Alert archive / Wyoming / Red Flag Warnings in 2020

Red Flag Warning 9, NWS Rapid City, SD

July 10, 2020Custer County, Fall River County, South Dakota; Campbell County, Crook County, Weston County, Wyoming

NWS Rapid City, SD issued this red flag warning at Jul 10, 2020, 2:26 AM MDT for Custer County, Fall River County, South Dakota; Campbell County, Crook County, Weston County, Wyoming. It took effect at Jul 10, 2020, 12:00 PM MDT. It was in force for 7 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
Jul 10, 2020, 2:26 AM MDT (08:26 UTC)
In effect from
Jul 10, 2020, 12:00 PM MDT
Expired
Jul 10, 2020, 7:25 PM MDT
In force
7 hr
Issued by
NWS Rapid City, SD

Counties Custer County, SD, Fall River County, SD, Campbell County, WY, Crook County, WY, Weston County, WY

The radar

The Rapid City radar (KUDX), 122 km from the middle of the area, began a volume at 08:28 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

Rapid City, SD (KUNR), launched 00:00Z, 8.4 hours before the alert went out and 117 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, Rapid City, SD at 00:00Z on 2020-07-10Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 363 joules per kilogram.LCLLFCEL10008507005003002001001 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, Rapid City, SD at 00:00Z on 2020-07-10The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 37 square meters per square second.193958Sfc1 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
363 J/kg
Mixed-layer CIN
-142 J/kg
Mixed-layer LCL
2028 m above ground
0-6 km bulk shear
44 kt
0-1 km storm-relative helicity
37 m²/s²
0-3 km storm-relative helicity
156 m²/s²
Significant tornado parameter
0.0
Supercell composite
3.1

Open this sounding in Storm Lab

What forecasters said that day

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

NWS Rapid City, SD wrote its last area forecast discussion before this red flag warning went out at Jul 9, 5:21 PM MDT, 9 hours 5 minutes earlier.

Area forecast discussion, Jul 9, 5:21 PM MDT, 9 hours 5 minutes before
Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
521 PM MDT Thu Jul 9 2020

.DISCUSSION...(This Evening Through Thursday)
Issued at 306 PM MDT Thu Jul 9 2020

An upper ridge will continue to build over the area from the west
this afternoon. At the surface, a weak trof extends from
northeastern South Dakota in southwester SD. Slightly drier air is
located over northwestern South Dakota, as a region of slightly
higher low level moisture has settled into the Black Hills,
southwestern South Dakota, and south central South Dakota. SBCAPE is
around 1500J/KG and radar is already showing storms over the
northern and central Black Hills. Steep low/middle level lapse rates
combined with the moisture pool, may allow for a few strong storms
this afternoon and evening. Convection looks to continue overnight,
moving from west to east. There are quite a few model differences in
the cams, but with the ingredients that are in place, a slight
chance seems warranted.

There is a greater chance for more widespread severe storms over
western South Dakota Friday and Friday night. A surface low develops
over Wyoming and eastern Montana, which will help to draw abundant
low level moisture into the region with dewpoints well into the 60s
on the South Dakota plains. The high dewpoints and temperatures in
the 90s will lead to moderate to strong instability developing
during the afternoon. Moisture convergence and instability to the
east of the sfc trough will be further enhanced by a cold front
dropping southeastward into the area along with increasing synoptic
scale lift aloft. Large hail and strong wind gusts are expected over
parts of western and central South Dakota on Friday afternoon and
night.

Saturday will be slightly cooler. With a noticeably drier airmass
in place, dry weather is expected for Saturday and most of the
day on Sunday.

More active weather will return for Sunday night through next
week as an upper low slowly crosses the Canadian prairie
provinces, producing a period of fast westerly flow across the
northern plains. While models differ on the timing of the various
disturbances in the flow, it appears there will be a chances for
showers and thunderstorms on many days with temperatures near or
slightly cooler than average.

&&

.AVIATION...(For the 00Z TAFS Through 00Z Friday Evening)
Issued At 517 PM MDT Thu Jul 9 2020

Isolated to scattered thunderstorms expected to continue
developing across the region this evening and overnight, with
brief IFR conditions in stronger storms. VFR conditions expected
outside of any storms through the night. Strong to severe storms
expected again Friday afternoon, especially north and east of the
Black Hills.

&&

.FIRE WEATHER...
Issued at 306 PM MDT Thu Jul 9 2020

Critical fire weather conditions may develop over parts of
northeastern Wyoming and far southwestern South Dakota Friday
afternoon and evening. These weather conditions combined with
already dry fuels, has prompted a Fire Weather Watch for part of the
area. A cold front moves through Friday afternoon, causing wind
speeds to increase and shift to the northwest. Sustained winds of 15
to 25 mph with gust to 35 mph are possible behind the front. Minimum
relative humidity values of 10 top 15 percent will be possible.
There is also the potential for an isolated thunderstorm with little
to no precipitation.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...Fire Weather Watch from Friday afternoon through Friday evening
     for SDZ322.

