A very warm and wet atmospheric river approached the west coast of the CONUS on the 5th, which brought gusty winds and significant rains to the Sierra and western Nevada the 6th through the 7th. In the foothills of western Nevada, rainfall amounts ranged from about a third of an inch to as much as three-quarters of an inch.
Every event with a place to put it; 2 filed by county or forecast zone are drawn at its center, in a lighter ring. Tap one for its entry below.
Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS REV wrote it up.
A very warm and wet atmospheric river approached the west coast of the CONUS on the 5th, which brought gusty winds and significant rains to the Sierra and western Nevada the 6th through the 7th. In the foothills of western Nevada, rainfall amounts ranged from about a third of an inch to as much as three-quarters of an inch. The valleys of the basin and range country in western Nevada saw generally less than half an inch, but the higher elevations received up to an inch or more.
The local office's own words before the first event, 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 the first event at Apr 6, 1:44 AM PST, 26 minutes earlier.
Area Forecast Discussion
National Weather Service Reno NV
244 AM PDT Fri Apr 6 2018
.SYNOPSIS...
A strong storm with an impressive deep moisture plume for April
will impact eastern California and western Nevada through Saturday,
bringing periods of moderate to heavy rain, very high snow
levels, gusty winds, and flooding concerns along some rivers and
streams. Additional storm systems producing lighter amounts of
rain and snow are possible next week.
&&
.SHORT TERM...
Changes to the ongoing short term forecast were mainly confined to
adjusting POPs and QPF slightly this evening east of the Sierra
and lowering snow levels a bit more for Saturday afternoon.
Model solutions for this system has been quite consistent over
the past couple of days. They are coalescing on a period of less
precipitation east of the Sierra this evening and overnight and
showing slightly less intensity in the precipitation for the
Sierra and northeast California late this evening. That change is
primarily driven by the lack of forcing in the late evening and
early overnight hours.
The first significant upper level wave is shown passing through
the region later today. This is providing something of a hybrid
type of forcing that involves both warm air advection and some
dynamic forcing...but it is primarily the warm air advection that
is driving the precipitation. This can be seen in the rising snow
level forecast as well. Snow levels climb well above 10,000 feet
today and stay at that level into the overnight hours. Precipitation
amounts through the daytime hours should become quite significant
for early April...but the heavier precipitation looks to be
Saturday.
Gusty winds may develop a little faster than forecast if there is
a lack of precipitation east of the Sierra this evening. We still
have a Wind Advisories in effect starting at 3 am...but stronger
winds are possible as early as 10 pm this evening.
The approach of the main upper level trough...along with a rather
impressive upper level jet nearing 150 kt late tonight and early
Saturday morning...will increase forcing and provide the impetus
for much higher rainfall rates from just before sunrise Saturday
morning into the late morning hours for much of the forecast area.
This heavier rain should combine with melting snowpack in the
Sierra to cause rapid rises in many small streams and creeks and
cause some minor nuisance in low lying and poor drainage areas.
Snow levels start to fall by early afternoon as the trough gets
closer...but they remain above 6000-7000 feet until Saturday
evening. By then most of the precipitation has ended so snowfall
accumulations will be limited to the very highest elevations.
Following the rapid rise in small streams and creeks...the larger
river systems will see rises later Saturday into Saturday night
and Sunday. A comprehensive look at hydrology issues can be found
in the Hydrology Section below.
The approach of the 150+ kt jet and an increasing surface
pressure/temperature gradient will continue to drive stronger
winds through much of Saturday. Wind Advisories continue into
Saturday evening for western Nevada. Sustained winds could reach
20-30 mph with gusts in the 45-55 mph range...higher in winds
prone areas.
Rain and high elevation snow tapers to showers by Saturday
evening with minimal snow accumulation. By the time the heaviest
precipitation has ended...total liquid amounts could be in the
range of 2.50 to 4 inches in the highest elevations of the Sierra
with 1.50 to 2.50 inches in the Sierra valleys. In the western
Nevada foothills amounts of 1 to 1.50 inches are possible while
the lower valleys and western Nevada...northwest Nevada...and
northeast California could pick up from 0.60 to as much as 1.10
inches of rain. In the basin and range country amounts could vary
from 0.25 inches to as much as 0.60 inches.
Drying begins for Sunday with lighter winds. This will be short-
lived as we move into another active period later in the week. XX
.LONG TERM...Monday through Friday...
Next week continues to look somewhat active, but did make some
changes to the forecast. The latest model suite is not as wet with
the storms and the latest AR tools show this as well. That said, the
storms are still there, and they are colder than the current one.
Monday short wave ridging remains with temps quite mild and about 10
degrees above normal. The first system next week will move through
Tuesday, but it will mainly be a wind maker. The brunt of it is now
shifting north in response to the system upstream (for Wed
night/Thurs) deepening. It looks warmer too with snow levels near
8000 feet for the event, but amounts look to be quite light and
generally less than a quarter inch. Winds will be gusty and 40-50
mph in the valleys looks likely, stronger on ridges.
