Select Your Area NWS Weather Forecast Office
NWS Area Weather Forecast Discussion
County Warning Area [CWA]: STO
Regional NWS Weather Office: Sacramento, CA

000
FXUS66 KSTO 241046
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
346 AM PDT Wed Apr 24 2019


.SYNOPSIS...
Dry weather and above normal temperatures through the week. A few
thunderstorms could be possible over the high mountains this
afternoon and Thursday. A cooling trend is possible over the
weekend.

&&

.DISCUSSION...
Upper level ridge remains over NorCal this week with dry weather
and warm temperatures. Another day of 90 degree temperatures today
with readings 10 to 20 degrees above normal. Many locations will
again approach or exceed record temperatures, which are in the
low 90`s.

A system passing north of the area this afternoon and Thursday
may bring extremely isolated thunderstorms to the Southern
Cascades and northern Sierra near the crest. Model agreement
remains poor, but will maintain low-end precip chances in line
with HREF and mesoscale WRF models.

Temperatures will cool into the 80`s Friday and through the
weekend with lowering heights, as disturbances pass north of the
area.

&&


.EXTENDED DISCUSSION (Sunday THROUGH Wednesday)

To conclude the weekend and entering next week, a split flow
regime is evident in the guidance. A compact upper low within the
southern stream will stay well to the south of the region as it
moves through extreme northern Baja California early Monday. The
northern extent of the precipitation shield could reach Tuolumne
County which affords a risk for a few showers. Have kept the
threat of showers in the forecast into Monday given models have
trended slower with the passage of the trough.

The longwave pattern within the northern stream should remain
amplified into next week. Operational and ensemble solutions favor
further elongation of this flow down into the Central Great Basin
next Tuesday and Wednesday (Apr 30-May 1). If the forcing from
this trough moves far enough west, some showers will be possible
across the Sierra. A tightening pressure gradient should afford an
uptick in dry, northerly winds across the Valley. Given modest
ensemble spread with the pattern, expect some of these details to
change in the upcoming days.

Temperatures should move closer to climatology next week given the
presence of lower heights over the region. Mid to upper 70s will
likely be the norm for Valley highs while mountain and foothill
locations stay in the 50s and 60s, respectively.  ~BRO

&&

.AVIATION...

Generally light west to northerly flow aloft underneath the ridge.
VRF conditions expected over all TAF sites with surface winds
remaining below 10 knots. Isolated afternoon thunderstorms are
possible across the northern Sierra crest between 21Z Wed and 02Z
Thu.  ~BRO/PCH
&&

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

$$

Forecast Discussion from: NOAA-NWS Script developed by: El Dorado Weather