Area Forecast Discussion
Issued by NWS Sacramento, CA

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852
FXUS66 KSTO 251512
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
812 AM PDT SAT JUN 25 2016

.SYNOPSIS...
Hot and dry weather for the next week. Locally breezy north wind
will increase fire weather danger across Sacramento Valley today.

&&

.Discussion...
Warming trend continues today with high pressure and northerly
surface gradient. Already seeing some gusts around 20-30 mph
across portions of the Sacramento Valley and surrounding
foothills. Expect winds to peak this morning, then decrease by
this evening. Current forecast on track. No updates.

&&

.PREVIOUS DISCUSSION...
Westerly flow aloft has moved into Northern California as an upper
low over the Northern Rockies moves eastward. Surface high
pressure has slowly built into eastern Oregon and Idaho, resulting
in a modest northerly pressure gradient developing over NorCal.
North winds are fairly light for the most part across the region,
though some locally breezy winds are being reported mainly across
favored northern Sierra and Shasta-Trinity canyons.

Expect a fair bit of airmass warming today as heights and
thicknesses increase, and some adiabatic compressional heating
with north winds. High temperatures are expected to reach right
around the century mark across the Valley today, with 70s to 90s
for the mountains. High temperatures will warm another degree or
two each day for the next few days. Tuesday and Wednesday
currently look to be the hottest days of this heat stretch, with
temperatures expected to reach the 102 to 107 degree range across
the Valley. Dang

&&

.EXTENDED DISCUSSION (WEDNESDAY THROUGH SATURDAY)...
High pressure over the southwest U.S. dominates the weather
pattern through the extended period bringing mainly fair skies and
above normal temperatures. The warmest temperatures of the week
are forecast to hit on Wednesday where many valley locations will
see high temperatures of 105 or higher. Some extended models
hinting at some moisture working up the southern Sierra possibly
bringing afternoon showers or thunderstorms northward. The best
chance of this moisture making it within the CWA borders looks to
be Wednesday or Thursday as the upper flow becomes most southerly.
At this time impact from any isolated shower activity appears
would be very limited staying south of Tahoe and only over higher
elevations of the northern Sierra. A slight cooling trend begins
on Thursday and carries on through the end of the week as the
upper ridge shifts inland slightly. This is in response to weak
troughing that develops over the eastern Pacific. Models differ a
bit on strength of this trough but do have some consistency in its
existence during the later half of the week. A more onshore flow
Friday and Saturday will continue to bring a slight cooling trend
although daytime highs will remain above normal by several
degrees. Meanwhile a more southwest to west flow aloft should
shunt any afternoon Sierra shower activity south and east of the
forecast area.

&&

.AVIATION...
VFR conditions next 24 hours. Breezy north to northeast winds
today up to 10 to 15 knots with local gusts to 25 knots through
today. Winds generally below 10 knots this evening and tonight.

&&

.STO Watches/Warnings/Advisories...
Red Flag Warning until 6 PM PDT this evening for Central
Sacramento Valley in Glenn, Colusa, Yuba, Northern Sutter, and
Butte County Below 1000 Ft-Eastern Mendocino NF-Eastern Portion
of Shasta/Trinity NF-Lake County Portion of Lake-Napa-Sonoma
Unit-Northern Sacramento Valley to Southern Tehama County Line
Below 1000 Ft-Northern Sierra Foothills from 1000 to 3000 Ft.
Includes portions of Shasta-Trinity and Butte Units-Northern
Sierra Including Lassen NP and Plumas and Lassen NF/S West of
the Sierra Crest (West of Evans Peak-Grizzly Peak-Beckworth
Peak)-Southeast Edge Shasta-Trinity NF and Western Portions of
Tehama-Glenn Unit-Southern Sacramento Valley in Yolo-Sacramento
Far Western Placer, southern Sutter and Solano County Below 1000
Ft.

&&

$$



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