Strong, even damaging west-southwest winds increased travel hazards especially to high profile trucks but also increased the danger for destructive avalanches across the region. Snow started at all elevations Thursday evening with snow levels rapidly rising Friday morning.
Every event with a place to put it; 8 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.
Strong, even damaging west-southwest winds increased travel hazards especially to high profile trucks but also increased the danger for destructive avalanches across the region. Snow started at all elevations Thursday evening with snow levels rapidly rising Friday morning. Heavy, wet snow (Sierra Nevada Cement) fell across higher elevation areas as snow levels rose to 7000 feet over the region. Heavy rainfall increased the possibility of flooding for lower elevation creeks, streams, along with urban drainage issues due to snow berms. Significant rises on mainstem rivers were monitored for flooding. Deep, cold snowpack absorbed most liquid precipitation during this second AR supported storm system.
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 Mar 9, 3:28 AM PST, 2 hours 32 minutes earlier.
Area Forecast Discussion
National Weather Service Reno NV
328 AM PST Thu Mar 9 2023
.SYNOPSIS...
A potent atmospheric river storm will bring rising snow levels
with strong winds, heavy mountain snow and lower elevation rain
this afternoon through Friday, with possible flooding in poor
drainage areas. Additional waves of moisture will keep rain and
snow chances going at times from this weekend into next week.
&&
.SHORT TERM...Through Friday Night...
A very active and impactful weather pattern for the upcoming week
will be highlighted by a surge of atmospheric river moisture
accompanied by a 150 kt subtropical jet headed directly into the
Sierra starting this afternoon, then spreading across western NV
this evening. Peak precip rates, wind speeds and impacts are
expected this evening through Friday afternoon. Additional waves
of moisture, although not as intense or warm, are projected to
continue through the weekend. Expect widespread road/air travel
impacts today through the weekend.
* WINDS: Winds will continue to increase along the Sierra crest
today, before all elevations see gusty winds by early Friday
morning. A 65 kt 700 mb jet moving over the Sierra will push
gusts along the ridges upwards of 130 mph Friday morning/early
afternoon, sustained 65-75 mph. Western NV valleys could see
gusts up to 50 mph Friday afternoon, except wind prone
locations, especially along US-395, could gust up to 75 mph.
Winds will taper off and become light overnight into Saturday,
though Sierra ridges will remain breezy at around 40 mph gusting
to 60+ mph.
* QPF: Precip amounts with this storm remain rather impressive.
Starting with the most QPF, the Sierra crest (above 7500') from
the Tahoe Basin down through Mono County has an 80% chance of
7-10 inches of liquid. The remaining 20% is leaning more towards
10-11". Next up is Mono County below 7500', which could see
3-5" of liquid along US-395, and a gradient going from 4" to 1"
east of US-395. NE CA west of US-395 has a 90% chance of 2-3",
while east of US-395 would see only 1-2". Far western NV,
including the Reno/Carson/Minden areas, are expected to get
1-3", though Washoe Valley could see upwards of 4". The rest of
western NV and NE CA, including Surprise
Valley/Fallon/Lovelock/Hawthorne, have a 60% chance of at least
0.5", while the remaining 40% is leaning less than 0.5".
