Area Forecast Discussion
Issued by NWS San Joaquin Valley, CA
FXUS66 KHNX 180954
Area Forecast Discussion
National Weather Service San Joaquin Valley - Hanford CA
254 AM PDT Sat Mar 18 2017
.SYNOPSIS...A weak low pressure system is expected to move into
central California this afternoon and evening with light showers
possible near Yosemite. A cold front will cross the area Monday
night with more widespread precipitation into Tuesday. Afternoon
and evening thunderstorms will be possible Tuesday and Wednesday.
Finally, a stronger storm system will bring the potential for
heavy precipitation Friday and next Saturday.
.DISCUSSION...Latest satellite images show a cold front currently
over northern California. This system has very little moisture
associated with it, so we are not expecting significant impacts
in terms of precipitation. Some light showers are possible
over the Sierra Nevada mainly around Yosemite this afternoon,
although short-term high resolution models show this system
weakening further as it moves southward. Therefore, have left a
slight chance of showers for this area. Weak ridging with a dry
southwest flow aloft will be in store for Sunday and Monday with
above average temperatures and dry conditions to persist.
The next low pressure system that arrives on Monday night will
bring precipitation chances to much of our region into Tuesday.
Snow levels will likely remain fairly high initially, or around
7,500 to 8,000 feet. Sufficient instability for afternoon and
evening thunderstorms is possible Tuesday, although we expect
a better chance for thunderstorms on Wednesday as instability
parameters are more favorable due to the upper-level trough and
colder air aloft behind the Tuesday system. Some thunderstorms
could be strong and produce at least some small hail. In
addition, snow levels are expected to fall significantly on
Wednesday, or to around 5,000 feet.
Chances for showers will continue Thursday, though we will likely
be in between systems before another low pressure system arrives
by Friday evening. Due to difficulty to forecast exact timing at
this range, we have opted to at keep mainly slight chance to
chance category POPs for Thursday. Unsettled conditions with near
average to below average temperatures will likely prevail for
the latter half of next week. Models have consistently been
showing a stronger storm system during Friday evening and into
next Saturday, as this system could have a decent subtropical
moisture tap with another cold core low pressure system. So,
this storm will have the potential to bring us more widespread
moderate to heavy precipitation. Stay tuned as we get closer.
Increasing areas of MVFR and local mountain obscuring IFR in low
clouds and showers over the southern Sierra Nevada north of Fresno
County after 18Z Sat. Otherwise, VFR conditions can be expected
across the Central CA Interior during the next 24 hours.
.AIR QUALITY ISSUES...
The level of certainty for days 1 and 2 is medium.
The level of certainty for days 3 through 7 is high.
Certainty levels include low...medium...and high. Please visit
www.weather.gov/hnx/certainty.php for additional information
an/or to provide feedback.