Area forecast discussion
National Weather Service San Joaquin Valley - Hanford California
934 PM PDT Friday may 24 2013
Update...probability of precipitation lowered for Memorial Day except in the Sierra
north of Kings Canyon. Maximum temperatures lowered slightly on Memorial
Day and Tuesday. Weather grid amended for Memorial Day.
&&
Synopsis...
low pressure over the Pacific northwest is bringing a cool onshore
flow to the central California interior. Temperatures will remain
near normal through Sunday. Memorial Day will bring increasing
clouds and cooler afternoon temperatures with the possibility of
light precipitation mainly over the High Sierra toward evening.
&&
Discussion...temperatures are generally trending 3 to 7 degrees higher
throughout the County Warning Area compared to 24 hours ago which will put min temperature
forecasts on target for tonight. An onshore flow this weekend will
keep afternoon temperatures from getting any higher than normal in
the sj valley as ocean-cooled air flows steadily through the SAC Delta.
Already this evening winds have picked up a bit in the northern sj
valley from Modesto northward...and it will not be long before a
noticeable reinforcement of marine air is felt in much of the rest
of the sj valley this evening.
In the bigger picture...little has changed since Tuesday. A storm
system anchored over the Pacific northwest will sit nearly idle through Sunday.
The models forecast this storm to slowly deepen during the next 72
hours. As a consequence...the onshore flow will strengthen each of
the next 3 days and Memorial Day will become noticeably cooler and
increasingly cloudy. Both the ecm and GFS forecast a 300 mb jet maximum
(85 kts) to come across Kern County Sunday afternoon and evening
which will likely support potentially strong westerly winds through
and below the mountain passes...possibly to advisory levels. Monday
afternoon and evening will probably be windier in these areas as
the upper level trough deepens and the onshore flow strengthens.
The models differ on exactly how much digging the upper level trough
does along the West Coast early next week and how deep the moisture
gets. The ecm is substantially deeper with the trough than the GFS
and carries a very wet bias. Initially...moisture will be rather
shallow when it arrives on Memorial Day so there will be little
more than sprinkles in the sj valley and adjacent foothills from Fresno
County northward with at most a few showers over the High Sierra.
Monday night and Tuesday look more favorable for measurable precipitation...
especially over the mountains...and it will be cold enough for a
small accumulation of snow at this time above 8000 feet. Otherwise...
Memorial Day through Tuesday will be much cooler throughout the
central California interior.
Although a warming trend will occur during the middle to later part
of the week...temperatures may still fall shy of normal by next
Friday as a dry west to northwest flow aloft prevails over central
California. This is the kind of pattern that will bring shallow intrusions
of marine air into the sj valley and produce gusty winds in the Kern
County mountains and desert.
&&
Aviation...
VFR conditions will prevail across the central California interior.
&&
Previous disc... /issued 312 PM PDT Friday may 24 2013/
Discussion...cool dry conditions Omega block pattern continues
across the US as large closed low center remains nearly stationary
over the Pacific northwest. Additional disturbances will move through the low
during the weekend maintaining the trough and onshore flow into
central California. This will result in cool dry conditions across central
California for much of the weekend. A stronger disturbance will
push through Sunday increasing onshore grads across central California
Sunday afternoon with breezy conditions below the mountain passes
of the Kern County mountains and desert.
A stronger trough is expected to move through the area late Monday
and Tuesday. The ecm is deeper and further S with the low center
as it dives south towards scal. The ecm is also significantly
wetter than the GFS. The 12z operational models are in poor
agreement atmosphere. However the ensemble means of ec and GFS remain in
reasonable agreement. At the moment will be taking a blend of the
two ensemble means. Satellite images show a fetch of subtropical
moisture with the weather system S of the Aleutians prognosticated to
move through central California Monday night and Tuesday. Models indicate
precipitable waters of 1-2 Standard deviations above normal across central California
Monday night. Temperatures at 10kft drop to -2c by Tuesday
morning. This could lower the snow level to near 8kft with some
snow accumulations over the Sierra. Breezy to windy conditions
will develop Monday afternoon and Tuesday especially in the Kern
County mountains and desert area.
The trough moves through pretty quick and keep US in a strong northwest
flow through next week which will keep the temperatures in check as cool
onshore flow will prevail.
Aviation...
VFR conditions will prevail across the central California interior.
&&
Air quality issues...
none.
&&
Certainty...
The level of certainty for days 1 and 2 is high.
The level of certainty for days 3 through 7 is low.
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.
&&
Climate...
records
site date hi_max:year lo_max:year hi_min:year lo_min:year
Kfat 05-24 103:1943 64:1916 68:2001 41:1953
kfat 05-25 102:1890 59:1906 68:1890 42:1980
kfat 05-26 103:1974 66:1946 68:1951 40:1953
Kbfl 05-24 107:1982 68:1980 76:1982 41:1916
kbfl 05-25 106:1982 58:2008 77:1982 39:1893
kbfl 05-26 107:1951 68:1998 72:1979 40:1918
&&
Hnx watches/warnings/advisories...
none.
&&
$$
Public...durfee
AVN/fw...Bingham
previous discussion...mv
synopsis...andersen
Weather.Gov/Hanford
