Area Forecast Discussion
Issued by NWS San Joaquin Valley, CA
FXUS66 KHNX 182225
Area Forecast Discussion
National Weather Service San Joaquin Valley - Hanford CA
225 PM PST Wed Jan 18 2017
.SYNOPSIS...A series of Pacific storm systems will track eastward
across the state through Monday, bringing periods of rain and
mountain snow to the region.
.DISCUSSION...The first storm of at least three storms is making
inroads into the central California interior this afternoon and
bringing a return of wet weather as expected. In the southern
Sierra, snow levels have generally been above 7,000 feet but will
lower to about 5,000 feet by daybreak as the storm system moves
inland. Before then, southerly winds will become locally strong
and gusty over the Grapevine and at the south end, west side and
the northern part of the San Joaquin Valley. A Wind Advisory is in
effect accordingly for these areas into early Thursday morning.
Steady precipitation will become showery during the midday hours
Thursday behind the cold front associated with this storm system.
It will also become cold enough aloft for increased atmospheric
instability over the San Joaquin Valley and much of Kern County
Thursday where isolated afternoon and early evening thunderstorms
with small hail are possible. Moderately high CAPE and lifted
indices near -2 support this idea and is also in good agreement
with the latest forecast from SPC. Although this storm will make
steady eastward progression across central California and snow
levels will be relatively low compared to storms earlier this month,
a few locations could experience minor flooding during the next
24 hours. Additionally, notable rises are possible along small
streams and creeks where flooding has recently occurred.
What break there is between this storm and storm #2 will be brief.
A few showers may linger over mostly the higher terrain Thursday
evening through the wee hours Friday morning. Precipitation from
storm #2 will likely overspread the central California interior
later Friday morning. By late Friday afternoon, the cold front
associated with this second storm will be exiting south and east
of our CWA. The air will again be cold enough in the post frontal
environment for isolated thunderstorms in the San Joaquin Valley
Friday afternoon. This concurs with the latest forecast from SPC.
Otherwise, we can expect scattered to numerous showers over the
central California interior Friday afternoon and evening. Snow
levels may fall as low as 3,000 feet Friday night with an
accompanying threat of a little snow and/or ice over the Kern
County mountain passes and the Sierra foothills.
After storm #2 departs and before storm #3 arrives, much of the
central California interior will get a respite from wet weather
Saturday through Saturday evening. This is a period when the
models forecast a transitory short wave ridge aloft to move
across the CWA. If skies clear for any length of time underneath
this ridge Saturday night, patchy dense fog could form in the
San Joaquin Valley. Right now it appears there may be too much
mid level moisture present for that to happen, but it`s not out
of the realm of possibility.
Storm #3 will be the wettest and coldest storm in this series
of storms and will probably bring with it more significant
weather impacts such as heightened threat of localized highway,
urban and stream flooding in the San Joaquin Valley and foothills
and potentially hazardous winter travel over the higher terrain.
Snow levels could fall as low as 2,000 feet as this storm moves
inland over central California Monday morning. The combined
effects from all three storms will bring a substantial increase
in the Sierra snowpack above 7,000 feet by late Monday.
Otherwise, Monday will be chilly and unsettled with additional
showers and perhaps isolated afternoon thunderstorms.
A drying but cold northerly flow can be expected in the wake of
storm #3 Monday night and Tuesday. Northerly breezes might become
pretty gusty on the west side of the San Joaquin Valley and across
Merced County Tuesday afternoon. Despite a return of sunshine in
most areas Tuesday, temperatures will remain slightly cooler than
normal. An EPAC ridge will build over central California during
the mid to later part of next week and bring a warming trend along
with dry weather.
In the San Joaquin Valley, areas of MVFR in mist and rain with local
IFR between after 06Z Thursday. In the southern Sierra Nevada,
widespread mountain obscuring IFR in low clouds and precipitation.
VFR conditions will prevail over the Central CA Interior for the
next 24 hours.
.AIR QUALITY ISSUES...
On Wednesday January 18 2017... Firepalce/Wood Stove Burning
Status is: No Burning Unless Registered in Fresno... Kern...
Kings... Madera... Merced and Tulare Counties.
Further information is available at Valleyair.org
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 Storm Warning until 2 PM PST Thursday ABOVE 5000 FEET FOR
Wind Advisory from 7 PM this evening to 4 AM PST Thursday