Area Forecast Discussion
Issued by NWS Reno, NV

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FXUS65 KREV 190324
AFDREV

Area Forecast Discussion
National Weather Service Reno NV
824 PM PDT Mon Jun 18 2018

.UPDATE...

As a ridge starts to build into the region...the upper low that
caused showers and thunderstorms is lifting to the northeast. Most
of the instability associated with this low is over north central
and northeast Nevada and points farther north and east. We have
seen a few showers from northwest Lassen County east across
northern Washoe County and far northern Pershing County...but
these are diminishing. The current forecast appears to handle the
situation well so no significant updates are expected.

The latest word we have from the NV DWR and Washoe County is that
mitigation efforts are working as crews plug the breach and the
threat of a dam failure has diminished. Even though the threat has
decreased early this evening...we will maintain the Flood Watch
for Steamboat Creek from Little Washoe Lake down to the Steamboat
area to help maintain heightened public awareness.

&&

.PREVIOUS DISCUSSION... /Issued 441 PM PDT Mon Jun 18 2018/

UPDATE...

We have issued Flood Watch for Steamboat Creek in the southern
part of Washoe County. The dam at Little Washoe Lake has developed
a partial breach...BUT HAS NOT FAILED. Crews are working on
repairs at this time. We will continuously monitor the situation
through the evening and overnight hours and update the watch as
needed.

PREVIOUS DISCUSSION... /Issued 247 PM PDT Mon Jun 18 2018/

SYNOPSIS...

The coming week will feel much more like early summer compared to
this past weekend, favoring warming and drying conditions. Gusty
afternoon winds are projected for Wednesday and Thursday, along
with well above normal temperatures. Thunderstorm risks remain
quite low through at least next weekend.

DISCUSSION...

Much more typical mid to late June weather for this week with lots
of 9`s in the MOS highs for RNO. Here`s the highlights:

* Temperatures well above normal starting Wednesday with localized
  heat health impacts for sensitive groups. Guidance has been
  somewhat "unstable" past Day 3 the last couple weeks, so my
  confidence in temperature forecasts for this weekend is only
  medium. GFS brings a brush-by cold front through which could
  cool temps some.

* Winds may kick up to a little more than a normal zephyr
  Wednesday and Thursday as short wave scoots by to our north.
  Wind prone spots could see some travel or recreation impacts,
  but main concern is fire weather. Critical wind and humidity
  conditions possible for dry grassy areas south of Hwy 50 and
  east of Hwy 395 where we`ve already seen large fires. Winds
  would be on the low-end of red flag spectrum but humidity is
  looking super-low especially Thursday (<5% RNO?), so some alerts
  possible as we draw closer.

* No appreciable thunderstorm risk through next weekend and
  perhaps into the following week with dry mainly west to
  northwest flow over the region. That may change late next week
  (~28th) when 4-corners high looks to get established per ECMWF
  and GEFS guidance. That could bring enough moisture northward
  for t-storm risks to increase.

-Chris

AVIATION...

* Scattered to broken clouds will result in some terrain
  obscuration into this evening, especially north of a SVE- WMC
  line. A few t-storms possible in this same area but coverage
  will be isolated. This is all associated with low-pressure
  lifting northeast away from the region.

* Patchy fog possible again tonight in normally prone valleys and
  those that saw rainfall Sunday. TRK has a 80% chance of seeing
  VCFG and 40% chance of LIFR fog at the field late tonight into
  Tuesday morning. Can`t rule out some VCFG near TVL but much
  less certain.

* Elsewhere including RNO, CXP, MMH no major aviation weather
  hazards of note through much of this week. Density altitude and
  gusty southwest winds may become an issue region-wide Wednesday
  and Thursday afternoons coupled with well above normal
  temperatures.

-Chris

FIRE WEATHER...

Main period of concern is Wednesday and Thursday for lower
elevations of W Nevada where dry grasses exist. Critical wind
and humidity conditions possible for dry grassy areas south of Hwy
50 and east of Hwy 395 where we`ve already seen large fires this
season. Winds would be on the low-end of red flag spectrum
Wednesday and Thursday (slight zephyr enhancement) but humidity
is looking super-low especially Thursday (5% or less Sierra Front
and points east?), so some alerts possible as we draw closer.
Particualrly poor humidity recoveries Wed night and Thurs night
for mid-slopes. At the very least this pattern will rapidly dry
out remaining 2018 grass fuels below 6000 ft or so.

Keep an eye on next Monday-Tuesday as latest simulations show
stronger winds and a more widespread critical scenario. T-storm
days look to hold off until sometime mid to late next week.

-Chris

&&

.REV Watches/Warnings/Advisories...
NV...Flood Watch until 5 AM PDT Tuesday NVZ003.

CA...None.
&&

$$

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



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