Scientific Forecaster Discussion
fxus65 krev 170911
Area forecast discussion
National Weather Service Reno Nevada
211 am PDT Wed Jul 17 2019
Quiet weather conditions are expected for the rest of this week
with seasonable temperatures, typical late day winds, and no
thunderstorms. That could change next week as high pressure over
the Desert Southwest builds, allowing some moisture to work
northward into our region.
The only change this morning was to warm temperatures up a few
degrees across western Nevada today and Thursday.
The upper trough that brushed our region Tuesday and brought the
slight cool down will lift out of the region today. This will
allow for heights to rise and temperatures to rebound rather
quickly. 700 mb temperatures will climb to between 14-15c which
corresponds to mid-upper 90s across lower elevations from I-80
south and low 80s for the Sierra valleys today and Thursday. As
the jet stream dips southward a bit toward the Oregon border
Friday, temperatures aloft cool some. The change may allow
temperatures to cool a degree or two Friday afternoon - probably
not enough to notice.
Model soundings continue to show it too dry and stable for any
thunderstorms. In fact, there is a pretty decent capping
inversion in the mid levels. So despite the heating, any
convection would be limited to a few cumulus/shallow buildups
along the eastern Sierra south of Highway 50 and in the Lassen
County convergence zone north of Susanville Thursday and Friday.
Winds will be light except for the typical afternoon/evening
breezes with most peak gusts remaining around 25 mph. Lxviii
Long term...Saturday through Tuesday...
The extended forecast period is getting more interesting as most
models and ensemble members now agree that a ridge will begin
building over the southwestern U.S. Late this week and into the
weekend. That will bring changes to the forecast for our area. Some
of these changes have already been incorporated into the forecast.
Other adjustments may be needed as we get closer to the weekend and
into early next week as we see how the pattern evolves.
Saturday still looks rather quiet...but we do begin to see high
temperatures warming as the zonal flow over the region begins to
shift to the south-southwest with the building ridge. That would
allow highs to rise. Some forecast soundings even hint at the start
of an influx of mid-level moisture as early as Saturday. For now we
have left convection out of the forecast.
As we move into Sunday and beyond the model simulations are in
better agreement that mid-level moisture begins to make its way
farther north into the forecast area. Along with this increase in
moisture we see increased temperatures with the ridge axis to the
east. These Four-Corners highs often Bode well for our area getting
back in on thunderstorm development. This situation should be no
The first day of convection can be a dry thunderstorm day as
instability is increased along with mid-level moisture...but
moisture is too sparse for precipitation to make it to the surface.
So...we included a slight chance of just thunder for Sunday across
parts of the southern half of the forecast area. That may raise fire
By Monday and Tuesday moisture is increasing. That...along with
increased high temperatures and low-to mid-level instability...
should allow for increasing coverage of thunderstorms and a few
showers. We have capped the pops at very low end chances for
now...but this may need to be increased as the situation evolves.
Highs each day will be near or slightly above climatological
averages. By the latter half of July we are into the warmest period
of the year with highs typically in the mid to upper 90s for the
lower valleys and 80s in the Sierra valleys. Xx
VFR conditions should continue for the rest of this week and into
the early part of the coming weekend. Winds are likely to be typical
for Summer with late afternoon/early evening gusts in the range of
20-25 kts. Some late afternoon turbulence due to surface heating
is also expected.
Thunderstorms are not expected into the early part of the
weekend...but a return to a pattern more conducive to thunderstorm
development is becoming a much stronger possibility as we move into
Sunday and beyond. Rev