Area Forecast Discussion
Issued by NWS Sacramento, CA

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FXUS66 KSTO 191147

Area Forecast Discussion
National Weather Service Sacramento CA
414 AM PDT Fri May 19 2017

Dry with a warming trend forecast for the next several days.
NorCal`s first triple digit heat possible early next week. A
chance of Sierra showers and isolated thunderstorms early next


.Discussion (Today through Sunday)...
Clear skies over the CWA this morning under building high
pressure aloft. Airmass warms several more degrees today bringing
daytime highs up to about 10 degrees above normal. Northerly
winds will continue today under light northerly flow but gradients
have weakened since yesterday so should see a little lighter
winds. A shortwave trough dropping through the Pacific northwest
will keep temperatures fairly level on Saturday although they may
still bump up a degree or two. Models somewhat in agreement in
developing weak troughing over the state on Sunday. GFS
consistently deeper with this trough and develops enough
instability for a slight threat of showers over the Sierra in the
afternoon. The highest instability will be from Tahoe southward
so limited thunderstorm threat to south of about U.S 50.
Elsewhere will see continued fair skies and a bit more warming.
Upper level ridge axis centers over the west coast on Monday
bringing more airmass warming. Daytime highs may top 100 in the
northern Sacramento valley with a few weaker high temperature
records possibly falling. GFS still showing a slight instability
over the northern Sierra so could see another day of isolated
Northern Sierra afternoon or evening thunderstorms.


High pressure strengthens early next week. 100 degree heat is
projected across the northern portions of the Sacramento Valley
Monday and Tuesday. By Tuesday, the heat will be limited as the
Delta Breeze develops and brings cooler air into the Valley. An
upper low spinning well off the California coast will cause
cooling influence of the onshore flow starting Tuesday as the
ridge weakens slightly toward the middle of next week.

Enough instability and moisture may exist in the high Sierra for
a chance of afternoon/evening showers and thunderstorms near and
south of Lake Tahoe through Monday and up through Lassen Park
Tuesday and Wednesday. Thunderstorms diminish Thursday and Friday
under southwest flow aloft.     JClapp



VFR conditions the next 24 hours with light winds.     JClapp



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