Area Forecast Discussion
Issued by NWS San Joaquin Valley, CA

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FXUS66 KHNX 182246
AFDHNX

Area Forecast Discussion
National Weather Service San Joaquin Valley - Hanford CA
346 PM PDT Thu Apr 18 2019

.SYNOPSIS...
A ridge of high pressure will progress eastward across the
western United States today through Friday, resulting in high
temperatures well above normal for this time of year. Maximum
temperatures this weekend should return to near normal values for
late April as a couple of weak storm system brushes the southern
Sierra. A second significant warming trend is expected early next
week.

&&

.DISCUSSION...
Long wave ridging is now in place over the western third of the
CONUS and has brought mostly clear skies and warming temperatures.
Today high temperatures across the San Joaquin Valley and Kern
County desert areas have reached the mid and upper 80s. A few
desert locations reached the lower 90s. Tomorrow the ridge will be
further eastward and we should see our warmest temperatures over
the next few days with much above normal levels, and most
locations across the SJV and Kern County desert reaching the upper
80s and some locations surpassing the 90 degree mark. There is a
weak tropical system currently centered over 25N 130W over the
Pacific that will meander eastward and could introduce some
increased high clouds that may mitigate some of the solar
insolation tomorrow and keep temperatures a degree or two cooler
than forecast.

This system will also have to be watched as it moves over the Kern
County mountains on Saturday and could increase chances of a
thunderstorm or two over those locations. However, the lack of
moisture is the limiting factor and therefore kept mention of
thunderstorms over the Kern County mountains out of the forecast
at this time.

There will be a phasing of this tropical system with a mid-
latitude system dropping southeastward from the Gulf of Alaska on
late Saturday into Sunday which will increase chances for light
showers over the southern Sierra. Winds will also become breezy to
gusty with this system passage. A northerly flow will develop late
Sunday into Monday. There is a little bit of uncertainty that
develops as this phased system moves over the Four Corners by late
Monday because the trough becomes more cutoff from the northern
jetstream. This could really slow down the evolution and eastward
movement of the system and would slow the approach of a Pacific
ridge set to move eastward over the west coast. The increased wrap
around clouds and lack of synoptic heights may keep temperatures
only slightly above normal. This will need to be monitored as
there are run to run guidance differences that could have big
implications on how hot it gets next week. As of right now
forecasted high temperatures in the beginning through the middle of
next week would be in the lower 90s. But, if we get too much wrap
around cloud cover with the slowed system we will have overshot
things a bit. By the middle of next week another Gulf of Alaska
system is progged to move southward and could bring further
slight cooling to the area keeping temperatures cooler.
In other words, all bets are off on temperatures next week and
uncertainty is large at this time. Subsequent shifts over the
weekend will have more information to work with and as we get
closer things should be better resolved.

&&

.AVIATION...
VFR conditions will prevail across the Central California interior
over the next 24 hours.

&&

.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.

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...MV
synopsis...Andersen

weather.gov/hanford


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