919
FXUS66 KSTO 162038
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
138 PM PDT Thu May 16 2024

.SYNOPSIS...
Seasonably warm weather continues. Mostly sunny and dry
conditions persist with periodically breezy winds. Isolated
shower or thunderstorm chances over the High Sierra south of
Highway 50 Saturday afternoon.

&&

.DISCUSSION (Today through Sunday)...
Current GOES-West satellite imagery shows abundant sunshine being
observed across interior northern California on this Thursday
afternoon. The small area of marine stratus that moved in through
the Delta and into portions of the southern Sacramento Valley this
morning has dissipated. Temperatures are currently trending
approximately 5 to 15 degrees cooler than this time yesterday
afternoon, valid at 1 PM PDT, as a trough to the north is
flattening the ridge that brought us the very warm temperatures
the past several days. Slightly cooler, but still seasonably warm
temperatures prevail over the short term.

Generally quiet and dry conditions continue over the short term,
with the exception of the potential for isolated shower or
thunderstorm development over the High Sierra from Highway 50
southward Saturday afternoon through early evening, where the
National Blend of Models (NBM) suggests a 15-25% probability of
thunderstorm development. The Extreme Forecast Index (EFI) also
highlights the mountain areas for CAPE. Otherwise, the Delta
Breeze may bring some marine stratus into the Delta area and
southern Sacramento Valley tonight, and high resolution guidance
suggests a 30-40% probability of the low clouds over that general
area.

&&

.EXTENDED DISCUSSION (Monday THROUGH Thursday)...
Ensemble guidance and cluster analysis generally indicate dry and
seasonably warm weather prevailing from early to mid next week
with daytime high temperatures trending slightly above the
climatological normal for the third week of May as more of a
troughing influence (rather than ridging, observed over the past
few days) is favored over the extended forecast period. Heat Risk
is expected to remain in the Minor category for the Valley, with
highs generally in the 80s. Towards the second half of the week,
model guidance suggests another trough dropping down from the Gulf
of Alaska mid to late next week. Uncertainty remains in the
potential for any shower chances with this trough, and there is
still a fairly large spread in high temperatures over this
timeframe.

&&

.AVIATION...
VFR conditions next 24 hours except local IFR/MVFR ceilings
possible vicinity western Delta into portions of the Sacramento
metro area 14-17Z associated with marine layer stratus. Breezy
southwesterly surface wind gusts 25-35 kts (Delta breeze) continue
in the west Delta with local southerly surface wind gusts 15-20
kts in the Sacramento Valley into tonight, otherwise winds
generally less than 12 kts.

&&

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

&&

$$