684
FXUS66 KSTO 240755
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
1255 AM PDT Tue Sep 24 2024

.Synopsis...
Hot weather continues with Moderate HeatRisk today, then cooler
temperatures return Wednesday and Thursday. Temperatures warm up
again on Friday and Saturday with Moderate HeatRisk before
returning to near/slightly above normal high temperatures into
next week.

&&

.Discussion...
Mostly clear and light, variable winds prevail around interior
NorCal early this morning. The hot weather will stay around with
us for one more day, as broad ridging aloft will continue to
dominate the synoptic pattern today. The National Blend of Models
(NBM) advertises around a 20-60% chance of high temperatures
reaching 100 degrees in the Valley/Delta and the thermal belts of
the foothills today. The best chances will be in the Sacramento
area, the Delta, and the northern Sacramento Valley. Although the
NBM is not favoring widespread triple-digits, given the upper-
level pattern and generally light winds forecast for today, we
could see several locations in the Valley hit the triple digit
mark this afternoon.

On Wednesday, upper level troughing from the Pacific Northwest
will help lower heights over the area, as well as enhance onshore
flow so high temperatures will fall into the low 80s and low 90s
for the Valley/foothills, with upper 70s forecast for the higher
elevations. Breezy to locally gusty winds are also in the forecast
for Wednesday. The Valley could see wind gusts around 15-25 mph
Wednesday afternoon and the Delta could see wind gusts up to 30
mph, as the trough moves through NorCal. Little to no
precipitation is anticipated at this time however, as the trough
is lacking significant/efficient moisture to cause any significant
precipitation concerns for the area. Humidity values will also
increase Wednesday thanks to the enhanced onshore flow and the
trough moving through, with daytime humidity values in the upper
20s to mid 30s with better overnight recoveries expected as well.

Thursday, our pattern will begin to shift again, as a more zonal
upper level flow overtakes the area, with a weak closed low off
the Baja California coast and ridging developing the Four Corners
Region. These somewhat stagnant heights will lead to another
slight warming trend heading into the end of the work week, where
temperatures will climb into the mid to upper 90s for the Valley.
Upper level troughing will begin to move eastward in the PacNW,
and with the weak closed low off the Baja California coast we will
see northerly winds and poor daytime/overnight humidity values,
which could setup another period of elevated fire weather concerns
on Friday.

&&

.EXTENDED DISCUSSION (Saturday THROUGH Tuesday)...

As we head into the weekend, ensembles and clusters show a weak
area of high pressure develop over NorCal, which will raise our
heights slightly and keep temperatures slightly warmer than normal
for this time of year. High temperatures will continue to be
around 5-10 degrees above normal through the extended forecast
period. There remains some variability with the temperature
forecast and the upper level pattern that will develop, as the NBM
shows a 5-10 degree temperature difference from the mean
temperature forecast, so expect the high temperature forecast to
fluctuate as we move through the work week. Even with the slightly
higher than normal temperatures forecast, HeatRisk looks to remain
Minor throughout the extended forecast with only isolated areas of
Moderate HeatRisk on Monday mainly in the foothills/thermal belts.

Wood

&&

.AVIATION...

VFR conditions persist across interior NorCal next 24 hours. Surface
winds generally less than 12 kts expected, with breezy north to east
winds through the morning shifting to south to west winds after 18z.
Some gusts to 25 kts then possible across the Delta vicinity through
the evening.

&&

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

$$