Area Forecast Discussion
Issued by NWS Sacramento, CA

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FXUS66 KSTO 200455
AFDSTO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
955 PM PDT Tue Aug 19 2014

.Synopsis...
Near to slightly cooler than normal temperatures expected through
the weekend. A slight chance of thunderstorms will be possible
over the mountains Wednesday.

.Discussion...
Upper low is over SoCal. Mostly clear skies overnight over
NorCal. Strong onshore flow is keeping temperatures cool over the
southern Sacramento valley...where evening temperatures are 4-8
degrees cooler versus 24 hours ago. Current forecast is on track
and no evening update will be needed.

.Previous Discussion...
Water vapor satellite imagery shows closed upper low currently
centered along the California coast near San Luis Obispo, and
sliding southeastward. Isolated showers have begun to develop
along the Shasta-Trinity and along the Southern Cascades, but have
generally remained just outside of our forecast area. A
substantial marine influence is keeping parts of the forecast area
rather cool this afternoon, but that influence tapers off with
distance from the Delta. Temps are generally running 3 to 6
degrees cooler than yesterday.

Isolated thunderstorms will continue to be possible across
interior NorCal mountains this evening. Forcing is rather limited,
which will inhibit the coverage of this convection. NAM progs show
a bit of elevated instability remaining over the Sierra, perhaps
enough for a few sprinkles or light showers overnight tonight.

Relatively cool temperatures will continue the next few days. The
marine layer remains quite deep and delta breeze relatively strong
this afternoon. These factors bode well for some more marine
stratus intruding through the Delta into the Sacramento area
Wednesday morning. We start to lose a bit of delta breeze
influence late tomorrow, and more so the following days, which
will allow for a bit more warming across interior Northern
California.

Dang

&&


.Extended Discussion (Saturday through Tuesday)

By late this week, the upper low will have shifted to southern
California and into Arizona. Dry northwesterly flow will be
present over Northern California. Expect benign weather and near
normal temperatures to continue this weekend and into early next
week.

Dang


&&

.Aviation...

Mainly VFR conditions the next 24 hours across interior Northern
California. Marine stratus may intrude through the Delta and bring
MVFR/IFR cigs across Sacramento TAF sites 12-16z Wednesday.
Thunderstorms will also be possible over the mountains this
evening and again Wednesday afternoon. South to west winds 10-15
kt across the Valley will diminish tonight. Near the Delta, SW
winds 15-25 kt will continue.

Dang


&&

.STO Watches/Warnings/Advisories...
None.
&&

$$






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