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941
FXUS66 KSTO 250834 CCA
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
125 AM PDT Wed Sep 25 2024

.Synopsis...
Cooler high temperatures today and Thursday with
breezy onshore winds. Warmer and drier conditions return Friday
through early next week.

&&

.Discussion...
Mostly clear skies and upper 60s to mid 70s temperatures around
interior NorCal this early Wednesday morning. Temperatures will
cool today, as a closed low phases with a trough in the PacNW and
heights will fall as a result. High temperatures in the late
afternoon are expected to be 10+ degrees cooler than yesterday &
enhanced onshore flow will begin to develop later this morning.
Latest National Blend of Models (NBM) probabilities of wind gusts
exceeding 30 mph today are around 60-90% in the Delta and around a
30-60% chance of 25 mph wind gusts across the rest of the area.
Better probabilities for 25 mph wind gusts are along the I-5
corridor from Woodland into Red Bluff. Humidity values will also
increase today, as the cooler and moist air intrudes into the
Valley.

Only a slight warmup is anticipated on Thursday, as broad upper
level ridging starts build in the Four Corners region and the
weak closed low off the Baja California coast retrogrades towards
the west. This upper level pattern will lead to northerly winds
developing Thursday and Friday, with drier conditions overtaking
the area on Friday. With daytime humidity values in the teens to
low 20s, elevated fire weather conditions will prevail on Friday.
Along with the drier air, Friday our area will warmup as the
upper level air pattern becomes somewhat stagnant and zonal, with
temperatures in the mid 90s to triple digits in the northern
Sacramento Valley.

Saturday, high temperatures will remain similar to Friday`s, with
only modest cooling in the Delta anticipated as broad upper level
troughing will develop offshore. Winds should return to a more
diurnal pattern across the region. Daytime humidities will still
be relatively dry (15-25%) across the area, but the northerly
winds will have subsided with wind speeds generally around 10 to
15 mph.

Wood

&&

.EXTENDED DISCUSSION (Sunday THROUGH Wednesday)...
-- Changed Discussion --
Heights trend up Sunday into Tuesday as EPAC high and Desert SW High
gradually merge over NorCal. Closed upper low remains well south of
the forecast area. Slightly cooler Wednesday as upper ridging
weakens in response to short wave trough progressing across the
northern states. High temperatures forecast to be slightly above
normal with moderate heat risk into Tuesday, then near normal
Wednesday. Locally gusty north to east wind at times Sunday into
Tuesday will result in periods of elevated fire weather conditions.
-- End Changed Discussion --


&&

.AVIATION...

VFR conditions over interior NorCal next 24 hrs. Sfc wind mainly
at or below 12 kts except vcnty of Delta, SWly sfc wind 15-25 kts.

&&

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

$$