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Area Forecast Discussion (AFD)

Issued by San Joaquin Valley, CA (HNX)

                            
000
FXUS66 KHNX 182114
AFDHNX

Area Forecast Discussion
National Weather Service San Joaquin Valley - Hanford CA
114 PM PST Mon Feb 18 2019

.SYNOPSIS...
A cold air mass will settle over the San Joaquin Valley tonight.
The next storm system should impact Central California around the
middle of the week. This storm system will be moisture starved,
with precipitation amounts much less than what fell in the
forecast area this past weekend. Temperatures will remain below 
normal for this time of year for at least the next several days.

&&

.DISCUSSION...
An upper-level trough of low pressure will slowly progress
eastward through the Desert Southwest tonight and Tuesday. Minimum
temperatures in rural locations throughout the San Joaquin Valley
late tonight into early Tuesday morning will end up between 27 
and 32 degrees. Outside of major urban areas, sub-freezing 
temperatures are likely for a period of five to seven hours. A
Freeze Warning is in effect for the San Joaquin Valley from late
tonight until 9 AM PST Tuesday morning. 

The next storm system will begin to slide southward through
Western Canada Tuesday night. This low pressure system will
progress to the south-southeast across the Pacific Northwest
Wednesday. The storm system will move southward through the Golden
States Wednesday night and Thursday, prior to making it to
Southern California Thursday night. This low pressure system will
be moisture starved. Rain amounts will vary from as low as one
hundredth of an inch in the western portion of the San Joaquin
Valley to around one tenth of an inch in the extreme eastern part
of the San Joaquin Valley. Snow amounts should vary from one to
two inches in the Southern Sierra Nevada foothills to two to four
inches in the Kern County mountains to three to six inches in the
Southern Sierra Nevada. Snow levels could drop to about 1,000 feet
Thursday morning. 

The aforementioned storm system will move eastward through the
Desert Southwest Friday through Saturday. From this point forward,
forecast certainty takes a nose dive as numerical model output
solutions diverge. The GFS numerical model indicates a much 
deeper upper-level trough of low pressure passing eastward 
through Northern California late this weekend, which would favor 
higher precipitation chances Sunday and Sunday night. On the other
hand, the European numerical model depicts a much flatter trough 
of low pressure aloft, thereby keeping precipitation north of 
Central California. This forecast cycle will split the difference 
until numerical model output guidance comes into agreement.

&&

.AVIATION...
Areas of MVFR and local IFR in low clouds in south end of the San 
Joaquin Valley and the valley facing slopes of the Southern Sierra 
Nevada south of Kings Canyon and the Tehachapi Mountains through
12Z Tuesday. Otherwise, VFR conditions can be expected across the
central CA Interior for 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 
and/or to provide feedback.

&&

.HNX Watches/Warnings/Advisories...
Freeze Warning from midnight tonight to 9 AM PST Tuesday 
CAZ089>092.

&&

$$

public...BS
avn/fw...DS
synopsis...BS

weather.gov/hanford