Alert archive / Idaho / Flash Flood Warnings in 2021

Flash Flood Warning 19, NWS Pocatello, ID

August 1, 2021Blaine County, Idaho

NWS Pocatello, ID issued this flash flood warning at Aug 1, 2021, 3:47 PM MDT for Blaine 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
Aug 1, 2021, 3:47 PM MDT (21:47 UTC)
Expired
Aug 1, 2021, 6:45 PM MDT
In force
3 hr
Issued by
NWS Pocatello, ID
Area
Storm-based polygon
Flood severity
None

County Blaine County, ID

The radar

The Boise radar (KCBX), 129 km from the middle of the area, began a volume at 21:48 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

TimeReportWhereRemark
Aug 1, 5:00 PM MDTFLASH FLOOD10 Sse Galena, IDSEVERAL INCHES OF MUD, ROCKS AND DEBRIS OVER BAKER CREEK ROAD THAT CLOSED DOWN THE ROAD. A SURVEY TEAM FOUND THIS WAS IN AN AREA OF PREVIOUS FIRE BURN AND IN DISCUSSIONS WITH LOCAL OFFICIALS, IT WAS DETERMINED THIS WAS THE SECOND TO TWO SIMILAR SLIDES IN THE S

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, 9.8 hours before the alert went out and 125 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, Boise Airport, ID at 12:00Z on 2021-08-01Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 4 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Boise Airport, ID at 12:00Z on 2021-08-01The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 78 square meters per square second.1939Sfc1 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
4 J/kg
Mixed-layer CIN
-186 J/kg
Mixed-layer LCL
1142 m above ground
0-6 km bulk shear
16 kt
0-1 km storm-relative helicity
78 m²/s²
0-3 km storm-relative helicity
92 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

168 
WGUS55 KPIH 012147
FFWPIH
IDC013-020045-
/O.NEW.KPIH.FF.W.0019.210801T2147Z-210802T0045Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Pocatello ID
347 PM MDT Sun Aug 1 2021

The National Weather Service in Pocatello has issued a

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

* Until 645 PM MDT.

* At 347 PM MDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. The expected rainfall rate is 
  0.5 to 1 inch in 1 hour or less. Flash flooding is 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 County. 

This includes the following streams and drainages...
  North Fork Thompson Creek, Warm Springs Creek, West Fork Prairie 
  Creek, Placer Creek, South Fork Baker Creek, Newman Creek, Big 
  Wood River, Baker Creek, South Fork Warm Springs Creek, Norton 
  Creek, Deer Creek, Butterfield Creek, East Fork Baker Creek, 
  Anderson Creek, Apollo Creek, Snow Creek, Spruce Creek, Prairie 
  Creek, Left Fork Placer Creek, Castle Creek and Thompson Creek.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4381 11471 4376 11451 4351 11457 4352 11458
      4353 11460 4356 11459 4358 11462 4357 11463
      4359 11465 4359 11468 4361 11468 4362 11467
      4366 11466 4369 11469 4370 11468 4372 11468
      4374 11467 4375 11469 4379 11469

FLASH FLOOD...RADAR INDICATED
EXPECTED RAINFALL...0.5-1 INCH IN 1 HOUR

$$

JKeyes
1 follow-up statement
370 
WGUS75 KPIH 020037
FFSPIH

Flash Flood Statement
National Weather Service Pocatello ID
637 PM MDT Sun Aug 1 2021

IDC013-020047-
/O.EXP.KPIH.FF.W.0019.000000T0000Z-210802T0045Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Blaine ID-
637 PM MDT Sun Aug 1 2021

...FLASH FLOOD WARNING WILL EXPIRE AT 645 PM MDT THIS EVENING FOR 
NORTHWESTERN BLAINE COUNTY...

The heavy rain has ended. Flooding is no longer expected to pose a 
threat.

A Flash Flood Watch remains in effect until 900 PM MDT Monday for a 
portion of central Idaho.

LAT...LON 4381 11471 4376 11451 4351 11457 4352 11458
      4353 11460 4356 11459 4358 11462 4357 11463
      4359 11465 4359 11468 4361 11468 4362 11467
      4366 11466 4369 11469 4370 11468 4372 11468
      4374 11467 4375 11469 4379 11469

$$

TW

The office that day

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

IssuedProductOfficeCountiesLasted
Jul 31, 7:07 PM MDTFlash Flood WarningPIHCassia3 hr
Aug 1, 2:01 PM MDTFlash Flood WarningPIHPower3 hr
Aug 1, 2:06 PM MDTAreal Flood AdvisoryPIHCassia, Minidoka114 min
Aug 1, 2:21 PM MDTFlash Flood WarningPIHCassia3 hr
Aug 1, 3:04 PM MDTAreal Flood AdvisoryPIHBear Lake, Franklin116 min
Aug 1, 3:09 PM MDTAreal Flood AdvisoryPIHCassia111 min
Aug 1, 3:51 PM MDTAreal Flood AdvisoryPIHBannock, Caribou, Franklin114 min
Aug 1, 4:01 PM MDTAreal Flood AdvisoryPIHBingham, Caribou119 min
Aug 1, 4:21 PM MDTAreal Flood AdvisoryPIHBlaine114 min
Aug 1, 4:55 PM MDTSpecial Weather StatementPIHBlaine50 min
Aug 1, 5:05 PM MDTAreal Flood AdvisoryPIHBlaine, Butte115 min
Aug 1, 5:09 PM MDTAreal Flood AdvisoryPIHCassia2 hr
Aug 1, 5:25 PM MDTSpecial Weather StatementPIHPower50 min
Aug 1, 5:36 PM MDTAreal Flood AdvisoryPIHPower114 min

Nearby

Flash Flood Warnings in Idaho, 2021Every 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.