Areal Flood Warning 4, NWS Reno, NV

Area Forecast Discussion
National Weather Service Reno NV
814 PM PST Sun Jan 8 2017

.UPDATE...

A complex pattern gets a little more complex. Snow levels are
starting to fall in the higher elevations. That should cut off
some of the high elevation run off. Precipitation rates are
decreasing as well. That's good, possibly limiting the extent of
flooding beyond tonight.

In Mono County the precipitation rates are the highest and snow
levels are falling faster than to the north. Thus...we have
updated snow amounts and will start the Winter Storm Warning now
for Mono County. Low elevation areas will not change over to snow
until tomorrow and so some minor flooding is still possible in the
lower elevations...but the higher passes will begin to see
effects from snow overnight.

Elsewhere...flooding will be a serious and continuing issue for
valleys and foothills from Carson City north and northwest through
the Tahoe Basin...the Sierra Front and parts of northeast
California near Susanville and Portola. A widespread Flood
Warning remains in effect into the overnight hours and many
streams and rises have already breached their banks. Widespread
flooding of low lying areas continues and some evacuations have
occurred int the Reno/Sparks area. 20

&&

.PREVIOUS DISCUSSION... /Issued 352 PM PST Sun Jan 8 2017/

SYNOPSIS...Very heavy rainfall continues across the region this
afternoon with widespread flooding being reported. Snow levels
will fall by Monday morning with lessening flood threat. However,
downstream areas may not reach their flood peak until Monday.
Heavy snow is expected to follow in the Sierra and portions of
northeast California with rain and snow showers across western
Nevada through Wednesday night.

SHORT TERM...

Heavy rainfall continues across the area this afternoon with
widespread flooding being reported across roadways, low lying
areas, farmland, and rivers, creeks, and streams. Multiple
roadways are closed due to flood waters, and conditions are only
expected to worsen through this evening. If you can stay home,
please do so. Rivers are running fast and are extremely cold and
it's not recommended to be anywhere near waterways this afternoon
through Monday morning. Mainstem rivers are expected to crest
tonight into Monday morning which makes flooding that much more
dangerous as it is difficult to see the depth of flood waters at
night. Roads will continue to be impacted into Monday morning, so
check your route before heading out the door to see if it's open.

Snow levels will begin to fall overnight into Monday morning which
will help to ease flood concerns, however, all the water will
still need to run downstream with peaks in the lower reaches of
river basins occurring Monday.

Heavy, wet snow is falling is the high Sierra and avalanche
danger is extreme. An Avalanche Warning remains in effect. Please
check sierraavalanchecenter.org for the latest information.

Nearly continuous snowfall is expected in the Sierra and portions
of northeast California Monday through the middle of the week and
Winter Storm Warning have been issued. For western Nevada, snow
levels will be near valley floors with a mix of rain and snow.
Snow accumulation for areas above 5500 feet is likely and places
like the Virginia City Highlands may see decent accumulation. More
details on these storms can be found in the long term section.
-Dawn

LONG TERM...Tuesday through Next Weekend...

Adjustments were mainly marginal and generally to increase
precipitation overall along the Sierra Crest. Elsewhere, there are
indications of more distinctive shadowing along the Sierra Front
Tuesday into Wednesday; QPF was generally lowered here. All said and
done, we're looking at another 6 inches of liquid along the Sierra
Crest down to 1 inch along the Sierra Front. Otherwise, snow levels
were lowered later in the week where the EC/GFS show colder air
filter into the region.

The overall pattern continues to be wet with additional, but
relatively weaker and colder, atmospheric river impulses through
the work week. This pattern continues to promote a heavy snow
scenario for Sierra locations and elevations above 6000 feet.
Previous estimates for snow accumulations remain valid where 2-3
feet of snow may accumulate around Lake Tahoe, 4-8 feet above 7500
feet around Tahoe, 1-3 feet for Mono County above 7500 feet with
localized higher totals around Mammoth Mountain, and around 12
inches near Virginia City. There is potential for a couple of inches
down to valley floors along the Sierra Front, but this comes after a
stronger cold front pushes through early Thursday.