* SNOW LEVELS/AMOUNTS: And now for the trickiest part of the
forecast... Snow levels this afternoon when the precip begins
will start off around 5000-5500'. Western NV valleys could see a
few snowflakes at the very beginning of the storm, though any
precip will be light. If the precip starts to spillover quicker,
around 1-2 PM, light snow could last a little longer, though any
accumulations will be nil. This evening between 10 PM and 4 AM
Friday, snow levels will increase to 8000-9000', at the same
time the most intense precip is expected to occur. However,
there's potential for an isothermal layer to develop for a short
period this afternoon into early Friday morning as indicated by
multiple model soundings. This could drop snow levels by
1000-2000' briefly during that time. Snow levels will then start
to come down Friday morning from the north, as cold air comes
down into western NV. There remains some uncertainty as to how
far south the cold air will get pushed, though blended guidance
currently has a snow level gradient of 4000-8000' following
along I-80 pretty closely Friday afternoon. Then later into
Friday night, the snow level gradient decreases as temperatures
begin to drop. Snow levels will bottom out around 7000' in Mono
County, 5500-6000' in the Tahoe Basin, and 3000' in
Lassen/northern Washoe counties. Total snow accumulations for
this storm through Friday night:
Tahoe Basin 5500-7000' has a 70% chance 10-30" and a 80% chance of
50-70" above 7000'. Sierra crest in Mono County above 8000' could
see anywhere from 90-120". NE CA west of US-395 has a 80% chance
of 6-12", east of US-395 up to 4". Very little accumulations can
be expected for the rest of western NV, except 4-8" in northern
Washoe County.
-Justin/MJD
.LONG TERM...Saturday through next week...
* For the weekend and Monday, our area will be between two notable
IVT plumes/shortwave troughs with the main jet axis and moisture
plume shifting southward. Moderate to heavy snow will be ongoing
in the Sierra, especially from Alpine Count southward into Mono
County Saturday morning with occasional showers elsewhere. Snow
levels will be a bit lower as a result of a shortwave trough
tracking across the Pacific NW late Friday-Friday night, ranging
from 4500-5500' across northeast CA/northwest NV to around 6000'
in the Tahoe Basin and 7000' for areas south of Hwy 50. Some
slushy light accumulations may occur as low as Lake Tahoe level,
foothills around Reno and northeast CA with another foot of snow
for the high Sierra. The main plume and more steady heavy
precipitation will begin to taper back Saturday afternoon with a
moist southwest to west flow to continue providing almost
continuous snow showers along the Sierra with occasional showers
spilling over into western NV. Snow levels do not change much
through Monday with another 1-2' of snow from late Saturday to
Monday right along the Sierra crest, and 4 to 8" for Sierra
communities above 7500 feet in Mono County, including Mammoth
Lakes and June Lakes. Light accumulations may occur at lake
level for the Tahoe region and eastern Sierra of Mono County
between 7000- 7500 feet.
* Latest medium range model guidance continues to point to the
next decent but fairly progressive shortwave trough. Right now
it looks a bit colder than the first storm coming through late
this week with NBM guidance indicating snow levels briefly
bumping back up to 7000-7500 feet Monday evening before falling
to 5500-6500 feet Tuesday. GEFS/ECS IVT plumes are fairly robust
with room for warmer snow levels so we will have to keep an eye
on this one for a couple more days to get a better handle on its
impacts. Prepare for more travel impacts for sure with a heavy
wet snow almost a guarantee higher up.
&&
.AVIATION...
* This morning and early afternoon will be the last decent travel
window for awhile. Latest model scenarios continue to show a
very active pattern through next week with the potential for a
couple of big storms. Aviators should expect periods of strong
winds and turbulence along with heavy precipitation. Right now,
storms are lined up to impact the region this afternoon-
Saturday and Monday night to Wednesday next week. These storms
will be the warmer variety with snow accumulation confined
mainly to the high Sierra, occasionally dropping down to Sierra
terminals on the backside of each storm.
* Snow will move into the Sierra this afternoon with widespread
MVFR conditions and terrain obscurement developing. An inch or
two of snow is possible for Sierra terminals before snow levels
rise and moderate to heavy rain takes over later tonight through
Friday night. For lower elevation sites, it will all be rain
with occasional MVFR CIGS/VSBY in heavier rain bands.
* Turbulence and LLWS are likely as FL100 winds increase to around
50-60 kts and surface gradients tighten for south-southwest
winds 20-30 kts with gusts 35+ kts at times by this evening.
Hohmann
&&
.AVALANCHE...
High confidence for a strong atmospheric river storm through
Saturday morning, producing very heavy precipitation with
variable snow levels and significant impacts for avalanche
concerns.
