Area forecast discussion National Weather Service San Joaquin Valley - Hanford California 320 am PDT Sat may 25 2013 Synopsis... a storm system over the Pacific northwest will bring a cool onshore flow to the central California interior through the Holiday weekend. Temperatures will be 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... satellite loops show the upper-level low over the Pacific northwest this morning with a trough moving over the northern half of California. A westerly jet moving around the base of the trough has produced local gusts over 40 miles per hour near Cache creek...but these have been confined to that area and do not plan any wind headlines at this time. At 09z /0200 PDT/ this morning...temperatures in the central and southern San Joaquin Valley were running mostly a few degrees above persistence. With the trough nearly stationary...little change is forecast in 500-mb heights from 00z Saturday /1700 PDT Friday/ to 00z Sunday. The onshore flow likely will offset the slightly longer daylight period and high temperatures today should be similar to Friday. Sunday should be similar to today...except that as the trough deepens there will be better support for an increase in desert winds. The forecast problem for this morning is the possibility of precipitation for Memorial Day and Tuesday. There is disagreement between the 00z GFS and the 00z European model (ecmwf)...with the GFS having a dry solution and the European model (ecmwf) being the wetter model. Both models bring the trough axis through the Hanford warning/forecast area Monday night and the main difference between the two models is that the European model (ecmwf) has more middle-level moisture. The forecast is a blend between the two models with heavier weight toward the European model (ecmwf). Precipitation will begin Monday afternoon near Yosemite National Park...with the snow level around 8500-9000 feet. Rain and high-elevation snow will spread south overnight...with chance probability of precipitation as far south as Kings and the northern half of Tulare County...and slight chance probability of precipitation south through the Tehachapi Mountains and the western Kern County desert. Precipitation will diminish from the south Tuesday into Tuesday evening...lingering over the southern Sierra Nevada through Tuesday night. At this time...total snow accumulations for Yosemite National Park are forecast to be 1-2 inches above 9000 feet. Temperatures are forecast to remain a few degrees below normal through the weekend...then fall back into the 70s Monday as the trough deepens over the central California interior. Temperatures will warm back into the lower 80s Wednesday...and will be near normal by the end of the week. && 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 05-25 102:1890 59:1906 68:1890 42:1980 kfat 05-26 103:1974 66:1946 68:1951 40:1953 kfat 05-27 104:1974 55:1971 69:1896 46:1998 Kbfl 05-25 106:1982 58:2008 77:1982 39:1893 kbfl 05-26 107:1951 68:1998 72:1979 40:1918 kbfl 05-27 106:1974 66:1971 75:1974 42:1917 && Hnx watches/warnings/advisories... none. && $$ Public...Sanger AVN/fw...bean synopsis...durfee Weather.Gov/Hanford