Scientific Forecaster Discussion
Area forecast discussion
National Weather Service San Joaquin Valley - Hanford California
248 PM PST Friday Nov 28 2014
Synopsis... high pressure will weaken and allow a weather
disturbance to pass across mainly northern California tonight
through early Sunday. High pressure will then rebuild over the
region Monday before a potentially much stronger storm system
moves in on Tuesday.
Discussion...high pressure parked off the coast of northern
Baja California is bringing another pleasant...sun filled afternoon to
the central California interior with well above normal temperatures.
In the meantime...a weak short wave trough is trekking eastward
through the Pacific northwest. The cold front trailing southward from this
feature will drag its feet through northern California tonight then stall
out across the northernmost portion of our County Warning Area Saturday. Clouds
will increase in these areas later tonight and may produce spotty
light precipitation north of Fresno County Saturday. South of this
frontal boundary...skies will be relatively clear which means a
recurrence of patchy dense fog is possible in the sj valley later
tonight into Saturday morning. Otherwise...our County Warning Area will be divided
Saturday with a repeat of balmy afternoon temperatures south of
the front and relatively cool temperatures and cloudy skies from about
Fresno County northward.
The frontal boundary will jog a little farther southward Sunday
as a weak impulse rides eastward along it. So areas north of Kern
County might get some sprinkles or isolated showers but it will
be nothing that disrupts travel for those heading home from the
Thanksgiving Holiday. The frontal boundary will wash out over
central California Sunday evening as the upper level ridge rebuilds over
the state. Monday should be a pretty nice day with milder than
normal afternoon temperatures as the ridge remains in control.
Afterward...we will turn our attention to a deepening storm
system over the eastern Pacific. The models are in much better
agreement now with the timing and track of this storm and now
forecast this system to bring a healthy dose of precipitation
into much of the central California interior Tuesday into Wednesday.
A strong southwesterly flow aloft on the eastern flank of this
storm will be embedded with subtropical moisture when it moves
over the southern half of our County Warning Area Tuesday afternoon and night. It
is difficult to determine right now where this water hose sets up
over central California. The models currently position this atmospheric
river over Kern County and Tulare County...but it could end up
farther north. Whatever the case...jet dynamics coupled with this
surge of subtropical moisture will generate copious orographical
precipitation in the mountains by midweek. Precipitation amounts will be
minimized somewhat on the west side and south end of the sj
valley and the Kern County desert by some rain shadowing. (The
latest forecast of storm totals can be found on our facebook...
twitter and National Weather Service web pages.) Snow levels will be relatively high
with this storm...generally above 8k feet. Above this elevation...
snow accumulations of 2 feet or more are possible near the Sierra
crest. In addition...heavy rainfall could cause localized flooding
in the foothills and higher elevations. Mud and debris flows are
possible in the vicinity of the burn scars in the mountains from
late Tuesday into Wednesday.
Precipitation will diminish to scattered showers by midday Wednesday as
the storm weakens and moves inland over northern California. The rest of
next week will remain unsettled with a slight chance of showers...
particularly over the mountains. The ecm tries to build another
upper level ridge over California by next Friday while the other models
maintain a fairly weak zonal flow pattern across the County Warning Area which is
more in line with the latest ensemble forecast. Otherwise...high
temperatures in the 4 to 7 day period will be much closer to normal. The
presence of clouds and relatively good atmospheric mixing later
next week will tend to keep min temperatures a little milder than normal.
Aviation...in the San Joaquin Valley...widespread MVFR visibilities
in haze. Local IFR visibilities in mist from 09z Sat to 16z Sat. In
the southern Sierra Nevada...increasing areas of IFR after 16z Sat
in...low clouds...mountain obscurations and precipitation spreading
southward during the day. Otherwise...VFR conditions will prevail
across the central California interior during the next 24 hours.
Air quality issues...
on Saturday November 29 2014... unhealthy for sensitive groups in
Kern... Kings and Tulare 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 high.
The level of certainty for days 3 through 7 is medium.
This information is provided as part of a trial project conducted
by the National Weather Service San Joaquin Valley - Hanford.
Certainty levels include low...medium...and high. Please visit
www.Weather.Gov/hnx/certainty.Php /all lower case/ for additional
information and/or to provide feedback.
site date hi_max:year lo_max:year hi_min:year lo_min:year
Kfat 11-28 76:1891 46:1972 52:1966 28:1969
kfat 11-29 76:1947 47:1905 58:1901 26:1975
kfat 11-30 77:1924 44:1972 57:2012 29:1906
Kbfl 11-28 82:1993 46:2000 55:1904 28:1905
kbfl 11-29 80:1924 51:2006 57:1938 28:1919
kbfl 11-30 83:1924 46:1965 54:2012 28:1907