Scientific Forecaster Discussion
fxus66 khnx 240918
Area forecast discussion
National Weather Service San Joaquin Valley - Hanford California
218 am PDT Wed may 24 2017
Synopsis...an area of low pressure will move into the area from
the Pacific as high pressure weakens. Temperatures will cool due
to increased onshore flow and cooler air aloft today and Thursday.
A ridge of high pressure will then become reestablished this
weekend for another warming trend.
Discussion...the Rex block pattern with high pressure over low
pressure is quickly breaking down the as the high weakens over
the Great Basin and the low pressure moves northward off the
coast. Water vapor imagery shows the low now centered near
32n/127w and lifting northward. Some convection is noted moving
west of Point Conception as the cooler air aloft associated with
the low is more unstable. At this time it appears any showers will
remain offshore based on the current trajectory. In the very near
term, the hrrr model brings big increase in winds over the
western San Joaquin Valley beginning early this afternoon as the
onshore gradient increases and a marine intrusion begins. As is
always the case, cooler air will spill into the San Joaquin
Valley, lower slopes as well as the Kern County desert later this
afternoon and evening. By later Thursday, models absorb the
remnants of the weakening offshore low and move it onshore flow
some additional cooling due to lower heights aloft.
From Friday through the weekend, models then are in good agreement
in building a ridge along the West Coast and this will bring
another warming trend. The ridge looks to Max out on Sunday night
and Monday for a dry and warm Memorial Day weekend.
possible slight chance of thunderstorms over the Sierra Nevada crest
during the afternoon and early evening. VFR conditions are otherwise
expected across the central California interior during the next 24 hours.
Air quality issues...
on Wednesday may 24 2017... unhealthy for sensitive groups in
Fresno... Kern... Kings... Madera and Tulare counties.
Further information is available at valleyair.Org
The level of certainty for days 1 and 2 is medium.
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.