Area Forecast Discussion
Issued by NWS Reno, NV

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FXUS65 KREV 192131

Area Forecast Discussion
National Weather Service Reno NV
231 PM PDT Sat May 19 2018


Another low pressure area will settle over California and western
Nevada, bringing an increased chance for storms through the
remainder of the weekend and into the middle of next week. Some of
these storms will produce locally heavy rainfall, especially
Monday and Tuesday.



Isolated showers and thunderstorms have initiated this afternoon
mainly along and east of the I-580/HWY 395 corridor. Storms will
drift northeastward through the afternoon with most activity
remaining east of US95 Alternate from Yerington to Fernley
extending north through Pyramid Lake and Gerlach this evening.
Brief periods of heavy rain and small hail are possible.

We will remain in an active pattern for the remainder of the weekend
and heading into next with chances for showers and storms
continuing. On Sunday the upper low will begin to move southeast
into CA with a more southwest flow in advance of it. This will
provide lesser chances for storm development roughly through the
I-80 corridor through Tahoe and western Nevada. The best chances
to see storms looks to be across northern Lassen County into far
northwest Nevada and also through Mono and Mineral counties.

Chances for showers and storms become more widespread by Monday as
the upper low closes off near the southern Sierra and the focus
turns to more widespread rain bands and embedded thunder across the
eastern Sierra and western NV, especially south of I-80. Localized
areas of heavy rainfall and small hail are possible with storm
motions drifting southwestward on the backside of the low. These
storm motions will continue to be west-southwest on Tuesday which
should lessen and confine most shower and storm activity along and
west of the Sierra crest. Fuentes

.LONG TERM...Wednesday through next weekend...

As one low pressure area begins to slowly exit the Great Basin by
midweek, one more low could approach the region toward the end of
next week and the start of the Memorial Day weekend.

For Wednesday, wrap around showers may be ongoing in the morning
mainly north of I-80 as the upper low slowly exits the Great Basin,
with plenty of residual moisture likely in place. Daytime heating
combined with this low level moisture will lead to unstable
conditions favorable for afternoon thunderstorm development mainly
near the Sierra and into northeast CA. Upper level forcing and
dynamics do not look very impressive, although a light westerly push
off the Sierra and outflow boundary interactions could be sufficient
to spread thunderstorm activity into western NV through Wednesday

From Thursday through Friday, a weak upper level ridge looks to
build over western NV with a slow warming trend (highs rising into
the lower-mid 80s for lower elevations/lower 70s near the Sierra).
However, with weak flow continuing and a lack of any mechanism to
clear out the residual moisture, the potential for afternoon showers
and isolated thunderstorms is likely to continue mainly near the
Sierra and northeast CA, with a few cells possibly spreading into
far western NV each evening. Overall coverage both days is likely to
be less compared to Wednesday.

For the early part of next weekend, there is more disagreement among
the medium range guidance as another upper low approaches the west
coast. Some scenarios push this low through western NV but others
keep it off the west coast and lift it to the north. Even if the low
takes this largely offshore track, forcing may be sufficient for
some cells developing as a negative tilt trough axis sweeps across
the region, so we will continue to mention thunder chances with
probabilities and coverage trending a bit upward compared to Friday.

A quick look ahead to the remainder of the Memorial Day weekend may
finally show a more definitive drying trend as a ridge axis develops
east of the region with southwest flow aloft over the Sierra.
Daytime temperatures will be dependent on the location and amplitude
of the ridge, although the warmer scenarios may bring temperatures
close to 90 degrees for some lower valleys. MJD



For this afternoon and evening, showers and thunderstorms are most
likely across northwest/west central NV and northeast CA. For the
main terminals, the potential for thunder is trending lower, except
a few cells may affect KMMH until around 02z. As is typical with
most thunderstorms, expect localized stronger outflow gusts and
turbulence with brief periods of lowered cigs and vsbys. Otherwise,
VFR conditions should prevail except another round of fog is likely
around KTRK and the Martis Valley late tonight until 16-17Z Sunday

For Sunday, thunderstorm chances look best for areas north of
Susanville-Gerlach, and south of US-50 in western NV. For the main
terminals, KMMH has about a 20-30 percent potential for thunder,
with marginal chances elsewhere. Overall shower and thunderstorm
chances increase again Monday and Tuesday with more widespread
coverage of lower ceilings and mountain obscurations. Thunderstorms
are likely to be present in portions of the forecast area each day
through next Saturday. MJD


.REV Watches/Warnings/Advisories...



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