The next system then rapidly arrives late Wednesday with the brunt
of it Wednesday night. This one is colder still, with snow levels
below 7000 feet, possibly falling to all valley floors by Thursday
morning. QPF amounts are still light, with perhaps a half inch near
the Sierra Crest. With it being colder, some snow is looking more
likely for the passes. However, it is still 6 days out, and the
models remain inconsistent for next week so this could change. It
will also be quite a bit colder Thursday behind the front with highs
only in the 40s to mid 50s. X
&&
.AVIATION...
Main concerns will be with the winds, turbulence and LLWS for the
next 36 hours. Yes, there will be rain too with areas of MVFR
CIGS/VIS. Will break it down by terminals from here.
KTVL/KTRK: Mainly MVFR CIGS/VIS today through 16Z Saturday, with a
period of IFR VIS 08-16Z Saturday in the heaviest part of the storm.
For winds, expect SW winds 10G20 for the most part and some mtn wave
turbulence, but no significant LLWS through 21Z. Then ridge winds
increase to 50+ kts by 00Z. Expect SFC winds to increase too with
gusts to 35 kts, with LLWS due to the strong ridge winds. LLWS will
continue to be in issue through 21Z Sat.
KRNO/KCXP: VFR conditions with periods of -RA and CIGS 4-5000 feet
through 09Z, then MVFR CIGS/VIS in RA through 16Z and VFR after.
Winds will be SW with gusts 25-30 kts today and mtn wave turbulence.
LLWS becomes a much bigger issue after 21Z as the ridge winds
increase with some rotors likely at times. SFC gusts will be
erratic, occasionally gusting to 40-45 kts, and other times quite
light and perhaps NE with the rotor. LLWS threat decreases some
after 16Z behind the front, mainly for KCXP. KRNO will still have
some issues with more S channeling at the surface and W winds aloft.
KMMH: VFR conditions through 06Z tonight in -RA, but there will be
brief periods of MVFR CIGS at times. MVFR conds afterward through
18Z in RA. Winds will gust to 25 kts today with mtn wave turbulence,
then increase this evening with LLWS likely after 02Z this evening.
The gusty winds, LLWS and turbulence to continue through Sat
afternoon. X
&&
.HYDROLOGY...
Hydrology issues remain fairly consistent leading up to this
event. The main change in drivers are leaning towards a slightly
longer period of light to moderate rainfall and a slightly shorter
period of intense precipitation, and highest snow levels lasting
a bit longer. These subtle changes are difficult to resolve in
both the hydro model as well as in physical impacts on the ground,
and have resulted in very little change in river level forecasts.
Warm temperatures and high sun angles initiated snowmelt in lower
elevations and on sun exposed aspects. Light to moderate rains
today will further ripen the mid-elevation snowpack as well as
increase soil moisture, which is already quite elevated especially
in the Tahoe and Truckee Basins. This should result in highly
efficient period of runoff with the peak rainfall intensities and
very high snow levels tonight and Saturday morning. The ability
of the snowpack at different elevations and aspects to retain rain
versus passing the rain through with additional snowmelt is an
area of forecast uncertainty; most snow below ~7000 feet on all
aspects, and below ~8000 feet on sunny aspects, has been observed
to be ripe and will contribute to runoff. Higher elevations and
shady aspects will take additional energy to ripen and may start
to contribute later in the event.
There is high confidence in rivers and streams rising rapidly
tonight and Saturday, leading to minor to moderate flooding.
While flooding is most likely along small streams, poor drainage
areas, recent burn areas, mountain communities, and closed basins,
flooding is becoming more likely along main-stem rivers,
especially in the Truckee and Carson basins. Flood warnings have
been issued for the Truckee near Truckee and for the East and West
Forks of the Carson in Carson Valley including the main-stem to
HWY 395. Minor flooding is likely along the Truckee between HWY
395 and Vista, and along Steamboat Creek. A flood advisory has
been issued for high releases below Lahontan Reservoir. Near bank
full conditions are expected through Fallon. Minor flooding is not
currently expected, but is possible on the Susan, the Middle Fork
of the Feather, and the Walker Rivers. In general, flows and
impacts are expected to exceed the March 22nd, 2018 and Nov 18th,
2017 events. Is this as bad as January - February 2017? Region-
wide this is unlikely, but we can't rule out some isolated areas
of similar impacts. REV
&&
.REV Watches/Warnings/Advisories...
NV...Flood Watch from this afternoon through Sunday morning
NVZ002-003.
Wind Advisory from 3 AM to 11 PM PDT Saturday NVZ001-003>005.
Lake Wind Advisory from 11 PM this evening to 11 PM PDT Saturday
for Lake Tahoe in NVZ002.
CA...Flood Watch from this afternoon through Sunday morning
CAZ071>073.
Wind Advisory from 3 AM to 11 PM PDT Saturday CAZ070-073.
Lake Wind Advisory from 11 PM this evening to 11 PM PDT Saturday
for Lake Tahoe in CAZ072.
