Alert archive / Nevada / Flash Flood Warnings in 2017

Flash Flood Warning 4, NWS Reno, NV

February 21, 2017Lyon County, Nevada

NWS Reno, NV issued this flash flood warning at Feb 21, 2017, 12:39 PM PST for Lyon County, Nevada. 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
Feb 21, 2017, 12:39 PM PST (20:39 UTC)
Expired
Feb 21, 2017, 6:30 PM PST
In force
6 hr
Issued by
NWS Reno, NV
Area
Storm-based polygon
Flood severity
Major

County Lyon County, NV

The radar

The Reno radar (KRGX), 54 km from the middle of the area, began a volume at 20:42 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

Reno, NV (KREV), launched 12:00Z, 8.7 hours before the alert went out and 117 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, Reno, NV at 12:00Z on 2017-02-21Temperature 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 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Reno, NV at 12:00Z on 2017-02-21The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 122 square meters per square second.1939587897117136156Sfc1 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
679 m above ground
0-6 km bulk shear
103 kt
0-1 km storm-relative helicity
122 m²/s²
0-3 km storm-relative helicity
306 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

855 
WGUS55 KREV 212039
FFWREV
NVC019-220230-
/O.NEW.KREV.FF.W.0004.170221T2039Z-170222T0230Z/
/00000.3.DM.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Reno NV
1239 PM PST TUE FEB 21 2017

...IMMINENT RETENTION POND FAILURE AFFECTING EAST DAYTON...

The National Weather Service in Reno has issued a

* Flash Flood Warning for...
  A Dam Break in...
  Central Lyon County in west central Nevada...

* Until 630 PM PST

* At 1233 PM PST, emergency management reported the imminent failure 
  of the South Dayton Retention Pond in the next 30 minutes to one 
  hour. Between 2 and 4 feet of water could inundate areas of East 
  Dayton within 2 to 3 hours of failure.

* Areas affected include East Dayton including, but not limited to, 
  these streets...Comstock, Sutro, Dayton Valley Road.

Move to higher ground now. This is an extremely dangerous and
life-threatening situation. Do not attempt to travel unless you are
fleeing an area subject to flooding or under an evacuation order.

LAT...LON 3929 11948 3925 11945 3923 11952 3926 11954
      3928 11953

$$

SS
2 follow-up statements
203 
WGUS75 KREV 212158
FFSREV

Flash Flood Statement
National Weather Service Reno NV
158 PM PST TUE FEB 21 2017

NVC019-220230-
/O.CON.KREV.FF.W.0004.000000T0000Z-170222T0230Z/
/00000.0.DM.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Lyon NV-
158 PM PST TUE FEB 21 2017

...THE FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 630 PM PST FOR
NORTHERN LYON COUNTY...

At 153 PM PST, the Lyon County Emergency Manager indicated that the 
South Dayton Retention Pond is full and overflowing into drainages. 
No failure has occurred and no homes or properties are currently 
threatened. However, the situation could change in the next few 
hours.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Pay attention to the latest information from emergency officials and 
the National Weather Service in case the water retention pond fails.

&&

LAT...LON 3928 11951 3926 11951 3925 11952 3926 11954
      3928 11953

$$

SS
780 
WGUS75 KREV 220024
FFSREV

Flash Flood Statement
National Weather Service Reno NV
424 PM PST TUE FEB 21 2017

NVC019-220030-
/O.CAN.KREV.FF.W.0004.000000T0000Z-170222T0230Z/
/00000.0.DM.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Lyon NV-
424 PM PST TUE FEB 21 2017

...THE FLASH FLOOD WARNING FOR NORTHERN LYON COUNTY IS CANCELLED...

We have received word from Lyon County Emergency Management that the 
water has receded in the Southwest Dayton Retention Pond and it is 
no longer expected to fail. With flood waters receding and no threat 
remaining to life or property at this time, the flash flood warning 
is cancelled.

LAT...LON 3928 11951 3926 11951 3925 11952 3926 11954
      3928 11953

$$

DJ

The office that day

Everything else NWS Reno, NV issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Feb 20, 8:26 PM PSTAreal Flood WarningREVWashoe15 hr

Nearby

Flash Flood Warnings in Nevada, 2017Every flash flood warning in 2017

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.