Area Forecast Discussion
Issued by NWS San Joaquin Valley, CA

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000
FXUS66 KHNX 251130
AFDHNX

Area Forecast Discussion
National Weather Service San Joaquin Valley - Hanford CA
330 AM PST Sat Feb 25 2017

.SYNOPSIS...
A couple of weak disturbances will move through the region this
weekend into early next week with generally light precipitation.
Dry weather will return by the middle of next week.

&&

.DISCUSSION...
Upper level low off the Pacific Northwest Coast prepared to
introduce another round of precipitation across the district this
weekend. Currently, the upper low is located some 300 miles west
of the Southern Oregon Coast and tracking almost due south. The
orientation of the flow aloft has the upper low in a positive tilt
trof position with Northern California under the best dynamics in
the area of difluences. Short term model analysis has the upper
low turning east and toward California after dropping south of
Eureka near 130W long. The trajectory of the upper low will place
the district under difluent flow after 4 pm PST with a slight
chance of precipitation during the later afternoon. Will maintain
the wording of this timing with generally light precipitation
during the late evening hours. Lates upper air observation and
mountain surface data show the freezing level just above 4000
feet. Therefore, will keep today`s snow above 4000 feet and
confined to the Sierra Nevada.

In the meanwhile, temperatures were running a few degrees warmer
this morning compared to Friday morning. Therefore, while near
freezing conditions will be reached in the favored areas of the
San Joaquin Valley, widespread freezing will not be seen this
morning. A change in the flow aloft to a westerly direction is
supporting the warming of overnight low temperatures. Therefore,
will not expect freeze warning criteria to be met this morning.

The orientation of the upper level flow during the approaching
disturbance may not favor significant precipitation during the
storm event. While moisture will be drawn northward as the upper
level low moves toward Central California today, the positive
tilting of the trof may force the moisture into Southern
California with Central California receiving limited moisture.
Yet, light precipitation is expected during the event with the
heaviest accumulation on Sunday. In addition, Sunday will see a
second stronger trof (with good difluent flow over Central
California) push into the area for a continuation of
precipitation. By Monday, cyclonic flow over the region will allow
for the continuation of unsettled conditions. In addition,
convective parameters show some instability over the region.
Therefore, some showers could linger over the area on Monday
(mainly over the Sierra Nevada) with the region drying on Tuesday.


Longer range models still indicate the possibility of a dry
extended as a ridge pattern settles over the West Coast by mid-
week. Models confidence is not high, but models are trending
toward a ridge over the west through next weekend. Currently, the
ECMWF shows a disturbance riding over the ridge next Friday, but,
keeps the main energy well north of the district. Therefore,
confidence toward a dry extended forecast is growing and will
therefore maintain that wording for now.


&&

.AVIATION...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...
None.

&&

$$

public...Molina
avn/fw...Dudley
synopsis...Molina

weather.gov/hanford



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