Scientific Forecaster Discussion
fxus66 khnx 162350
Area forecast discussion
National Weather Service Hanford California
350 PM PST Sat Nov 16 2019
..updated air quality section...
dry weather will continue over the district through Tuesday. Above
normal afternoon temperatures can be expected Sunday and Monday.
A cooling trend will occur for the remainder of next week with the
possibility of wet weather from Tuesday night into Thursday night,
especially over the mountains and desert.
Discussion...for the first time this month, high temperatures
finally returned to seasonable levels over the district. Another
first in a long while was the formation of fog in parts of the
San Joaquin Valley early this morning. While on the subject of
firsts, there still are prospects for wet weather by midweek, but
it probably won't bring an end to the dry spell everywhere in our
County Warning Area. There are plenty of uncertainties in the 4 to 7 day period.
We'll address this in more detail later in this discussion.
As for the short term, we can thank a weak upper level trough for
the cool change in our weather lately. Unfortunately this system
hasn't been able to mix out the valley crud, so haze and patchy
morning fog will still be a part of the San Joaquin Valley weather
picture for some time to come. The trough will exit into the
Great Basin tonight and allow a strong upper level ridge of high
pressure to build in over central California during the next 48
hours. High temperatures will trend upward during the next two
days as a result. Thermometer readings could top 80 degrees in
parts of the San Joaquin Valley Monday afternoon. If so, high
temperature records for November 18th could be broken in a few
valley locations. (The record high in Fresno for Monday happens
to be 80 degrees, which was previously established in 2008.)
Another upper level trough (stronger than our current departing
one) will squash the high pressure ridge over central California
by Monday night as it moves into the Pacific northwest. The models
dig this trough southward over California Tuesday through
Wednesday, and although they differ on the trajectory of the
upper level low associated with the trough, one thing is certain;
Tuesday through Wednesday will bring a significant cooling trend
across the entire district. Afternoon temperatures Wednesday may
be no higher than the 50s in the Kern County desert and no higher
than the lower 60s in the San Joaquin Valley. Ditto for Thursday.
The atmosphere will also become increasingly unstable during this
period so showers, and possibly even thunderstorms, could pop up
just about anywhere over the County Warning Area from late Tuesday through
Thursday. The best chance of showers, however, will be over the
mountains and desert. Precipitation totals during this period will
be rather light. Several inches of snow could also fall over the
highest elevations of the Sierra by Thursday evening, especially
if an easterly flow to the north of the closed low over Southern
California slams enough moisture into the upslope side of the
Sierra. If it all comes together just right, this could end up as
the first winter storm of the season over the High Sierra later next
week. Hikers and campers will want to closely monitor National Weather Service forecasts
on this change in the pattern and its potential winter impacts.
Near the end of the week into next weekend, a drier and more
stable air mass will settle in over the County Warning Area as what's left of this
upper level trough finally exits into The Rockies. The ecm is
more sluggish moving this trough eastward. If so, clouds could
linger over the Kern County desert through Friday. Otherwise,
Friday and Saturday will be dry with temperatures averaging pretty
close to normal.
Aviation...areas of MVFR visibilities in haze can be expected in
the San Joaquin Valley through 00z Monday. Local IFR/LIFR
visibilities due to fog are possible in the San Joaquin Valley
between 10z and 17z Sunday. VFR conditions will prevail elsewhere
over the central California interior during the next 24 hours.
Air quality issues...
on Sunday November 17 2019... fireplace/wood stove burning status
is: no burning unless registered in Fresno...Kern...Kings...Madera
and Tulare counties.
Further information is available at valleyair.Org
The level of certainty for days 1 and 2 is high.
The level of certainty for days 3 through 7 is low.
Certainty levels include low...medium...and high. Please visit
www.Weather.Gov/hnx/certainty.Html for additional information
an/or to provide feedback.