Area Forecast Discussion
Issued by NWS San Joaquin Valley, CA

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FXUS66 KHNX 171050

Area Forecast Discussion
National Weather Service San Joaquin Valley - Hanford CA
350 AM PDT Sat Mar 17 2018

A weather disturbance will provide unsettled conditions Today
with showers and possible thunderstorms producing heavy rain and
snow over the Sierra Nevada. Weak High pressure will begin moving
into the region Sunday bringing a return to warming and drying
conditions through early next week. Another storm system will then
begin impacting our area by the middle of next week.


Upper low over the Pacific Northwest/Northern California continues
to influence the weather over the region this morning. While
showers currently continue to diminish, another impulse pushing
through the region will allow for more isolated showers this
afternoon. Regional Doppler radar`s are already showing showers
developing along the coast that will progress eastward and into
the Central California Interior later today. Snow levels on Friday
will averaging around 4000 and above with rain observed below
that level. While the Foothills and mountains received the higher
amounts of precipitation, the valley locations fared-well with
many observing amounts of a quarter of an inch or more.

Now that satellite imagery shows some clearing across the region
before the next band of showers, the potential for fog development
is high due to the saturation of the environment before day-
break. Will mention at least patchy conditions for this morning as
a few locations were already reporting visibility in the range of
a few miles. Convective parameters were indicating the
possibility of afternoon Thunderstorms across the San Joaquin
Valley this Saturday. Will mention a slight chance of
Thunderstorms from around noon to near sunset. Afterward, the
region will transition toward a quiet period before the next big
storm next week.

Central California is now in a post cold frontal environment with
convection a possibility this afternoon. Afterward, while models
show the West Coast under a modified ridge environment, models do
show a piece of energy pushing through the region which may
introduce good mixing of the atmosphere as winds pick-up during
the passage of the vort lobe. Afterward, models in good agreement
with keeping a ridge pattern over the west coast through early
Tuesday. Therefore, Sunday and Monday will see minimal chances of
precipitation with clouds lingering on Sunday.

Big chance will start on Tuesday as precipitation returns to the
region in the form of a possible Atmospheric River event. While
model uncertainty increases toward next Tuesday, models still
leaning toward developing a closed low circulation some 800 miles
West of the San Francisco area that will support the northeastward
surge of subtropical moisture into the region toward mid-week.
Model Integrated Water Vapor Transport and Standardized Anomaly
Analysis support the arrival of subtropical moisture into the
region later on Tuesday. Standardized Anomaly Analysis even has up
to 4 standard deviations above climatological normal with precip-
water values above 1 inch a possibility late Tuesday into
Wednesday. Therefore, confidence is high that significant
precipitation will return to the area around the mid-week period.
Afterward, models place a stronger ridge pattern over the west
around next weekend to terminate the unsettled conditions.
Therefore, before the ridge pattern, the district will remain
unsettled with precipitation potential through at least the end of
the week.


Areas of MVFR conditions due to showers in the San Joaquin Valley,
along with local IFR in heavier showers. Also expect areas of
terrain obscuration due to clouds/precipitation in the Sierra
Nevada and adjacent foothills, as well as the Kern County
mountains. Otherwise, VFR conditions will prevail for the next 24





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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