Alert archive / Idaho / Flash Flood Warnings in 2021

Flash Flood Warning 12, NWS Pocatello, ID

July 31, 2021Power County, Idaho

NWS Pocatello, ID issued this flash flood warning at Jul 31, 2021, 1:37 PM MDT for Power 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 31, 2021, 1:37 PM MDT (19:37 UTC)
Expired: Jul 31, 2021, 4:00 PM MDT
In force: 2 hr
Issued by: NWS Pocatello, ID
Area: Storm-based polygon
Flood severity: None

County Power County, ID

The radar

The Pocatello radar (KSFX), 42 km from the middle of the area, began a volume at 19:37 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 31, 3:00 PM MDT	FLASH FLOOD	8 Nw Crystal, ID	AN NWS SURVEY FOUND EVIDENCE OF HIGH WATER ALONG SEVERAL STRETCHES OF ARBON VALLEY ROAD. ROAD AND BRIDGE CREWS WERE ACTIVELY WORKING ON CLEANING UP DEBRIS. TIME ESTIMATED VIA RADAR.

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

The nearest sounding before it

Salt Lake City I, UT (KSLC), launched 12:00Z, 7.6 hours before the alert went out and 227 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: 149 J/kg
Mixed-layer CIN: -128 J/kg
Mixed-layer LCL: 1716 m above ground
0-6 km bulk shear: 5 kt
0-1 km storm-relative helicity: 44 m²/s²
0-3 km storm-relative helicity: 76 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

469 
WGUS55 KPIH 311937
FFWPIH
IDC077-312200-
/O.NEW.KPIH.FF.W.0012.210731T1937Z-210731T2200Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Pocatello ID
137 PM MDT Sat Jul 31 2021

The National Weather Service in Pocatello has issued a

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

* Until 400 PM MDT.

* At 137 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...
  American Falls Reservoir, Fort Hall Bannock Creek Lodge, Fort Hall 
  Bannock Peak, Pocatello Airport and Pauline.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4279 11278 4284 11280 4291 11258 4252 11253
      4253 11276

FLASH FLOOD...RADAR INDICATED

$$

DV

2 follow-up statements

483 
WGUS75 KPIH 312048
FFSPIH

Flash Flood Statement
National Weather Service Pocatello ID
248 PM MDT Sat Jul 31 2021

IDC077-312200-
/O.CON.KPIH.FF.W.0012.000000T0000Z-210731T2200Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Power ID-
248 PM MDT Sat Jul 31 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 4 PM MDT THIS 
AFTERNOON FOR EAST CENTRAL POWER COUNTY...

At 248 PM MDT, Doppler radar indicated thunderstorms producing heavy 
rain across the warned area. Between 1 and 2 inches of rain have 
fallen. The expected rainfall rate is 0.5 to 1 inch in 1 hour. 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...
  American Falls Reservoir, Fort Hall Bannock Creek Lodge, Fort Hall 
  Bannock Peak, Pocatello Airport and Pauline.

More storms are moving in from the south, so heavy rain and flooding 
will likely continue.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4279 11278 4284 11280 4291 11258 4252 11253
      4253 11276

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

$$

JKeyes

668 
WGUS75 KPIH 312157
FFSPIH

Flash Flood Statement
National Weather Service Pocatello ID
357 PM MDT Sat Jul 31 2021

IDC077-312207-
/O.EXP.KPIH.FF.W.0012.000000T0000Z-210731T2200Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Power ID-
357 PM MDT Sat Jul 31 2021

...FLASH FLOOD WARNING WILL EXPIRE AT 4 PM MDT THIS AFTERNOON FOR 
EAST CENTRAL POWER COUNTY...

This warning has been replaced by a new Flash Flooding Warning that 
includes areas south of the original warning.

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

LAT...LON 4279 11278 4284 11280 4291 11258 4252 11253
      4253 11276

$$

JK

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 31, 8:46 AM MDT	Areal Flood Advisory	PIH	Bingham, Bonneville, Jefferson	119 min
Jul 31, 12:20 PM MDT	Special Weather Statement	PIH	Power	40 min
Jul 31, 1:08 PM MDT	Areal Flood Advisory	PIH	Power	29 min
Jul 31, 1:08 PM MDT	Areal Flood Advisory	PIH	Bannock	112 min
Jul 31, 1:46 PM MDT	Areal Flood Advisory	PIH	Bannock, Power	119 min
Jul 31, 1:55 PM MDT	Areal Flood Advisory	PIH	Bear Lake	2 hr
Jul 31, 2:04 PM MDT	Areal Flood Advisory	PIH	Caribou	3 hr
Jul 31, 2:16 PM MDT	Areal Flood Advisory	PIH	Bear Lake, Franklin	3 hr
Jul 31, 2:28 PM MDT	Areal Flood Advisory	PIH	Bannock, Oneida, Power	3 hr
Jul 31, 2:38 PM MDT	Special Weather Statement	PIH	Bear Lake	37 min
Jul 31, 3:01 PM MDT	Areal Flood Advisory	PIH	Caribou	6 min
Jul 31, 3:07 PM MDT	Flash Flood Warning	PIH	Caribou	113 min
Jul 31, 3:10 PM MDT	Areal Flood Advisory	PIH	Bingham	3 hr
Jul 31, 3:20 PM MDT	Special Weather Statement	PIH	Bonneville	25 min
Jul 31, 3:32 PM MDT	Areal Flood Advisory	PIH	Bannock	3 hr
Jul 31, 3:50 PM MDT	Flash Flood Warning	PIH	Power	77 min
Jul 31, 4:02 PM MDT	Areal Flood Advisory	PIH	Cassia	118 min
Jul 31, 4:06 PM MDT	Areal Flood Advisory	PIH	Bannock, Franklin, Oneida	3 hr
Jul 31, 4:42 PM MDT	Flash Flood Warning	PIH	Bannock, Franklin, Oneida	2 hr
Jul 31, 5:14 PM MDT	Areal Flood Advisory	PIH	Franklin	2 hr
Jul 31, 5:45 PM MDT	Areal Flood Advisory	PIH	Cassia	64 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.