Area Forecast Discussion
Issued by NWS Reno, NV

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617
FXUS65 KREV 141001
AFDREV

Area Forecast Discussion
National Weather Service Reno NV
301 AM PDT Thu Sep 14 2017

.SYNOPSIS...

A cold front will bring gusty winds and another chance for
showers and a few thunderstorms today. Daytime temperatures will
be at their coolest levels of the past three months by Friday,
with a modest warm up for the weekend. Below average temperatures
with increased winds and a chance for showers are expected next
week starting on Tuesday as a stronger cold front passes through.

&&

.SHORT TERM...

The long hot summer that largely persisted since mid-June and set
multiple records is finally coming to an end. A much cooler air
mass will reach northeast CA-northwest NV later today, and spread
across all areas Friday.

By this afternoon and evening, the approaching cold front will
bring another round of showers and isolated thunderstorms mainly
north of I-80 in eastern CA and far western NV, and north of US-50
in west central NV. The best chance for rain through late
afternoon initially favors the northern half of Lassen County,
with possible shower bands then forming this evening along and
just behind the cold front boundary as it moves south of
Susanville to near I-80 in northeast CA and far western NV (mainly
north of Reno-Sparks). Across west central NV southward to Mono
County, instability and moisture in the warm sector appears
sufficient to support isolated shower and thunderstorm activity
this afternoon and early evening. The other effect of this front
will be increasing southwest to west winds this afternoon and
evening, with peak gusts 35-40 mph across most of western NV and
northeast CA. The Lake Wind Advisory will remain in effect for
Pyramid Lake today, and we`ll add Tahoe as increased sustained
winds this afternoon should produce a few hours of choppy
conditions mainly on that lake`s east shores.

Later this evening and overnight, forcing along the front is
projected to weaken, but lighter showers remain possible as upper
level jet moves south across northern CA and the Sierra. Any
leftover shower activity should diminish by daybreak Friday as
drier air begins to spread overhead, with no precipitation
expected from Friday through Saturday.

Temperatures today are expected to remain near average from I-80
southward, with some cooling farther north as the cold front
approaches. By Friday, highs mainly in the lower 70s are expected
for lower elevations and 60s near the Sierra, followed by a few
degrees of warming by Saturday. By early Saturday morning, some
typically cooler valleys in west central NV could dip into the
upper 30s, but at this time the potential for freezing
temperatures is low. MJD


.LONG TERM...Sunday into next week...

Models remain consistent with a colder trough for early next week so
few changes were made to the going forecast. There are some
differences in timing of individual short waves with the main
trough, however. EC/GFS/Ensembles all show a deep trough, but the EC
brings 2 prominent short waves in quick succession while the GFS has
a brief short wave ridge between the two. Both do bring the initial
cold front through Monday evening.

Winds will increase again Sunday afternoon and be breezy, but the
strongest winds are expected on Monday afternoon. Southwest winds on
Sunday could gust 30-35 mph, but gusts as high as 50 mph are
possible in the valleys with 75+ mph over ridges possible Monday.
Winds will continue into the evening Monday then diminish
overnight. Sunday is expected to be dry, followed by a chance of
showers north of I-80 Monday afternoon and evening on the back
side of the front. Snow levels will still remain fairly high at
8000+ feet.

Tuesday/Wednesday both look cold, with highs struggling to reach 70
in the Western NV valleys and remaining in the 50s for the Sierra
valleys. Scattered showers are possible under the trough, with
better chances for Tuesday on the EC, while the GFS shows Wednesday.
At this point, kept the chances in both days as the trough will also
be slow moving. Overnight lows will be chilly, but with some
moisture around it may not get too chilly in outlying valleys. That
said, many areas will see their first frost of the season if not a
hard freeze. Wallmann

&&

.AVIATION...
VFR conditions today with gusty southwest winds up to 30 kts ahead
of a cold front. The front will move through this evening with winds
dropping off after 03-06Z. Some mtn wave turbulence, but it will be
moderate at best. Isolated showers are expected ahead of the front
for most areas with a thunderstorm or two, but nothing like the past
2 days. Showers will likely be more numerous near KSVE-KLOL this
evening behind the front with local MVFR CIGS possible.

Drier Friday behind the cold front with lighter NW winds. Another
strong cold front is expected Monday with gusty winds the main
threat that could see peak gusts 40-45 kts and stronger mtn wave
activity. Wallmann

&&


.REV Watches/Warnings/Advisories...
NV...Lake Wind Advisory from 2 PM this afternoon to 8 PM PDT this
     evening for Pyramid Lake in NVZ004.

     Lake Wind Advisory from noon today to 8 PM PDT this evening for
     Lake Tahoe in NVZ002.

CA...Lake Wind Advisory from noon today to 8 PM PDT this evening for
     Lake Tahoe in CAZ072.

&&

$$

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



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