
building.

Torrential rainfall is occurring with this storm, and may lead to
flash flooding. Do not drive your vehicle through flooded roadways.

&&

LAT...LON 4271 9574 4296 9554 4292 9491 4256 9492
      4256 9507
TIME...MOT...LOC 1458Z 288DEG 39KT 4278 9540 

HAIL...<.75IN
WIND...60MPH
 
$$

SG

332 
WWUS53 KFSD 201511
SVSFSD

Severe Weather Statement
National Weather Service Sioux Falls SD
1011 AM CDT Sat Jul 20 2019

IAC021-035-041-141-201521-
/O.EXP.KFSD.SV.W.0088.000000T0000Z-190720T1515Z/
Cherokee IA-Buena Vista IA-Clay IA-O'Brien IA-
1011 AM CDT Sat Jul 20 2019

...THE SEVERE THUNDERSTORM WARNING FOR NORTHEASTERN CHEROKEE...BUENA
VISTA...SOUTHERN CLAY AND SOUTHEASTERN O'BRIEN COUNTIES WILL EXPIRE
AT 1015 AM CDT...
                
The storm which prompted the warning has weakened below severe
limits, and no longer poses an immediate threat to life or property.
Therefore, the warning will be allowed to expire.  However gusty
winds and heavy rain are still possible with this thunderstorm.

A Severe Thunderstorm Watch remains in effect until 1100 AM CDT for
northwestern Iowa.

LAT...LON 4271 9574 4296 9554 4292 9491 4256 9492
      4256 9507
TIME...MOT...LOC 1511Z 288DEG 39KT 4274 9523 

$$

SG

What forecasters said that day

The local office's own words before this severe thunderstorm warning went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Sioux Falls, SD wrote its last area forecast discussion before this severe thunderstorm warning went out at Jul 20, 3:58 AM CDT, 5 hours 39 minutes earlier.

Area forecast discussion, Jul 20, 3:58 AM CDT, 5 hours 39 minutes before

AREA FORECAST DISCUSSION
National Weather Service Sioux Falls SD
358 AM CDT Sat Jul 20 2019

.SHORT TERM...(Today and Tonight)
Issued at 358 AM CDT Sat Jul 20 2019

The humidity is still here for now, with 08Z dew points still in the
70s to around 80 across much of the forecast area. Relief is on the
way, though as lower dew points gradually filter southward into the
area behind a cool front today. By late afternoon, expect dew points
around 8-10 degrees lower than current readings. With decrease in
humidity and cooler temperatures, attention for today shifts from
oppressive heat to convective chances and associated risk of severe
weather and heavy rain.

Ongoing convection across northwest quarter of South Dakota will be
immediate concern. This driven largely by a mid level wave across
northwest South Dakota which will continue moving across SD through
the morning. Storms should remain largely elevated as they move into
and across our northern CWA this morning, with surface boundary over
our southern counties from northeast Nebraska into northwest Iowa
between Spencer and Storm Lake as of 08Z. This activity will work
into area with 1-2kJ/kg elevated instability and 40+ kt deep shear,
which should support at least isolated severe threat near/north of
I-90 as the storms advance east across our forecast area early to
mid morning. Hail still seems to be primary threat given elevated
nature of storms, but have already seen isolated severe wind
gusts with the storms in central South Dakota, so this certainly
cannot be ruled out with WSW oriented 0-3km shear vectors of
30-45kt and DCAPE values in excess of 1000J/kg indicated through
mid-morning by the latest RAP.

Approaching wave will provide little additional southward push to
the front through the morning, with the boundary becoming reinforced
by cooling from the rain/storms over our northern counties. This
could result in a fairly strong thermal gradient by mid afternoon
with readings in the upper 60s-lower 70s in southwest MN, to lower
80s in our far southern counties toward Sioux City-Storm Lake, with
surface front likely pushed to just south of the forecast area by
20Z. Despite slight surface cooling through the late afternoon,
enough lift from elevated front to keep a threat of scattered storms
across our southeast forecast area through the late afternoon and
evening. Still some elevated instability to work with, but deep
shear weaker in this area with strongest winds aloft remaining
farther north, so would expect a more isolated severe threat due to
less organized storm potential.

In addition to any severe threat, deep warm layer and precipitable
water values near 2 inches still at or above the 90th percentile in
climatology, heavy rainfall rates and potential flash flooding
remain a large concern with any storms through this evening. This
highlighted well by WPC Excessive Rainfall Outlook, as well as
recently issued Mesoscale Precip Discussion.

Storm threat should gradually wane from north to south through the
late evening and overnight hours today as front finally makes a
stronger southward push into the central Plains.
.

.LONG TERM...(Sunday through Friday)
Issued at 358 AM CDT Sat Jul 20 2019

Much cooler and less humid air mass settles into the region for the
latter half of the weekend. Though overall air mass will be drier
than recent days, a couple of waves moving across the region could
produce isolated to scattered showers or non-severe storms, mainly
in the afternoon.

Cooler than normal temperatures remain in place through early next
week as an upper ridge builds over the Intermountain West, placing
us in northwest flow pattern. Ridging begins to work east during the
latter half of the week, which should spread more seasonable
temperatures back into the region from Wednesday onward. Despite
weak disturbances dropping through the region, a lack of deep
moisture in this pattern will keep precipitation chances on the low
side.

&&

.AVIATION...(For the 06Z TAFS through 06Z Saturday night)
Issued at 1033 PM CDT Fri Jul 19 2019

Models continue to trend slower with convection on Saturday as
cooler air started to settle across the region. Favored area
through 18Z Saturday appears to be north of I-90, with more
scattered activity further south. Therefore, do not have
thunderstorm mention in KFSD and KSUX. Behind the convection,
potential for some MVFR stratus.

