Area Forecast Discussion
Issued by NWS San Joaquin Valley, CA

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FXUS66 KHNX 202125

Area Forecast Discussion
National Weather Service Hanford CA
225 PM PDT Tue Apr 20 2021

.SYNOPSIS...Cooler and breezier conditions today ahead of a trough
of low pressure that will reach the area tomorrow. As the trough
reaches the area tomorrow, isolated showers and thunderstorms will
be possible across the Sierra Nevada with cool dry weather in the
valley. Dry weather through Saturday before another storm arrives


Cooler conditions across the San Joaquin Valley this afternoon as
a trough of low pressure approaches the area. Latest GOES-17
imagery shows high clouds streaming over the forecast area, which
is helping subdue afternoon highs a bit today. Breezy conditions
with wind gusts around 40 mph are occuring along the West Side
Hills this afternoon and will continue through this evening. Winds
should back off by tomorrow morning when the upper low is overhead
and the jet axis loft is more northerly compared to the westerly
component we are seeing today. The westerly winds today are
providing the forecast area with some onshore flow as well. Upper
level heights fall considerably over the region by tomorrow
afternoon, which will aid in dropping afternoon highs several
degrees from today... blended model guidance is showing mid to
upper 70s in the valley. Along with this upper low will be cool,
unstable air aloft that will most directly impact the mountains.
This instability will be enough to trigger showers over the
mountains, with an isolated thunderstorm or two possible by early
afternoon. Showers are expected to abate by nightfall as
instability wanes.

Residual showers may persist on Thursday in the Sierra Nevada
however coverage would be limited. Warming trend back into the mid
80s Friday and Saturday as a shortwave ridge of high pressure
moves over the area. A pattern change arrives on Sunday as
ensemble guidance shows a larger trough approach the area. Blended
model guidance shows precipitation in the valley and mountains
overnight Sunday. NBM probabilistic guidance is showing 67% chance
of measureable precipitation in Fresno Sunday night into Monday,
with a 56% chance in Bakersfield. Much cooler weather is expected
with this trough as well. Stay tuned for more details as the
pattern change evolves.


.AVIATION...Wind gusts in excess of 30 kts will develop this
afternoon and evening along the West-Side Hills and western third
of the valley. Wind gusts in excess of 35kts are also possible by
the afternoon in the Kern county mountains and desert. VFR
conditions are forecast to prevail across the central CA interior
over the next 24 hours.





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 for additional information
an/or to provide feedback.




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