Scientific Forecaster Discussion
Area forecast discussion
National Weather Service San Joaquin Valley - Hanford California
251 PM PDT Sat Oct 3 2015
a northwesterly flow will help keep the central California
interior dry on Saturday with high temperatures near seasonal
averages. A storm system originating in western Canada will track
southward and bring much cooler weather and a chance of rain showers
and snow...especially at locations above 9000 feet...on Sunday and
while sunny skies dominated the central California interior this
Saturday...a storm continues to drop from the Pacific northwest.
Currently...the center of the storm was still over Oregon and
moving due south toward the Bay area tonight. In the meanwhile...
ahead of the colder air...temperatures have been able to rise some
1-4 degree-f above Friday afternoon/S readings. Yet...this will be
short lived as the cold air rushes down on Sunday along with the
strong upper low.
Models showing high confidence in the track of the upper low as it
drops into California overnight and through central California on
Sunday. Good difluent flow and orographic lift expected over the
Sierra Nevada starting late tonight. As the upper low drops...it
is expected to draw-up some moisture to help feed the precipitation over
the region on Sunday. Model precip-water...while below one inch
during the event...rises to near 0.75 of an inch on Sunday.
Therefore... models progging light amounts of rain and snow above
and below 9000 feet during storm passage.
Convectively...the upper low will not be a very cold storm as
500mb temperatures only reach the minus upper teens degree-c on Sunday
along with weak cape values. Short range models place widespread
cape values of 400-800 j/kg...but show very little cape in the
1000 j/kg range. However...models do show Li/S in the negative
range...from Fresno County southward with the lowest values over
the Tulare County mountains. Therefore...while remaining in the
slight chance category...will continue to mention thunderstorms
for much of the district on Sunday.
By Monday...the upper low stalls out over Southern California.
Wrap around moisture with orographic lift may allow for the
continuation of precipitation and isolated thunderstorms for one more
day. However...will confine thunderstorms to the mountains on
Monday. The upper low will continue to slowly move east on Tuesday
and closer to Arizona...allowing precipitation to diminish over the
district. While clouds will still form along the Sierra Nevada
crest on Tuesday...precipitation potential will be minimal. The low will
move far enough on Wednesday to allow a ridge to move into the
region. Slight warming and drying trend will start and continue
through the remainder of the period.
IFR and MVFR conditions and mountain obscurations in thunderstorms
over the Sierra crest after 00z Sunday. Otherwise...VFR conditions
can be expected throughout the central California 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.
This information is provided as part of a trial project conducted
by the National Weather Service San Joaquin Valley - Hanford.
Certainty levels include low...medium...and high. Please visit
www.Weather.Gov/hnx/certainty.Php /all lower case/ for additional
information and/or to provide feedback.
site date hi_max:year lo_max:year hi_min:year lo_min:year
Kfat 10-03 101:1980 62:1916 69:2012 41:1908
kfat 10-04 102:1980 64:1916 69:1917 42:1957
kfat 10-05 101:1980 64:1916 66:1904 40:1969
Kbfl 10-03 103:1933 64:1916 72:2012 34:1908
kbfl 10-04 104:1933 60:1912 71:1970 33:1908
kbfl 10-05 104:1933 66:2007 71:1980 36:1908
Winter Storm Watch from late tonight through late Sunday night
for the Tulare County mountains /caz097/.