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000
FXUS66 KSTO 232112
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
212 PM PDT Tue Apr 23 2024


.Synopsis...
Cooler thru mid-week along with a chance for afternoon showers
and thunderstorms over the mountains. Precipitation chances
increase Thursday into Friday as a weather system moves through,
best chances in the foothills and mountains.

&&

.Discussion...
Scattered showers continue to trek along both the Sierra and
Coastal Range this afternoon as shown on RADAR. GOES-West shows
mostly cloudy skies across interior NorCal this afternoon which
have helped keep daytime highs cooler than yesterday. As of 2:00
pm, Valley highs are in the 60s & 70s with foothills/mountain
highs in the 50s & 60s.

Onshore flow continues through the Delta and Valley today
bringing in cooler marine air, low-level moisture, and gusty winds
(20-25 mph). The National Blend of Models indicates a
strengthening in the low-level flow resulting in gusty winds
through the Delta and Valley continuing Thursday and Friday with
gusts 15 to 25 mph.

Mid-level moisture and instability has begun to get drawn
northward ahead of the offshore trough as it moves onshore. The
National Blend of Models has a 15 to 35% chance of thunderstorms
over the northern Sacramento Valley and adjacent mountains this
afternoon/evening. Heading into Wednesday and Thursday,
probabilities drop slightly to around 20% over similar area and
over the mountains south of HWY 50, as the initial trough and
closed low pass mainly to the south of us into SoCal.

Behind that system, a couple shortwaves and associated vorticity
lobes are forecast to drop into NorCal later in the week
reinforcing the cool and unsettled pattern and bringing a better
chance for showers on Friday with a broad swath of 15 to 20%
chance over the Valley/foothills/Sierra. The National Blend of
Models indicates a 10%-25% chance of 0.10" or more of
precipitation in the Valley with a 20%-30% of 0.50" or more in the
mountains and foothills. Snow levels will be around 7000` meaning
most of the precipitation will fall as rain. Impacts are expected
to be on the lower end with only minimal travel impacts.

&&

.EXTENDED DISCUSSION (Saturday THROUGH Tuesday)...
By Saturday morning, conditions will have dried as the trough
moves further east away from the forecast area. NBM probabilities
try to keep some lingering sprinkles over the mountains Saturday
morning but any accumulating precipitation is not likely.
Afterwards, weak ridging briefly develops, warming the area this
weekend. Valley highs will be in the mid to upper 70s with 60s and
50s across the foothills and mountains respectively by early next
week. By early next week, clusters have Northern CA under zonal
flow, keeping the forecast quiet with troughing in the Pacific NW
aiding in keeping temperatures near normal across the Valley. &&

.AVIATION...
VFR conditions over next 24 hrs outside of localized MVFR/IFR
conditions from isolated showers/t-storms over the foothills,
mountains, and portions of the Northern Sacramento Valley through
03Z Wednesday. Localized MVFR conditions may linger in the
Northern Sacramento Valley near RDD through 09Z Wednesday from
isolated showers. Areas of southwesterly gusts 15-25 kts over the
Delta through 12Z Wednesday and Valley gusts 10-15 kts through 06Z
Wednesday before weakening.


&&

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

$$