Winds will also be higher Tuesday through Thursday for valley
locations. Sierra valleys could see whiteout conditions in this
timeframe making travel even more hazardous outside of significant
snowfall. Otherwise, high profile vehicles may have trouble along
Highway 395 especially for Washoe Valley and around Doyle.

Weak ridging will likely build into the region for the end of the
week and weekend. Waves and moisture will still be able to reach the
northern Sierra with this flatter ridge in place, but the best
precipitation chances will shift northward more into Oregon. A
series of weaker systems may begin to move through as early as
Sunday. Boyd

AVIATION...

Ongoing strong atmospheric river is bringing moderate to heavy rain
to most of northeast CA and far western NV. Lighter rain out into
west-central NV will increase in intensity this afternoon and
evening. In addition, there have been scattered in-cloud lightning
and cloud-to-ground lightning strikes near the Sierra crest south of
highway 50...with a few additional discharges possible through the
evening. Finally, based on AMDAR/aircraft data there are pockets of
LLWS in the immediate lee of the Sierra with light/variable winds
increasing to southerly over 25-30 kts between 015-020 AGL.

For the rest of the afternoon and early evening (thru ~03Z), the
main concerns around northeast CA, the eastern Sierra, and western
NV terminals will be extensive terrain obscuration in RA/+RA
(especially west of highway 95), occasional/erratic bursts of winds
over 35 kts, and localized LLWS. In the Eastern Sierra south of
highway 50, there is also the added concern for isolated
thunderstorms, with winds possibly gusting over 45 kts near any
storms.

After about 06Z/10 PM tonight, CIGS for KTRK/KTVL will begin to
lower as snow levels start to come down...with rain changing to snow
after about 09Z/1 AM. Accumulations of around 4-7 inches are
expected Monday for untreated areas of KTRK/KTVL with SHSN and
occasional +SHSN. For Mono County terminals along highway 395
including KO57/KMMH, rain is expected to change to snow after about
12Z Monday although CIGS/VIS to start lowering after about 01Z-03Z
as the heaviest rain ensues.

Looking ahead to Monday for western NV and the lower valleys of
northeast CA, snow levels to lower to or to near valley floors.
However, precipitation will taper to showers with little or no
accumulation for valley floors in western NV. In the foothills west
of highway 395 and in northeast CA (including KSVE), a light
accumulation will be possible on Monday. On a more localized level,
water may backup from Dry Creek and approach the southeast side of
KRNO between about 10Z-18Z Monday morning as the main wave of water
comes down into the Truckee Meadows. Snyder

HYDROLOGY...

* Intense rainfall will continue through tonight
* Widespread flooding is occurring
* Rivers are still rising, expected to crest tonight into Monday

Well advertised atmospheric river is affecting the region
with intense rainfall continuing through tonight. Snow levels are
still in the 8000-10000 foot range, however pockets down to 7500
feet have occurred in the heaviest precipitation. Overall, snow
levels will not fall until after midnight tonight. Falling snow
levels will help to mitigate the flood risk, but keep in mind that
the lower reaches of river basins will not peak until Monday.

Widespread flooding, mudslides, and rockslides are being reported
across the area with many roads closed. Conditions are only
expected to worsen into tonight. Travel is strongly discouraged
and if you can stay home, please do so. We know that seeing the
rivers at their peak is exciting, but it is also very dangerous.
The water is extremely cold and can easily sweep you away. Stay
away from all water ways tonight into Monday!

Precipitation will continue through the week, but snow levels will
be between 4500-7000 feet, with a much lower flood risk. -Dawn

&&

.REV Watches/Warnings/Advisories...
NV...Flood Watch through Monday afternoon NVZ002-003.

     Winter Storm Warning from 4 AM Monday to 4 AM PST Thursday
     NVZ002.

     Flood Watch from 4 AM PST Monday through Tuesday afternoon
     NVZ004.

CA...Flood Watch until 4 AM PST Monday CAZ071.

     Winter Storm Warning from 4 AM Monday to 4 AM PST Thursday
     CAZ071.

     Flood Watch until 8 AM PST Monday CAZ073.

     Winter Storm Warning until 4 AM PST Thursday CAZ073.

