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Area Forecast Discussion (AFD)

Issued by San Joaquin Valley, CA (HNX)

                            
000
FXUS66 KHNX 261033
AFDHNX

Area Forecast Discussion
National Weather Service San Joaquin Valley - Hanford CA
333 AM PDT Fri Apr 26 2019

.SYNOPSIS...
High pressure will remain over the area through today with well 
above normal temperatures. Isolated mountain thunderstorms are
also possible this afternoon. The high pressure will begin to 
weaken this weekend before an area of low pressure passes to the 
south of our area on Sunday night and Monday bringing cooler 
temperatures and increased chances of mainly mountain showers 
along with a slight chance of thunderstorms.

&&

.DISCUSSION...
Broad ridging over the western CONUS on yesterday brought another
round of much above normal temperatures and hot high temperatures
were on tap for many of the San Joaquin Valley and Kern County 
desert locations. However, when all was said and done the high 
temperature in Bakersfield came up just shy of the record high of 
97 for the date with a 96. Fresno record highs were pretty safe 
with a record for the date of 101 and also registered a 96 for the
daily high. Today the broad ridging is still in place but slightly
weaker as a system moving through the Pacific Northwest will
flatten the ridge allowing for a very slight amount of synoptic 
cooling. Still temperatures will be above normal with many 
locations in the SJV and desert areas still reaching the lower to 
mid 90s. Interestingly, diurnal cooling has been meager with 
current 10z temperatures here at the Hanford weather office 
sitting at 70 degrees. This lack of diurnal cooling will almost 
mitigate some of the synoptic cooling affect by giving the 
atmosphere a head start when the sun begins to warm things up in 
the morning allowing for temperatures today very close to 
yesterdays levels.

By Sunday the synoptic cooling will increase and high temperatures
will be still above normal but highs in the SJV and parts of the
Kern desert areas will struggle to get out of the upper 80s.
Increased clouds associated with a cutoff low moving slowly 
eastward into southern California on Sunday will also help cool 
things down through decreased solar insolation. The cutoff low 
will bring an increase in chances for showers and even a 
thunderstorm or two to the Kern County mountains as it moves 
eastward into Arizona. This system will have to be watched as even
though it is not very strong and lacks major moisture support, 
there will be a chance for even a thunderstorm or two to develop 
in the Kern County desert areas, especially Monday night. 
Northeasterly flow on the northern side of this feature will also 
bring an increase in shower and isolated thunderstorm for the 
higher elevations of the Sierra Nevada on Monday and into Tuesday.
By Wednesday ridging begins to build into the region once again
and bringing warming temperatures. 

One thing that we have really been trying to get across to people
is that with the introduction of hot temperatures this week and
this Spring is that there will be plenty of snowmelt occuring
during the Hot patches and this will increase river levels and
being that it is in fact melted snow will be very cold. As
tempting as it may be to want to jump into area rivers, keep in
mind that flows are very strong and with the cold water
temperatures it takes almost no time to begin suffering from
hypothermia. This can lead to drowning. So be very careful and if
you must test the waters at least wear a life vest. At the very 
least the life vest will make rescue or recovery efforts that 
much easier if things do go south. Please don't become a 
statistic this Spring. Now getting off of my soap box.

&&

.AVIATION...
Isolated showers and thunderstorms near the crest of the Southern 
Sierra Nevada and near Frazier Park in Kern county are possible 
thru 03Z Saturday. Otherwise, VFR conditions will prevail across 
the Central CA Interior over the next 24 hours.

&&

.AIR QUALITY ISSUES...
On Friday April 26 2019... Unhealthy for sensitive groups in
Sequoia National Park and Forest.
Further information is available at Valleyair.org

&&

.CERTAINTY...

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.html for additional information
an/or to provide feedback.

&&

.HNX Watches/Warnings/Advisories...
NONE.
&&

$$

public...Andersen
avn/fw...JDB
synopsis...Andersen

weather.gov/hanford