Area Forecast Discussion
Issued by NWS Reno, NV

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FXUS65 KREV 250152
AFDREV

Area Forecast Discussion
National Weather Service Reno NV
652 PM PDT Wed Apr 24 2019

.UPDATE...

We are going to issue a minor update this evening to adjust
shower and isolated thunderstorm coverage through 9 pm. The
convection should not be very significant...but it has held
together and moved into areas we did not have included initially.
With the loss of heating...the activity should diminish later this
evening.

We are also going to update the Flood Watch for the West Carson
River in the Carson Valley of Douglas County. The most recent
forecast includes the potential for reaching flood stage Saturday
night along with Thursday and Friday nights. So we will adjust
the watch accordingly. It must be reiterated...the West Fork
Carson River is expected to BARELY reach flood stage. This would
only affect small parts of the southern end of the Carson Valley.

&&

.PREVIOUS DISCUSSION... /Issued 228 PM PDT Wed Apr 24 2019/

SYNOPSIS...

Well above average temperatures this week will lead to increased
mountain snowmelt with cold and swift flows for area streams,
with minor flooding possible for agricultural areas in the Carson
Valley by early Friday morning. Isolated showers and thunderstorms
are possible Wednesday and Thursday afternoon and evening. It will
turn cooler with a chance of showers next week.

SHORT TERM...

Well above average temperatures and terrain heating have brought
some modest cumulus development so far over higher, non snow-
covered terrain and slopes, with cumulus drifting off to the east
in the flow aloft. For the high, snow-covered Sierra, convection
has been inhibited (snow restricting surface heating) with cumulus
generally forming near the boundary between snow-covered and non
snow-covered terrain (slopes). This afternoon and evening, still
cannot rule out very isolated light showers in the Basin west of
Hawthorne north to between Pyramid Lake/Reno and up to near and
east of Susanville. Thunderstorm chances remain very low (around
5-10%).

Thursday, the chances for a few showers (or a thunderstorm or two)
shifts to the favored Lassen and Mineral county convergence zones,
with increased westerly flow aloft kicking any building instability
and sustained convergence out of western Nevada. Temperatures will
remain well above average with 70s to mid 80s for valleys.

Shower-free conditions with a gradual easing back from the well
above average temperatures (although still ~8-12 degrees above
average) will ensue Friday and Saturday as cooler northwest flow
develops. -Snyder

LONG TERM...End of April - beginning of May...

Warm end to the weekend will give way to a cooler start to next
week. Ensemble systems in agreement with trough dropping into the
west coast and possibly pushing a decent cold front through the
Sierra and western NV late Monday and Tuesday. Best confidence in
the forecast is for a cool down next week.

As with most spring systems, a wide range of possibilities is on the
table due to uncertainty in the track and strength of the system
late Monday and Tuesday. There are some simulations that drive a
dynamic system with potential for snow levels as low as 5000-5500
feet Tuesday morning, while others are in the brush by category with
minimal precipitation potential.

The west coast trough should hang around through at least the first
weekend of May, which would favor afternoon highs in the 50s-low 60s
in the Sierra and 60s-low 70s for NV valleys, with additional
chances for showers. Brong

AVIATION...

Expect VFR conditions and generally light winds this afternoon thanks
to a high pressure system over our area. There is a low chance of
thunderstorms (~5-10%) into the evening for terminals in NE California
and far W Nevada. Any thunderstorms that do develop will bring the
chance of outflow winds up to 30kts, lightning, and brief periods
of -RA/RA.

Breezier winds return Thursday and Friday, with another chance of
afternoon thunderstorms for far NE California and W Central Nevada,
including Mineral County (KHTH) on Thursday. Cassie

HYDROLOGY...

The RFC forecast for Thursday-Saturday on the West Fork of the
Carson River near Woodfords has not changed much since yesterday
so no big change in thinking for the Carson Valley.

Most rivers and streams are expected to stay significantly below
flood stages this week; however, the West Fork of the Carson
River through the Carson Valley is forecast to approach flood
stage Thursday night into Friday morning and again Friday night
into Saturday morning. The Flood Watch for the West Fork in the
Carson Valley continues and will be re-evaluated Thursday morning,
with the watch either being dropped or POSSIBLY being converted
to an advisory for very minor flooding in agricultural areas of
the Carson Valley.

High flows are expected to continue into the weekend. Still, the
highest flows are still beyond the forecast window for most rivers
and streams draining high elevation terrain, especially from the Lake
Tahoe area south through Mono County. Remember: snowmelt peaks
typically occur in the evening and overnight hours in the higher
portions of the basin while peaks are more likely in the early
morning hours in the lower portions of the basin. -Snyder/Bardsley

&&

.REV Watches/Warnings/Advisories...
NV...Flood Watch from Thursday evening through late Saturday night
     NVZ002-003.

CA...None.
&&

$$

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


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