Area Forecast Discussion
Issued by NWS Reno, NV

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997
FXUS65 KREV 241143
AFDREV

Area Forecast Discussion
National Weather Service Reno NV
443 AM PDT TUE MAY 24 2016

.UPDATE...
An area of rain and snow moving west across the south end of Lake
Tahoe is producing light snow accumulations over the passes with
slushy roads around South Lake Tahoe. Travel will be hazardous
this morning along US-50 (Spooner and Echo), Highway 207 and
sections of CA-89 near Emerald Bay and Luther Pass. Snow may also
impact Carson Pass.

This area of rain and snow will continue to move east and should
pass west of the Sierra Crest by 7 am. However travel around South
Lake may remain hazardous until 9 or 10 am this morning. Brong

&&

.SYNOPSIS...

Scattered showers and thunderstorms with below average temperatures
are expected through Wednesday as low pressure moves slowly south
across California. Snow may produce occasional travel impacts over
higher passes through midweek. Near average temperatures are then
expected through the Memorial Day weekend with decreasing chances
for showers and thunderstorms.


&&

.PREVIOUS DISCUSSION... /Issued 212 AM PDT TUE MAY 24 2016/

SHORT TERM...

So far the upper low moving into northern CA has been more of a
stratiform rain producer, with totals so far generally between
0.10 and 0.40 inch for western NV south of US-50 and much of
eastern CA near the Sierra.

Although widespread cloud cover limited most thunderstorm
development yesterday and could do so again today, short term
guidance has consistently indicated more instability and forcing
today. This should lead to a better potential for thunderstorms
with some cells developing by late morning, then increasing
through this afternoon. Areas north of US-50 will initially be
more favorable for storms, since clouds from the current rain
area south of US-50 will be slower to disperse. While any portion
of the region is fair game for thunderstorm activity through early
evening, we boosted coverage up a bit higher in areas from
Susanville-Gerlach northward. Some of the model guidance scenarios
have been producing some enhanced convection in this known
convergence zone.

For later tonight, The main deformation zone associated with the
upper low still favors areas south of Us-50, although it appears
less concentrated compared to this morning. We will keep the
higher shower probabilities in place for these locations. but
would expect lesser amounts of additional rain during the
overnight-early morning hours.

For Wednesday, similar amounts of instability are expected with
another round of showers and thunderstorms initially across most
of the region, then favoring areas near and south of I-80 as the
upper low moves inland across southern CA. We will still limit
thunderstorm coverage to isolated for now, but if today ends up
active then Wednesday will probably follow suit.

For both today and Wednesday, stronger cells could produce
accumulating small hail and heavy downpours, while higher Sierra
passes above 7500-8000 feet today and above 8500 feet Wednesday
may occasionally be affected by snow covered or slushy roads.

For Wednesday night, forcing over western NV will weaken as upper
low pulls into the Desert Southwest, resulting in most convective
activity diminishing during the evening.

For Thursday, overall potential for showers and thunderstorms
will decrease as northwest flow aloft prevails. However, residual
moisture with a few more degrees of heating may produce a few
showers and thunderstorms by mid-late afternoon mainly near the
Sierra and in adjacent portions of western NV including the
Reno-Carson City vicinity. MJD

LONG TERM...Memorial Day weekend into the start of June...

No big changes in the models over the last couple days. Low pressure
over the Gulf of Alaska will drop into southern Oregon and northern
Nevada by Friday then linger over the Great Basin for Memorial Day
weekend. This will maintain a chance of showers and a few
thunderstorms with afternoon highs in the 60s and 70s and
overnight lows in the 30s and 40s. For those heading outdoors for
an extended period of time, be prepared for rain, high elevation
snow and chilly nights. Breezy west to northwest winds may also
lead to choppy conditions on lakes over the holiday weekend.

Looking into the start of June, simulations have been leaving a
persistent trough along the west coast into the start of June. A few
model runs over the last day or so are trying to develop a ridge
over the west for June 2nd and 3rd, which could bring more summer
like conditions. Brong

AVIATION...
Showers and thunderstorms remain possible into Wednesday with low
pressure over California and Nevada.

Currently an area of rain is producing MVFR conditions and
mountain obscurements south of KTRK-KRNO-KNFL. This area of rain
should move east of the Sierra Crest or diminish by 14z.

Showers start to redevelop around 18z due to the moist and unstable
conditions. Cloud cover and surface based heating may limit
thunderstorm coverage today. Breaks in the clouds could allow a few
thunderstorms to kick off around 18z, though most thunderstorms
probably won`t occur until 21z or later. Main threats for today
are moderate/heavy rain, small hail and gusty outflow winds to
30-35 kts.

Another low may lead to additional showers and thunderstorms for a
portion of the Memorial Day weekend. Brong

&&

.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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