Alert archive / Nevada / River Flood Warnings in 2017

River Flood Warning 24, NWS Reno, NV

May 18, 2017Lyon County, Nevada

NWS Reno, NV issued this river flood warning at May 18, 2017, 12:36 PM PDT for Lyon County, Nevada. It took effect at May 21, 2017, 3:00 PM PDT. It was in force for 18 days.

The area

The outline as issued.

The facts

Issued
May 18, 2017, 12:36 PM PDT (19:36 UTC)
In effect from
May 21, 2017, 3:00 PM PDT
Expired
Jun 8, 2017, 3:13 AM PDT
In force
18 days
Issued by
NWS Reno, NV
Area
Storm-based polygon
Flood severity
Moderate

County Lyon County, NV

The radar

The Reno radar (KRGX), 90 km from the middle of the area, began a volume at 19:38 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 river

Written for the forecast point Walker River near Mason - Snyder Lane (MASN2).

Action stage
9 ft
Minor stage
9.8 ft
Moderate stage
11 ft
Major stage
11.6 ft

This gauge today: stage, forecast and historic crests

Stage from the USGS instantaneous record for site 10300600, one reading an hour, from a day before the product to a day after it ended. Flood stages are today's.

The text

As transmitted.

431 
WGUS45 KREV 181936
FLWREV


Flood Warning
National Weather Service Reno NV
1236 PM PDT Thu May 18 2017

...The National Weather Service in Reno has issued a Flood Warning 
for the following rivers in Nevada... 

  Walker River Near Mason affecting Lyon County

For the Mainstem Walker River...including Mason...Moderate flooding 
is forecast.

Rising temperatures this weekend and early next week will produce
increased snowmelt in the upper part of the Walker River basin. This
increased runoff will create very high flows in the Walker River
basin from above the confluence of the East and West Walker Rivers
downstream through the Mason Valley/Yerington area to Weber
Reservoir. 

These high flows are likely to last into June and may also cause
flooding from Coleville through the Antelope and Smith Valleys along
the West Walker River and along the East Walker River above Mason
Valley.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

These river forecasts are based on forecast rainfall and temperature 
conditions at time of issuance. If actual conditions vary from these
forecasts...river conditions will vary accordingly. River forecasts
include current and planned reservoir releases.

&&

NVC019-231936-
/O.NEW.KREV.FL.W.0024.170521T2200Z-000000T0000Z/
/MASN2.2.ER.170521T2200Z.170523T1100Z.000000T0000Z.UU/
1236 PM PDT Thu May 18 2017

The National Weather Service in Reno has issued a 

* Flood Warning for 
  The Walker River Near Mason.
* from Sunday afternoon until further notice...Or until the warning 
  is cancelled.
* At 11:15 AM Thursday the stage was 9.4 feet.
* Flood stage is 9.8 feet.
* Moderate flooding is forecast.
* Forecast...Rise above flood stage by Sunday afternoon and continue 
  to rise to near 11.2 feet by early Tuesday morning. Additional 
  rises are likely thereafter.
* Impact...At 11.0 feet...Moderate flooding of lowlands...pasture and 
  farmland adjacent to the river throughout Mason Valley-Yerington
  area. Minor flooding is likely along the East Walker River from
  above Strosnider Ditch to the confluence with the West Walker.
  Several rural and some secondary public roads begin to flood. 
  Yards and basements of lowest homes adjacent to the river in
  Mason and Yerington begin flooding. Possible damage to irrigation
  structures and levees. The river is likely to be higher than
  the floods of summer 2011.

&&

LAT...LON 3881 11920 3917 11927 3919 11898 3912 11890 3885 11908

$$
18 follow-up statements
553 
WGUS45 KREV 191950
FLWREV


Flood Warning
National Weather Service Reno NV
1250 PM PDT Fri May 19 2017

...Forecast flooding changed from Moderate to Major severity for the 
following rivers in Nevada...

  Walker River Near Mason affecting Lyon County

For the Mainstem Walker River...including Mason...Major flooding is 
forecast.

Rising temperatures this weekend and early next week will produce
increased snowmelt in the upper part of the Walker River basin. This
increased runoff will create very high flows in the Walker River
basin from above the confluence of the East and West Walker Rivers
downstream through the Mason Valley/Yerington area to Weber
Reservoir. Major to near record flooding is possible through the
Mason Valley. 

These high flows are likely to last into June and may also cause
flooding from Coleville through the Antelope and Smith Valleys along
the West Walker River and along the East Walker River above Mason
Valley.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

These river forecasts are based on forecast rainfall and temperature 
conditions at time of issuance. If actual conditions vary from these
forecasts...river conditions will vary accordingly. River forecasts
include current and planned reservoir releases.

&&

NVC019-221950-
/O.EXT.KREV.FL.W.0024.170522T1200Z-000000T0000Z/
/MASN2.3.ER.170522T1200Z.170524T1200Z.000000T0000Z.UU/
1250 PM PDT Fri May 19 2017

...Forecast flooding increased from Moderate to Major severity...
The Flood Warning continues for 
 The Walker River Near Mason.
* from late Sunday night until further notice.
* At 12:15 PM Friday the stage was 9.2 feet.
* Flood stage is 9.8 feet.
* Major flooding is forecast.
* Forecast...Rise above flood stage by early Monday morning and 
  continue to rise to near 12.1 feet by early Wednesday morning. 
  Additional rises are possible thereafter.
* Impact...At 12.0 feet...Major flooding in the Mason
  Valley/Yerington area.  Many homes...businesses...structures...
  roads...bridges and well over a thousand acres of farmland and
  pasture near the river could become flooded. Some portions of
  Yerington will likely flood. Flooding could reach near record
  levels similar to the extent of flooding in January 1997.