* 24-hr Snow Water Equivalent (SWE): High-end SWE of 4-6" along
the crest through Friday afternoon, with hourly rates of
0.25-0.50" at times during peak intensity. SWE rates decrease by
Friday night but additional 1-3" possible through the weekend.
* Snow-Liquid Ratios: Lower snow-liquid ratios of 7-10 to 1,
except 10-13 to 1 for the Sierra crest above 9000 ft through
Friday. Cooler air will increase snow-liquid ratios to 10-14 to
1 for Friday night-Saturday morning.
* Winds: Strong southwest winds expected with gusts to 100+ mph
across the ridges this afternoon through Saturday morning.
Active pattern will continue through the middle of next week with
the highest probability for more impactful snow and wind Monday
night-Wednesday. MJD/Hohmann
&&
.HYDROLOGY...
Bottom Line: Increasing confidence in flooding along creeks and
streams and areas of poor drainage where deep snow may confine
flow and limit drainage. Significant rises are expected on main
stem rivers. While flooding is not currently forecast, rises to
monitor stage are now forecast for several points, and minor to
moderate flooding can't be ruled out if the system overperforms
in terms of precipitation amounts and/or prolonged periods of
higher snow levels occur.
The flood threat does not go away Sunday. Any additional rains next
week could lead to additional rises, and some rivers will be slow
to respond to the current storm event.
Late today through Saturday, rain combined with strong winds and
high humidity will add considerable energy into our record to
near-record deep regional snowpack at mid to lower elevations.
While higher elevation and deepest snowpacks will continue to
accumulate snow and water equivalent, deep mid-elevation snowpacks
are expected to retain most of the projected rain. Some of these
areas may begin to develop preferential pathways for melt and
start releasing rainfall after prolonged periods of rain, but are
unlikely to contribute significant snowmelt to the runoff. It is
the areas of relatively shallow snowpack on the order of inches to
a couple of feet that we are most concerned about having
significant melt and contributing to the flood concerns.
Fortunately, these areas are confined to low elevation drainages
and to limited portions of the main stem rivers.
Our greatest concern continues to be creeks and streams draining
large areas of terrain with shallow snowpacks (below ~5500 feet)
and urban poor drainage areas where deep snow may be restricting
drainage. Confidence is increasing in flood impacts for these
areas.
The main-stem rivers forecasts have ramped up somewhat, but still
remain below flood stages. Keep a close eye on the Pit River into
Big Valley, the Susan River, The Middle Fork of the Feather, and
the forks and main stem of the Carson River. The Susan River will
respond very rapidly to heavy rain, while the response for the
Pit River into Big Valley and the Middle Fork of the Feather may
take several days. The latest guidance from the CNRFC now has the
East fork of the Carson and the main stem Carson River near
Carson City exceeding monitor stages.
The potential for additional rainfall early next week will require
close monitoring as the current system will help prime the
snowpack and stream responses. Check back for forecast updates at
cnrfc.noaa.gov. Changes in storm track could lead to changes in
precipitation and or rain snow elevation that could exacerbate or
mitigate flooding concerns. -Bardsley
&&
.REV Watches/Warnings/Advisories...
NV...Wind Advisory from 10 PM this evening to 7 PM PST Friday
NVZ001-003>005.
Flood Watch from this afternoon through Sunday morning
NVZ001>003.
Winter Storm Warning from 4 PM PST this afternoon to 11 AM PDT
Sunday NVZ002.
CA...Wind Advisory from 10 PM this evening to 7 PM PST Friday CAZ070.
Flood Watch from this afternoon through Sunday morning
CAZ071>073.
Winter Storm Warning from 4 PM PST this afternoon to 11 AM PDT
Sunday CAZ071.
Winter Storm Warning from 4 PM PST this afternoon to 11 AM PDT
Sunday CAZ072.
Winter Storm Warning from 4 PM PST this afternoon to 11 AM PDT
Sunday CAZ073.
&&The national radar mosaic for the moment the first event began.
