Area Forecast Discussion
Issued by NWS Sacramento, CA

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FXUS66 KSTO 242219
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
319 PM PDT Sat Jun 24 2017

.SYNOPSIS...
Cooling expected for the entire region Sunday into early next
week. Isolated afternoon/evening thunderstorms possible over
portions of mountains through Sunday.

&&

.Short Term Discussion (Tonight through Tuesday)...
Delta Breeze cooling today in the Delta-influenced areas while
the excessive heat continue for the Northern and Central
Sacramento Valley adjacent foothills. Upper ridge from the Desert
SW extends northwest over the Pacific Northwest, turning mid
level flow more southerly to southeasterly today. However, High
Resolution Rapid Refresh models generally keep thunderstorm
activity southward of Hwy 50 in the Sierra.

Upper ridging shifts east into the Great Basin Sunday as the upper
trough approaches the coast. This will help deepen the marine
layer and strengthen onshore flow. Some synoptic cooling will also
result and expect a 5 to 10 degree drop in max temperatures from
today to Sunday. Threat of isolated afternoon thunderstorms
continues over the Sierra Nevada Sunday and possibly along the
coastal range as some models hint at vort max lifting across that
area in southerly flow aloft. Cooling continues on Monday and
Tuesday as weakening upper trough shifts north and east.
JClapp

&&

.EXTENDED DISCUSSION (Wednesday THROUGH Saturday)
Upper troughing moves through Wednesday helping to keep
temperatures somewhat moderated. Dynamics look weak and not
expecting any weather with this wave. Upper ridging builds over
the area Thursday bringing some warming. Ridging weakens Friday
and is replaced with another upper trough Saturday. Models differ
with depth of this wave but current forecast leans towards weaker
EC solution which implies little impact on temperatures or
weather.

&&

.AVIATION...
Sly flow alf as upr rdg ovr NorCal movs into Grt Basin. VFR conds
ovr Intr NorCal nxt 24 hrs exc isold MVFR poss in mtn shwrs/tstms
btwn 23z-03z poss isold MVFR/IFR in ST vcnty of Delta btwn 10z-
19z. SWly sfc wnd gsts up to 35 kts poss thru Carquinez Strait
btwn 00z and 18z Sun.


&&

.STO WATCHES/WARNINGS/ADVISORIES...
Heat Advisory until 11 PM PDT this evening for Central
Sacramento Valley-Clear Lake/Southern Lake County-Motherlode-
Mountains Southwestern Shasta County to Northern Lake County-
Northeast Foothills/Sacramento Valley-Shasta Lake Area /
Northern Shasta County-Western Plumas County/Lassen Park.

Excessive Heat Warning until 11 PM PDT this evening for Northern
Sacramento Valley.

&&

$$



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