Area Forecast Discussion
Issued by NWS Reno, NV
FXUS65 KREV 291358
Area Forecast Discussion
National Weather Service Reno NV
658 AM PDT MON AUG 29 2016
Will push out a quick update to increase cloud cover over the
northern CWA this morning. This should not affect temps very much
as clouds will thin later today. 20
.PREVIOUS DISCUSSION... /Issued 247 AM PDT MON AUG 29 2016/
Incoming trough of low pressure along the west coast will bring
breezy afternoon winds Tuesday through Thursday and slowly
cooling temperatures through the week.
First of a series of shortwaves will move into northern
California tonight as a large scale trough digs into the Pacific
Northwest. The main impacts to the Sierra and western Nevada will
be an increase in afternoon winds, a few more clouds, and a slow
cooling of temperatures to near normal by mid-week.
Models have continued to back off on convection Tuesday morning
for our area with the best chances now well west of the Sierra.
However, there are now some indications of nocturnal convection
Tuesday night over the central Sierra. For more in-depth
discussion of the possibility of convection as well as the
increasing winds mid-week see the Fire Weather discussion below.
Some haze will continue to affect the area today from numerous
wild fires in California. Model simulations currently show some
clearing north of I-80 with an increase in haze and smoke for
areas south of I-80 but this will be very dependent on fire
LONG TERM...Thursday through Sunday...
The main feature present during most of the extended period will be
a long wave trough over the Pac NW draped south into far northern CA
and northwest NV. Most of the medium range guidance has coalesced
around a solution that keeps the bulk of the energy associated with
said trough north of our forecast area through Saturday and keeps
the region dry. The biggest impact could be increased winds Thursday.
Thursday appears to have the strongest winds through the period due
to an increased thermal gradient and stronger mid level winds. It is
not out of the question for gusts to reach 35+ mph late Thursday
afternoon over the northern third of the forecast area. This would
raise...or continue...fire weather concerns over the region.
Surface frontal passage Friday will see some gusty winds...but not
as strong as Thursday. Then part of the long wave carves farther
south by late Saturday. Temps should be a few degrees cooler for
Saturday. Lastly...the part of the trough that drops over the area
Saturday starts to weaken and lift out by late Sunday. This may
allow temps to rebound to near or slightly above normal by Sunday.
VFR conditions again today and through the week. The only reductions
to visibility could come with haze today...but this would not impact
flight operations substantially. Blowing dust could also reduce
visibility in some areas starting Tuesday.
Typical afternoon/evening westerly winds are likely today. These
winds increase starting Tuesday as a series of short wave troughs
impact the region. The strongest gusts each day will be east of the
Sierra from roughly Highway 50 to Interstate 80 and east of Highway
395 across northeast CA and northwest NV to near the Oregon border.
Gusts up to 35 mph are possible in wind prone locations.
Blowing dust associated with the increased winds could reduce low
level visibility each day starting Tuesday downwind of the typical
Fire weather concerns begin to mount Tuesday as an area of low
pressure lifts across northeast CA and brings an increase in surface
winds by Tuesday afternoon. A very dry air mass will be in place so
the possibility of critically low humidity and gusty winds exists
for Tuesday. Thus...a Fire Weather Watch remains in effect for zones
Both Wednesday and Thursday could also have gusty winds over much of
the same area. A series of short wave troughs will lift through the
overall southwest flow and thermal gradients will increase. Each day
could see at least localized critical conditions with Thursday
currently looking like the windiest day.
Subsequent forecast shifts will evaluate the need for additional
watches and/or warnings as we move through the week. For now...be
aware that very low humidity and gusty winds are likely to impact
areas from the Sierra Front into far northeast CA and northwest NV
from Tuesday through at least Thursday.
One other item to note for fire weather concerns: There is a small
chance of elevated overnight/morning convection early Wednesday in
parts of the northern Sierra and northeast CA from roughly Truckee
to east of Susanville. A weak wave is noted lifting across the
region around daybreak Wednesday morning. Mid to upper level lapse
rates are marginal at this time and the jet support is not as strong
as we would normally like to see...but there is a slot of mid level
moisture overlying very dry low level air and the models also show
enough upper level instability to warrant some concern. As yet we
have not included dry thunderstorms for Wednesday morning as the
likelihood is a bit too low...but we felt we needed give some
advanced notice of this possibility.
NV...Fire Weather Watch from Tuesday afternoon through Tuesday
CA...Fire Weather Watch from Tuesday afternoon through Tuesday
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