&&

LAT...LON 3881 11920 3917 11927 3919 11898 3912 11890 3885 11908


$$
584 
WGUS85 KREV 192253
FLSREV
Flood Statement
National Weather Service Reno NV
353 PM PDT Fri May 19 2017

...The Flood Warning continues for the following rivers in Nevada...

  Walker River Near Mason affecting Lyon County

Rising temperatures this weekend and early next week will produce
increased snowmelt in the upper part of the Walker River basin. This
increased runoff will create very high flows in the Walker River
basin from above the confluence of the East and West Walker Rivers
downstream through the Mason Valley/Yerington area to Weber
Reservoir. Major to near record flooding is possible through the
Mason Valley. 

These high flows are likely to last into June and may also cause
flooding from Coleville through the Antelope and Smith Valleys along
the West Walker River and along the East Walker River above Mason
Valley.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

These river forecasts are based on forecast rainfall and temperature 
conditions at time of issuance. If actual conditions vary from these
forecasts...river conditions will vary accordingly. River forecasts
include current and planned reservoir releases.

&&

NVC019-222253-
/O.CON.KREV.FL.W.0024.170522T1200Z-000000T0000Z/
/MASN2.3.SM.170522T1200Z.170524T1200Z.000000T0000Z.UU/
353 PM PDT Fri May 19 2017

The Flood Warning continues for
  The Walker River Near Mason.
* from late Sunday night until further notice.
* At  3:15 PM Friday the stage was 9.2 feet.
* Flood stage is 9.8 feet.
* Major flooding is forecast.
* Forecast...Rise above flood stage by early Monday morning and 
  continue to rise to near 12.1 feet by early Wednesday morning. 
  Additional rises are possible thereafter.
* Impact...At 12.0 feet...Major flooding in the Mason
  Valley/Yerington area.  Many homes...businesses...structures...
  roads...bridges and well over a thousand acres of farmland and
  pasture near the river could become flooded. Some portions of
  Yerington will likely flood. Flooding could reach near record
  levels similar to the extent of flooding in January 1997.
  
&&

LAT...LON 3881 11920 3917 11927 3919 11898 3912 11890 3885 11908


$$
524 
WGUS85 KREV 201812
FLSREV
Flood Statement
National Weather Service Reno NV
1112 AM PDT Sat May 20 2017

...The Flood Warning continues for the following rivers in Nevada...
 
  Walker River Near Mason affecting Lyon County

For the Mainstem Walker River...including Mason...Major flooding 
is forecast.

Rising temperatures will produce increased snowmelt in the upper part 
of the Walker River basin. This increased runoff will create very high 
flows in the Walker River basin from above the confluence of the East 
and West Walker Rivers downstream through the Mason Valley/Yerington
area to Weber Reservoir. Major to near record flooding is possible 
through the Mason Valley. 

These high flows are likely to last into June and may also cause
flooding from Coleville through the Antelope and Smith Valleys along
the West Walker River and along the East Walker River above Mason
Valley.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

These river forecasts are based on snowmelt and temperature conditions 
at time of issuance. If actual conditions vary from these forecasts...
river conditions will vary accordingly. River forecasts include current 
and planned reservoir releases.

&&

NVC019-222012-
/O.EXT.KREV.FL.W.0024.170522T2000Z-000000T0000Z/
/MASN2.3.SM.170522T2000Z.170525T1000Z.000000T0000Z.UU/
1112 AM PDT Sat May 20 2017

The Flood Warning continues for
  The Walker River Near Mason.
* from Monday afternoon until further notice.
* At  9:15 AM Saturday the stage was 9.2 feet.
* Flood stage is 9.8 feet.
* Major flooding is forecast.
* Forecast...Rise above flood stage by early Monday afternoon and 
  continue to rise to near 12.9 feet by early Thursday morning. 
  Additional rises are expected thereafter.
* Impact...Major flooding in the Mason Valley-Yerington area. Well 
  over a thousand acres of farmland and pasture could become flooded...
  as well as some portions of Yerington. Flows are forecast to be higher 
  than 1983 and 1986...at about 3300 CFS...by Wednesday evening. HOWEVER...
  IT IS IMPOSSIBLE TO FORECAST WHETHER THE RIVER WILL BREACH through 
  the channel in Mason Valley. IF THE RIVER BREACHES...IT COULD CAUSE 
  MUCH MORE SIGNIFICANT IMPACTS...INCLUDING IMPACTS FOR MUCH OF YERINGTON.
  
&&

LAT...LON 3881 11920 3917 11927 3919 11898 3912 11890 3885 11908


$$
013 
WGUS85 KREV 211922
FLSREV
Flood Statement
National Weather Service Reno NV
1222 PM PDT Sun May 21 2017

...The Flood Warning continues for the following rivers in Nevada...
 
