Alert archive / Iowa / Red Flag Warnings in 2020

Red Flag Warning 4, NWS Sioux Falls, SD

September 30, 20206 counties in Iowa

NWS Sioux Falls, SD issued this red flag warning at Sep 30, 2020, 3:33 AM CDT for 6 counties in Iowa. It took effect at Sep 30, 2020, 2:00 PM CDT. It was in force for 5 hr. No storm report in the archive falls inside the area while it was in force.

The area

The counties it named.

The facts

Issued
Sep 30, 2020, 3:33 AM CDT (08:33 UTC)
In effect from
Sep 30, 2020, 2:00 PM CDT
Expired
Sep 30, 2020, 7:00 PM CDT
In force
5 hr
Issued by
NWS Sioux Falls, SD

Counties Buena Vista County, IA, Cherokee County, IA, Ida County, IA, Plymouth County, IA, Sioux County, IA, Woodbury County, IA

The radar

The Sioux Falls radar (KFSD), 127 km from the middle of the area, began a volume at 08:36 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.

The nearest sounding before it

Omaha, NE (KOAX), launched 00:00Z, 8.6 hours before the alert went out and 159 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-pSkew-T log-p diagram, Omaha, NE at 00:00Z on 2020-09-30Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Omaha, NE at 00:00Z on 2020-09-30The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 105 square meters per square second.1939587897Sfc1 km3 km6 km9 kmRMLM
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
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
3070 m above ground
0-6 km bulk shear
61 kt
0-1 km storm-relative helicity
105 m²/s²
0-3 km storm-relative helicity
202 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

770 
WWUS83 KFSD 300833
RFWFSD

URGENT - FIRE WEATHER MESSAGE
National Weather Service Sioux Falls SD
333 AM CDT Wed Sep 30 2020

IAZ012-020>022-031-032-NEZ249-SDZ258-301645-
/O.NEW.KFSD.FW.W.0004.200930T1900Z-201001T0000Z/
Sioux-Plymouth-Cherokee-Buena Vista-Woodbury-Ida-
Extreme Northeast Nebraska-
Lower James River To Lower Big Sioux River Valley-
333 AM CDT Wed Sep 30 2020

...RED FLAG WARNING IN EFFECT FROM 2 PM THIS AFTERNOON TO 7 PM
CDT THIS EVENING FOR STRONG WINDS AND LOW RELATIVE HUMIDITY FOR 
FIRE WEATHER ZONES 012, 020, 021, 022, 031, 032, 249, AND 258...

The National Weather Service in Sioux Falls has issued a Red Flag
Warning, which is in effect from 2 PM this afternoon to 7 PM CDT
this evening. 

* AFFECTED AREA...Fire weather zones 012, 020, 021, 022, 031, 
  and 032.Fire weather zone 249.Fire weather zone 258. 

* WIND...Northwest winds will rapidly increase this morning and
  become gusty through the remainder of the day. Wind gust up to
  40 mph are expected through the afternoon hours. 

* HUMIDITY...Lowest afternoon relative humidity values will be
  between 20 and 25 percent.

* IMPACTS...any fires that develop will likely spread rapidly. 
  Outdoor burning is not recommended.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Red Flag Warning means that critical fire weather conditions
are either occurring now....or will shortly. A combination of
strong winds...low relative humidity...and warm temperatures can
contribute to extreme fire behavior.

&&

$$
3 follow-up statements
139 
WWUS83 KFSD 302026
RFWFSD

URGENT - FIRE WEATHER MESSAGE
National Weather Service Sioux Falls SD
326 PM CDT Wed Sep 30 2020

...RED FLAG WARNING IN EFFECT FROM 2 PM THIS AFTERNOON TO 7 PM
CDT THIS EVENING FOR STRONG WINDS AND LOW RELATIVE HUMIDITY FOR 
FIRE WEATHER ZONES 012, 020, 021, 022, 031, 032, 249, AND 258...

IAZ012-020>022-031-032-NEZ249-SDZ258-010000-
/O.CON.KFSD.FW.W.0004.000000T0000Z-201001T0000Z/
Sioux-Plymouth-Cherokee-Buena Vista-Woodbury-Ida-
Extreme Northeast Nebraska-
Lower James River To Lower Big Sioux River Valley-
326 PM CDT Wed Sep 30 2020

...RED FLAG WARNING REMAINS IN EFFECT UNTIL 7 PM CDT THIS EVENING
FOR STRONG WINDS AND LOW RELATIVE HUMIDITY FOR FIRE WEATHER ZONES
012, 020, 021, 022, 031, 032, 249, AND 258...

* AFFECTED AREA...Fire weather zones 012, 020, 021, 022, 031, 
  and 032.Fire weather zone 249. Fire weather zone 258. 

