Alert archive / Idaho / Flash Flood Warnings in 2026

Flash Flood Warning 13, NWS Pocatello, ID

September 18, 2026Jefferson County, Madison County, Idaho

NWS Pocatello, ID issued this flash flood warning at Sep 18, 2026, 10:44 AM MDT for Jefferson County, Madison County, Idaho. It was in force for 89 min. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued
Sep 18, 2026, 10:44 AM MDT (16:44 UTC)
Expired
Sep 18, 2026, 12:13 PM MDT
In force
89 min
Issued by
NWS Pocatello, ID
Area
Storm-based polygon
Damage threat
Considerable
Flood severity
None

Counties Jefferson County, ID, Madison County, ID

The radar

The Pocatello radar (KSFX), 101 km from the middle of the area, began a volume at 16:44 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.

The nearest sounding before it

Salt Lake City I, UT (KSLC), launched 12:00Z, 4.7 hours before the alert went out and 320 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, Salt Lake City I, UT at 12:00Z on 2026-09-18Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 878 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, Salt Lake City I, UT at 12:00Z on 2026-09-18The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 151 square meters per square second.19395878Sfc1 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
878 J/kg
Mixed-layer CIN
-89 J/kg
Mixed-layer LCL
1649 m above ground
0-6 km bulk shear
36 kt
0-1 km storm-relative helicity
151 m²/s²
0-3 km storm-relative helicity
170 m²/s²
Significant tornado parameter
0.1
Supercell composite
1.4

Open this sounding in Storm Lab

The text

As transmitted.

499 
WGUS55 KPIH 181644
FFWPIH
IDC051-065-181945-
/O.NEW.KPIH.FF.W.0013.260918T1644Z-260918T1945Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Pocatello ID
1044 AM MDT Fri Sep 18 2026

The National Weather Service in Pocatello has issued a

* Flash Flood Warning for...
  The Big Rock burn scar in...
  Southeastern Jefferson County in southeastern Idaho...
  South Central Madison County in southeastern Idaho...

* Until 145 PM MDT.

* At 1044 AM MDT, Doppler radar indicated thunderstorms producing
  heavy rain over the Big Rock Burn Scar. The expected rainfall rate
  is 0.5 to 1 inch in 1 hour. Already saturated and filled ditches
  and culverts could become quickly inundated. Flash flooding is
  ongoing or expected to begin shortly. Excessive rainfall over the
  burn scar will result in debris flow moving through the Big Rock
  burn scar. The debris flow can consist of rock, mud, vegetation and
  other loose materials.

  HAZARD...Life threatening flash flooding. Thunderstorms producing
           flash flooding in and around the Big Rock Burn Scar.

  SOURCE...Radar indicated.

  IMPACT...Life threatening flash flooding of areas in and around the
           Big Rock Burn Scar.

* Some locations that will experience flash flooding include...
  Heise.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

This is a life threatening situation. Heavy rainfall will cause
extensive and severe flash flooding of creeks...streams...and ditches
in the Big Rock Burn Scar. Severe debris flows can also be
anticipated across roads. Roads and driveways may be washed away in
places. If you encounter flood waters...climb to safety.

&&

LAT...LON 4366 11172 4367 11173 4368 11172 4366 11170
      4366 11167 4367 11165 4365 11163 4364 11164
      4364 11165 4363 11166 4363 11169 4364 11169
      4365 11171

FLASH FLOOD...RADAR INDICATED
FLASH FLOOD DAMAGE THREAT...CONSIDERABLE
EXPECTED RAINFALL RATE...0.5-1 INCH IN 1 HOUR

$$

TAX
1 follow-up statement
785 
WGUS75 KPIH 181813
FFSPIH

Flash Flood Statement
National Weather Service Pocatello ID
1213 PM MDT Fri Sep 18 2026

IDC051-065-181823-
/O.CAN.KPIH.FF.W.0013.000000T0000Z-260918T1945Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Jefferson ID-Madison ID-
1213 PM MDT Fri Sep 18 2026

...FLASH FLOOD WARNING FOR THE BIG ROCK BURN SCAR IS CANCELLED FOR
SOUTHEASTERN JEFFERSON AND SOUTH CENTRAL MADISON COUNTIES...

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

There is potential for an additional round of showers and
thunderstorms later today.

A Flood Watch remains in effect until 1200 AM MDT Saturday for
portions of central, eastern, and southeast Idaho.

&&

LAT...LON 4366 11172 4367 11173 4368 11172 4366 11170
      4366 11167 4367 11165 4365 11163 4364 11164
      4364 11165 4363 11166 4363 11169 4364 11169
      4365 11171

$$

TAX

The office that day

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

IssuedProductOfficeCountiesLasted
Sep 17, 6:14 PM MDTSpecial Weather StatementPIHBingham31 min
Sep 17, 7:32 PM MDTSevere Thunderstorm WarningPIHBear Lake29 min
Sep 17, 7:52 PM MDTSpecial Weather StatementPIHJefferson53 min
Sep 17, 8:25 PM MDTSpecial Weather StatementPIHBingham50 min
Sep 17, 9:08 PM MDTSevere Thunderstorm WarningPIHBingham, Bonneville52 min
Sep 17, 9:32 PM MDTSevere Thunderstorm WarningPIHBingham43 min
Sep 17, 9:51 PM MDTFlash Flood WarningPIHMadison5 hr
Sep 17, 10:00 PM MDTFlash Flood WarningPIHBonneville, Jefferson4 hr
Sep 17, 10:05 PM MDTSevere Thunderstorm WarningPIHBannock, Bingham, Oneida, Power29 min
Sep 17, 10:11 PM MDTSevere Thunderstorm WarningPIHBingham, Bonneville, Jefferson36 min
Sep 17, 10:25 PM MDTFlash Flood Warning Considerable damage threatPIHJefferson, Madison4 hr
Sep 17, 10:37 PM MDTSevere Thunderstorm WarningPIHBannock, Bingham, Caribou, Power38 min
Sep 17, 11:24 PM MDTSpecial Weather StatementPIHBonneville, Teton66 min
Sep 17, 11:26 PM MDTSpecial Weather StatementPIHBonneville49 min
Sep 18, 12:17 AM MDTSpecial Weather StatementPIHBonneville, Madison, Teton43 min
Sep 18, 12:21 AM MDTSpecial Weather StatementPIHBingham39 min
Sep 18, 2:52 AM MDTFlash Flood WatchPIHBonneville, Fremont, Jefferson, Madison8 hr
Sep 18, 8:28 AM MDTSpecial Weather StatementPIHBannock, Bear Lake, Caribou32 min
Sep 18, 9:08 AM MDTFlash Flood Warning Considerable damage threatPIHBlaine5 hr
Sep 18, 10:30 AM MDTFlood WatchPIHBannock, Bear Lake, Bingham, Blaine, Bonneville, Butte and 10 more8 hr
Sep 18, 1:37 PM MDTFlash Flood WarningPIHBlaine, Butte, Custer3 hr

Nearby

Flash Flood Warnings in Idaho, 2026Every flash flood warning in 2026

Sources

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