Area Forecast Discussion
Issued by NWS San Joaquin Valley, CA
FXUS66 KHNX 042230
Area Forecast Discussion
National Weather Service San Joaquin Valley - Hanford CA
230 PM PST Sun Dec 4 2016
.SYNOPSIS...High pressure will keep dry conditions and seasonable
temperatures through early this week. A colder airmass will then
push into the region by midweek. A low pressure system will spread
increasing chances of precipitation into the area on Thursday and
.DISCUSSION...High pressure strengthened over the area overnight
and this morning and that has reflected with temperatures
trending upward by 4-8 DEG F over the San Joaquin Valley and by
2-5 DEG F over the Kern County deserts after another frosty
morning. Even more noticeable warming has taking place over the
Kern County mountains where many locations are currently running
more than 10 DEG F above yday.
Meanwhile, visible imagery is indicating high clouds are
streaming into Central CA today with RH progs indicating
increasing high level moisture over our area tonight. Combined
with the warming airmass expect temepratures tonight to be above
the freezing mark throughout the valley. Some patchy fog will be
possible near daybreak on Monday which might impact the morning
12Z WRF indicating a low pressure system dropping out of the Gulf
of AK tonight and into the PAC NW on Monday. This system is then
progged to drop into the Great Basin on Tuesday. RH progs are
indicating that this system is moisture deficient and the models
have been trending further north with the low. We are therefore
not expecting any precipitation from this system. However, colder
air will push into our area on Tuesday and with skies on Tuesday
night expected to be mostly clear, sub-freezing temperatures
might be in store for portions of the San Joaquin valley on
Wednesday morning; but this will dependent on how rapidly the
post frontal winds diminish on Tuesday night.
The 12Z runs of the GFS, GEM and ECMWF all indicate a fairly
moist trough pushing into the PAC NW and Norcal toward the end of
the week with the GFS being the most aggressive at spreading
precipitation southward into our area. Ensemble support is not
very good concerning the placement of the low, but all of the
models are trending toward a faster timing with increasing
moisture spreading into our area by Thursday. Have continued the
ongoing trend and have raised POPs and sky cover for our area for
Thursday and Friday as there is increased confidence that
precipitation will occur at least from Fresno County northward.
There is still a lot of uncertainty dealing with how far south the
precipitation will extend and how much precipitation occurs with
this system in our area. All of the models are indicating a mild
height pattern with the 500 mb 570 DM height line over or just
north of our CWFA so snow levels will likely be fairly high with
this system (above 7000 feet). The GFS is indicating a pac
shortwave with push through Norcal on Sunday and will clip the
northern portion of our CWFA with a brief shot of precipitation.
The 12Z ECMWF is further north with this field. With the mod trend
indicating negative regression over our area on Sunday; however,
feel that it is necessary to mention increased clouds for our
area; and at least a slight chance of showers for the Southern
Sierra Nevada for now next Sunday.
.AVIATION...Areas of IFR/MVFR visibilities due to haze and fog
across the San Joaquin Valley possible after 06z Monday.
Otherwise, VFR conditions can be expected across the central
California interior during the next 24 hours.
.AIR QUALITY ISSUES...On Monday December 5 2016... 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.php for additional information
an/or to provide feedback.