Area Forecast Discussion
Issued by NWS Reno, NV

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FXUS65 KREV 221010
AFDREV

Area Forecast Discussion
National Weather Service Reno NV
310 AM PDT Sun Jul 22 2018

.SYNOPSIS...

Showers and thunderstorms will persist early this week with the
best coverage along the eastern Sierra from Mono and Alpine
Counties northward to the Sierra Front of western Nevada. Locally
heavy rain will keep the flash flood potential around at least
through Monday. High pressure will build mid to late week for a
decrease in thunderstorms and a return to hot temperatures.

&&

.SHORT TERM...

Nocturnal convection has remained across central and northeast NV
with partial breaks in the cloud cover over the Sierra and western
NV. This should allow for enough daytime heating to fire another
round of thunderstorms along the higher terrain of the Sierra this
afternoon with activity spreading north into the Sierra Front late
in the afternoon. One thing that will be absent today will be the
added lift from an upper jet that was retreating to the north and
out of the area this morning. So thunderstorms are going to
depend more on daytime heating and resulting instability along
with outflow/terrain induced winds to maintain their strength.
Given PWATs are near 1" and surface dewpoints are quite high along
the Sierra Front (mid 40s to mid 50s, locally around 60 degrees),
there is definitely plenty of moisture available for stronger
storms to produce more heavy rain and thus the potential for one
or two flash floods given the expected slow storm motions.

The GFS seems to be going overboard with the nocturnal convection
with the lack of any larger scale forcing, so we lowered that
chance. The exception could be Monday night as a subtle wave
rotates around upper ridge into the Great Basin late Monday. Model
scenarios differ on the timing with this feature which could
really get things going during the afternoon Monday, or in later
scenarios keep thunderstorms that do form from daytime heating to
continue well into the evening and possibly overnight. We have
increased chances for thunderstorms today and Monday from Mono and
western Mineral County northward to the Carson Range and Sierra
Front. We have also continued a low end chance of thunderstorms
along the Lassen Convergence each afternoon and evening although
the airmass there is not quite as moist.

By Tuesday, the ridge will build a bit farther westward and
thunderstorms should begin to decrease with best chances south of
Highway 50. That means temperatures will also start to heat up
again. Smoke from mainly the Ferguson Fire will keep some haze and
areas of smoke around as well although rains and storm outflows
could disrupt this smoke over the next couple days. The fire is
still burning actively based on satellite, and finer scale models
bring another round of smoke later today.

There are many outdoor festivals and sporting events occurring
around the area, so please pay close attention to the weather
surrounding you. Some things to keep in mind -- if you can hear
thunder, you are close enough to be struck by lightning. Also,
heavy rain can drop temperatures by 30 degrees in a short period
of time. This can easily catch campers/backpackers off guard, so
prepare for wet weather. Hohmann

.LONG TERM...Wednesday through Sunday...

The ridge over Arizona will continue to be the main player in the
forecast into the weekend. It will be flattened somewhat by a weak
trough over Washington, but this looks to be delayed by a day.
Therefore, some threat of thunderstorms was maintained north to
Highway 50 and east of Tahoe for Wednesday. Temperatures will
still continue to climb to around 100 in Western Nevada and well
into the 80s for the Sierra.

Thursday through Saturday looks similar with west to southwest flow
aloft on the north side of the high. This will continue the drying
trend with any storms limited to eastern Mono and western Mineral
Counties if they were to occur.

The high is then expected to move northwest over Nevada Sunday and
beyond. It would keep highs hot, and would eventually portend
another increase in moisture and thunderstorms. For now, we are
keeping Sunday dry, but this may change as we move forward. X

&&

.AVIATION...

TSRA are the main concern today from 20-03Z. The best coverage is
again expected to be along the 395 corridor from KMMH north through
KRNO/KRTS with a 50-60% chance of a direct hit. Terminals most
affected would be KMMH, KMEV, KCXP, KRNO, KRTS. Outflow gusts to 45
kts, heavy rain and small hail will continue to be the concerns.
Lesser chances for KTVL/KTRK/KSVE today due to SW ridge level winds.
Looking at 30-40% chances, but still much better than Saturday.
Storms may continue overnight, but only a 10-20% chance. A repeat is
expected Monday with continued deep moisture and similar
timing/chances.

As far as smoke from the Ferguson Fire, visibility is expected to
remain VFR today, but with haze all day. It may restrict the
slantwise visibility more than the surface visibility. The main
impact from smoke this morning will be from Tahoe into Reno. Then
this afternoon south of highway 50 based on the latest HRRR smoke
run. One factor is that afternoon convection will help to rain out
much of the particulates so the impacts may not be as bad as the
HRRR suggests. X

&&


.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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