Area Forecast Discussion
Issued by NWS Reno, NV

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FXUS65 KREV 140413 AAA

Area Forecast Discussion...UPDATED
National Weather Service Reno NV
913 PM PDT Thu Jul 13 2017

Convection was winding down with the loss of daytime heating and
only a few isolated showers remain south and east of Fallon.
In addition, satellite imagery showed clouds rapidly diminishing
and skies should clear overnight. Winds too will continue to
subside as gradients relax and the atmosphere decouples. We have
updated the zone forecast to reflect the latest trends. A quick
look at the latest 00Z GFS/NAM for Friday and Saturday shows
little appreciable change to the afternoon forecast. They
indicate storms will remain isolated but spread a little farther
north. Hohmann


.PREVIOUS DISCUSSION... /Issued 329 PM PDT Thu Jul 13 2017/


Isolated showers and thunderstorms could develop as far north as
Reno and Fallon Friday afternoon and evening. Shower and
thunderstorm chances are expected to increase for the Sierra and
western Nevada over the weekend before drier air ends thunderstorm
chances early next week. Temperatures will remain near or
slightly above average through next week.


Minimal change to the short term forecast today. Showers and
isolated thunderstorms have developed this afternoon along and
east of Highway 395 in Mono County and west of Highway 95 in
Mineral County. Convection through this evening will move off to
the north and east, possibly reaching up into the Pine Nut
Mountains of eastern Douglas County and into Lyon and southern
Churchill counties, generally south of Highway 50. Storms should
be generally "garden-variety" with gusts to 40 to 50 mph,
occasional lightning, and brief light to moderate rain.

Friday, isolated thunderstorms are once again expected with daytime
heating. With modest south to southwest flow aloft, storms could
creep farther north into the Carson Range east of Lake Tahoe and
into the Reno-Sparks area, as well as to near Highway 50 out in
the Basin and Range. Storm intensities and movement (less than 10
mph) Friday look similar to today.

As we go into the weekend, areal coverage of showers and
thunderstorms is expected to increase as the atmosphere slowly
moistens with southerly flow around an upper ridge centered over
southern Nevada and southwestern Utah. The NAM and GFS simulations
are at odds as to how much convective development the region will
see over the weekend. We feel that the GFS (more convection) is
more on track given the upper flow pattern and convergence likely
to form in the lee of the Sierra as the zephyr pushes off each
afternoon and evening. Also, both models show an upper disturbance
moving over the region later on Saturday which could enhance
chances for daytime convection, as well as keep light showers
overnight across western and west-central NV.

Sunday, drier southwest flow begins to impinge on northeast CA and
far western NV, bringing a slightly stronger zephyr flow. With
some antecedent moisture in place (PWATs up to around 0.75") and
the strengthening afternoon/evening convergence with the zephyr,
Sunday may feature storms becoming a bit stronger with heavier
rain than Saturday. The flow is expected to displace most of the
storms farther east...from the Pine Nut and Virginia Ranges
eastward into the Basin and Range. -Snyder

LONG TERM...Monday through Thursday...

Dry, stabilizing southwest flow develops over northeast CA and
western NV for much of next week as weak upper waves move through
the Pacific Northwest and ridging retreats into the Desert Southwest.

For Monday, enhancing thermal gradients across the region with the
upper ridge breaking down will result in stronger winds. Gusts to
35 mph or so, generally north of Highway 50, and drier air will
bring heightened fire weather concerns. This is especially so if
lightning over the weekend starts new fires as the gusty winds
could bring conditions conducive for rapid fire spread.

Although there will still be some breeziness Tuesday and Wednesday,
winds should be waning to more typical zephyr breezes. Temperatures
will remain near or slightly above average next week. -Snyder


Mainly VFR this evening with typical zephyr winds in the 20-25 kt
range. Convection this evening should remain mainly well south of
Highway 50. KMMH/KHTH have the best chance of seeing storms close
to the terminals. Outflow gusts to 40 kts and a few lightning strikes
could accompany any storms this evening.

Convective chances begin to increase Friday and lift north with
the best chances Saturday and Sunday. Friday, and especially
Saturday, could see storms reaching up as far north and west as
the Carson Range. Storms Sunday are more likely be confined to
mainly areas east of a line from Bridgeport to KLOL as drier
westerly flow begins to intrude far northeast CA and extreme
western NV. -Snyder


.REV Watches/Warnings/Advisories...


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