  Walker River Near Mason affecting Lyon County

For the Mainstem Walker River...including Mason...Major flooding 
is forecast.

Rising temperatures will produce increased snowmelt in the upper
part of the Walker River basin. This increased runoff will create
very high flows in the Walker River basin from above the confluence
of the East and West Walker Rivers downstream through the Mason
Valley/Yerington area to Weber Reservoir. Major to near record
flooding is possible through the Mason Valley. 

These high flows are likely to last into June and may also cause
flooding from Coleville through the Antelope and Smith Valleys along
the West Walker River and along the East Walker River above Mason
Valley.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

These river forecasts are based on snowmelt and temperature
conditions at time of issuance. If actual conditions vary from these
forecasts...river conditions will vary accordingly. River forecasts
include current and planned reservoir releases.

&&

NVC019-241922-
/O.EXT.KREV.FL.W.0024.170523T1100Z-000000T0000Z/
/MASN2.3.SM.170523T1100Z.170526T1200Z.000000T0000Z.UU/
1222 PM PDT Sun May 21 2017

The Flood Warning continues for
  The Walker River Near Mason.
* from early Tuesday morning until further notice.
* At 11:15 AM Sunday the stage was 9.2 feet.
* Flood stage is 9.8 feet.
* Major flooding is forecast.
* Forecast...Rise above flood stage by early Tuesday morning and 
  continue to rise to near 13.3 feet by early Friday morning. 
  Additional rises are possible thereafter.
* Impact...At 13.0 feet...Near record flooding in the Mason 
  Valley-Yerington area. Significant flooding of homes and businesses
  in Yerington is possible if breaches develop and the river spreads 
  east. Extensive flooding of agricultural lands likely. Many primary
  and secondary roads flooded. About 3500 cfs.  

&&

LAT...LON 3881 11920 3917 11927 3919 11898 3912 11890 3885 11908


$$
145 
WGUS85 KREV 221733
FLSREV
Flood Statement
National Weather Service Reno NV
1033 AM PDT Mon May 22 2017

...The Flood Warning continues for the following rivers in Nevada...
 
  Walker River Near Mason affecting Lyon County

For the Mainstem Walker River...including Mason...Minor flooding 
is now forecast.

Above normal temperatures will produce increased snowmelt in the upper
part of the Walker River basin through this week. This increased runoff will create high flows in the Walker River basin from above the confluence
of the East and West Walker Rivers downstream through the Mason
Valley/Yerington area to Weber Reservoir. Up to moderate flooding is 
possible through the Mason Valley. These high flows are likely to 
last into June.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

These river forecasts are based on snowmelt and temperature
conditions at time of issuance. If actual conditions vary from these
forecasts...river conditions will vary accordingly. River forecasts
include current and planned reservoir releases.

&&

NVC019-232333-
/O.EXT.KREV.FL.W.0024.170524T1600Z-000000T0000Z/
/MASN2.1.SM.170524T1600Z.170526T2200Z.000000T0000Z.UU/
1033 AM PDT Mon May 22 2017

The Flood Warning continues for
  The Walker River Near Mason.
* from Wednesday morning until further notice.
* At 10:15 AM Monday the stage was 9.3 feet.
* Flood stage is 9.8 feet.
* Minor flooding is forecast.
* Forecast...Rise above flood stage by late Wednesday morning and 
  continue to rise to near 10.8 feet by Friday afternoon.
* Impact...At 10.8 feet...Minor flooding of lowlands...pasture and 
  farmland adjacent to the river throughout the Mason 
  Valley-Yerington area. Some rural roads flood. Preventative 
  sandbagging of low structures in Mason and Yerington may be 
  necessary as river rises...but little flooding occurs.  Some minor 
  flooding of basements and yards in Mason. 

&&

LAT...LON 3881 11920 3917 11927 3919 11898 3912 11890 3885 11908


$$
856 
WGUS85 KREV 221738 CCA
FLSREV
Flood Statement
National Weather Service Reno NV
1033 AM PDT Mon May 22 2017

...The Flood Warning continues for the following rivers in Nevada...
 
  Walker River Near Mason affecting Lyon County

For the Mainstem Walker River...including Mason...Minor flooding 
is now forecast.

Above normal temperatures will produce increased snowmelt in the upper
part of the Walker River basin through this week. This increased
runoff will create high flows in the Walker River basin from above
the confluence of the East and West Walker Rivers downstream through
the Mason Valley/Yerington area to Weber Reservoir. Up to moderate
flooding is possible through the Mason Valley. These high flows are
likely to last into June.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

These river forecasts are based on snowmelt and temperature
conditions at time of issuance. If actual conditions vary from these
forecasts...river conditions will vary accordingly. River forecasts
include current and planned reservoir releases.

&&

NVC019-232333-
/O.EXT.KREV.FL.W.0024.170524T1600Z-000000T0000Z/
/MASN2.1.SM.170524T1600Z.170526T2200Z.000000T0000Z.UU/
1033 AM PDT Mon May 22 2017

The Flood Warning continues for
  The Walker River Near Mason.
* from Wednesday morning until further notice.
* At 10:15 AM Monday the stage was 9.3 feet.
* Flood stage is 9.8 feet.
* Minor flooding is forecast.
* Forecast...Rise above flood stage by late Wednesday morning and 
  continue to rise to near 10.8 feet by Friday afternoon.
* Impact...At 10.8 feet...Minor flooding of lowlands...pasture and 
  farmland adjacent to the river throughout the Mason 
  Valley-Yerington area. Some rural roads flood. Preventative 
  sandbagging of low structures in Mason and Yerington may be 
  necessary as river rises...but little flooding occurs.  Some minor 
  flooding of basements and yards in Mason. 