* WIND...Northwest winds sustained between 20 and 30 mph will
  continue through this afternoon. Wind gusts up to or over 40 
  mph are expected at times.

* HUMIDITY...Lowest afternoon relative humidity values will be
  between 20 and 27 percent.

* IMPACTS...any fires that develop will likely spread rapidly. 
  Outdoor burning is not recommended.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Red Flag Warning means that critical fire weather conditions
are either occurring now....or will shortly. A combination of
strong winds...low relative humidity...and warm temperatures can
contribute to extreme fire behavior.

&&

$$
159 
WWUS83 KFSD 302123
RFWFSD

URGENT - FIRE WEATHER MESSAGE
National Weather Service Sioux Falls SD
423 PM CDT Wed Sep 30 2020

...RED FLAG WARNING IN EFFECT UNTIL 7 PM CDT THIS EVENING FOR 
STRONG WINDS AND LOW RELATIVE HUMIDITY FOR FIRE WEATHER ZONES 012,
020, 021, 022, 031, 032, 249, 256, AND 258...

SDZ256-010000-
/O.EXA.KFSD.FW.W.0004.000000T0000Z-201001T0000Z/
Middle James River Valley-
423 PM CDT Wed Sep 30 2020

...RED FLAG WARNING IN EFFECT UNTIL 7 PM CDT THIS EVENING FOR
STRONG WINDS AND LOW RELATIVE HUMIDITY FOR FIRE WEATHER ZONE 
256...

The National Weather Service in Sioux Falls has issued a Red Flag
Warning, which is in effect until 7 PM CDT this evening. 

* AFFECTED AREA...South Dakota Fire weather zone 256. 

* WIND...Northwest winds sustained between 20 and 30 mph will 
  continue through this afternoon. Wind gusts up to or over 40 
  mph are expected at times.

* HUMIDITY...Lowest afternoon relative humidity values will be 
  between 20 and 27 percent.

* IMPACTS...Any fires that develop will likely spread rapidly. 
  Outdoor burning is not recommended.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Red Flag Warning means that critical fire weather conditions
are either occurring now....or will shortly. A combination of
strong winds...low relative humidity...and warm temperatures can
contribute to extreme fire behavior.

&&

$$

IAZ012-020>022-031-032-NEZ249-SDZ258-010000-
/O.CON.KFSD.FW.W.0004.000000T0000Z-201001T0000Z/
Sioux-Plymouth-Cherokee-Buena Vista-Woodbury-Ida-
Extreme Northeast Nebraska-
Lower James River To Lower Big Sioux River Valley-
423 PM CDT Wed Sep 30 2020

...RED FLAG WARNING REMAINS IN EFFECT UNTIL 7 PM CDT THIS EVENING
FOR STRONG WINDS AND LOW RELATIVE HUMIDITY FOR FIRE WEATHER ZONES
012, 020, 021, 022, 031, 032, 249, AND 258...

* AFFECTED AREA...Iowa Fire weather zones 012, 020, 021, 022, 031,
  and 032. Nebraska Fire weather zone 249. South Dakota Fire
  weather zone 258.

* WIND...Northwest winds sustained between 20 and 30 mph will 
  continue through this afternoon. Wind gusts up to or over 40 
  mph are expected at times.

* HUMIDITY...Lowest afternoon relative humidity values will be 
  between 20 and 27 percent.

* IMPACTS...Any fires that develop will likely spread rapidly. 
  Outdoor burning is not recommended.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Red Flag Warning means that critical fire weather conditions
are either occurring now....or will shortly. A combination of
strong winds...low relative humidity...and warm temperatures can
contribute to extreme fire behavior.

&&

$$
896 
WWUS83 KFSD 010002
RFWFSD

URGENT - FIRE WEATHER MESSAGE
National Weather Service Sioux Falls SD
702 PM CDT Wed Sep 30 2020

IAZ012-020>022-031-032-NEZ249-SDZ256-258-010115-
/O.EXP.KFSD.FW.W.0004.000000T0000Z-201001T0000Z/
Sioux-Plymouth-Cherokee-Buena Vista-Woodbury-Ida-
Extreme Northeast Nebraska-Middle James River Valley-
Lower James River To Lower Big Sioux River Valley-
702 PM CDT Wed Sep 30 2020

...RED FLAG WARNING HAS EXPIRED FOR STRONG WINDS AND LOW HUMIDITY 
FOR FIRE WEATHER ZONES 012, 020, 021, 022, 031, 032, 249, 256, AND
258...

Relative humidities across the region have begun to improve from 
their mid-late afternoon low points, and winds have been tapering
off as mixing decreases. Therefore the Red Flag Warning has been
allowed to expire.

$$

Nearby

Red Flag Warnings in Iowa, 2020Red Flag Warnings in Nebraska, 2020Red Flag Warnings in South Dakota, 2020Every red flag warning in 2020

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.