993
FXUS66 KSTO 302120
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
220 PM PDT Tue Apr 30 2024

.Synopsis...
Gusty north winds expected through the Valley tonight through
Wednesday afternoon. Quiet and dry weather prevail through
Friday. Precipitation chances return this weekend.

&&

Abundant sunshine across Northern California this afternoon as
high pressure ridging keeps our weather dry, quiet, warm, and
sunny through Friday. Several short-wave troughs pass over the
Pacific Northwest with broad ridging over the eastern Pacific and
Northern California. As those troughs pass through, the surface
pressure gradient is expected to tighten resulting in gusty
northerly winds throughout the Valley. Winds pick up tonight and
are expected to last through late morning on Wednesday with gusts
of 35-40 mph. The strongest winds are forecast over the western
half of the Sacramento Valley along the I-5 corridor and through
the Delta. The National Blend of Models (NBM) has a 50 to 70%
chance of gusts greater than 40 mph over the area and A Wind
Advisory is in effect from now until 5PM Wednesday. Difficult
driving conditions are anticipated and unsecured, loose objects
may blow around. Winds weaken by Wednesday afternoon, but
northerly gusts of 15 to 20 mph return to the Valley on Thursday before
returning to a breezy diurnal flow pattern on Friday. Valley high
temperatures will be in the upper 70s to mid 80s through Friday,
as we follow a gradual warming trend. Looking ahead to this
weekend, a weather system will bring returning precipitation
chances to interior NorCal along with cooler temperatures.

&&
.EXTENDED DISCUSSION (Saturday THROUGH Tuesday)...


Confidence in increasing in a cooler, wetter pattern for the
weekend as a cold core low from the Gulf of Alaska drops southward
into the region. Ensembles and clusters do have some uncertainty
in the exact track of this low, though, which will determine
exactly how wet this system will be. A surface cold front is
expected to move through on Saturday. This will bring widespread
moderate showers to the area. National Blend of Models has trended
quite a bit higher with current forecast rainfall amounts, with
ensembles leaning more towards the low passing near/over the
area. WPC liquid storm total QPF is now forecasting around a third
of an inch to two thirds of an inch of rain in the Valley. An
inch to around 2 inches of liquid precipitation is now projected
in the foothills and mountains.

Snow levels start high, over 8,000 feet, then are projected to
drop down to 4000-5000 feet by early Sunday, as the system is
winding down. Current forecast shows a few inches of snow
impacting the Sierra passes. There is currently a 40-50%
probability of 4" for the higher Sierra over the weekend. This
could bring minor travel impacts at the passes, with the best
potential for accumulating snow Saturday night into early Sunday. The
pattern suggests some potential for convection, though the
current Thunderstorm Probability is below 15%. If the core of the
low tracks more over land, this would increase the potential for
thunderstorms, so this will be watched closely.

Temperatures cool down quite a bit for the weekend, with Saturday
highs about 20 degrees lower than on Friday. Sunday could see a
little warming as the clouds begin to break up, but will still
remain well below normal for this time of year.

Model uncertainty continues into early next week, with an
unsettled pattern, though a general shift to northwest flow
should limit the potential for most precipitation to the northern
mountains and foothills. There is a wide spread in National Blend
of Models high temperatures, so we will have to wait and see how
things trend temperature-wise as we get closer to that period.

&&

.AVIATION...

Clear skies and VFR conditions expected across interior NorCal
over the next 24 hrs. Gusty northerly surface winds are expected
through the Sacramento Valley after 06Z Wednesday, with sustained
winds 15 to 25 kts and gusts 35 to 40 kts. Gusts up to 25 kts
elsewhere in the Valley. Over the mountains, northeasterly gusts
20 to 30 kts are expected 06Z to 18Z Wednesday.
&&

.STO WATCHES/WARNINGS/ADVISORIES...
Wind Advisory from 11 PM this evening to 5 PM PDT Wednesday for
Carquinez Strait and Delta-Central Sacramento Valley-Northern
Sacramento Valley-Southern Sacramento Valley.

&&

$$