&&

LAT...LON 3881 11920 3917 11927 3919 11898 3912 11890 3885 11908


$$
598 
WGUS85 KREV 231639
FLSREV
Flood Statement
National Weather Service Reno NV
939 AM PDT Tue May 23 2017

...The Flood Warning continues for the following rivers in Nevada...
 
  Walker River Near Mason affecting Lyon County

For the Mainstem Walker River...including Mason...Minor flooding is 
forecast.

Above normal temperatures will produce increased snowmelt in the
upper part of the Walker River basin through the Memorial Day
weekend and into next week. This increased runoff will create high
flows in the Walker River basin from above the confluence of the East
and West Walker Rivers downstream through the Mason Valley and
Yerington area to Weber Reservoir. High flows are likely to last into
June.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

These river forecasts are based on snowmelt and temperature
conditions at time of issuance. If actual conditions vary from these
forecasts, river conditions will vary accordingly. River forecasts
include current and planned reservoir releases.

&&

NVC019-242239-
/O.EXT.KREV.FL.W.0024.170525T1700Z-000000T0000Z/
/MASN2.1.SM.170525T1700Z.170527T0000Z.000000T0000Z.UU/
939 AM PDT Tue May 23 2017

The Flood Warning continues for 
 The Walker River Near Mason.
* from Thursday morning until further notice.
* At 8:15 AM Tuesday the stage was 9.3 feet.
* Flood stage is 9.8 feet.
* Minor flooding is forecast. Moderate flooding is possible next
  week.
* Forecast...Rise above flood stage sometime Thursday and remain
  above flood stage into the Memorial Day weekend. The river will
  likely rise again next week and may exceed moderate flood stage.
* Impact...Minor flooding of lowlands, roads, pasture and farmland
  near the river in the Mason Valley-Yerington area. Flood impacts
  may become more severe next week.

&&

LAT...LON 3881 11920 3917 11927 3919 11898 3912 11890 3885 11908


$$
073 
WGUS85 KREV 242007
FLSREV
Flood Statement
National Weather Service Reno NV
107 PM PDT Wed May 24 2017

...The Flood Warning continues for the following rivers in Nevada...
 
  Walker River Near Mason affecting Lyon County

Warm temperatures in the high Sierra will produce increased snowmelt
in the upper part of the Walker River basin into next week. This
increased runoff will create high flows in the Walker River basin
from above the confluence of the East and West Walker Rivers
downstream through the Mason Valley and Yerington area to Weber
Reservoir. High flows are likely to last into June.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

These river forecasts are based on forecast rainfall and temperature 
conditions at time of issuance. If actual conditions vary from these
forecasts...river conditions will vary accordingly. River forecasts
include current and planned reservoir releases.

&&

NVC019-260207-
/O.EXT.KREV.FL.W.0024.170526T2200Z-170528T1600Z/
/MASN2.1.SM.170526T2200Z.170526T2200Z.170528T0400Z.UU/
107 PM PDT Wed May 24 2017

The Flood Warning continues for
  The Walker River Near Mason.
* from Friday afternoon to Sunday morning.
* At 12:15 PM Wednesday the stage was 9.3 feet.
* Flood stage is 9.8 feet.
* Forecast...The river is expected to rise to near flood stage Friday
  afternoon. Additional rises are possible next week.
* Impact...Minor flooding of lowlands, roads, pasture and farmland
  near the river in the Mason Valley-Yerington area. Flood impacts
  may become more severe next week.

&&

LAT...LON 3881 11920 3917 11927 3919 11898 3912 11890 3885 11908


$$
786 
WGUS85 KREV 260041
FLSREV
Flood Statement
National Weather Service Reno NV
541 PM PDT Thu May 25 2017

...The Flood Warning continues for the following rivers in Nevada...
 
  Walker River Near Mason affecting Lyon County

Warm temperatures in the high Sierra will produce increased snowmelt
in the upper part of the Walker River basin into next week. This
increased runoff will create high flows in the Walker River basin
from above the confluence of the East and West Walker Rivers
downstream through the Mason Valley and Yerington area to Weber
Reservoir. High flows are likely to last into June.

The forecast for the Mason-Yerington area is changing each day due
to changes in the snowpack and forecast temperatures and more
precise management of both Bridgeport Reservoir and Topaz Lake.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

These river forecasts are based on forecast rainfall and temperature 
conditions at time of issuance. If actual conditions vary from these
forecasts...river conditions will vary accordingly. River forecasts
include current and planned reservoir releases.

&&

NVC019-290041-
/O.EXT.KREV.FL.W.0024.170529T1900Z-000000T0000Z/
/MASN2.1.SM.170529T1900Z.170530T0100Z.000000T0000Z.UU/
541 PM PDT Thu May 25 2017

The Flood Warning continues for
  The Walker River Near Mason.
* from Monday afternoon until further notice.
* At 5:15 PM Thursday the stage was 9.5 feet.
* Flood stage is 9.8 feet.
* Forecast...the river will rise to around 10.0 feet by Monday.
  Additional rises are likely later next week.
* Impact...Minor flooding of lowlands, roads, pasture and farmland
  near the river in the Mason Valley-Yerington area. Flood impacts
  may become more severe next week.