6 flood, 5 heavy snow, 4 heavy rain, 3 high wind. Local standard time, as filed.
The public reported that Olympic Valley road and Alpine Meadows road were closed for operations due to flooding and lift operations. Palisades Tahoe at Alpine Meadows.
The public located 1.0 SSW of Northstar Ski Base, Bear Valley Ski Resort, and the Palisades Tahoe Ski Base reported 24-hour snowfall totals of 16, 15, and 8.0 inches respectively.
A COCORAHS, CA-ED-20, located 2.0 mi NW of Meyers, CA, and CA-ED-9 located at Tahoma, CA, both reported 24-hour rainfall totals of 2.11 inches.
A COCORAHS (CA-ED-51) located 2.0 mi N of Truckee, CA reported 24 hour rainfall totals of 1.56 inches, and snowfall total of 2.0 inch.
A COCORAHS, CA-MN-6, located 5.0 mi NNW of Lee Vining, CA reported 24-hour rainfall totals of 1.99 inches.
The public reported that State Route 182 has been closed from the town of Bridgeport to the Nevada state line in Mono County due to reports of flooding. There was no estimated time of reopening.
The public located at Mammoth Mountain Ski Base, a trained spotter located 1.0 mi SW of Toms Place, and the public located at June Mountain Ski base reported a 24-hour snowfall totals of 15.0, 10.0 (with 1.7 inches SWE), and 8.0 inches respectively.
The public located at June Mountain Ski Base reported a 3 day storm total snowfall of 30.0 inches at 8600 feet.
A COCORAHS, CA-PM-9, located 3.3 mi E of Beckwourth, CA, reported 24-hour rainfall totals of 0.78 inches.
The public reported the area 2.0 mi SW of South Lake Tahoe is experiencing isolated flooding throughout the city.
Inyo County sheriff reported Lower Rock Creek Road/Old Sherwin Grade Road along lower Rock Creek closed due to flooding. The community of Paradise, CA, was cut-off and had been advised to shelter-in-place.
CALTRANS reported US-6 in Hamill valley has flooding across the roadway.
The public reported 4.0 mi ENE of Sattley, CA, of flooding along CA-49 from Sierraville, CA, and Loyalton, CA. Most of the flooding is due to the berms blocking the flow of water off the roadway. It was only 1-3 inches deep in most locations.
Mesonet stations located at the Northstar Ski Summit, Heavenly Ski Summit, CA, and 1.0 mi ESE of the Palisades Tahoe Alpine Lodge reported peak winds of 69 mph, 71 mph, and 80 mph, respectively.
Mesonet station (XMLC1) Mill Canyon located 4.0 mi SSW of Walker, CA, reported a peak wind of 77 mph.
Mesonet station (MTH01) located 0.9 mi S of Mammoth Mountain Ski resort reported a peak wind of 102 mph.
The public located at the Palisades Tahoe Ski Base, 1.0 mi SSW of Northstar Ski Base, CA, 4.0 mi NW Truckee of Tahoe-Donner Ski Area, CA, and the Heavenly Ski Base, CA, and reported 24-hour snowfall totals of 16, 14, 13, and 11 inches respectively. |Northstar Ski Base, CA, Palisades Tahoe Ski Base, Heavenly Ski Base, CA, and Tahoe-Donner Ski Area all reported 3-day storm total snowfall totals of 37 (@8600 feet), 31 (@8000 feet), 31 (@8900 feet), and 21 (@6750 feet), inches respectively.
A COCORAHS, CA-MN-6, located 5.0 mi NNW of Lee Vining, CA reported a 24-hour snowfall total of 9.2 inches.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in California in 2023Every state in 2023This day in weather historyWarnings in California, March 2023
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: 1099335, 1099087, 1099107, 1099108, 1099109, 1099336, 1099090, 1099112, 1099110, 1099337, 1099338, 1099339, 1099340, 1099082, 1099085, 1099083, 1099111, 1099113.