Special Weather Statement, NWS Reno, NV

Area Forecast Discussion
National Weather Service Reno NV
1251 PM PDT Tue Aug 9 2022

.SYNOPSIS...

An active thunderstorm pattern will continue today with plenty of
moisture for thunderstorms, some with heavy rain, strong gusty
winds and small hail. Low pressure off the northern California
coast then lifts northeast with a drier, more stable airmass
decreasing storm potential the remainder of the week. Seasonal
temperatures and typical afternoon breezes will also return.

&&

.SHORT TERM (Through Wednesday Night)...
Convection got off to an early start this morning with showers
and a couple rumbles of thunder quickly moving north near 30
knots. Thunderstorm coverage will continue to spread through the
afternoon hours thanks to broad synoptic forcing as our area
resides under the right entrance region of an upper-level jet
streak. The 12Z RAOB from our office in Reno sampled 0.99 PWAT,
and 06Z ECMWF ensembles tend to agree that Fallon's PWATs are
right around 1.25 +/- 0.05 inches. Storms, therefore, will be
rather juicy with high rain rates today and will be capable of
localized flash flooding if they happen to train over one area for
a period of time. In our far northern areas (N Lassen, E Modoc, N
Washoe), there is a marginal severe risk this afternoon,
primarily due to damaging wind gusts as 0-6km bulk shear of
35-45 kt and DCAPE 1200-1600 J/kg will support a few discrete
cells capable of producing strong/damaging wind and perhaps some
small hail. With the quick storm motion, some storms may not
produce enough precip quick enough to compensate bursts of CG
lightning. Therefore there is an elevated risk of new fire starts
in these areas. As for high temperatures today, we're looking
right around 80 in Sierra valleys and upper 80s to low 90s in
western Nevada; ultimately, highs will be contingent on shower and
storm activity through the day...

By Wednesday, the area of low pressure that has been pestering us
for some time will finally begin pulling off to the north,
paralleling the Pacific Coastline. While the main forcing that we
have been experiencing in recent days will be subsiding as the low
pulls away, upper level divergence on the southeastern side of
the jet combined with abundant daytime heating (highs in the mid-
90s across western NV) will support at least isolated
thunderstorms. Bulk shear of 25-30 kt hanging around will support
quicker storm motions and DCAPE of 1500-2000 J/kg will support
stronger downdrafts and gusty winds. With the drier air intruding
into the area on the backside of the low, isolated to scattered
storm chances will mainly be confined along and east of US-95.
-Dustin

.LONG TERM (Thursday through Next Weekend)...

A nearly stationary upper level disturbance spinning over the Gulf
of Alaska and strong upper ridge with a 5960 hPA central high
anchored over the central Rockies/Upper Plains will maintain a
drier southwest upper flow over the region Friday. This pattern
effectively shuts off the flux of monsoonal moisture over the
Sierra and far western NV for the time being through this weekend.
Some residual moisture coupled with SFC heating will still an
increased risk of an isolated shower or T-storm (15-20%) over the
Mono-Mineral convergence zone that could meander into southeast
Churchill County bringing gusty outflows to 45 mph and brief
visibility reductions in blowing dust. The weekend should see a
brief return of the afternoon Zephyr breezes to 25 mph and more
seasonal summer temperatures in the mid 90s in lower valleys and
80s for Sierra locations.

But this current break from the higher humidity and afternoon
storms will be short-lived. The upper low hanging just off-shore
the Pacific Northwest will get a jet-stream boost and lift
northeast into southwest BC Saturday, dragging a negative tilted
upper trough east and southeast across WA/OR as well ad northern
CA. Ensemble cluster guidance does focus some uncertainty as to
the extent the upper trough influences northern NV with European
EPS simulations weighing heavily towards that solution.

As this upper wave continues east, it will flatten then shift the
ridge axis more west back over the Four-Corners and Great Basin by
early next week. Once again the tap of monsoonal moisture is twisted
open to sweep north in the Sierra and western NV. Ensemble meteogram
guidance foresees moisture increasing over the region with the
majority of simulations bring PWATs values close to a 0.6” to 0.9”
range. As per ensemble blended guidance, an increased chance of
afternoon/evening showers and/or hybrid type thunderstorms (15-20%)
will once again dot the region with gusty outflow winds, localized
blowing dust, lightning (not necessarily dry), and heavy rainfall
cores. -Amanda

&&

.AVIATION...
Thunderstorms will once again develop this afternoon starting
around 20-21Z and continuing until about 03Z. The greatest risk
and coverage is expected in west central NV including
KHTH/KNFL/KLOL, with fast moving storms potentially bringing short
bursts of heavy rain and small hail, gusty outflow winds 40-50
kts, low-level turbulence, and reduced visibility in blowing dust.
For the main terminals in far western NV southward to KMMH, the
thunderstorm threat is lower, with occasional thunder, brief light
rain and outflow gusts to 30 kt possible generally between 20Z-
00Z. For the Tahoe area terminals, the risk for thunder is quite
low today as drier SW flow sets up across the Sierra.

For Wednesday, thunderstorm activity is expected to decrease with
isolated PM storms limited to areas east of US-95. Elsewhere,
drier and more stable conditions return with afternoon zephyr
gusts of 20-25 kt, with these drier conditions also extending to
west central NV by Thursday. MJD

&&

.FIRE WEATHER...
* Scattered thunderstorms will bring increased risk of new
  lightning fire starts in northwest and west central NV this
  afternoon and into the evening. Although most of these storms
  will contain substantial moisture and produce bursts of heavier
  rain, they'll move quickly with potential for lightning strikes
  outside the precip cores, along with strong outflow gusts of
  40-60 mph.

* Most storm activity is expected to remain east of the higher
  risk burn scars in eastern CA and far western NV. Isolated brief
  rain showers are possible but rainfall amounts will be sparse.
  The Poodle Fire burn scar in northwest NV has a bit more risk,
  with about a 20% probability of a stronger cell moving through
  this area later this afternoon.

* From Wednesday through the rest of this week, we're looking at a
  return to a drier weather pattern with typical zephyr breezes
  20-30 mph each afternoon, which could bring the emergence of
  holdover lightning fire starts from recent thunderstorm
  activity. MJD

&&

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

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

Special Weather Statement
National Weather Service Reno NV
215 PM PDT Tue Aug 9 2022

NVZ003-004-092200-
Western Nevada Basin and Range including Pyramid Lake NV-
Greater Reno-Carson City-Minden Area NV-
215 PM PDT Tue Aug 9 2022

...A strong thunderstorm will impact portions of Storey and northern
Lyon Counties through 300 PM PDT...

At 215 PM PDT, Doppler radar was tracking a strong thunderstorm 7
miles east of Dayton, or 12 miles east of Virginia City, moving north
at 30 mph.

HAZARD...Wind gusts up to 50 mph and penny size 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...
Fernley, Dayton, Fort Churchill Station, Silver Springs, Stagecoach,
Junction U.S 50 And Six Mile Canyon-Ft Churchill Rd, Rawe Peak and
Silver Springs Airport.

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.

This storm may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.

&&

LAT...LON 3918 11932 3920 11955 3956 11952 3955 11911
TIME...MOT...LOC 2115Z 194DEG 25KT 3926 11942

MAX HAIL SIZE...0.75 IN
MAX WIND GUST...50 MPH

DN