Bouldin Island, California Weather Forecast Discussion

402
FXUS66 KSTO 182048
AFDSTO
Area Forecast Discussion
National Weather Service Sacramento CA
148 PM PDT Thu Sep 18 2025
For additional details on weather and expected impacts over the
next 7 days, please visit weather.gov/sto/briefing.
.SYNOPSIS...
The remnants of former tropical storm Mario continue to push
north through southern California reaching northern California
later this afternoon into the evening and overnight hours. A few
thunderstorms with heavy rain (especially along the Sierra)
tonight into tomorrow. Showers within the valley with the
potential for a few isolated storms. Conditions dry out over the
weekend and into early next week, with a ridge building into the
region and a deepening trough over the Gulf of Alaska. This trough
moves into the area mid next week bringing further chances for
rain and thunderstorms across the area. Coverage, intensity, and
development remain low in confidence at this time.
&&
.KEY MESSAGES...
* TONIGHT - SATURDAY:
- Remnants of former Tropical Storm Mario move through tonight
   and through Saturday, with period of showers and thunderstorms.
- There will be a short period this evening with the potential
   for new fire starts from isolated dry thunderstorms before we
   start to moisten up the atmosphere.
- There is a threat for heavy rain as the remnants move through,
   with the highest chances over the Sierra. Less than 10 percent
   chance debris flow thresholds are reached for areas where
   thunderstorms develop in the vicinity of burn scars.
* SUNDAY - MONDAY:
-  Ridge builds in briefly, with warmer temperatures and drier
    conditions across the area. Northerly breezy winds late Sunday
    into Monday morning may bring elevated fire concerns when co-
    located with low RH values in the teens.
* TUESDAY -  WEDNESDAY:
-  Confidence continues to remain low (20 to 30 percent) across
    the forecast region for coverage, intensity, and development
    of showers and storms Tuesday, Wednesday, and into the early
    portions of Thursday. However, a more active pattern is
    expected thanks to a surge of higher PWATS from southwesterly
    flow.
.AVIATION...
Sky coverage will continue to increase with clouds as the remnants
of former Tropical Storm Mario shift through the region. Chances
for showers and storms near MOD, SCK, RDD, with shower chances for
the other TAF locations this evening and overnight. Chances
increase from the south around 2-4z and reach RDD and RBL around
07-09z. Chances continue through the end of the TAF period and
beyond. Ceilings remain VFR, with BKN to OVC skies through the TAF
period. Winds remain light around 5-10kts.
&&
.STO WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$

NWS STO Office Area Forecast Discussion