&&

LAT...LON 3881 11920 3917 11927 3919 11898 3912 11890 3885 11908


$$
523 
WGUS85 KREV 262255
FLSREV
Flood Statement
National Weather Service Reno NV
355 PM PDT Fri May 26 2017

...The Flood Warning continues for the following rivers in Nevada...
 
  Walker River Near Mason affecting Lyon County

Above normal temperatures in the high Sierra will continue producing
increased snowmelt in the upper part of the Walker River basin later
this weekend and early next week. This increased runoff will create
high flows in the Walker River basin from above the confluence of the
East and West Walker Rivers downstream through the Mason Valley and
Yerington area to Weber Reservoir. High flows are likely to last well
into June.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

These river forecasts are based on forecast rainfall and temperature 
conditions at time of issuance. If actual conditions vary from these
forecasts...river conditions will vary accordingly. River forecasts
include current and planned reservoir releases.

&&

NVC019-282255-
/O.EXT.KREV.FL.W.0024.170527T0100Z-000000T0000Z/
/MASN2.1.SM.170527T0100Z.170530T2200Z.000000T0000Z.UU/
355 PM PDT Fri May 26 2017

The Flood Warning continues for
  The Walker River Near Mason.
* until further notice.
* At 3:15 PM Friday the stage was 9.7 feet.
* Flood stage is 9.8 feet.
* Minor flooding is forecast. The river will continue to slowly rise
  into early next week. Additional rises are likely late next week. 
* Impact...At 10.3 feet...Minor flooding of lowlands...pasture and 
  farmland begin in Mason Valley-Yerington area. Preventative
  sandbagging of lowest homes and businesses immediately adjacent to
  river should begin if further rises are possible...but little
  flooding occurs.  Some isolated flooding of rural roads.  

&&

LAT...LON 3881 11920 3917 11927 3919 11898 3912 11890 3885 11908


$$
937 
WGUS85 KREV 282155
FLSREV
Flood Statement
National Weather Service Reno NV
255 PM PDT Sun May 28 2017

...The Flood Warning continues for the following rivers in Nevada... 

 Walker River Near Mason affecting Lyon County

Above normal temperatures in the high Sierra will continue producing
increased snowmelt in the upper part of the Walker River basin the
week ahead with a rapid increase in flow anticipated by the end of
the work week. This increased runoff will create high flows in the
Walker River basin from above the confluence of the East and West
Walker Rivers downstream through the Mason Valley and Yerington area
to Weber Reservoir. High flows are likely to last well into June.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

These river forecasts are based on forecast rainfall and temperature 
conditions at time of issuance. If actual conditions vary from these
forecasts...river conditions will vary accordingly. River forecasts
include current and planned reservoir releases.

&&

NVC019-310955-
/O.CON.KREV.FL.W.0024.000000T0000Z-000000T0000Z/
/MASN2.1.SM.170528T1940Z.170601T2300Z.000000T0000Z.UU/
255 PM PDT Sun May 28 2017

The Flood Warning continues for
  The Walker River Near Mason.
* until further notice.
* At  2:15 PM Sunday the stage was 9.8 feet.
* Flood stage is 9.8 feet.
* Minor flooding occurring and minor flooding is forecast.
* Forecast...Rise to near 10.7 feet by Thursday afternoon. 
  Additional rises are possible thereafter.
* Impact...At 10.8 feet...Minor flooding of lowlands...pasture and 
  farmland adjacent to the river throughout the Mason 
  Valley-Yerington area. Some rural roads flood. Preventative 
  sandbagging of low structures in Mason and Yerington may be 
  necessary as river rises...but little flooding occurs.  Some minor 
  flooding of basements and yards in Mason.


&&

LAT...LON 3881 11920 3917 11927 3919 11898 3912 11890 3885 11908


$$
333 
WGUS85 KREV 310233
FLSREV
Flood Statement
National Weather Service Reno NV
733 PM PDT Tue May 30 2017

...The Flood Warning continues for the following rivers in Nevada...

  Walker River Near Mason affecting Lyon County

Warming temperatures in the high Sierra will continue producing
increased snowmelt in the upper part of the Walker River basin for
much of this week and into the weekend. This increased runoff will
create high flows in the Walker River basin from above the confluence
of the East and West Walker Rivers downstream through the Mason
Valley and Yerington area to Weber Reservoir. High flows are likely
to last well into June.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

These river forecasts are based on forecast rainfall and temperature 
conditions at time of issuance. If actual conditions vary from these
forecasts...river conditions will vary accordingly. River forecasts
include current and planned reservoir releases.

