027
FXUS65 KREV 020932
AFDREV

Area Forecast Discussion
National Weather Service Reno NV
232 AM PDT Thu May 2 2024

.SYNOPSIS...

We will have a quick warming trend from today through tomorrow.
However, periods of showers are likely in the far northern
portions of the region and breezy winds this afternoon. Active
weather effectively returns to the area on Saturday with a storm
system bringing gusty winds along with valley rain and mountain
snow. Conditions slowly improve on Sunday. Early next week, a slow
warming trend with low chances for precipitation remain in the
forecast.

&&

.DISCUSSION...

A quick warming trend starts today, even though a weak shortwave
trough will be passing through just north of our area. Periods of
showers are expected in the far northern portions of the CWA
including the Surprise Valley, far north Washoe near the OR border
and northern Lassen Co. as seen on multiple members of the HREF.
Additionally breezy conditions are expected to develop this
afternoon with the tightening of the pressure gradient at the
surface. Shower activity will end during the evening hours at the
same time that winds subside across the region. Tomorrow, we will
have fair weather with afternoon highs between 65-75F valleys,
and 50-65F mountains.

The next storm system is expected this weekend. A closed low
descending from the Gulf of Alaska will push through OR/CA/NV on
Saturday and Sunday. This system brings strong and gusty winds as
well as periods of valley rain and mountain snow. Wind appears to
be the main hazard as an upper level jet with 100+ kts sets over
the Sierra and W NV on Saturday. The 700 mb winds show winds
greater than 60 kts over the Sierra. The NBM 10th percentile shows
gusts in excess of 40 mph for western NV and 50-70 mph for the
Sierra. Furthermore, the probability of gusts greater than 60 mph
in the higher elevations of the Sierra south of Lake Tahoe and the
Wassuk Range from Walker Lake down to Powell Mountain is over
80%. Gusts in excess of 40 mph are very likely across most of the
area per the NBM guidance. These winds will also generate periods
of blowing dust over Pershing and Churchill counties on Saturday
afternoon during the peak winds.

The next hazard with this system is valley rain and mountain snow.
Snow levels start around 8-10 kft on Friday night and descend to
6 kft behind the frontal passage in the late afternoon on Saturday.
Snow levels will be down to valley floors by Sunday morning.
However, by then most of the precipitation would have ended.
Therefore, we are not really expecting accumulations at the valley
floor on Sunday morning as of this moment. In the meantime, snow
amounts in the Sierra will be generally light at lake level and
adjacent communities. The probability of 4+ inches of snow in the
Tahoe Basin including Truckee is 20-40%. For the communities along
US-395 in Mono Co. the prob for 4+ inches is 20% or less. The
Sierra crest has a 10-20% chance of reaching 12 inches of snow in
the Tahoe Basin, and slightly higher over portions of the crest in
Mono Co. Therefore, the main concern will be around Sierra passes
and near the crest where the highest amounts are expected between
4-8", possibly up to 12" in isolated locations near the crest.
Rainfall amounts for western NV valleys are expected to remain
mostly below 0.25 inches, except for the far northern portions of
Washoe Co near the OR border where up to 0.75 inches are possible
as this area is closer to the center of the low. Amounts greater
than 0.5 inches are not very likely as the probability remains
below 20% over western NV, except for far north Washoe with
30-50%.

Conditions slowly improve on Sunday as the upper low slowly exits
the area towards UT and ID. Early next week, we will continue to
experience cool temperatures behind this system as well as low
chances for precipitation through mid-week, especially in the
northern portions of the region. At least models are not
indicating any significant systems at the time, just minor
inconveniences through most of the week.

-Crespo

&&

.AVIATION...

Mainly VFR conditions continue through the period. Periods of
showers in the far northern portions of the region may lead to
MVFR conditions due to lower CIGS and VIS. Otherwise, most of the
area will be dry with no restrictions. Winds continue to be the
main hazard today with localized LLWS and light turbulence near
area mountains. Terrain-driven winds this morning become from the
west and west-northwest with speeds between 10-15 kts and gusts up
to 25 kts after 20Z. Winds subside for most areas except mountain
ridges after 3Z this evening. Ridge winds drop overnight.

A storm system this weekend brings periods of valley rain and
mountain snow, as well as strong and gusty winds. This will cause
reductions in CIGS and VIS along with turbulence and LLWS.

-Crespo

&&

.REV Watches/Warnings/Advisories...
NV...None.
CA...None.
&&

$$