Alert archive / California / Flash Flood Warnings in 2021

Flash Flood Warning 2, NWS Phoenix, AZ

January 20, 2021Imperial County, California

NWS Phoenix, AZ issued this flash flood warning at Jan 20, 2021, 11:29 AM PST for Imperial County, California. It was in force for 6 hr. 2 reports 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
Jan 20, 2021, 11:29 AM PST (19:29 UTC)
Expired
Jan 20, 2021, 5:30 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), 75 km from the middle of the area, began a volume at 19:31 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

TimeReportWhereRemark
Jan 20, 12:18 PM PSTFLASH FLOOD5 Ene Glamis, CA***DELAYED REPORT** LAW ENFORCEMENT REPORTED STRANDED VEHICLES ON HIGHWAY 78 DUE TO FLOODING.
Jan 20, 12:32 PM PSTHEAVY RAIN 0.511 Ene Glamis, CA***DELAYED REPORT*** LAW ENFORCEMENT REPORTED WATER FLOWING ACROSS HIGHWAY 78, BUT THE ROAD REMAINED PASSABLE.

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

The nearest sounding before it

San Diego, CA (KNKX), launched 12:00Z, 7.5 hours before the alert went out and 217 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, San Diego, CA at 12:00Z on 2021-01-20Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 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, San Diego, CA at 12:00Z on 2021-01-20The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 35 square meters per square second.193958Sfc1 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
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.

244 
WGUS55 KPSR 201929
FFWPSR
CAC025-210130-
/O.NEW.KPSR.FF.W.0002.210120T1929Z-210121T0130Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Phoenix AZ
1129 AM PST Wed Jan 20 2021

The National Weather Service in Phoenix has issued a

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

* Until 530 PM PST Wednesday.

* At 1129 AM PST, Doppler radar indicated heavy rain across the 
  warned area. Between 0.5 and 1 inch of rain has fallen. Flash 
  flooding is ongoing or expected to begin shortly along route 78.

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

  SOURCE...Doppler radar.

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

* Some locations that will experience flash flooding include...
  mainly rural areas of Northeastern 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 3329 11473 3321 11483 3311 11486 3307 11490
      3301 11496 3299 11507 3302 11508 3304 11501
      3306 11497 3311 11495 3311 11491 3325 11487
      3332 11477

FLASH FLOOD...RADAR INDICATED
FLASH FLOOD DAMAGE THREAT...CONSIDERABLE

$$

18
2 follow-up statements
276 
WGUS75 KPSR 202036
FFSPSR

Flash Flood Statement
National Weather Service Phoenix AZ
1236 PM PST Wed Jan 20 2021

CAC025-210130-
/O.CON.KPSR.FF.W.0002.000000T0000Z-210121T0130Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Imperial CA-
1236 PM PST Wed Jan 20 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 530 PM PST THIS 
AFTERNOON FOR NORTHEASTERN IMPERIAL COUNTY...

At 1236 PM PST, Local law enforcement reported water flowing across 
highway 78 and vehicles stuck. Heavy rain continues across the 
warned area with between 0.5 and 1.5 inches of rain. 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 Northeastern 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 3329 11473 3321 11483 3311 11486 3307 11490
      3301 11496 3299 11507 3302 11508 3304 11501
      3306 11497 3311 11495 3311 11491 3325 11487
      3332 11477

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

$$

18
856 
WGUS75 KPSR 210126
FFSPSR

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

CAC025-210136-
/O.EXP.KPSR.FF.W.0002.000000T0000Z-210121T0130Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Imperial CA-
526 PM PST Wed Jan 20 2021

...FLASH FLOOD WARNING WILL EXPIRE AT 530 PM PST THIS AFTERNOON FOR 
NORTHEASTERN 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 any remaining road closures.

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

LAT...LON 3329 11473 3321 11483 3311 11486 3307 11490
      3301 11496 3299 11507 3302 11508 3304 11501
      3306 11497 3311 11495 3311 11491 3325 11487
      3332 11477

$$

INS

The office that day

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

IssuedProductOfficeCountiesLasted
Jan 20, 10:11 AM PSTFlash Flood Warning Considerable damage threatPSRImperial6 hr

Nearby

Flash Flood Warnings in California, 2021Every 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.