&&
For more information from the National Weather Service visit...
http://weather.gov/renoThe national radar mosaic for the moment the first event began.
21 heavy rain, 2 high wind, 2 flood, 1 debris flow. Local standard time, as filed.
Trained weather spotter 4 miles south-southwest of Reno reported 0.65 inches of storm total rainfall from 6 April 0210PST to 7 April 1410PST.
ASOS LOL, Lovelock Derby Field airport (elevation 3901 feet) reported 0.53 inches of rainfall in a 24 hour period from 6 April 0353PST to 7 April 0353PST.
CoCoRaHS station NV-PR-4, Lovelock reported 0.77 inches of rainfall during a 24 hour time period from 6 April 0600PST to 7 April 0600PST.
CoCoRaHS station NV-DG-17, 1 mile south-southeast of Zephyr Cove reported 0.80 inches of rainfall in a 24 hour period from 6 April 0700PST to 7 April 0700PST.
CoCoRaHS station NV-LY-14, 3 miles west-northwest of Fernley reported 0.69 inches of rainfall in a 24 hour period from 6 April 0700PST to 7 April 0700PST.
CoCoRaHS station NV-LY-29, 1 mile southeast of Fernley reported 0.58 inches of rainfall in a 24 hour period from 6 April 0700PST to 7 April 0700PST.
CoCoRaHS station NV-LY-15, 2 miles east-southeast of Six Mile Canyon reported 0.67 inches of rainfall in a 24 hour period from 6 April 0700PST to 7 April 0700PST.
CoCoRaHS station NV-WH-149, near Washoe City reported 0.99 inches of rainfall in a 24 hour period from 6 April 0700PST to 7 April 0700PST.
Mesonet station BNCN2, Bernice Canyon (elevation 5812 feet) reported 0.65 inches of rainfall in a 24 hour period from 6 April 0720PST to 7 April 0720PST.
Mesonet station E7891, 3 miles east of Spanish Springs (elevation 4662 feet) reported 0.82 inches of rainfall in a 24 hour period from 6 April 0732PST to 7 April 0732PST.
CoCoRaHS station NV-CC-21, Carson City reported 0.59 inches of rainfall in a 24 hour period from 6 April 0800PST to 7 April 0800PST.
Mesonet station MRSN2, Mount Rose Summit (elevation 8799 feet) reported 1.60 inches of rainfall in a 24 hour period from 6 April 0800PST to 7 April 0800PST.
Mesonet station MJBN2, 20 miles west-northwest of Imlay (elevation 5293 feet) reported 0.77 inches of rainfall in a 24 hour period from 6 April 0847PST to 7 April 0847PST.
Mesonet station BMWN2, 5 miles southeast of Verdi (elevation 8234 feet) reported 1.70 inches of rainfall in a 24 hour period from 6 April 0900PST to 7 April 0900PST.
Mesonet station AU485, 5 miles east-northeast of Lahontan Reservoir (elevation 4098 feet) reported 0.62 inches of rainfall in a 24 hour period from 6 April 0939PST to 7 April 0939PST.
ASOS NFL, Fallon Naval Air Station (elevation 3934 feet) reported 0.59 inches of rainfall in a 24 hour period from 6 April 0956PST to 7 April 0956PST.
Mesonet station F0371, near Gerlach (elevation 3953 feet) reported 0.58 inches of rainfall in a 24 hour period from 6 April 1014PST to 7 April 1014PST.
Social media user in Genoa reported 0.92 inches of rainfall in a 24 hour period from 6 April 1040PST to 7 April 1040PST.
Trained weather spotter 2 miles north of Stewart measured 0.54 inches of rainfall in a 24 hour period from 6 April 1047PST to 7 April 1047PST.
Trained weather spotter 1 mile north-northwest of Gardnerville reported 1.18 inches of rainfall in a 24 hour period from 6 April 1044PST to 7 April 1044PST.
NWS Reno official observation of 0.51 inches of heavy rain in a 24 hour period from 6 April 1053PST to 7 April 1053PST.
Kingsbury Grade (State Route 207) was closed due to a landslide from the early afternoon of 6 April to the afternoon of 7 April.
AWOS Station RTS, 2 miles north of Stead (elevation 5050 feet) reported a wind gust of 58 mph.
AWOS RTS, 2 miles north of Stead (elevation 5050 feet) recorded a wind gust of 58 mph.
Trained weather spotter DO-12 reported that approximately 4 inches of water was covering half of Nevada Highway 88 at Centerville Lane. This was very close to the location of Rocky Slough.
Trained weather spotter reported that the East Fork of the Carson River was above its banks between Cedarwood Drive and Muller Lane. Ending time of flooding is based upon data from a nearby USGS gauge.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Nevada in 2018Every state in 2018This day in weather historyWarnings in Nevada, April 2018
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 753576, 753612, 754205, 754100, 754197, 754198, 754199, 754210, 754099, 754206, 754096, 754207, 754203, 754208, 754098, 754097, 754209, 754101, 754095, 754103, 753611, 752064, 753610, 754343, 752052, 753609.