&&

NVC019-020233-
/O.CON.KREV.FL.W.0024.000000T0000Z-000000T0000Z/
/MASN2.1.SM.170528T1940Z.170604T0100Z.000000T0000Z.UU/
733 PM PDT Tue May 30 2017

The Flood Warning continues for
  The Walker River Near Mason.
* until further notice.
* At 7:15 PM Tuesday the stage was 9.8 feet.
* Flood stage is 9.8 feet.
* Minor flooding is forecast.
* Forecast...Rise to near 10.8 feet by Saturday evening. Additional
  rises are possible thereafter.
* Impact...At 10.8 feet...Minor flooding of lowlands...pasture and 
  farmland adjacent to the river throughout the Mason 
  Valley-Yerington area. Some rural roads flood. Preventative 
  sandbagging of low structures in Mason and Yerington may be 
  necessary as river rises...but little flooding occurs.  Some minor 
  flooding of basements and yards in Mason. 
  
&&

LAT...LON 3881 11920 3917 11927 3919 11898 3912 11890 3885 11908


$$
395 
WGUS85 KREV 010442
FLSREV
Flood Statement
National Weather Service Reno NV
942 PM PDT Wed May 31 2017

...The Flood Warning continues for the following rivers in Nevada...

  Walker River Near Mason affecting Lyon County

Warming temperatures in the high Sierra will continue producing
increased snowmelt in the upper part of the Walker River basin for
much of this week and into the weekend. This increased runoff will
create high flows in the Walker River basin from above the confluence
of the East and West Walker Rivers downstream through the Mason
Valley and Yerington area to Weber Reservoir. High flows are likely
to last well into June.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

These river forecasts are based on forecast rainfall and temperature 
conditions at time of issuance. If actual conditions vary from these
forecasts...river conditions will vary accordingly. River forecasts
include current and planned reservoir releases.

&&

NVC019-031642-
/O.CON.KREV.FL.W.0024.000000T0000Z-000000T0000Z/
/MASN2.1.SM.170528T1940Z.170605T0600Z.000000T0000Z.UU/
942 PM PDT Wed May 31 2017

The Flood Warning continues for
  The Walker River Near Mason.
* until further notice.
* At  9:15 PM Wednesday the stage was 9.9 feet.
* Flood stage is 9.8 feet.
* Minor flooding is occurring and Minor flooding is forecast.
* Forecast...Rise to 10.4 feet by Saturday morning, then to 10.7 feet
  by Tuesday morning. Additional rises are possible thereafter.
* Impact...At 10.8 feet...Minor flooding of lowlands...pasture and 
  farmland adjacent to the river throughout the Mason 
  Valley-Yerington area. Some rural roads flood. Preventative 
  sandbagging of low structures in Mason and Yerington may be 
  necessary as river rises...but little flooding occurs.  Some minor 
  flooding of basements and yards in Mason. 

&&

LAT...LON 3881 11920 3917 11927 3919 11898 3912 11890 3885 11908


$$
772 
WGUS85 KREV 020455
FLSREV
Flood Statement
National Weather Service Reno NV
955 PM PDT Thu Jun 1 2017

...The Flood Warning continues for the following rivers in Nevada...

  Walker River Near Mason affecting Lyon County

Warming temperatures in the high Sierra will continue producing
increased snowmelt in the upper part of the Walker River basin into
the weekend. This increased runoff will create high flows in the
Walker River basin from above the confluence of the East and West
Walker Rivers downstream through the Mason Valley and Yerington area
to Weber Reservoir. High flows are likely to last well into June.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

These river forecasts are based on forecast rainfall and temperature 
conditions at time of issuance. If actual conditions vary from these
forecasts...river conditions will vary accordingly. River forecasts
include current and planned reservoir releases.

&&

NVC019-041655-
/O.CON.KREV.FL.W.0024.000000T0000Z-000000T0000Z/
/MASN2.1.SM.170528T1940Z.170606T0300Z.000000T0000Z.UU/
955 PM PDT Thu Jun 1 2017

The Flood Warning continues for
  The Walker River Near Mason.
* until further notice.
* At  9:15 PM Thursday the stage was 9.9 feet.
* Flood stage is 9.8 feet.
* Minor flooding is occurring and Minor flooding is forecast.
* Forecast: Rise to 10.2 feet by Friday morning, then to 10.7 feet
  by Wednesday morning of next week. Additional rises are possible
  thereafter.
* Impact...At 10.8 feet...Minor flooding of lowlands...pasture and 
  farmland adjacent to the river throughout the Mason 
  Valley-Yerington area. Some rural roads flood. Preventative 
  sandbagging of low structures in Mason and Yerington may be 
  necessary as river rises...but little flooding occurs.  Some minor 
  flooding of basements and yards in Mason. 

&&

LAT...LON 3881 11920 3917 11927 3919 11898 3912 11890 3885 11908


$$
326 
WGUS85 KREV 030513
FLSREV
Flood Statement
National Weather Service Reno NV
1013 PM PDT Fri Jun 2 2017

...The Flood Warning continues for the following rivers in Nevada...

  Walker River Near Mason affecting Lyon County

Warming temperatures in the high Sierra will continue producing
increased snowmelt in the upper part of the Walker River basin into
the weekend. This increased runoff will create high flows in the
Walker River basin from above the confluence of the East and West
Walker Rivers downstream through the Mason Valley and Yerington area
to Weber Reservoir. High flows are likely to last well into June.

Note: The downward change in the forecast is due to an increased
number of flow measurements taken in recent days leading to a rating
curve shift.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

These river forecasts are based on forecast rainfall and temperature 
conditions at time of issuance. If actual conditions vary from these
forecasts...river conditions will vary accordingly. River forecasts
include current and planned reservoir releases.