     Flood Watch through Monday afternoon CAZ072.

     Winter Storm Warning from 4 AM Monday to 4 AM PST Thursday
     CAZ072.

&&

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

PRELIMINARY LOCAL STORM REPORT...CORRECTED
NATIONAL WEATHER SERVICE RENO NV
902 PM PST SUN JAN 08 2017

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0742 PM     FLOOD            3 NNW DOYLE             40.06N 120.13W
01/08/2017                   LASSEN             CA   DEPT OF HIGHWAYS

            LONG VALLEY CREEK IS FLOWING OVER HIGHWAY 395 SOUTH OD
            DOYLE. HIGHWAY IS SHUT DOWN IN BOTH DIRECTIONS.

0750 PM     HEAVY RAIN       5 NNW RENO              39.60N 119.87W
01/08/2017  M3.00 INCH       WASHOE             NV   TRAINED SPOTTER

            A TRAINED WEATHER SPOTTER IN THE HORIZON HILLS
            SUBDIVISION AT THE BASE OF PEAVINE PEAK REPORTED 3.00
            INCHES OF PRECIPITATION IN THE PAST 24 HOURS.

0807 PM     HEAVY RAIN       3 WSW GARDNERVILLE RANC 38.87N 119.80W
01/08/2017  M2.60 INCH       DOUGLAS            NV   TRAINED SPOTTER

            A TRAINED WEATHER SPOTTER MEASURED 2.60 INCHES OF
            PRECIPITATION SINCE 915 AM THIS MORNING.

0832 PM     FLOOD            BRIDGEPORT              38.26N 119.22W
01/08/2017                   MONO               CA   DEPT OF HIGHWAYS

            HIGHWAY 395 FROM LEE VINING TO THE NEVADA STATELINE AND
            HIGHWAY 182 FROM BRIDGEPORT TO THE NEVADA STATELINE ARE
            CLOSED DUE TO FLOODING.

0847 PM     FLOOD            RAVENDALE               40.80N 120.36W
01/08/2017                   LASSEN             CA   DEPT OF HIGHWAYS

            HIGHWAY 395 IS CLOSED FROM WENDEL ROAD, 4 MILES NORTH OF
            LITCHFIELD, TO TERMO.

0901 PM     FLOOD            DAGGET PASS             38.98N 119.89W
01/08/2017                   DOUGLAS            NV   LAW ENFORCEMENT

            A SINKHOLE HAS CLOSED HIGHWAY 207 FROM DAGGET PASS TO
            FOOTHILL DRIVE.

&&

BRONG

PRELIMINARY LOCAL STORM REPORT...CORRECTED
NATIONAL WEATHER SERVICE RENO NV
932 PM PST SUN JAN 08 2017

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1053 AM     NON-TSTM WND GST 3 SSW SOUTH LAKE TAHOE  38.90N 120.00W
01/08/2017  M62.00 MPH       EL DORADO          CA   ASOS

            THE WEATHER SENSOR AT THE SOUTH LAKE TAHOE AIRPORT
            RECORDED A WIND GUST OF 62 MPH.

1234 PM     DEBRIS FLOW      BLAIRSDEN               39.78N 120.62W
01/08/2017                   PLUMAS             CA   AMATEUR RADIO

            MUD FLOW ACROSS HIGHWAY 70 BETWEEN GRAEAGLE AND PORTOLA.
            DRIVER WENT TOWARDS CALPINE AND FEATHER RIVER WITHIN 1
            FOOT OF ROAD.

0148 PM     NON-TSTM WND GST 4 E INCLINE VILLAGE     39.24N 119.88W
01/08/2017  M64.00 MPH       WASHOE             NV   PARK/FOREST SRVC

            THE RAWS SENSOR AT LITTLE VALLEY RECORDED A WIND GUST OF
            64 MPH.

0818 PM     NON-TSTM WND GST 5 SE MOUNT ROSE SKI ARE 39.27N 119.82W
01/08/2017  M69.00 MPH       WASHOE             NV   DEPT OF HIGHWAYS

            THE NDOT SENSOR IN WASHOE VALLEY RECORDED A WIND GUST OF
            69 MPH.

&&

O'HARA