Scientific Forecaster Discussion
fxus66 khnx 230012 aaa
Area forecast discussion...updated
National Weather Service San Joaquin Valley - Hanford California
512 PM PDT Mon may 22 2017
..updated air quality section...
high pressure over the region will maintain dry and hot
conditions through Wednesday. Temperatures in the San Joaquin
Valley will hit or slightly exceed triple digits, especially on
Monday and Tuesday. Temperatures then begin to cool Wednesday
night and Thursday. Only isolated showers or thunderstorms are
possible over the Sierra crest through mid week.
upper level ridge pattern expected to dwell over
the West Coast for another day or so before a change in the
weather occurs. Currently, models showing high confidence in
attempting to swing an upper low across the Pacific northwest and
through the inter- mountain west. This will occur on Wednesday,
allowing for the start of a cooling trend across the West Coast.
Beforehand, the district will see another day of triple-digit heat
across the San Joaquin Valley and Mojave Desert. Based on current
precip-water analysis from across the area, the atmosphere is too
dry for anything more then isolated afternoon convection.
Therefore, with a northerly flow aloft, orographic lift will be
the main force for possible convection confined to the Sierra
Cooler temperatures, breezy conditions and clouds may return to
the central California interior during the latter part of the
week after the breakdown of the current ridge pattern. While positive vorticity advection
vort lobe dynamics will be very limited during the passage of
the trof to the north, cooler temperatures will filter in the
region along with an increase in surface winds. Precipitation
analysis only shows any accumulation along the Sierra Nevada crest
throughout the week with the passage of the trof that exits the
region my the weekend. Before this occurs, the flow aloft will be
mostly onshore, allowing for the introduction of cooler air.
Models do show some uncertainty in the flow aloft toward the end
of the week and into the weekend. Yet, models are doing a very
good job of possibly introducing another ridge pattern over the
West Coast later this weekend. The strong onshore flow will
terminate by the end of the week with a Saturday as the transition
period. That will be followed by a warming trend that will start
on Saturday/Sunday. Therefore, near normal temperatures will be
replace with heat starting next Monday.
local IFR possible over the Sierra Nevada crest due to mountain
obscurations from isolated thunderstorms during this afternoon and
into early this evening. VFR conditions are otherwise expected
across the central California interior during the next 24 hours.
Air quality issues...on Tuesday may 23 2017...unhealthy for
sensitive groups in Fresno... Kern... Kings...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.
Certainty levels include low...medium...and high. Please visit
www.Weather.Gov/hnx/certainty.Php for additional information
an/or to provide feedback.