Weather Service Report


001 
FXUS66 KHNX 172320
AFDHNX

Area Forecast Discussion
National Weather Service San Joaquin Valley - Hanford CA
320 PM PST Sat Feb 17 2018

.SYNOPSIS...
Dry and mild conditions through Saturday. Next weather system 
brings stronger winds and a chance of showers to mainly the 
mountains late Sunday and Monday followed by cold temperatures 
early next week with a possible widespread freeze.

&&

.DISCUSSION...
High pressure over the West Coast allowed for another warm and  
sunny day across Central California. Yet, the position of the high
pressure ridge will make it possible for disturbances to move 
across the area. The position of the retrograded ridge pattern is 
now at about 1000 miles west of the Bay area with one disturbance 
expected through Central California by later on Sunday night. Even
with the retrograde position, temperatures were able to reach 
well into the 60s and approach the 70s. However, dew point remain 
low with many valley locations reporting values in the mid 20s to 
mid 30s. With dew point reading that low, will not have a 
difficult time reaching the freezing mark again Sunday morning as 
light winds and mostly clear skies continue. 

Current model prog timing has the disturbance and associated cold  
front crossing into Central California at around mid-day on Sunday
with a possible increase in surface winds. The cold front is 
expected to enter the region later during the day on Sunday and 
reach the southern portion of the district before sunset. At which
time, the disturbance aloft will drop into the region but place 
most if its energy offshore along the Central Coast. Model prog is
currently showing the flow pattern in a more channel flow pattern
characteristic. This channel flow pattern is more indicative of 
strong winds than precipitation. Therefore, the higher confidence 
levels are with the strong winds then the lower confidence of 
possible precipitation. Yet, a portion of the wind component could
become perpendicular to the Sierra Nevada Range and Tehachapi 
Mountains. Therefore, can not rule out precipitation over the 
higher terrain. However, forecast precipitation accumulation is 
small for this event as Central California is not favored in this 
flow pattern. 

Behind Sunday cold front, models have been very consistent in prog  
sub-freezing temperatures across the San Joaquin Valley from 
around Tuesday through Thursday morning. While during the early 
onset of the cold frontal passage, the coldest air will reside 
over the area with possible moderation in conditions going into 
Thursday morning. Therefore, the best chances of a hard freeze 
[min's < 28F] will exist on Tuesday morning (once the winds settle
down and the skies clear out from Monday's event) with a good 
chance of freezing [min's < 32F but > 28F] Wednesday morning. 
While not as widespread as Wednesday morning, freezing will still 
be possible on Thursday morning. By Friday, Modification of the 
air-mass will make the potential for freezing less likely. 
Furthermore, another disturbance will enter the region on Thursday
afternoon, which will increase winds and clouds along with mixing
of the atmosphere to prevent the freeze potential. While the 
potential for precipitation is unlikely during the late week 
period, will increase clouds to reflect the possibility for 
another storm across Central California. 

In addition, models hint toward possible light precipitation over
the Grapevine Monday night in the post frontal environment. While
cold air will filter down to the Grapevine by Monday, the lack of
significant moisture may make it difficult for much accumulating
snow during the event. Therefore, will mention possible snow with
no big highlight in the forecast.

&&

.AVIATION...
Strong surface winds with gusts to 45 knots developing after 22Z on 
Sunday across the Kern County Mountains and Deserts. IFR conditions 
in Blowing Dusts will be also be possible across the Mojave Desert 
after 22Z Sunday. Otherwise, VFR conditions will prevail across the 
Central CA Interior during 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 medium.

Certainty levels include low...medium...and high. Please visit
www.weather.gov/hnx/certainty.php for additional information
an/or to provide feedback.

&&

.HNX Watches/Warnings/Advisories...
Wind Advisory from 3 PM Sunday to 4 PM PST Monday CAZ095-098-099.

Freeze Watch from Monday evening through Thursday morning 
CAZ089>092.

&&

$$

public...Molina
avn/fw...JEB
synopsis...Molina

weather.gov/hanford

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