Area Forecast Discussion
Issued by NWS Sacramento, CA
FXUS66 KSTO 201636
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
936 AM PDT Sun Jul 20 2014
An upper level disturbance continues over northern California
today with the greatest probability for thunderstorms over
mountains. An offshore trough may trigger thunderstorms over
Tehama, Shasta, and Plumas county area Monday and Tuesday. Then
expect a warm up Wednesday through the weekend.
.Short Term Discussion (Today through Tuesday)...
Monsoonal moisture continues to spread northward over the region
today. Some sprinkles and light showers have are moving westward
over the western portions of the valley and delta this morning.
This activity is expected to decrease over the next couple of
hours. A disturbance over the Central Sierra will move
northward through the region on today along the crest. By noon
thunderstorms may start to form again over the Sierra Nevada.
Precipitable waters remain high so any thunderstorms that develop
will likely contain very heavy rainfall. Most of the activity
today is expected over the same general areas as the last couple
of days with the best chance of storms over the western slopes
remaining south of I-80 today.
That disturbance will linger over the northern areas for Monday.
That feature combined with a low pressure trough deepening along
the coast may enhance activity over the northern areas both for
Monday. Increased cloud cover for Sunday and Monday will bring
The low will deepen along the coast on Tuesday and may continue to
bring afternoon thunderstorms to the northern mountain areas as a
weak disturbance moves through the region from the southwest.
Good onshore flow will continue the next several days and
temperatures will be below normal for this time of year.
A trough will begin to move into the Pacific Northwest on
Wednesday. Skies should be clearing and thunderstorm activity
should be focused more north of the area and into Oregon.
Temperatures should warm a little but still be below seasonal
.Extended Discussion (Thursday through Sunday)
NorCal is under some form of benign southwesterly flow aloft into
next weekend. The four corners high is forecast to gradually build
northwestward back into NorCal for a significant warming trend
beyond midweek. The monsoonal moisture will have exited and
provide for a clearer sky and less humidity. Triple digit heat
appears to return to portions of the Central Valley by Friday with
additional warming through the weekend. We will need to watch for
the potential of more monsoonal moisture to make its way into
forecast area late in the period, but will keep a dry forecast for
now. JClapp, Part Deux
VFR conditions over the Valley today with a band of iso -SHRA
moving through this morning. SCT mountain thunderstorms will
spread from south of I80 this morning to the Southern Cascades by
around 21z. Gusts to 30 kt in the Delta. Erratic gusts to around
30kt near thunderstorms.