Severe Thunderstorm Warning 2, NWS Reno, NV

Area Forecast Discussion
National Weather Service Reno NV
1206 PM PDT Sat May 27 2023

.SYNOPSIS...

Daily showers and thunderstorms (30-60% chances) are forecast
through the holiday weekend and into next week. Stronger storms
may produce locally heavy rainfall, small hail, gusty outflow
winds, and frequent lightning. Snowmelt will keep streams
running cold and fast, with main flood concerns for the Walker
River.

&&

.DISCUSSION...

No significant changes to the ongoing forecast. Plan on daily
afternoon thunderstorms (30-60% chances) through the holiday and
into early next week as well as ongoing snow melt impacts.
Thunderstorm impacts each day will include: locally heavy
rainfall, small hail, gusty and erratic outflow winds, and
frequent lightning.

TODAY: A cut off low across the Pacific Northwest is punting a
shortwave across northern CA/NV this afternoon and evening and
triggering convective activity for areas along and north of
Interstate 80 today. Visible satellite imagery shows an expansive
area of cumulus buildups well underway with thunderstorm
initiation occurring across northern Lassen and northern Washoe
counties. Areas of showers and thunderstorms are already ongoing
across Lassen and Washoe counties with a west to east track.
Outdoor enthusiasts be aware of the rapidly changing conditions
and be prepared to shelter in a sturdy building or vehicle if
you hear thunder. Even small pea-sized hail is quite painful if
you get stuck outside in a storm!

REST OF THE HOLIDAY WEEKEND: The cut off low drops south along
the CA coast and meanders about CA from this weekend into midweek
next week. East surface winds combined with southerly steering
will result in directional shear across the Sierra and western
Nevada on Sunday. The combination of low to mid level shear,
surface instability, and upper level divergence may produce
stronger, longer-duration storms midday Sunday into the evening,
especially for storms that form along and south of Interstate 80.
As the low lingers offshore, thunderstorm potential will shift
slightly with the best potential (30-40% chances) along the
Sierra, northeast CA, and far western NV.

Generally with thunderstorms this weekend into early next week,
we could see localized heavy rainfall rates that may aggravate
flooding impacts in sensitive areas such as recent burn scars,
steep canyons, and along rivers and creeks already running fast
and high from spring snowmelt.

Plan on the unsettled pattern with above normal precipitation
chances (due to showers and thunderstorms) appears to linger on
with the West as we head into early June. No signals for building
high pressure ridge for the CA/NV region. -Edan

&&

.AVIATION...

A steady pattern of scattered afternoon showers and thunderstorms
will be possible through the weekend. There will be a 30-40% chance
for storms impacting KTRK-KTVL as well as KRNO-CXP-KMEV through
03z this evening. Storms may produce brief heavy rainfall, with
terrain obscuration, gusty and erratic outflow winds in excess of
40 kts, and small hail. More widespread shower and storms chances
will be possible Sunday afternoon (40-50% chance). Outside of
storms, conditions will be VFR with scattered to broken cumulus
decks. Periods of fog will be possible overnight at KTRK from
10-15z. Fuentes

&&

.HYDROLOGY...

No significant updates or changes in ongoing flood concerns.
Headwater flows have diminished a bit with cooler temperatures,
and crests are slowly migrating down mainstem rivers.

* WALKER: Prolonged minor to moderate flooding will continue
  along the East Fork and main-stem of the Walker River. The
  Walker River in the Mason Valley continues to trend slightly
  downward. Very minimal decreases in flow are expected this
  weekend, but it will depend on reservoir management adjustments
  which are intended to maintain storage and to mitigate future,
  and potentially, higher peaks.

* CARSON: Minor flood impacts may be a concern along the East and
  West Forks of the Carson, but trends are down from earlier in
  the week.

* MONO COUNTY: Keep a close eye on Mono county small streams
  which have been running very high.

* THUNDERSTORMS: Thunderstorms will continue to be a wild card.
  Unsettled, storm pattern continues for the weekend and into next
  week. With saturated soils and elevated streamflows, additional
  rain will result in rapid rises and enhanced flooding
  potential. These storms will be most impactful along smaller
  creeks and streams, but could also exacerbate problems along
  mainstem rivers which are already flooding or are very close to
  flood impact levels. Note: River forecasts are incapable of
  incorporating these short duration high intensity rain events.

-Bardsley/Edan

&&

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

&&

Special Weather Statement
National Weather Service Reno NV
100 PM PDT Sat May 27 2023

NVZ003>005-272100-
Western Nevada Basin and Range including Pyramid Lake NV-
Northern Washoe County NV-Greater Reno-Carson City-Minden Area NV-
100 PM PDT Sat May 27 2023

...Strong thunderstorms will impact Pyramid Lake through 200 PM
PDT...

At 1259 PM PDT, Doppler radar was tracking a cluster of strong
thunderstorms over Pyramid Lake, moving east at 30 mph.

HAZARD...Winds in excess of 40 mph and half inch hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could capsize small vessels on the lake. Minor
         damage to outdoor objects is possible.

Locations impacted include...
Pyramid Lake, Sutcliffe, Nixon, The Needle Rocks and Tohakum Peak.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

&&

LAT...LON 3995 11968 4022 11981 4029 11948 3984 11936
      3981 11949
TIME...MOT...LOC 1959Z 263DEG 25KT 4008 11958

MAX HAIL SIZE...0.50 IN
MAX WIND GUST...40 MPH

TF

Special Weather Statement
National Weather Service Reno NV
246 PM PDT Sat May 27 2023

NVZ004-272200-
Western Nevada Basin and Range including Pyramid Lake NV-
246 PM PDT Sat May 27 2023

...A strong thunderstorm will impact portions Interstate 80
near Trinity Jct (US-95) through 300 PM PDT...

At 244 PM PDT, Doppler radar was tracking a strong thunderstorm over
Trinity Junction, or 20 miles southwest of Lovelock, moving east at
40 mph.

HAZARD...Winds in excess of 40 mph and half inch hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor damage to outdoor objects is
         possible.

Locations impacted include...
Trinity Junction and Junction I 80 And U.S 95 (exit 83).

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

Torrential rainfall is also occurring with this storm and may lead to
localized flooding. Do not drive your vehicle through flooded
roadways.

&&

LAT...LON 3989 11878 4000 11881 4007 11862 3990 11852
TIME...MOT...LOC 2144Z 265DEG 34KT 3994 11869

MAX HAIL SIZE...0.50 IN
MAX WIND GUST...40 MPH

TF