Area Forecast Discussion
Issued by NWS Sacramento, CA

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FXUS66 KSTO 232210

Area Forecast Discussion
National Weather Service Sacramento CA
310 PM PDT Tue May 23 2017

Triple digit heat continues today in the Central Valley then
cooling Wednesday into Friday with near to slightly below normal
readings by the end of the week. Isolated afternoon showers or
thunderstorms possible over the southern Sierra Nevada today and
over the northern interior mountains Wednesday.


.Discussion (Today through Friday)...
Strong upper ridging over Interior NorCal today is resulting in
triple digit heat again in portions of the Central Valley. Hottest
temps across the CWA this afternoon are occurring in the Northern
Sacramento and Northern San Joaquin Valleys. Potential for some
additional record highs to be broken today as the record for KRDD
and KRBL is 101 and 99 at Modesto. Afternoon CU and some TCU have
developed along the Sierra Nevada and will need to be watched,
however latest HRRR not showing any showers or thunderstorms

Delta breeze expected to ramp up this evening becoming moderate
to strong tonight into Wednesday morning. Marine layer deepens
tonight as offshore upper low approaches and combined with Delta
breeze will provide low level CAA into portions of the Central
Valley overnight.

Upper troughing over the PacNW digs towards the Great Basin
tomorrow as associated weak cold front stalls over northern
portions of CA. This may provide enough lift to set off a few
afternoon showers or thunderstorms over the Coastal and northern
interior mountains. Increased Delta breeze and synoptic cooling
over the area Wednesday will result in about a 10 degree drop in
max temps.

Broad upper troughing continues over the forecast Thursday into
Friday providing additional cooling. Highs expected in the 80s
throughout the Central Valley Thu/Fri, 70s in the Delta, and 50s
to around 80 for the mountains and foothills.



A ridge will be in place for the holiday weekend and that will
bring warming temperatures and quiet weather. If you have outdoor
plans over the weekend you will want to be prepared for hot
weather. Highs on Saturday will be in the 80`s and 90`s but we
will warm into the 90`s and lower 100`s by Memorial Day. A Delta
breeze will keep that region a little more comfortable throughout
the weekend though. We will also see some instability build into
the higher elevations and we could see a few isolated afternoon
and evening t-storms in the Sierra. The ridge starts to flatten
out later Monday and a short wave trough moves into the region on
Tuesday. This will keep isolated t-storm chances in the forecast
for the Sierra. Temperatures will also be a bit cooler on Tuesday
but still above normal.



VFR conditions expected at the TAF sites the next 24 hours. Local
wind gusts to 20 knots possible in the Delta after 00z Wed
otherwise 5-10 knot winds can be expected. Slight chance for
isolated t-storms over the Sierra south of US-50 between 23-03z.




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