&&

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

SHORT TERM...JH
LONG TERM...JH
AVIATION...BT

Hazardous weather outlook, Jul 20, 4:57 AM CDT, 4 hours 40 minutes before

Hazardous Weather Outlook
National Weather Service Sioux Falls SD
457 AM CDT Sat Jul 20 2019

IAZ001-MNZ071-072-080-081-089-090-097-098-SDZ038>040-050-052>069-
211000-
Lyon-Lincoln-Murray-Cottonwood-Nobles-Jackson-Pipestone-Rock-Beadle-
Kingsbury-Brookings-Gregory-Jerauld-Sanborn-Miner-Lake-Moody-Brule-
Aurora-Davison-Hanson-McCook-Minnehaha-Charles Mix-Douglas-
Hutchinson-Turner-Bon Homme-Yankton-
457 AM CDT Sat Jul 20 2019

This Hazardous Weather Outlook is for northwest Iowa, southwest
Minnesota, central South Dakota, east central South Dakota, south
central South Dakota and southeast South Dakota.

.DAY ONE...Today and tonight.

Strong to severe storms are expected to move east across the area
this morning into the early afternoon. Wind gusts to 60 mph, and
large hail up to ping pong ball size are the primary severe threats.
Heavy rainfall is also likely, with flash flooding possible.

.DAYS TWO THROUGH SEVEN...Sunday through Friday.

No hazardous weather is expected at this time.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may be needed this morning, possibly into the
early afternoon across southwest Minnesota.

IAZ002-003-012>014-020>022-031-032-NEZ013-014-SDZ070-071-211000-
Osceola-Dickinson-Sioux-O'Brien-Clay-Plymouth-Cherokee-Buena Vista-
Woodbury-Ida-Dixon-Dakota-Union-
457 AM CDT Sat Jul 20 2019

This Hazardous Weather Outlook is for northwest Iowa, west central
Iowa, northeast Nebraska and southeast South Dakota.

.DAY ONE...Today and tonight.

Scattered storms are expected to develop across the area this
afternoon and evening. Heavy rainfall with localized flash flooding
will be the primary threat, with large hail to half dollar size, and
wind gusts to 50 mph also possible.

.DAYS TWO THROUGH SEVEN...Sunday through Friday.

No hazardous weather is expected at this time.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may be needed between 2 pm and 9 pm.

In the hours before

Local storm report, Jul 20, 9:13 AM CDT, 24 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SIOUX FALLS SD
913 AM CDT SAT JUL 20 2019

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

0820 AM     TSTM WND DMG     3 E SIOUX FALLS         43.55N 96.66W
07/20/2019                   MINNEHAHA          SD   PUBLIC

            WIND SPLIT A LARGE MAPLE TREE.

&&

PR

Local storm report, Jul 20, 9:20 AM CDT, 17 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SIOUX FALLS SD
920 AM CDT SAT JUL 20 2019

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

0835 AM     TSTM WND GST     1 WSW BEAVER CREEK      43.61N 96.38W
07/20/2019  M61 MPH          ROCK               MN   DEPT OF HIGHWAYS

            MESONET STATION MN006 BEAVER CREEK I-90 MILE
            POST 4.

&&

PR

Local storm report, Jul 20, 9:21 AM CDT, 16 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SIOUX FALLS SD
921 AM CDT SAT JUL 20 2019

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

0900 AM     TSTM WND GST     2 NE RUSHMORE           43.64N 95.77W
07/20/2019  M65 MPH          NOBLES             MN   DEPT OF HIGHWAYS

            MESONET STATION MN007 I-90 MILE POST 35.

&&

PR

Local storm report, Jul 20, 9:22 AM CDT, 15 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SIOUX FALLS SD
922 AM CDT SAT JUL 20 2019

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

0910 AM     TSTM WND GST     3 NE SIBLEY             43.43N 95.71W
07/20/2019  M63 MPH          OSCEOLA            IA   DEPT OF HIGHWAYS

            MESONET STATION RSYI4 2 NE SIBLEY.

&&

PR

Local storm report, Jul 20, 9:24 AM CDT, 13 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SIOUX FALLS SD
924 AM CDT SAT JUL 20 2019

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

0915 AM     TSTM WND GST     3 W DOVRAY              44.06N 95.60W
07/20/2019  M58 MPH          MURRAY             MN   DEPT OF HIGHWAYS

            MESONET STATION MN038 DOVRAY MN-30 MILE POST
            49.

&&

PR

Local storm report, Jul 20, 9:29 AM CDT, 8 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SIOUX FALLS SD
929 AM CDT SAT JUL 20 2019

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

0812 AM     TSTM WND GST     1 NNW PIPESTONE         44.01N 96.32W
07/20/2019  M71 MPH          PIPESTONE          MN   MESONET

            PIPESTONE RAWS STATION. TIME ESTIMATED FROM
            RADAR.

&&

PR

The office that day

Everything else NWS Sioux Falls, SD issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jul 20, 8:15 AM CDT	Severe Thunderstorm Warning	FSD	Lyon, Sioux	30 min
Jul 20, 8:39 AM CDT	Severe Thunderstorm Warning	FSD	Lyon, Osceola, Sioux	36 min
Jul 20, 9:02 AM CDT	Severe Thunderstorm Warning	FSD	Clay, Dickinson, Lyon, O'Brien, Osceola, Sioux	43 min
Jul 20, 9:40 AM CDT	Severe Thunderstorm Warning	FSD	Buena Vista, Clay, Dickinson, O'Brien, Osceola	35 min
Jul 20, 9:46 AM CDT	River Flood Warning	FSD	Lyon	25 hr

Nearby

Severe Thunderstorm Warnings in Iowa, 2019 Every severe thunderstorm warning in 2019

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.