Area Forecast Discussion
Issued by NWS Reno, NV
FXUS65 KREV 040942
Area Forecast Discussion
National Weather Service Reno NV
242 AM PDT WED MAY 4 2016
Showers and a few thunderstorms are expected this afternoon and
evening as low pressure moves onshore. An increase in showers and
thunderstorms is expected Thursday with some of the storms being
strong. Unsettled weather will continue into the weekend with
locally heavy rain possible. Drier, warmer weather returns early
Made a few changes to the forecast, mainly to lower the rain
chances a bit into Thursday. We are still expecting a good event
and while most areas will see rain each day, it is showery so not
everyone will get hit.
The upper low that will be the main weather player into the
weekend will approach the coast today with moisture increasing.
A few showers are present this morning across Western Lassen
County and are fairly light. Expect these to increase today as the
low moves in. The models have continued the trend of backing off
on the instability and this looks reasonable. There is still quite
a bit of cloud cover, so expect more showers than thunderstorms.
With the best forcing not expected to arrive until evening, also
do not believe the thunderstorms will be that strong today. Still
could expect some brief heavy rains and small hail.
The jet moves north tonight as the upper low continues its slow
east trek. The dynamics are better, so showers will continue
overnight north of South Lake Tahoe/Minden with an isolated storm
Thursday looks like the better day for strong thunderstorms.
Instability increases with CAPE up to 1000 J/kg, and the S-N
upper jet is in a very favorable position over central NV. Expect
widespread showers and storms near Reno/Tahoe up to Cedarville
where instability is greatest with at least scattered
showers/storms everywhere else. Larger hail and brief heavy rains
will be the greatest threats.
Showers and storms to continue into Thursday evening and become
less numerous. Still enough moisture and instability to continue
scattered showers overnight. Friday more showers and storms are
expected with another day of good instability as the low moves
into Southern CA. Forcing won`t be quite as strong, but still
expect some locally heavy rains from them.
Friday night continues to look intriguing with a deformation band
developing on the NW side of the low. The models are coming into
better agreement with the location, the EC/GFS/NAM hitting the
Oregon border area into Lassen County. Moderate confidence in
this band location and development. Rainfall amounts Friday night
could approach 1" in this band alone. Wallmann
.LONG TERM...Saturday through Tuesday...
Upper low will be centered just south of Las Vegas Saturday with
the Sierra and western NV remaining in a favorable location for
additional showers and thunderstorms, some with locally heavy
rain. Aforementioned band of showers/storms over northeast CA and
northwest NV will be winding down Saturday morning as a second
shortwave feature rotates around upper low into western NV. Models
have been showing this Sat-Sat night band for several days now,
although there have been some slight variations in where heaviest
precipitation bands will set up as well as exact timing. It
appears this band will set up Sat afternoon as shortwave
approaches and instability increases across the Basin and Range.
The GFS is a bit farther north than the ECMWF, but generally south
of where the Friday night band sets up. This would focus heavier
rains on the Tahoe Basin and Sierra Front. Confidence is only
medium and this location could change. But most areas will see
showers and thunderstorms Sat-Sat night nonetheless. Some model
solutions keep this band going into Sunday morning.
As upper low slowly pulls out of the region Sunday, another day of
scattered showers and thunderstorms is expected although coverage
should begin to decrease. Favored areas will be south of I-80. By
Monday, a ridge will work into the west coast with a few showers
lingering mainly along the Sierra. After a cool weekend,
temperatures will warm quickly next week with some model
simulations indicating low-mid 80s for western NV Tue-Wed.
Showers and thunderstorms will be on the increase today and
Thursday with coverage of lightning generally isolated today,
increasing to scattered on Thursday. Storms will be capable of
lots of small hail and heavy rain, especially Thursday when
forcing/instability will be strongest. There will not be much
break overnight with a few storms possible.
As far as timing, showers/storms will develop along the Sierra
this afternoon and remain mostly locked to the terrain until late
afternoon/this evening when upper forcing shifts into western NV.
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