WY...Fire Weather Watch from Friday afternoon through Friday evening
     for WYZ314>317.

&&

DISCUSSION...MLS
AVIATION...Johnson
FIRE WEATHER...MLS
Hazardous weather outlook, Jul 9, 1:37 PM MDT, 12 hours 49 minutes before
Hazardous Weather Outlook
National Weather Service Rapid City SD
137 PM MDT Thu Jul 9 2020

SDZ001-002-013-014-032-046-049-101300-
Harding-Perkins-Northern Meade Co Plains-Ziebach-Haakon-Mellette-
Tripp-
137 PM MDT Thu Jul 9 2020 /237 PM CDT Thu Jul 9 2020/

This Hazardous Weather Outlook is for portions of western South
Dakota.

.DAY ONE...This Afternoon and Tonight

Isolated thunderstorms are possible, mainly tonight. Severe
thunderstorms are not expected.

.DAYS TWO THROUGH SEVEN...Friday through Wednesday

Thunderstorms will be possible on Friday, some of which could be
severe. More thunderstorms will be possible from Sunday night
through early next week.

.SPOTTER INFORMATION STATEMENT...

Spotter activation will not be needed today.

&&

Stay tuned to NOAA weather radio for further updates...or check
our web site at weather.gov/rapidcity

SDZ012-024>031-041>044-047-072>074-WYZ056-057-071-101300-
Butte-Northern Black Hills-Northern Foot Hills-Rapid City-
Southern Foot Hills-Central Black Hills-Southern Black Hills-
Custer Co Plains-Pennington Co Plains-Fall River-Oglala Lakota-
Jackson-Bennett-Todd-Sturgis/Piedmont Foot Hills-
Southern Meade Co Plains-Hermosa Foot Hills-Western Crook-
Wyoming Black Hills-Northeastern Crook-
137 PM MDT Thu Jul 9 2020 /237 PM CDT Thu Jul 9 2020/

This Hazardous Weather Outlook is for portions of northwestern
South Dakota...south central South Dakota...southwestern South
Dakota...the Black Hills of South Dakota...northeast Wyoming...
and the Black Hills of Wyoming.

.DAY ONE...This Afternoon and Tonight

Isolated thunderstorms are possible, mainly tonight. A few storms
may be strong or severe.

.DAYS TWO THROUGH SEVEN...Friday through Wednesday

Thunderstorms will be possible on Friday, some of which could be
severe. More thunderstorms will be possible from Sunday night
through early next week.

.SPOTTER INFORMATION STATEMENT...

Spotter activation will not be needed today.

&&

Stay tuned to NOAA weather radio for further updates...or check
our web site at weather.gov/rapidcity

WYZ054-055-058-101300-
Northern Campbell-Southern Campbell-Weston-
137 PM MDT Thu Jul 9 2020

This Hazardous Weather Outlook is for portions of northeast
Wyoming.

.DAY ONE...This Afternoon and Tonight

Isolated thunderstorms are possible tonight. A few storms may be
strong or severe.

.DAYS TWO THROUGH SEVEN...Friday through Wednesday

Dry weather is expected on Friday, but more thunderstorms will be
possible from Sunday night through much of next week.

.SPOTTER INFORMATION STATEMENT...

Spotter activation will not be needed today.

&&

Stay tuned to NOAA weather radio for further updates...or check
our web site at weather.gov/rapidcity

In the hours before

Local storm report, Jul 9, 10:01 PM MDT, 4 hours 25 minutes before
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Local storm report, Jul 9, 10:49 PM MDT, 3 hours 37 minutes before
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Local storm report, Jul 9, 11:22 PM MDT, 3 hours 4 minutes before
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Special weather statement, Jul 9, 11:23 PM MDT, 3 hours 3 minutes before
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Special weather statement, Jul 10, 12:35 AM MDT, 1 hour 51 minutes before
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Special weather statement, Jul 10, 12:39 AM MDT, 1 hour 47 minutes before
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The office that day

