Alert archive / California / Flash Flood Warnings in 2021

Flash Flood Warning 1, NWS Phoenix, AZ

January 20, 2021Imperial County, California

NWS Phoenix, AZ issued this flash flood warning at Jan 20, 2021, 10:11 AM PST for Imperial County, California. It was in force for 6 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: Jan 20, 2021, 10:11 AM PST (18:11 UTC)
Expired: Jan 20, 2021, 4:00 PM PST
In force: 6 hr
Issued by: NWS Phoenix, AZ
Area: Storm-based polygon
Damage threat: Considerable
Flood severity: None

County Imperial County, CA

The radar

The Yuma radar (KYUX), 51 km from the middle of the area, began a volume at 18:14 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

San Diego, CA (KNKX), launched 12:00Z, 6.2 hours before the alert went out and 218 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: 2031 m above ground
0-6 km bulk shear: 12 kt
0-1 km storm-relative helicity: 35 m²/s²
0-3 km storm-relative helicity: 106 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

816 
WGUS55 KPSR 201811
FFWPSR
CAC025-210000-
/O.NEW.KPSR.FF.W.0001.210120T1811Z-210121T0000Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Phoenix AZ
1011 AM PST Wed Jan 20 2021

The National Weather Service in Phoenix has issued a

* Flash Flood Warning for...
  Southeastern Imperial County in southeastern California...

* Until 400 PM PST.

* At 1011 AM PST, Moderate to heavy rain has fallen across the 
  warned area. Between 0.5 and 1 inch of rain has fallen. Law 
  enforcement reported flash flooding ongoing and has closed Ogilby 
  road

  HAZARD...Life threatening flash flooding. Heavy rain producing
           flash flooding.

  SOURCE...Law enforcement.

  IMPACT...Life threatening flash flooding of creeks and streams

* Some locations that will experience flash flooding include...
  mainly rural areas of Southeastern Imperial County

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

In hilly terrain there are hundreds of low water crossings which are 
potentially dangerous in heavy rain. Do not attempt to cross flooded 
roads. Find an alternate route.

&&

LAT...LON 3278 11485 3290 11489 3297 11492 3304 11494
      3309 11493 3309 11489 3296 11486 3292 11481
      3275 11481 3276 11486

FLASH FLOOD...OBSERVED
FLASH FLOOD DAMAGE THREAT...CONSIDERABLE

$$

18

3 follow-up statements

169 
WGUS75 KPSR 201955
FFSPSR

Flash Flood Statement
National Weather Service Phoenix AZ
1155 AM PST Wed Jan 20 2021

CAC025-210000-
/O.CON.KPSR.FF.W.0001.000000T0000Z-210121T0000Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Imperial CA-
1155 AM PST Wed Jan 20 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 4 PM PST THIS 
AFTERNOON FOR SOUTHEASTERN IMPERIAL COUNTY...

At 1155 AM PST, Local law enforcement reported flooding on Ogilby 
Road. Heavy rain across the warned area continues and between 0.5 
and 1.5 inches of rain has already fallen. Flash flooding is ongoing 
or expected to begin shortly.

HAZARD...Life threatening flash flooding. Heavy rain producing
         flash flooding.

SOURCE...Law enforcement.

IMPACT...Life threatening flash flooding of creeks and streams,
         and highways

Some locations that will experience flash flooding include...
  mainly rural areas of Southeastern Imperial County

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Excessive runoff from heavy rainfall will cause flooding of small 
creeks and streams, country roads, farmland, and other low lying 
spots.

In hilly terrain there are hundreds of low water crossings which are 
potentially dangerous in heavy rain. Do not attempt to cross flooded 
roads. Find an alternate route.

&&

LAT...LON 3278 11485 3290 11489 3297 11492 3304 11494
      3309 11493 3309 11489 3296 11486 3292 11481
      3275 11481 3276 11486

FLASH FLOOD...OBSERVED
FLASH FLOOD DAMAGE THREAT...CONSIDERABLE

$$

18

151 
WGUS75 KPSR 202111
FFSPSR

Flash Flood Statement
National Weather Service Phoenix AZ
111 PM PST Wed Jan 20 2021

CAC025-210000-
/O.CON.KPSR.FF.W.0001.000000T0000Z-210121T0000Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Imperial CA-
111 PM PST Wed Jan 20 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 4 PM PST THIS 
AFTERNOON FOR SOUTHEASTERN IMPERIAL COUNTY...

At 111 PM PST, Although heavy rain has ended, local law enforcement 
reported Olgilby road remained closed due to flooding. Between 0.5 
and 1.5 inches of rain have fallen. Flash flooding is already 
occurring.

HAZARD...Life threatening flash flooding. Heavy rain producing
         flash flooding.

SOURCE...Law enforcement.

IMPACT...Life threatening flash flooding of creeks and streams,
         and highways

Some locations that will experience flash flooding include...
  mainly rural areas of Southeastern Imperial County

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Excessive runoff from heavy rainfall will cause flooding of small 
creeks and streams, country roads, farmland, and other low lying 
spots.

In hilly terrain there are hundreds of low water crossings which are 
potentially dangerous in heavy rain. Do not attempt to cross flooded 
roads. Find an alternate route.

&&

LAT...LON 3278 11485 3290 11489 3297 11492 3304 11494
      3309 11493 3309 11489 3296 11486 3292 11481
      3275 11481 3276 11486

FLASH FLOOD...OBSERVED
FLASH FLOOD DAMAGE THREAT...CONSIDERABLE

$$

18

941 
WGUS75 KPSR 202359
FFSPSR

Flash Flood Statement
National Weather Service Phoenix AZ
359 PM PST Wed Jan 20 2021

CAC025-210009-
/O.EXP.KPSR.FF.W.0001.000000T0000Z-210121T0000Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Imperial CA-
359 PM PST Wed Jan 20 2021

...FLASH FLOOD WARNING WILL EXPIRE AT 4 PM PST THIS AFTERNOON FOR 
SOUTHEASTERN IMPERIAL COUNTY...

The heavy rain has ended. Flooding is no longer expected to pose a 
threat at this time. However, additional rounds of showers will 
remain possible. Please continue to heed remaining road closures.

A Flash Flood Watch remains in effect until 1200 AM PST Thursday for 
portions of southwest Arizona and California.

LAT...LON 3278 11485 3290 11489 3297 11492 3304 11494
      3309 11493 3309 11489 3296 11486 3292 11481
      3275 11481 3276 11486

$$

INS

The office that day

Everything else NWS Phoenix, AZ issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jan 20, 11:29 AM PST	Flash Flood Warning Considerable damage threat	PSR	Imperial	6 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.