Scientific Forecaster Discussion
fxus66 khnx 210026
Area forecast discussion
National Weather Service San Joaquin Valley - Hanford California
426 PM PST Mon Nov 20 2017
Update...updated air quality issues.
Synopsis...dry weather and above normal afternoon temperatures
can be expected across the central California interior through
the Holiday weekend. Patchy fog is possible in the San Joaquin
Valley during the late night and morning hours each day.
Discussion...temperatures are running several degrees warmer
this afternoon across much of the central California interior
compared to 24 hours ago and this is a trend we can expect for the
next few days. A westerly flow aloft will prevail through this
evening and bring little more than high clouds into the central
Otherwise, the weather pattern will remain dry and tranquil over
the central California interior for the rest of this week. That's
good news for folks traveling to spend time with friends and
family this Holiday. In truth, the only potentially adverse
weather for motorists this week might be patchy dense fog in the
San Joaquin Valley during the late night and morning hours.
Aside from that, the major highlight of our weather pattern
during the next 3 to 5 days will be the exceptionally warm
afternoons. Wednesday and Thanksgiving day will be the warmest
days; record challenging, in fact, with thermometer readings
peaking within a few degrees of 80 in the San Joaquin Valley,
lower foothills and the Kern County desert. (Record highs for
fat and bfl have been provided below this discussion.) We're
pretty confident that this will be one of the warmest Thanksgiving
days on record. In Fresno, that occurred in 1986 when the high
reached 77 degrees. Bakersfield had its warmest Thanksgiving ever
in 1932 with a high temperature of 81 degrees. There is a chance
that high temperature forecasts in the San Joaquin Valley this
week could fall short of our predictions wherever morning fog is
slow to dissipate. The foggiest locales will be over agricultural
land and in the vicinity of irrigated Orchards in the San Joaquin
Valley each night and morning. Otherwise, clear, calm conditions
over the County Warning Area each night will allow for ample radiational cooling
with thermometer readings bottoming out at seasonably chilly
levels this week.
So, what's going to cause this spell of near record warmth in
the days ahead? It's a strong upper level ridge of high pressure
that will remain centered over Baja California all week. The
ridge will build northward over California during the few days.
The air mass over the central California interior will further
stagnate through Thanksgiving day. A weak short wave trough that
treks eastward through the Pacific northwest Thursday evening
will flatten the upper level ridge over central California.
As a result, high temperatures on black Friday, Saturday and
Sunday will be slightly cooler, but still average well above
The models hint that we might get one more opportunity for wet
weather before November comes to a close. Admittedly, that
opportunity is a small one at this time, especially south of
Fresno County. The GFS is more bullish than the ecm and brings a
strong cold front and its associated upper level trough through
the County Warning Area next Monday with some precip over the foothills and higher
elevations of the Sierra mainly north of Tulare County. Otherwise,
this system will bring a seasonably cooler air mass into the
central California interior on day 7 accompanied by locally gusty
winds. Stay tuned.
Record high temperatures
Nov 22nd 77/1890 80/1945
Nov 23rd 78/1932 82/2015
local IFR conditions in fog across the San Joaquin Valley from 08z
to 18z tuesday; otherwise MVFR due to haze. Elsewhere, VFR
conditions will prevail across the central California interior during the
next 24 hours.
Air quality issues...
on Tuesday November 21 2017... unhealthy for sensitive groups in
Kings and Merced counties. Fireplace/wood stove burning status
is: no burning unless registered in Fresno... Kern... Kings...
Madera... Merced and Tulare counties. Further information is
available at valleyair.Org
The level of certainty for days 1 and 2 is medium.
The level of certainty for days 3 through 7 is medium.
Certainty levels include low...medium...and high. Please visit
www.Weather.Gov/hnx/certainty.Php for additional information
an/or to provide feedback.