&&

NVC019-051713-
/O.CON.KREV.FL.W.0024.000000T0000Z-000000T0000Z/
/MASN2.1.SM.170528T1940Z.170606T2100Z.000000T0000Z.UU/
1013 PM PDT Fri Jun 2 2017

The Flood Warning continues for
  The Walker River Near Mason.
* Until further notice.
* At 9:15 PM Friday the stage was 9.8 feet.
* Flood stage is 9.8 feet.
* Minor flooding is occurring and minor flooding is forecast.
* Forecast...Continue to rise to near 10.1 feet by early Tuesday
  afternoon. Additional rises are possible thereafter.
* Impact...At 10.0 feet...Minor flooding of lowlands...pasture...
  cropland and some rural roads throughout the Mason Valley/Yerington
  area.  No flooding of structures or roads. 

&&

LAT...LON 3881 11920 3917 11927 3919 11898 3912 11890 3885 11908


$$
076 
WGUS85 KREV 050114
FLSREV
Flood Statement
National Weather Service Reno NV
614 PM PDT Sun Jun 4 2017

...The Flood Warning continues for the following rivers in Nevada...

  Walker River Near Mason affecting Lyon County

Warming temperatures in the high Sierra will continue producing
increased snowmelt in the upper part of the Walker River basin. This 
continues to produce high flows in the Walker River basin from above
the confluence of the East and West Walker Rivers downstream through
the Mason Valley and Yerington area to Weber Reservoir. High flows
are likely to last well into June.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

These river forecasts are based on forecast rainfall and temperature 
conditions at time of issuance. If actual conditions vary from these
forecasts...river conditions will vary accordingly. River forecasts
include current and planned reservoir releases.

&&

NVC019-071314-
/O.CON.KREV.FL.W.0024.000000T0000Z-000000T0000Z/
/MASN2.2.SM.170528T1940Z.170609T0400Z.000000T0000Z.UU/
614 PM PDT Sun Jun 4 2017

The Flood Warning continues for
  The Walker River Near Mason.
* until further notice.
* At  4:15 PM Sunday the stage was 9.8 feet.
* Flood stage is 9.8 feet.
* Minor to Moderate flooding is forecast.
* Forecast...Continue to rise to near 11 feet by Thursday morning.
  Additional rises are  possible thereafter.
* Impact...At 11.0 feet...Minor to moderate flooding of
  lowlands...pasture  and farmland adjacent to river throughout Mason
  Valley-Yerington  area. Several rural and some secondary public
  roads flood. Yards and basements of lowest homes adjacent to the
  river in mason and  Yerington begin flooding...preventative
  sandbagging is necessary.
&&

LAT...LON 3881 11920 3917 11927 3919 11898 3912 11890 3885 11908


$$
562 
WGUS85 KREV 052256
FLSREV
Flood Statement
National Weather Service Reno NV
356 PM PDT Mon Jun 5 2017

...The Flood Warning continues for the following rivers in Nevada...

  Walker River Near Mason affecting Lyon County

Warming temperatures in the high Sierra will continue producing
increased snowmelt in the upper part of the Walker River basin. This 
continues to produce high flows in the Walker River basin from above
the confluence of the East and West Walker Rivers downstream through
the Mason Valley and Yerington area to Weber Reservoir. High flows
are likely to last well into June.

NOTE: Due to decreased releases out of Topaz Reservoir the forecast
has been adjusted downward for the Mason area. Keep in mind that if
additional changes are made to releases upstream that the forecast
may again change. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

These river forecasts are based on forecast rainfall and temperature 
conditions at time of issuance. If actual conditions vary from these
forecasts...river conditions will vary accordingly. River forecasts
include current and planned reservoir releases.

&&

NVC019-081056-
/O.CON.KREV.FL.W.0024.000000T0000Z-000000T0000Z/
/MASN2.1.SM.170528T1940Z.170606T1900Z.000000T0000Z.UU/
356 PM PDT Mon Jun 5 2017

The Flood Warning continues for
  The Walker River Near Mason.
* until further notice.
* At  3:15 PM Monday the stage was 9.9 feet.
* Flood stage is 9.8 feet.
* Minor flooding is occurring and Minor flooding is forecast.
* Forecast...The river will continue rising to near 10.4 feet by 
  early Tuesday afternoon then begin falling. Additional future
  rises are possible through the month of June.
* Impact...At 10.5 feet...Minor flooding of lowlands...pasture...
  farmland and some rural roads in Mason Valley. Preventative 
  sandbagging of lowest homes in Mason and Yerington should be done 
  as river rises...but little flooding occurs.  There may be some 
  minor flooding of yards and basements in Mason. 
* Flood history...This crest compares to a previous crest of 10.8
  feet on July 1 2011.


&&

LAT...LON 3881 11920 3917 11927 3919 11898 3912 11890 3885 11908


$$
403 
WGUS85 KREV 081013
FLSREV
Flood Statement
National Weather Service Reno NV
313 AM PDT Thu Jun 8 2017

...The Flood Warning is cancelled for the following rivers in 
Nevada...
 
  Walker River Near Mason affecting Lyon County

Cooler temperatures will result in reduced flows on the West Walker
River over the next few days. Flows will remain elevated on the East
Walker River. Below the confluence the Walker River through
Yerington will slowly fall today, but flows will remain elevated
farther downstream near Wabuska to Weber Reservoir.

