Scientific Forecaster Discussion
Area forecast discussion
National Weather Service San Joaquin Valley - Hanford California
605 PM PDT Monday Jul 25 2016
..updated air quality issues section...
a ridge of high pressure will provide the central California
interior with mostly clear skies and above average temperatures.
These conditions will persist over the region for most of this
week as the ridge of high pressure is expected to remain over the
area. Isolated afternoon showers and thunderstorms possible along
the Sierra crest by Thursday, then spreading to the Kern County
mountains and desert Friday through the weekend.
Previous discussion... /issued 248 PM PDT Jul 25 2016 /
clear and dry conditions across central California this afternoon.
Temperatures running a bit cooler in the northwest portions of the
central San Joaquin Valley. Otherwise a mix bag amounting to
little change. The slight cooling towards north Los Banos north Merced
area was due to a stronger onshore flow as a disturbance moved out
of the pacnw. A ridge in the SW U.S will expand into central California
Tuesday. This will diminish the marine layer along the coast and
decrease the onshore gradients resulting in a warmer trend.
The ridge core centered over The Four Corners region will drift
west to over southern Nevada by midweek. High temperatures will
remain several degrees above normal with widespread triple digit
heat in the lower elevations, but are not expected to reach record
levels. The dry air will allow temperatures to cool off overnight
for some relief from the heat with diurnal swings of 35 to 40
degrees. The ridge will finally begin to weaken and drift back
east next weekend. Op models and ensembles remain in good
agreement and show a trough in the northeast Pacific gradually
moving inland to our north. This will bring a modest cooling trend
with temperatures only lowering to slightly above normal during
the weekend. Of note, we are currently in the midst of the hottest
time of the year for the district climatologically, which runs
from mid July through early August.
The models have been advertising a push of monsoonal moisture this
week and satellite water vapor imagery shows it beginning to move
over Southern California. The mid-level moisture will gradually spread
northward with some afternoon cumulus possible over the mountains
Wednesday. Models have been trending little faster with the
moisture, with some light quantitative precipitation forecast of the southern Sierra by Wednesday
afternoon. Slight chance pops were in place for the mountains and
desert beginning Thursday. The moisture doesn't look very
impressive, but enough to support isolated afternoon convection.
The threat will continue into the weekend but a drier southwest
flow aloft should shift the moisture eastward by early next week.
VFR conditions can be expected through central California for at
least the next 24 hours.
Air quality issues...
on Tuesday July 26 2016... unhealthy in Fresno County and Sequoia
National Park and Forest. Unhealthy for sensitive groups in
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.
Certainty levels include low...medium...and high. Please visit
www.Weather.Gov/hnx/certainty.Php for additional information
an/or to provide feedback.