Everything else NWS Rapid City, SD issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Jul 9, 8:06 PM MDTSpecial Weather StatementUNROglala Lakota39 min
Jul 9, 8:17 PM MDTSevere Thunderstorm WarningUNRFall River, Oglala Lakota58 min
Jul 9, 10:29 PM MDTSevere Thunderstorm WarningUNRButte, Lawrence, Meade61 min
Jul 9, 11:23 PM MDTSpecial Weather StatementUNRButte52 min
Jul 9, 11:47 PM MDTSevere Thunderstorm WarningUNRButte, Meade58 min
Jul 10, 12:35 AM MDTSpecial Weather StatementUNRHaakon55 min
Jul 10, 12:39 AM MDTSpecial Weather StatementUNRCuster51 min
Jul 10, 12:43 AM MDTSevere Thunderstorm WarningUNRCuster35 min
Jul 10, 12:56 AM MDTSevere Thunderstorm WarningUNRHaakon, Meade, Pennington, Ziebach64 min
Jul 10, 3:24 AM MDTSpecial Weather StatementUNRBennett51 min
Jul 10, 3:26 AM MDTSpecial Weather StatementUNRMellette49 min
Jul 10, 4:20 AM MDTSpecial Weather StatementUNRBennett40 min
Jul 10, 4:23 AM MDTSpecial Weather StatementUNROglala Lakota52 min
Jul 10, 5:10 AM MDTSpecial Weather StatementUNRJackson50 min
Jul 10, 5:29 AM MDTSpecial Weather StatementUNRBennett46 min
Jul 10, 5:34 AM MDTSpecial Weather StatementUNRMeade41 min
Jul 10, 5:39 AM MDTSpecial Weather StatementUNRMeade51 min
Jul 10, 6:08 AM MDTSpecial Weather StatementUNRJackson52 min
Jul 10, 6:11 AM MDTSpecial Weather StatementUNRTodd49 min
Jul 10, 6:13 AM MDTSpecial Weather StatementUNRMeade47 min
Jul 10, 6:36 AM MDTSpecial Weather StatementUNRMeade39 min
Jul 10, 7:02 AM MDTSpecial Weather StatementUNRJackson43 min
Jul 10, 7:32 AM MDTFlash Flood WarningUNRButte, Meade2 hr
Jul 10, 7:49 AM MDTSpecial Weather StatementUNRTodd41 min
Jul 10, 8:01 AM MDTSpecial Weather StatementUNRMeade29 min
Jul 10, 8:28 AM MDTSpecial Weather StatementUNRTodd47 min
Jul 10, 8:30 AM MDTSpecial Weather StatementUNRHaakon45 min
Jul 10, 9:15 AM MDTSpecial Weather StatementUNRMellette, Todd45 min
Jul 10, 9:57 AM MDTSpecial Weather StatementUNRMellette, Todd48 min
Jul 10, 10:12 AM MDTSevere Thunderstorm WarningUNRTodd, Tripp50 min
Jul 10, 11:29 AM MDTSpecial Weather StatementUNRTodd46 min
Jul 10, 1:42 PM MDTSpecial Weather StatementUNR48 min
Jul 10, 2:22 PM MDTSevere Thunderstorm WarningUNRButte53 min
Jul 10, 2:50 PM MDTSevere Thunderstorm WarningUNRButte, Lawrence55 min
Jul 10, 3:21 PM MDTSevere Thunderstorm WarningUNRButte, Lawrence, Meade54 min
Jul 10, 3:48 PM MDTTornado WarningUNRLawrence, Meade27 min
Jul 10, 3:59 PM MDTSevere Thunderstorm WarningUNRLawrence, Meade, Pennington61 min
Jul 10, 4:26 PM MDTSevere Thunderstorm WarningUNRPennington34 min
Jul 10, 4:52 PM MDTSevere Thunderstorm WarningUNRMeade, Pennington40 min
Jul 10, 4:56 PM MDTSevere Thunderstorm WarningUNRCuster, Meade, Pennington64 min
Jul 10, 5:25 PM MDTSevere Thunderstorm WarningUNRCuster, Pennington33 min
Jul 10, 5:31 PM MDTSevere Thunderstorm WarningUNRCuster, Jackson, Oglala Lakota, Pennington59 min
Jul 10, 5:41 PM MDTSpecial Weather StatementUNRPennington49 min
Jul 9, 8:14 PM MDTSevere Thunderstorm WarningUNRCampbell61 min
Jul 9, 8:43 PM MDTSevere Thunderstorm WarningUNRCampbell32 min
Jul 9, 8:49 PM MDTSpecial Weather StatementUNRWeston41 min
Jul 9, 9:02 PM MDTSevere Thunderstorm WarningUNRCampbell, Crook58 min
Jul 9, 9:28 PM MDTSpecial Weather StatementUNRCrook47 min
Jul 9, 9:39 PM MDTSpecial Weather StatementUNRCrook36 min
Jul 9, 9:45 PM MDTSevere Thunderstorm WarningUNRCampbell, Crook, Weston45 min
Jul 10, 2:26 PM MDTSevere Thunderstorm WarningUNRCampbell, Crook49 min

Nearby

Red Flag Warnings in Wyoming, 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.