FXUS66 KSTO 272015
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
115 PM PDT Sat Jul 27 2024


.SYNOPSIS...
Cooler temperatures lasting through the middle of next week, then
an increase in high temperatures. Onshore flow will help raise
humidity values and lower fire weather risks. Locally breezy
conditions in the Delta.

&&

.Key Points...

- Below normal temperatures with gradual warming trend by the
  middle of next week.
- Smoke and haze from California fires will effect the northern
  Sacramento Valley and adjacent foothills.

&&

.Discussion...
Much cooler temperatures being observed today with most areas 15
to 20 degrees cooler from yesterday. This is in response to upper
trough that is moving across the area at this time. It has brought
with it higher humidities (20% to 30% higher) across the area.
This will allow a cool night with much better overnight/morning
humidity recoveries. All the above definately helping fire
conditions on the Park Fire.

Sunday...good agreement in ensembles that main axis of upper
trough will remain across the western U.S. but with some filling.
This will result in slightly warmer temperatures but still
generally 5 to 10 degrees below normal for this time of the year
in the mid 80s to lower 90s. Humidities still not a concern in the
20s and 30s.

Monday and Tuesday...above mentioned upper trough continues to
fill and weaken, leaving us with a weak westerly onshore flow. End
result is temperaturs slowly climbing back up with highs by
Tuessday near normal in the 90s. Onshore flow and weak southerly
surface winds should for the most part keep smoke from Park fire
to the north...but with the weaker flow some diurnal switches may
let it sneak south a bit but no big push of wind shift expected.
&&
.EXTENDED DISCUSSION (Wednesday THROUGH Saturday)...

Fairly straight forward extended with no major impacts looking to
be in play. Main story will be upper level ridge builds back into
the area, which there is good ensemble agreement in and pretty
small spread in NBM temperature percentiles. The axis of the ridge
will be off to the east, which will open up the chance of some
monsoonal moisture to drift north...but at this time nothing super
moist expected so will continue to keep the forecsat dry. Although
temperatures will be rising again...not seeing any significant
heat yet. Rasch
&&

.AVIATION...

VFR conditions next 24 hrs except areas MVFR/IFR in haze/smoke
vicinity of wildfires and limited VFR/MVFR in areas of the central
Valley near the Delta between 07Z and 17Z Sunday due to stratus
intrusion. Areas of south to west surface wind gusts 15-30 kts,
strongest vicinity west Delta.
&&

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

$$