Alert archive / Idaho / Flash Flood Warnings in 2021

Flash Flood Warning 11, NWS Pocatello, ID

July 30, 2021Cassia County, Idaho

NWS Pocatello, ID issued this flash flood warning at Jul 30, 2021, 3:02 PM MDT for Cassia County, Idaho. It was in force for 3 hr. 1 report came from inside the area while it was in force.

The area

The outline as issued, with what was reported inside it.

The facts

Issued: Jul 30, 2021, 3:02 PM MDT (21:02 UTC)
Expired: Jul 30, 2021, 6:15 PM MDT
In force: 3 hr
Issued by: NWS Pocatello, ID
Area: Storm-based polygon
Flood severity: None

County Cassia County, ID

The radar

The Pocatello radar (KSFX), 80 km from the middle of the area, began a volume at 21:04 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.

What was reported inside it

Time	Report	Where	Remark
Jul 30, 3:20 PM MDT	FLASH FLOOD	4 Wnw Heglar, ID	SIGNIFICANT FLASH FLOODING ACROSS A GRAVEL ROAD, AND WATER OVERTOPPING A SMALL BRIDGE ALONG A PAVED ROAD, IN THE AREA OF S 2950 E AND HEGLAR CANYON RD. PHOTOS AND VIDEOS SUBMITTED TO NWS POCATELLO VIA TWITTER STARTING AROUND 320 PM AND CONTINUING AT 451 PM.

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

The nearest sounding before it

Elko, NV (KLKN), launched 12:00Z, 9.0 hours before the alert went out and 199 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: 10 J/kg
Mixed-layer CIN: -189 J/kg
Mixed-layer LCL: 1966 m above ground
0-6 km bulk shear: 17 kt
0-1 km storm-relative helicity: 15 m²/s²
0-3 km storm-relative helicity: -39 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

603 
WGUS55 KPIH 302102
FFWPIH
IDC031-310015-
/O.NEW.KPIH.FF.W.0011.210730T2102Z-210731T0015Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Pocatello ID
302 PM MDT Fri Jul 30 2021

The National Weather Service in Pocatello has issued a

* Flash Flood Warning for...
  East Central Cassia County in southeastern Idaho...

* Until 615 PM MDT.

* At 302 PM MDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Between 1.5 and 2 inches of 
  rain have fallen. Flash flooding is ongoing or expected to begin 
  shortly.

  HAZARD...Flash flooding caused by thunderstorms.

  SOURCE...Radar.

  IMPACT...Flash flooding of small creeks and streams, urban
           areas, highways, streets and underpasses as well as
           other poor drainage and low-lying areas.

* Some locations that will experience flash flooding include...
  mainly rural areas of East Central Cassia County

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Turn around, don't drown when encountering flooded roads. Most flood 
deaths occur in vehicles.

&&

LAT...LON 4253 11324 4255 11301 4238 11300 4238 11323

FLASH FLOOD...RADAR INDICATED

$$

DV

1 follow-up statement

245 
WGUS75 KPIH 310012
FFSPIH

Flash Flood Statement
National Weather Service Pocatello ID
612 PM MDT Fri Jul 30 2021

IDC031-310022-
/O.EXP.KPIH.FF.W.0011.000000T0000Z-210731T0015Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Cassia ID-
612 PM MDT Fri Jul 30 2021

...THE FLASH FLOOD WARNING WILL EXPIRE AT 615 PM MDT THIS EVENING 
FOR EAST CENTRAL CASSIA COUNTY...

Excessive rainfall due to thunderstorms has ended. Flash flooding in 
the Heglar Canyon area is reported to be receding. Please continue 
to heed remaining road closures and do not drive through flooded 
roadways.

If you observed flooding, please report your observations to the 
National Weather Service in Pocatello via phone at 208-233-0834, or 
via social media.

A Flash Flood Watch remains in effect until 900 PM MDT Monday for 
portions of eastern Idaho and southeast Idaho.

LAT...LON 4253 11324 4255 11301 4238 11300 4238 11323

$$

KSmith

The office that day

Everything else NWS Pocatello, ID issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jul 30, 5:25 AM MDT	Special Weather Statement	PIH	Bear Lake	50 min
Jul 30, 12:50 PM MDT	Areal Flood Advisory	PIH	Bannock	22 min
Jul 30, 12:55 PM MDT	Flash Flood Watch	PIH	Bannock, Bear Lake, Bingham, Blaine, Bonneville, Butte and 10 more	3 days
Jul 30, 1:12 PM MDT	Flash Flood Warning	PIH	Bannock	108 min
Jul 30, 1:50 PM MDT	Flash Flood Warning	PIH	Bannock, Power	115 min
Jul 30, 1:55 PM MDT	Areal Flood Advisory	PIH	Power	2 hr
Jul 30, 1:57 PM MDT	Flash Flood Warning	PIH	Oneida	2 hr
Jul 30, 2:19 PM MDT	Areal Flood Advisory	PIH	Power	26 min
Jul 30, 2:24 PM MDT	Areal Flood Advisory	PIH	Bannock	81 min
Jul 30, 2:38 PM MDT	Flash Flood Warning	PIH	Cassia	3 hr
Jul 30, 2:45 PM MDT	Flash Flood Warning	PIH	Power	90 min
Jul 30, 3:09 PM MDT	Special Weather Statement	PIH	Cassia	51 min
Jul 30, 3:48 PM MDT	Areal Flood Advisory	PIH	Bonneville	117 min
Jul 30, 5:17 PM MDT	Areal Flood Advisory	PIH	Blaine	118 min

Nearby

Flash Flood Warnings in Idaho, 2021 Every flash flood warning in 2021

Sources

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