Reservoir management activities at Topaz Lake on the West Walker
River could result in higher flows later this week.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

These river forecasts are based on forecast rainfall and temperature 
conditions at time of issuance. If actual conditions vary from these
forecasts...river conditions will vary accordingly. River forecasts
include current and planned reservoir releases.

&&

NVC019-081043-
/O.CAN.KREV.FL.W.0024.000000T0000Z-170608T1013Z/
/MASN2.1.SM.170528T1940Z.170607T0345Z.170608T0000Z.UU/
313 AM PDT Thu Jun 8 2017

The Flood Warning is cancelled for
  The Walker River Near Mason.
* At 2:15 AM Thursday the stage was 9.6 feet.
* Flood stage is 9.8 feet.
* Fell below flood stage at 5:00 PM Wednesday.
* Forecast...The river will continue to fall to 9.3 feet by early 
  Friday morning.

&&

LAT...LON 3881 11920 3917 11927 3919 11898 3912 11890 3885 11908


$$

What forecasters said that day

The local office's own words before this river flood warning went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Reno, NV wrote its last area forecast discussion before this river flood warning went out at May 18, 3:11 AM PDT, 9 hours 25 minutes earlier.

Area forecast discussion, May 18, 3:11 AM PDT, 9 hours 25 minutes before
Area Forecast Discussion
National Weather Service Reno NV
311 AM PDT Thu May 18 2017

.SYNOPSIS...

A warming trend will start today, with above average temperatures
by Saturday. The above average temperatures this weekend will
accelerate snowmelt in the Sierra. River and stream flows will
increase with an enhanced risk for river flooding, especially on
the Walker River, and possibly the Carson River, by next week. A
few thunderstorms may form near the Sierra starting on Sunday.

&&

.SHORT TERM...

High pressure builds over the West Coast today beginning a
significant warming trend. Light easterly flow will keep high
temperatures somewhat tamped down today, upper 60s to around 70
for western Nevada and upper 50s to around 60 for Sierra valleys,
before the pressure gradient weakens further into the weekend.
Afternoon highs increase into the low 80s for western Nevada and
low/mid 70s for Sierra valleys by Sunday.

River Rises: While weather parameters are generally benign,
snowmelt will increase resulting in additional runoff into area
rivers. The bottom line is that all rivers will be running fast
and very cold; stay away from the rivers if possible. See our
hydrology section below for more flooding details. Boyd

.LONG TERM...Sunday through Wednesday...

Ridge of high pressure continues to amplify on Sunday along the
Pacific Northwest coast, while a weak shortwave trough dropping
through the northern Rockies splits off over CA. The ridge will
keep temperatures warm, around 5-10 degrees above average. The
weak low pressure dropping over CA will bring a few degrees of
cooling aloft that will help to increase instability over the
Sierra. This will bring chances of thunderstorms for the Sierra
Sunday through Wednesday, mainly driven by afternoon heating and
terrain convergence over the High Sierra.

Temperatures will continue to rise into next week as high pressure
dominates. Highs will reach into the mid 80s by next week in
western Nevada and mid 70s in the Sierra. Snowmelt will increase
with the well above normal temperatures. Rises are expected for
creeks, streams, and mainstem rivers coming out of the Sierra
through next week. See our hydrology section below for more
details of potential snowmelt flooding. Hoon

&&

.AVIATION...

VFR conditions through the rest of the week, with light winds and
mostly clear skies. Hoon

&&

.HYDROLOGY...

Warming temperatures late this week and into the weekend will
accelerate snowmelt in the Sierra. Overnight low temperatures in
the higher elevations are likely to remain above freezing as well...
and this will enhance snowmelt further.

This increased snowmelt will cause rises in many area small streams
and rivers from southern Mono County through the eastern Sierra and
into Sierra and Plumas counties. These higher flows are likely to
produce overbank flows in the smaller streams at the very least.
Farther downstream...flooding possibilities will increase for some
of the major basins. Minor flooding is possible by the middle of
next week for the Carson Valley area while moderate flooding is
highly likely for the Walker River system from Antelope Valley
downstream into the Mason Valley...with more extensive flooding
possible in Mason Valley. Higher flows are also likely below Weber
Reservoir...but the expected extent is unknown at this time.

Currently the extent of any flooding is uncertain. Some factors that
are unknown at this time include how high temperatures will reach
and for what period of time, as well as how reservoir operations
will change to mitigate flooding concerns. The Walker River is the
biggest concern at this point in time...but not the only area of
concern.

Make sure to check the most recent forecasts and observations if
you live near a stream or river...or plan to hike or camp near any
streams or rivers. Remember that snowmelt flows can be highest in
the evening and overnight in the smaller streams.

&&

.REV Watches/Warnings/Advisories...
NV...None.
CA...None.
&&

For more information from the National Weather Service visit...
http://weather.gov/reno

The office that day

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

IssuedProductOfficeCountiesLasted
May 18, 11:56 AM PDTFlood WatchREVDouglas, Lyon, Storey, Washoe5 days

Nearby

River Flood Warnings in Nevada, 2017Every river 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; radar from the NEXRAD Level II archive; the gauge from the NWS water service and the USGS.