Scientific Forecaster Discussion
Area forecast discussion...updated
National Weather Service San Joaquin Valley - Hanford California
421 PM PDT Tuesday Jul 28 2015
updated air quality section.
clear skies and increasing temperatures for couple days as high
pressure prevails over the area. Increasing clouds...shower and
thunderstorm activity expected by late Thursday as tropical moisture
moves in from the south.
Discussion...temperatures are running several degrees warmer
across the County Warning Area compared to Monday afternoon and it is one sure
sign that an upper level ridge of high pressure has strengthened
over central California. This ridge will continue to build over California during
the next 24 hours and that means Wednesday will become even hotter
in most locales...easily topping the century mark in the sj valley
and lower foothills.
In the meantime...an east to southeast flow aloft will gradually
bring monsoonal moisture in our direction. Its arrival will be
marked initially by an increase in middle and high clouds and
possibly an isolated dry thunderstorm...first over the Kern
County desert by late Wednesday afternoon then over the mountains
of Kern County and Tulare County Wednesday night. Afterward...
monsoonal moisture will advance northwestward over the remainder
of the County Warning Area Thursday and Thursday night with an increasing chance
of thunderstorms over mainly the higher terrain. Initially the
moisture that arrives will be high based so any thunderstorm
that develops from late Wednesday through Thursday evening may
not bring rain but rather dry lightning. A somewhat deeper influx
of monsoonal moisture Thursday night through Friday night will
tip thunderstorms to the wet side...especially over the mountains
and desert. However...this particular influx of monsoonal moisture
will be nothing like its predecessor and quantitative precipitation forecast amounts will most
likely be much lower in comparison.
The models forecast winds aloft to back to a southerly direction
Saturday with further backing to a southwesterly direction later
this weekend. If so...this will drive monsoonal moisture out of
central California and into the Great Basin by Sunday and diminish the
thunderstorm threat just about everywhere except over the higher
elevations of the Sierra. A southwesterly flow aloft is forecast
to prevail over the County Warning Area on days 6 and 7 with little more than
isolated afternoon thunderstorms near the Sierra crest early next
Regarding temperatures...the next 7 days will average warmer than
normal. Wednesday will be our hottest day. Maximum temperatures will be
curbed by increased cloudiness later this week. However...along
with the increase in clouds will come an increase in humidity and
warmer minimum temperatures. In the urban areas such as Fresno and bfl...
min temperature records could be challenged later this week.
VFR conditions can be expected throughout the central California interior
during the next 24 hours.
Air quality issues...
on Wednesday July 29 2015... unhealthy for sensitive groups in
Fresno... Kern... Madera and Tulare counties and Sequoia National
Park and Forest.
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 07-28 110:1980 89:1941 82:1980 55:1892
kfat 07-29 113:1898 87:1896 78:2003 57:1950
kfat 07-30 114:1898 80:1966 83:2003 57:1975
Kbfl 07-28 118:1908 85:1941 84:1931 50:1914
kbfl 07-29 114:1908 87:1965 86:2003 52:1914
kbfl 07-30 112:1908 82:1965 82:2014 48:1914