Alert archive / California / Flash Flood Warnings in 2021

Flash Flood Warning 1, NWS Medford, OR

July 27, 2021Siskiyou County, California

NWS Medford, OR issued this flash flood warning at Jul 27, 2021, 2:51 PM PDT for Siskiyou County, California. It was in force for 9 hr. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued: Jul 27, 2021, 2:51 PM PDT (21:51 UTC)
Expired: Jul 27, 2021, 11:45 PM PDT
In force: 9 hr
Issued by: NWS Medford, OR
Area: Storm-based polygon
Flood severity: None

County Siskiyou County, CA

The radar

The Medford radar (KMAX), 73 km from the middle of the area, began a volume at 21:54 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

Medford/Jackson, OR (KMFR), launched 12:00Z, 9.9 hours before the alert went out and 104 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: 1907 m above ground
0-6 km bulk shear: 36 kt
0-1 km storm-relative helicity: 25 m²/s²
0-3 km storm-relative helicity: 89 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

850 
WGUS56 KMFR 272151
FFWMFR
CAC093-280045-
/O.NEW.KMFR.FF.W.0001.210727T2151Z-210728T0045Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Medford OR
251 PM PDT Tue Jul 27 2021

The National Weather Service in Medford has issued a

* Flash Flood Warning for...
  Central Siskiyou County in northern California...

* Until 545 PM PDT.

* At 247 PM PDT, Cal Trans reported a debris flow from heavy rain 
  across the warned area. Up to one inch of rain has already fallen. 
  Flash flooding is ongoing.

  HAZARD...Debris flow along Whitney Creek area affecting Highway 97 
           9 miles north of Weed. Flows of 1 to 8 feet of rock and 
           mud flow are occurring.

  SOURCE...Cal Trans.

  IMPACT...Flooding of small creeks and streams, urban areas, 
           highways, streets and underpasses as well as other 
           drainage and low lying areas.

* Flash flooding will remain over mainly rural areas of central
  Siskiyou County.
  Excessive rainfall over the burn scar will result in debris flow 
  moving through the Whitney Creek Drainage area. The debris flow 
  can consist of rock, mud, vegetation and other loose materials.

Additional rainfall amounts of a half an inch are possible in the 
warned area.


PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4156 12224 4147 12223 4146 12231 4153 12235

FLASH FLOOD...OBSERVED

$$

SCHAAF/Clarstrom

2 follow-up statements

028 
WGUS56 KMFR 280038
FFWMFR
CAC093-280645-
/O.EXT.KMFR.FF.W.0001.000000T0000Z-210728T0645Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Medford OR
538 PM PDT Tue Jul 27 2021

The National Weather Service in Medford has extended the

* Flash Flood Warning for...
  Central Siskiyou County in northern California...

* Until 1145 PM PDT Tuesday.

* At 531 PM PDT, Cal Trans reported a debris flow from heavy rain 
  combined with glacial melt across the warned area. Flash flooding 
  is ongoing.

  HAZARD...Debris flow along Whitney Creek area affecting Highway 97 
           9 miles north of Weed. Flows of 1 to 8 feet of rock and 
           mud flow are occurring.

  SOURCE...California Department of Transportation.

  IMPACT...Flooding of small creeks and streams, urban areas, 
           highways, streets and underpasses as well as other 
           drainage and low lying areas.

* Flash flooding will remain over mainly rural areas of central
  Siskiyou County.
  Excessive rainfall combined with glacial melt will result in 
  debris flow moving through the Whitney Creek Drainage area. The 
  debris flow can consist of rock, mud, vegetation and other loose 
  materials.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4156 12224 4147 12223 4146 12231 4153 12235

FLASH FLOOD...OBSERVED

$$

MNF

908 
WGUS76 KMFR 280638
FFSMFR

Flash Flood Statement
National Weather Service Medford OR
1138 PM PDT Tue Jul 27 2021

CAC093-280645-
/O.EXP.KMFR.FF.W.0001.000000T0000Z-210728T0645Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Siskiyou CA-
1138 PM PDT Tue Jul 27 2021

...THE FLASH FLOOD WARNING FOR CENTRAL SISKIYOU COUNTY WILL EXPIRE AT
1145 PM PDT TUESDAY...

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

LAT...LON 4156 12224 4147 12223 4146 12231 4153 12235

$$

STOCKTON

The office that day

Everything else NWS Medford, OR issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jul 27, 2:54 PM PDT	Excessive Heat Watch	MFR	Siskiyou	12 hr

Nearby

Flash Flood Warnings in California, 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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.