140
FXUS66 KSTO 090908
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
208 AM PDT Wed Oct 9 2024



.Synopsis...
Temperatures will be significantly cooler today, with the cooling
trend continuing through the rest of the week. High temperatures
return to normal values by the weekend and remain near normal into
next week. A weak weather system will bring a chance of light
rain starting Friday night and continuing into Saturday, mainly
north of I-80.

.Discussion...
Tuesday was another hot day, with record highs set at Stockton
(100), Modesto (99) and tied Red Bluff (100). Downtown Sacramento
hit 100, the 6th day at 100 or higher for October, a new record,
and the 51st time for the year. A big change is in the works for
today, though, with onshore flow developing as the upper level
ridge axis has at least shifted eastward. There is a decent Delta
breeze, with sustained southwest wind at Fairfield 25 mph,
gusting to 31 mph. Temperatures are trending cooler this morning,
especially in Delta breeze influenced areas.

Mainly Minor HeatRisk is expected across the area today, with
the NBM highs in the Valley and Delta limited to the upper 80s to
around 90. Even further cooling is expected Thursday as westerly
flow aloft deepens from a broad upper low dropping south from the Gulf
of Alaska, with Valley highs in the 80s. A closed low rotating
southeastward from the trough approaches Friday, with additional
cooling and clouds spreading in late in the day.

This system will bring a slight chance of precipitation spreading
into the northern Coastal Range and northern Sacramento Valley
Friday night as it approaches. This upper low moves inland and
weakens Saturday. The potential for light rain spreads as far
south as the Delta and southern Sacramento Valley during the day,
then diminishes at night. Rainfall totals are trending lower, with
generally a tenth of an inch or less expected mainly over the
northern Coastal Range and the northern Sacramento Valley, so any
impacts should be limited. Humidity levels will be much higher
than seen recently, reducing fire weather concerns.

&&

.EXTENDED DISCUSSION (Sunday THROUGH Wednesday)...
Upper low exits interior NorCal early Sunday as weak short wave
upper ridging follows into Monday. Deeper upper trough in the the
EPAC approaches Tuesday into Wednesday. Some light precip possible
north of I-80 Wednesday, with best chances over the mountains.
Below normal high temperatures expected through the extended
forecast period.

&&

.AVIATION...
VFR conditions over interior NorCal next 24 hrs with sfc wind
mainly below 12 kts except vcnty of Delta, SWly wind up to 20 kts
til 18z and aft 00z Wed.

&&

.STO WATCHES/WARNINGS/ADVISORIES...
None.
&&

$$