Area Forecast Discussion
Issued by NWS Reno, NV

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FXUS65 KREV 052004
AFDREV

Area Forecast Discussion
National Weather Service Reno NV
104 PM PDT THU MAY 5 2016

.SYNOPSIS...

Widespread showers with scattered thunderstorms are expected today
with storms bringing frequent lightning and copious amounts of
small hail. Unsettled weather will continue into the weekend with
locally heavy rain possible. Drier, warmer weather returns next
week.

&&

.SHORT TERM...

Forecast remains on track with few changes made. Slowly moving
area of low pressure will bring wet and stormy weather to the
Sierra, northeast California, and northwest Nevada through Sunday.
There are multiple events this weekend that could be impacted by
showers and thunderstorms including the Reno River Festival, the
Reno Sculpture Festival, the Moms on the Run Race, the Pamper
Pedal Bike Ride near Mammoth, and the Nevada State Police Memorial
Parade and Car Show in Virginia City.

Best thunderstorm coverage will be today as large scale forcing
from a south-north oriented jet combines with instability both at
the surface and aloft. These storms have had a history of
producing large amounts of small hail which can cover roadways and
make for hazardous travel conditions. In addition, expect
deadly lightning, brief heavy rainfall and wind gusts of 40 to 45
mph. Snow levels are running around 8000-8,500 feet and
accumulation has been observed on Mt Rose Highway earlier today.
Mt Rose, Carson, and Monitor Passes may all be snow covered for
brief periods of time this afternoon and overnight tonight. There
is also potential for Conway and Deadman`s Summits on Highway 395
in Mono County to be briefly snow covered as well.

The jet will be shifting eastward tonight, but there will still be
upper level diffluence present along with steepening mid and upper
level lapse rates. This will likely keep chances for thunderstorms
going through the night. As storm motions slow tonight into
Friday, the risk for heavy rain will increase with less chances
for gusty winds. Minor flooding is possible if storms train over
the same region, but of greatest concern are recent burn scars
such as the Washington Fire. These will need to be monitored as it
will take much less rain to produce debris flows than usual. River
rises are expected, but there will not be any mainstem river
flooding.

As the upper low shifts inland this weekend, deformation bands
will form on the north side of the low. This is likely to bring
additional heavy rain to portions of northeast California, the
Sierra, and northwest Nevada. At this point it is hard to pinpoint
where the exact heaviest bands will be, but some locations will
receive copious amounts of rainfall over the course of the
weekend. Snow levels will also rise this weekend as the cold core
of the low drops south and warmer air wraps around the north side
of the low. The area of low pressure will slowly shift eastward
with just lingering showers and a few thunderstorms possible on
Sunday. -Dawn


.LONG TERM...Monday through Thursday...

Models continue to show an upper low moving over the northern
Rockies for the early to middle part of next week. This is forecast
to allow some cooler air to backdoor into western Nevada and
northeast California by Tuesday, with a slow warm up by Wednesday or
Thursday as the airmass modifies and high pressure strengthens aloft.

With some residual moisture and heating each day there will be a low
chance for afternoon and evening showers near the Sierra crest,
but it will remain dry elsewhere. Snyder

&&

.AVIATION...

Thunderstorms are expected to be strongest today for much of
northeast California and western Nevada as a large-scale upper low
approaches central and southern CA. Many storms will be capable of
copious amounts of small hail (1/2 to 3/4" possible), heavy rainfall
(+TSRAGS), and wind gusts to 35-40 kts. In addition, strong storms
could be longer-lived with a much longer track than is typical for
western NV/northeast CA. Terrain obscurement and MVFR conditions
will be possible in heavier thunderstorms.

Tonight, model simulations indicate re-development of rain and
embedded thunderstorms this evening and overnight. Wherever the area
of rain forms, expect widespread higher terrain obscuration and
occasional MVFR CIGS/VIS along with isolated-scattered lightning
strikes.

For Friday, another round of showers and thunderstorms is expected
as the upper trough moves to interior/southeast CA and southern NV.
The strongest, most long-lived storms look to be generally north of
Portola and KLOL...where +TSRAGS and wind gusts to 40 kts will
continue to be a threat. Elsewhere in western NV and the eastern
Sierra, slower moving storms will be capable of heavy rain but hail
should be more isolated in nature compared to Thursday. Snyder

&&


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

$$

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



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