NWS Area Weather Forecast Discussion
County Warning Area [CWA]: STO Regional NWS Weather Office: Sacramento, CA
FXUS66 KSTO 162030
Area Forecast Discussion
National Weather Service Sacramento CA
130 PM PDT Mon Jul 16 2018
Hot temperatures continue this week. Afternoon northern Sierra
thunderstorms possible this week.
.DISCUSSION (Today through Thursday)...
Area of high pressure continues to dominate the weather across
northern California. Water vapor imagery shows mostly dry air in
place over the interior, although some monsoon moisture continues
to linger off the coast and over southern California. Temperatures
across the region were running about 5 degrees warmer than
yesterday during the early afternoon.
Latest model forecasts continue to show height rises as high
pressure builds over the west for the next several days. As a
result, temperatures will continue to increase heading into
Wednesday. A heat advisory will continue with an excessive heat
warning for the northern Sacramento Valley Wednesday including
Red Bluff and Redding.
Models have some elevated instability over the Sierra and coastal
mountains each afternoon, mainly for the Sierra south of highway
50 through Wednesday. Chances increase for showers and
thunderstorms on Thursday, although confidence is low at this
Areas of smoke and haze will continue for the Sierra areas close
to the Ferguson fire near Yosemite NP.
.EXTENDED DISCUSSION (Friday THROUGH Monday)
Upper level high pressure system shifts eastward and will bring
some slight cooling to the area. Some easterly flow aloft will
allow some monsoon moisture to flow back into the Sierra, and in
combination with some potential instability, may produce some
afternoon showers and thunderstorms for the mountains through this
weekend into early next week.
VFR conditions the next 24 hours across TAF sites. South to west
winds will remain below 15 kt today, except gusts to 30 kt near
Heat Advisory until 8 PM PDT Wednesday for Central Sacramento
Valley-Clear Lake/Southern Lake County-Motherlode-Mountains
Southwestern Shasta County to Northern Lake County-Northeast
Foothills/Sacramento Valley-Northern Sacramento Valley-Shasta
Lake Area / Northern Shasta County.
Excessive Heat Warning from 11 AM to 8 PM PDT Wednesday for
Northern Sacramento Valley.