Scientific Forecaster Discussion
Area forecast discussion
National Weather Service San Joaquin Valley - Hanford California
329 am PDT Tuesday Jul 29 2014
Synopsis...a drier southwest flow will prevail over the area
today and Wednesday...keeping thunderstorm chances confined to the
higher elevations of the southern Sierra Nevada. Temperatures
will remain on the hot side through the remainder of the week.
Discussion...upper high pressure over The Four Corners regions
is continuing to retrograde westward with the upper flow aloft
turning toward the southwest. Infrared imagery is indicating skies have
been clearing out across the southern portion of our County warning forecast area as drier
air aloft has been pushing in and the monsoonal surge that
impacted our area on Monday moving north of our area. As a result
of the clearing...expect afternoon highs to be a few degrees
warmer across most locations today and triple digit readings will
be widespread across the San Joaquin Valley...southern Sierra
foothills and the Kern County deserts. Some high clouds from
Tropical Storm Hernan off the southern Baja California coast may stream into
our area this afternoon but will have little impact for our area.
Some residual moisture along with sufficient convective available potential energy and
instability will allow for some thunderstorms this afternoon and
evening over the higher elevations of the southern Sierra Nevada.
No precipitation is anticipated for the remainder of our area as
successive WRF runs have shown 850 mb dew points and mean layer
850-700 mb relative humidity forecasts with readings that are too low for convection
to take place. Tropical Storm Hernan is prognosticated by the National
Hurricane Center to track west-northwest over colder open waters
and dissipate over the next few days and have no impact for our
area other than providing US with some high clouds at times.
Little change is expect through Thursday with the upper ridge
remaining over the Desert Southwest and a dry southwest flow
aloft prevailing over our area. Temperatures will remain above
seasonal normals across our area and thunderstorm chances will
remain confined to the higher elevations of the southern Sierra
Nevada where there will be sufficient moisture and instability for
thunderstorm development each afternoon. Relative humidity forecasts indicating dry
air persisting in the middle levels for the remainder of the week
which will inhibit convection elsewhere.
The medium range models are indicating the potential for another
surge of tropical monsoonal moisture impacting southeastern California
this weekend. 850 mb forecasts and middle level relative humidity forecasts are indicating a
fairly sharp gradient just ot the east of our area over the Mojave
Desert so there is some uncertainty with how far west the deeper
moisture will extend. For now will follow the operational models
and keep the deeper moisture just to the east of our County warning forecast area and keep
precipitation chances confined to the southern Sierra Nevada...but
this will need to be watched over the next few model runs in case
the moisture surge pushes further west. Both the GFS and European model (ecmwf)
indicate a dry westerly flow breaks through early next week
pushing the monsoonal surge well to the east of our area.
Temperatures are expected to remain above normal at least through
Aviation...widely scattered thunderstorms with local MVFR
ceilings possible over the higher elevations of the southern
Sierra from 18z Tuesday through 06z Wednesday. Otherwise...VFR
conditions will prevail across the central California interior
during the next 24 hours.
Air quality issues...none.
The level of certainty for days 1 and 2 is high.
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 /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 07-29 113:1898 87:1896 78:2003 57:1950
kfat 07-30 114:1898 80:1966 83:2003 57:1975
kfat 07-31 114:1908 83:1976 81:1908 53:1895
Kbfl 07-29 114:1908 87:1965 86:2003 52:1914
kbfl 07-30 112:1908 67:1955 82:1980 45:1955
kbfl 07-31 110:1943 60:1916 79:1982 55:1905