Area Forecast Discussion
Issued by NWS Sacramento, CA

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FXUS66 KSTO 260508
AFDSTO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
1008 PM PDT Fri Jul 25 2014

.Synopsis...
Above normal temperatures this weekend into next week. The Sierra
crest will see a threat of thunderstorms Sunday through much of
next week and possibly as far north as the Shasta County mountains
on Wednesday.

&&

.Discussion...
Upper level ridge has shifted west over NorCal and has brought a
return to hot weather. Temperatures topped out above 100 degrees
at most valley locations this afternoon. These readings are about
10 degrees above normal. However...as hot as these readings are
they still remain about 10 degrees below the record high
temperatures across the area. At 10 pm readings are running 3-5
degrees warmer versus 24 hours ago. Have updated overnight lows to
warm them a few degrees which is more in line with short term
guidance(HRRR). This gives lows in the upper 60`s/low 70`s.
Otherwise...clear skies and light winds.
.Previous Discussion...
Warm high pressure building over the western US is causing heights
to rise over California...resulting in temperatures to be 5 to 9
degrees warmer today than this time yesterday and squashing out
the marine layer and delta breeze. This high pressure will persist
through the weekend and into next week which will continue to keep
temperatures several degrees above normal. On Sunday, a weak
trough will approach northern California which will increase
southerly flow aloft and support monsoonal moisture to start
spreading northward along the west side of the high. The moisture
combined with some instability over the mountains may generate
isolated Sierra crest thunderstorms Sunday afternoon/evening. By
Monday, the moisture will continue to spread over the Sierra as
another disturbance passes over the area, supporting another
threat of afternoon/evening isolated thunderstorms along the
Sierra. Shen


.Extended Discussion (Tuesday through Friday)

Little change expected through the extended period as upper ridge
axis remains east of Interior NorCal and upper troughing persists
over the eastern Pacific. Some monsoonal moisture progged mainly
along the Sierra Crest Tuesday with enough southwest component to
the mid level flow to suggest any afternoon thunderstorm
development will be mainly east of our Sierra Nevada zone. Models
show mid level flow becoming more southerly Wednesday as a small
scale upper trough clips the northwest portions of California.
Afternoon thunderstorm potential may expand northward along our
Sierra zone through the Western Plumas mountains into the Shasta
range on Wednesday. Progs then show more southwesterly flow
Thursday into Friday to keep any thunderstorm development mainly
north and east of the CWA. Fair skies forecast for the remainder
of Interior NorCal with above normal temperatures. Highs in the
Central Valley expected from the mid 90s to around 104, hottest in
the Northern Sacramento Valley, with mainly 80s to 90s for the
mountains and foothills.

&&

.Aviation...

SWly flow alf as upr trof ovr NorCal is replaced with upr rdg fm
Desert SW. VFR conds with genly lgt sfc wnds ovr Intr NorCal nxt
24 hrs.


&&

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

$$







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