Area Forecast Discussion
Issued by NWS Sacramento, CA

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FXUS66 KSTO 282221

Area Forecast Discussion
National Weather Service Sacramento CA
321 PM PDT THU JUL 28 2016

Hot temperatures will continue across NorCal this afternoon
through Friday. This weekend will also be warm, but temperatures
will cool slightly. Isolated thunderstorms are possible over the
Sierra crest south of Highway 50 each afternoon and evening
through Saturday.


.DISCUSSION (Today through Sunday Night)...

RAP 500 mb analysis and water vapor imagery showed a strong upper
level high pressure system positioned over the Great Basin region
this afternoon with very dry atmospheric air moving into the
forecast area under light southwest flow. As a result, clear skies
and warm temperatures continue to dominate the forecast for this
afternoon. Some monsoonal moisture is present along the Sierra
Nevada mountains and helping convective clouds develop.

Although the upper flow pattern is stagnant, some moisture
associated with the southwest monsoon will be advected northward
along the Sierra Nevada mountains, which could further develop
afternoon clouds and bring some slight chances for isolated
thunderstorms this afternoon mainly south of Lake Tahoe and
Highway 50. High temperatures will continue to be well above
normal through Friday reaching the upper 90s to upper 100s in the
valley, with some locations in the northern Sacramento valley
topping 110. Upper elevations will also be warm in the upper 80s
and lower 90s.

An approaching shortwave trough of low pressure across the Pacific
Northwest will lower temperatures slightly into the mid to upper
90s across the valley this weekend (70s and 80s for higher
elevations). Isolated thunderstorms are possible Friday and
Saturday afternoons along the Sierra crest, with activity mainly
being east of the crest and south of highway 50. Warm weather will
continue Sunday, and thunderstorm chances in the higher elevations
of the Sierra will become less likely.



An upper level trough located in the Pacific Northwest will
dominate our weather pattern through the extended period. This
will allow temperatures to hover right around seasonal normals
with mid 90s in the Southern Sacramento Valley and temperatures
right around 100 for the northern valley. Troughing will keep the
afternoon/evening delta breeze intact and will make for some
pleasant evenings in and around the delta. Dry weather is expected
through the extended. Wilson



Weak onshore flow will continue with VFR conditions the next 24
hours. Gusts up to 25 kts can be expected in the Delta with
mostly terrain driven winds elsewhere. Isolated thunderstorms are
expected along and east of the Sierra crest this afternoon and
evening. Locally hazy conditions possible in Northern San Joaquin
from Soberanes Fire. Wilson/Kochasic


.STO Watches/Warnings/Advisories...


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