FXUS66 KHNX 182335
Area Forecast Discussion
National Weather Service San Joaquin Valley - Hanford CA
335 PM PST Sun Feb 18 2018
A southward moving cold front will bring an unseasonably cold air
mass into the central California interior by this evening.
Blustery winds will accompany the change to colder weather this
afternoon through Monday and snow showers are possible in the
mountains and foothills by this evening. Below freezing
temperatures are likely in the San Joaquin Valley Tuesday morning
and Wednesday morning. Colder than normal weather will continue
for the remainder of the week.
Change is finally in store for Central California as a cold front
from the Gulf of Alaska continues to descend toward the district.
While the sun continued to shine this Sunday, clouds and showers
have spread into Northern California behind the cold front.
Surface Frontal analysis has the cold front over Northern
California and quickly approaching the Central California
Interior. Many surface observations are already showing a more
northwesterly wind component which places the cold front nearby.
Satellite IR imagery is showing the cold air cellular cloud
formations pushing past the Bay area and moving further southward.
Therefore, the cold air-mass will descend down into the region
tonight with elevated wind speed being the saving grace from a
very cold night. Clouds development from marginal instability will
be the other saving grace, but will also produce spotty showers
tonight as snow level could reach down into the foothills.
However, moisture continues to lack which will keep precipitation
on the lower accumulation-side with a few inches possible over the
higher terrain of the Sierra Nevada.
Current model prog timing still has the disturbance and associated
cold front crossing into Central California today as surface winds
have already started to increase. The cold front is entering the
region and should reach the southern portion of the district just
after sunset. At which time, the disturbance aloft will drop into
the region and place a good portion of its energy offshore along
the Central Coast. Model prog is still showing the flow pattern in
a more channel flow pattern characteristic. This channel flow
pattern is more indicative of strong winds than precipitation.
Satellite imagery and surface observations are already showing
this trend. 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. Yet, the
lack of precipitation and the fact that lower elevations may see
snow will warrant the winter weather advisories for tonight.
Behind Today's 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 very low, will at least mention a
potential as very low accumulation will be likely. By next
weekend, an inside slider will maintain clouds, winds and possible
mixing of the atmosphere to moderate temperatures.
Strong surface winds with gusts to 45 knots developing this
evening across the Kern County Mountains and Deserts. IFR
conditions in Blowing Dust will be also be possible across the
Mojave Desert overnight. Increasing clouds this afternoon with
clouds and showers obscuring the mountains after 00Z Monday.
Otherwise, VFR conditions will prevail across the Central CA
Interior during the next 24 hours.
.AIR QUALITY ISSUES...
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.
Winter Weather Advisory from 9 PM this evening to 3 AM PST
Wind Advisory until 9 PM PST this evening CAZ095.
Winter Weather Advisory from 6 PM this evening to 4 PM PST
Hard Freeze Warning from midnight Monday night to 8 AM PST
Freeze Watch from late Tuesday night through Thursday morning
Wind Advisory until 4 PM PST Monday CAZ098-099.
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