Janesville, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

169
FXUS65 KREV 031038
AFDREV

Area Forecast Discussion
National Weather Service Reno NV
238 AM PST Tue Dec 3 2024

.SYNOPSIS...

* Strong inversions will allow for lighter winds and cold
  overnight low temperatures across the region this week.

* Freezing fog persists this week, becoming more extensive where it
  has lingered for the last couple of days.

* Although no significant storm is projected for the next week or
  two, a possible inside slider system may bring increased winds
  this weekend.

.DISCUSSION...

Based on the 03/00Z KREV sounding along with the ensemble forecast
soundings going through this week, temperature inversions look to
persist across the region that will strengthen during the
overnight hours and going into the morning. Due to this setup, the
CWA looks to see light winds persist along with cool overnight
temperatures. Areas of freezing fog and stratus are still in the
forecast for the next couple of days during the overnight and into
the morning hours particularly in the valley areas. Those
traveling through the region during these times may want to use
caution as not only could visibilities be reduced, but surfaces
may also be slick. A Freezing Fog Advisory continues this morning
for valley portions of the CWA north of I-80 observing these
conditions (which shows up pretty well on the Night Fog satellite
imagery). For more detailed information, please see the Advisory
product. Air stagnation will also continue as ventilation and
mixing remains poor to marginal with the inversions in the area.

When looking at the latest RAP analysis of the upper air pattern, an
upper air low is currently just to the west of the Bay Area while a
large ridge resides over the western CONUS this morning. The GEFS
and ECMWF ensembles both forecast the low to take a track across CA
and make it over AZ by Wednesday allowing for a Rex Block pattern to
setup and the stagnant conditions to continue in the region. This
still looks to be the case through at least Friday when the AZ
low continues a eastern progress allowing for a ridge to move in
over the CWA that lasts into Saturday. As a result of this,
daytime temperatures for the CWA may warm by a degree or two at
the start of the weekend. Deterministic forecast guidance then
shows a Pacific Northwestern trough moving into the picture late
Saturday that appears to take an "inside slider" track going
through Sunday and Monday. While this is not present in the GEFS
and ECMWF ensembles at the moment, the system appears be a
potential pattern changer for the CWA as it signals winds to
possibly pick up a bit on Sunday allowing for some mixing.
Temperatures also start to trend cooler too starting Sunday night
with this trend continuing into Monday and Tuesday. As for
precipitation chances, they still look low going into next week
with high pressure in the area. The exception does appear to be
on Saturday ahead of the potential trough in areas along the OR
border as they may see a slight chance (10-15%) for light
precipitation possible during the afternoon. Little to no QPF is
expected with this at this time. Will continue to monitor this
potential system for the beginning of next week as it could break
up the stagnant conditions seen in this week`s forecast. -078

&&

.AVIATION...

High pressure across the region will continue to bring strong
inversions today that allow for dense morning freezing fog as well
as areas of afternoon haze along with minor reductions to slantwise
visibility. While most area TAF sites look to stay mostly VFR
with light winds today, lower valley areas of western NV and the
Sierra will see periods of IFR/LIFR conditions through this
morning due to lower stratus ceilings and areas of dense freezing
fog.

Areas of particular interest continue to be across the Honey Lake
Basin, Pyramid Lake area that stretches north through the Black
Rock/Smoke Creek Deserts, and south to Fernley/Dayton where lower
terrain is currently or will be obstructed due to the areas of
dense freezing fog. Foggy conditions will continue through this
morning and do expect to not dissipate until around 03/16-18Z.
The cycle of freezing fog for these valley areas does look to
repeat again tonight into Wednesday morning though the timing may
not be exactly the same. Will continue to monitor this and update
the forecast when details become more apparent. -078

&&

.REV Watches/Warnings/Advisories...
NV...Freezing Fog Advisory until 11 AM PST this morning NVZ003>005.

CA...Freezing Fog Advisory until 11 AM PST this morning CAZ071.

&&

$$