Area Forecast Discussion
Issued by NWS San Joaquin Valley, CA

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FXUS66 KHNX 172145
AFDHNX

Area Forecast Discussion
National Weather Service San Joaquin Valley - Hanford CA
245 PM PDT Tue Oct 17 2017

.SYNOPSIS...There is a slight chance of showers and thunderstorms
through this evening. Little if any rainfall is expected with the
main threat being dry lightning along with gusty and erratic
winds. Otherwise, temperatures will remain above normal through
Wednesday then trend much cooler on Thursday and Friday. There is
a chance of light rain north of Fresno County Thursday night and
Friday morning along with a period of increased winds. Dry
conditions return this weekend with temperatures trending warmer.

&&

.DISCUSSION...Mid/high clouds continue to stream over Central CA
in a southwest flow aloft. IR imagery indicating an upper level
vort max of tropical origin with an area of elevated convection
and embedded thunderstorms approaching the Central CA coast which
will move inland later this afternoon and cross our area this
evening. While the WRF is indicating no surface based CAPE and a
stable airmass at the lower levels, the potential convection this
evening is elevated and has the potential to produce dry lighting
and downbursts containing gusty and erratic winds. This system is
progged to move east of our area by Wednesday morning and give
way to a day on Wednesday although there will be come high clouds
streaming through at times. Meanwhile, temperatures are
currently running 2-4 DEG F above yday across most of our area
and guidance is indicating that Wednesday will be a few degrees
warmer at most locations.

The WRF continues to advertise a strong upper trough dropping out
of the Gulf of AK and approaching the PAC NW coast on Thursday.
This system is progged to cross the PAC NW and Norcal on Thursday
Night. The models have consistently been trending further north
with the southern extent of the deeper moisture and stronger
dynamics with this system with each run and the 12Z runs are
limiting precipitation to areas north of Fresno County Thursday
Night through Friday morning and amounts will be light as the
latest QPF progs are indicating a tenth of an inch or less of
liquid precipitation with snow falling as low as 8500 feet in
Yosemite Park Friday morning. Some light upslope precipitation
will be possible in the south end of the San Joaquin Valley and
along the valley facing slopes of the Tehachapi Mountains on
Friday as the flow turns northwest on the back side of the trough.
The main impacts that this system will have for our area will be
a period of increased winds on Thursday Night and Friday in
downslope favored areas and a sharp cooling trend with daytime
temperatures expected to lower by 12-20 DEG F between Wednesday
and Friday.

The medium range models and their ensemble means remain in fairly
good agreement with strong high pressure building into CA this
weekend and strengthening over the region through the middle of
next week. This will result in a period of dry weather mainly
clear skies and a gradual warming trend each day with temperatures
expected to approach seasonal normals by Sunday and rise to above
normal levels from Monday onward.

&&

.AVIATION...Areas of MVFR visibilities due to smoke can be
expected in the San Joaquin Valley, southern Sierra foothills and
higher elevations of the southern Sierra Nevada for at least the
next 24 hours, with VFR conditions prevailing elsewhere across the
Central California Interior. Isolated thunderstorms possible in
the San Joaquin Valley, foothills, Sierra Nevada, and Kern County
Mountains through 08Z Wednesday.

&&

.AIR QUALITY ISSUES...None.

&&

.CERTAINTY...

The level of certainty for days 1 and 2 is medium.
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...DS
avn/fw...JEB
synopsis...DS

weather.gov/hanford


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