Alert archive / Idaho / Flash Flood Warnings in 2021

Flash Flood Warning 15, NWS Pocatello, ID

July 31, 2021Bannock County, Franklin County, Oneida County, Idaho

NWS Pocatello, ID issued this flash flood warning at Jul 31, 2021, 4:42 PM MDT for Bannock County, Franklin County, Oneida 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, 4:42 PM MDT (22:42 UTC)
Expired: Jul 31, 2021, 7:00 PM MDT
In force: 2 hr
Issued by: NWS Pocatello, ID
Area: Storm-based polygon
Flood severity: None

Counties Bannock County, ID, Franklin County, ID, Oneida County, ID

The radar

The Pocatello radar (KSFX), 100 km from the middle of the area, began a volume at 22:46 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, 6:00 PM MDT	FLASH FLOOD	5 Ene Malad City, ID	NWS SURVEY FOUND SEVERAL AREAS WHERE WATER HAD BEEN OVER HIGHWAY 36 AND DAMAGE TO CULVERTS WAS ALSO EVIDENT. IDAHO TRANSPORTATION DEPARTMENT WERE ACTIVELY CLEANING UP THE REMNANTS. TIME ESTIMATE 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, 10.7 hours before the alert went out and 171 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.

988 
WGUS55 KPIH 312242
FFWPIH
IDC005-041-071-010100-
/O.NEW.KPIH.FF.W.0015.210731T2242Z-210801T0100Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

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

The National Weather Service in Pocatello has issued a

* Flash Flood Warning for...
  South Central Bannock County in southeastern Idaho...
  Northwestern Franklin County in southeastern Idaho...
  East Central Oneida County in southeastern Idaho...

* Until 700 PM MDT.

* At 442 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 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...
  mainly rural areas of South Central Bannock, Northwestern Franklin 
  and East Central Oneida Counties.

This includes the following streams and drainages...
  Marsh Creek, Devil Creek, Cherry Creek, Weston Creek, and Campbell 
  Creek.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4241 11219 4240 11210 4232 11206 4229 11207
      4223 11209 4217 11211 4221 11220 4232 11220

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

$$

JKeyes

1 follow-up statement

093 
WGUS75 KPIH 010053
FFSPIH

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

IDC005-041-071-010103-
/O.EXP.KPIH.FF.W.0015.000000T0000Z-210801T0100Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Bannock ID-Franklin ID-Oneida ID-
653 PM MDT Sat Jul 31 2021

...FLASH FLOOD WARNING WILL EXPIRE AT 7 PM MDT THIS EVENING FOR 
SOUTH CENTRAL BANNOCK, NORTHWESTERN FRANKLIN AND EAST CENTRAL ONEIDA 
COUNTIES...

Widespread heavy rain has ended although localized moderate to heavy 
rain may continue for another hour or so. Flooding is no longer 
expected to pose a threat.

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

LAT...LON 4241 11219 4240 11210 4232 11206 4229 11207
      4223 11209 4217 11211 4221 11220 4232 11220

$$

JKeyes

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, 1:37 PM MDT	Flash Flood Warning	PIH	Power	2 hr
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, 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.