Area Forecast Discussion
Issued by NWS Sacramento, CA

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FXUS66 KSTO 311009

309 AM PDT Thu Jul 31 2014

Another day of Sierra crest showers and thunderstorms
today...then a drying trend. A return to Sierra showers
and thunderstorms possible again early/mid week next week.


Shower and thunderstorm activity has calmed down overnight as the
main disturbance has moved northeastward. Temperatures are running
similar to this time yesterday though main cloud coverage has
moved off to the northeast as some drier air shifts inland. A
moderate delta breeze continues this morning which should allow
for some additional cooling for the affected areas before

Some lingering mid-level moisture and afternoon instability over
the mountains will once again generate thunderstorm activity over
the higher terrain this afternoon/evening. Most of the activity
should be near the Sierra crest, and then east of the crest.
Temperatures are expected to be just as warm as yesterday, if not
a couple degrees hotter with less cloud cover over the valley as
the ridge of high pressure still lingers over the western US.

Friday we may see a decrease in thunderstorm activity as the high
pressure region moves slightly eastward. Temperatures will remain
above normal and similar to today. For Saturday and Sunday, the
thunderstorm activity pushes to the north and east of the area as
a weak wave moves towards the Pacific Northwest with the tail end
of the trough moving into California. Temperatures will also trend
slightly cooler each day. Shen


.Extended Discussion (Monday through Thursday)

Temperatures will continue to be cooler than they have been by
early next week as the dominating high pressure weakens over the
western US. A slight increase in southwesterly flow aloft will
generally keep the threat of afternoon thunderstorms outside of
the forecast area for Monday. By Tuesday and Wednesday, models
suggest a slight rebuilding of upper level ridging over the west
coast. Mid-level flow begins to turn more southerly and
southeasterly with another slug of monsoonal moisture working its
way into the forecast area, with embedded disturbances sneaking
through NorCal under the ridge. This may promote a slight chance
of afternoon Sierra thunderstorms Tuesday through Thursday...though
coverage, strength, and timing are still very uncertain. Temperatures
will remain near to slightly above normal through the extended
period. Shen



Upper level high pressure ridge over Western U.S. will bring VFR
conditions all TAF sites next 24 hours. Monsoon moisture will
bring isolated thunderstorms over Sierra Cascade range and Shasta
county mountains. Surface winds generally below 15 knots except 10
to 20 knots gusts to 30 knots through the delta.


.STO Watches/Warnings/Advisories...

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