Alert archive / Idaho / Flash Flood Warnings in 2021

Flash Flood Warning 5, NWS Pocatello, ID

July 28, 2021Blaine County, Custer County, Idaho

NWS Pocatello, ID issued this flash flood warning at Jul 28, 2021, 2:20 PM MDT for Blaine County, Custer County, Idaho. It was in force for 2 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 28, 2021, 2:20 PM MDT (20:20 UTC)
Expired: Jul 28, 2021, 4:49 PM MDT
In force: 2 hr
Issued by: NWS Pocatello, ID
Area: Storm-based polygon
Flood severity: None

Counties Blaine County, ID, Custer County, ID

The radar

The Boise radar (KCBX), 143 km from the middle of the area, began a volume at 20:23 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 28, 3:00 PM MDT	FLASH FLOOD	10 Sse Galena, ID	SEVERAL INCHES OF MUD, ROCKS AND DEBRIS OVER BAKER CREEK ROAD THAT CLOSED DOWN THE ROAD. THIS WAS IN AN AREA OF PREVIOUS FIRE BURN AND THE FIRST OF TWO SLIDE EVENTS THAT CLOSED DOWN THE ROAD. TIME ESTIMATED FROM RADAR.

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

The nearest sounding before it

Boise Airport, ID (KBOI), launched 12:00Z, 8.3 hours before the alert went out and 138 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: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 2303 m above ground
0-6 km bulk shear: 21 kt
0-1 km storm-relative helicity: -18 m²/s²
0-3 km storm-relative helicity: 68 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

028 
WGUS55 KPIH 282020
FFWPIH
IDC013-037-290000-
/O.NEW.KPIH.FF.W.0005.210728T2020Z-210729T0000Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Pocatello ID
220 PM MDT Wed Jul 28 2021

The National Weather Service in Pocatello has issued a

* Flash Flood Warning for...
  Northwestern Blaine County in central Idaho...
  Southwestern Custer County in central Idaho...

* Until 600 PM MDT.

* At 220 PM MDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Between 1 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 Northwestern Blaine and Southwestern Custer 
  Counties

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4390 11457 4392 11449 4390 11441 4385 11437
      4377 11440 4368 11450 4371 11461 4376 11465
      4383 11462

FLASH FLOOD...RADAR INDICATED

$$

KB

1 follow-up statement

478 
WGUS75 KPIH 282249
FFSPIH

Flash Flood Statement
National Weather Service Pocatello ID
449 PM MDT Wed Jul 28 2021

IDC013-037-282259-
/O.CAN.KPIH.FF.W.0005.000000T0000Z-210729T0000Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Blaine ID-Custer ID-
449 PM MDT Wed Jul 28 2021

...FLASH FLOOD WARNING IS CANCELLED FOR NORTHWESTERN BLAINE AND 
SOUTHWESTERN CUSTER COUNTIES...

The heavy rain has ended. Flooding is no longer expected to pose a 
threat. Please continue to heed remaining road closures.

LAT...LON 4390 11457 4392 11449 4390 11441 4385 11437
      4377 11440 4368 11450 4371 11461 4376 11465
      4383 11462

$$

DH

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 27, 11:19 PM MDT	Special Weather Statement	PIH	Minidoka	56 min
Jul 28, 10:18 AM MDT	Special Weather Statement	PIH	Bear Lake	42 min
Jul 28, 10:45 AM MDT	Flash Flood Warning	PIH	Bear Lake, Franklin	3 hr
Jul 28, 10:48 AM MDT	Special Weather Statement	PIH	Bingham	42 min
Jul 28, 11:14 AM MDT	Special Weather Statement	PIH	Fremont	46 min
Jul 28, 11:34 AM MDT	Special Weather Statement	PIH	Bear Lake	41 min
Jul 28, 11:57 AM MDT	Special Weather Statement	PIH	Custer	63 min
Jul 28, 12:42 PM MDT	Special Weather Statement	PIH	Bonneville	48 min
Jul 28, 4:09 PM MDT	Special Weather Statement	PIH	Bear Lake	51 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.