Alert archive / California / Flash Flood Warnings in 2020

Flash Flood Warning 21, NWS Phoenix, AZ

April 8, 2020Imperial County, California

NWS Phoenix, AZ issued this flash flood warning at Apr 8, 2020, 9:23 AM PDT for Imperial County, California. It was in force for 4 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
Apr 8, 2020, 9:23 AM PDT (16:23 UTC)
Expired
Apr 8, 2020, 1:15 PM PDT
In force
4 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), 113 km from the middle of the area, began a volume at 16:25 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

Yuma Prvg Ground, AZ (K1Y7), launched 12:00Z, 4.4 hours before the alert went out and 130 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, Yuma Prvg Ground, AZ at 12:00Z on 2020-04-08Temperature 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, Yuma Prvg Ground, AZ at 12:00Z on 2020-04-08The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 209 square meters per square second.1939587897Sfc1 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
1384 m above ground
0-6 km bulk shear
68 kt
0-1 km storm-relative helicity
209 m²/s²
0-3 km storm-relative helicity
318 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

170 
WGUS55 KPSR 081623
FFWPSR
CAC025-082015-
/O.NEW.KPSR.FF.W.0021.200408T1623Z-200408T2015Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Phoenix AZ
923 AM PDT Wed Apr 8 2020

The National Weather Service in Phoenix has issued a

* Flash Flood Warning for...
  North central Imperial County in southeastern California...

* Until 115 PM PDT.

* At 920 AM PDT, Doppler radar indicated heavy rain across the 
  warned area. Up to one inch 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...Radar indicated.

  IMPACT...Life threatening flash flooding of creeks and streams, 
           urban areas, highways, streets and underpasses.

* Some locations that will experience flooding include...
  Calipatria, Slab City and Niland. 

* This includes CA Route 111 between mile markers 31 and 45.
 
Additional rainfall amounts of up to a half inch per hour are 
possible in the warned area.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Please report flooding to your local law enforcement agency when you
can do so safely.

A Flash Flood Warning means that flooding is imminent or occurring.
If you are in the warned area move to higher ground immediately.
Residents living along streams and creeks should take immediate
precautions to protect life and property.

&&

LAT...LON 3322 11564 3343 11546 3342 11531 3310 11526
      3309 11552

FLASH FLOOD...RADAR INDICATED
FLASH FLOOD DAMAGE THREAT...CONSIDERABLE
EXPECTED RAINFALL...1-2 INCHES IN 3 HOURS.

$$

LJH
2 follow-up statements
113 
WGUS75 KPSR 081858
FFSPSR

Flash Flood Statement
National Weather Service Phoenix AZ
1158 AM PDT Wed Apr 8 2020

CAC025-082015-
/O.CON.KPSR.FF.W.0021.000000T0000Z-200408T2015Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Imperial CA-
1158 AM PDT Wed Apr 8 2020

...THE FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 115 PM PDT FOR
NORTH CENTRAL IMPERIAL COUNTY...

At 1156 AM PDT, Doppler radar indicated that heavy rainfall 
producing up to one and a half inches of rain has already fallen 
across the warned area. Flash flooding is ongoing or expected to 
begin shortly.

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

SOURCE...Radar indicated.

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

Some locations that will experience flooding include...
Slab City and Niland. 

This includes CA Route 111 between mile markers 39 and 45.
 
PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Please report flooding to your local law enforcement agency when you
can do so safely.

&&

LAT...LON 3319 11561 3326 11560 3343 11546 3342 11531
      3325 11528

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

$$

LJH
321 
WGUS75 KPSR 082010
FFSPSR

Flash Flood Statement
National Weather Service Phoenix AZ
110 PM PDT Wed Apr 8 2020

CAC025-082019-
/O.EXP.KPSR.FF.W.0021.000000T0000Z-200408T2015Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Imperial CA-
110 PM PDT Wed Apr 8 2020

...THE FLASH FLOOD WARNING FOR NORTH CENTRAL IMPERIAL COUNTY WILL
EXPIRE AT 115 PM PDT...

The heavy rain has ended. Flood waters have receded. Flooding is no
longer expected to pose a threat. Please continue to heed any
remaining road closures.

LAT...LON 3319 11561 3326 11560 3343 11546 3342 11531
      3325 11528

$$

LJH

The office that day

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

IssuedProductOfficeCountiesLasted
Apr 8, 8:21 AM PDTAreal Flood AdvisoryPSRImperial3 hr
Apr 8, 9:06 AM PDTAreal Flood AdvisoryPSRRiverside, San Bernardino3 hr
Apr 8, 2:48 PM PDTSpecial Weather StatementPSRImperial27 min
Apr 8, 3:15 PM PDTSpecial Weather StatementPSRImperial30 min

Nearby

Flash Flood Warnings in California, 2020Every flash flood warning in 2020

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.