NWS Area Weather Forecast Discussion
County Warning Area [CWA]: STO Regional NWS Weather Office: Sacramento, CA
FXUS66 KSTO 261616
Area Forecast Discussion
National Weather Service Sacramento CA
916 AM PDT Wed Apr 26 2017
Weak weather system will bring light precipitation today. Dry
weather Thursday through much of next week, with breezy north
winds Thursday and Friday.
A shortwave trough is currently moving into the Pacific Northwest,
with moist westerly flow aloft across the region. In fact, blended
Total Precipitable Water (TPW) products suggest atmospheric
moisture content above 200% of normal for this time of year.
Forcing is rather weak, and so mainly sprinkles or very light
showers have been detected on radar.
We do expect precipitation to become a bit more widespread later
today, as the shortwave trough brushes by the region. Most of the
precipitation should remain over the mountains, but some light
rain totals will be possible across the Sacramento Valley. Snow
levels are projected to remain above 8000-9000 feet with this
system, so snow should not play a factor across major Sierra
The upper air pattern amplifies beginning Thursday as the trough
deepens over the Great Basin, and a ridge of high pressure
strengthens over the eastern Pacific. This "inside slider" pattern
traditionally brings breezy north winds to Northern California,
and will be the case Thursday into Friday. Warmer weather is
expected for the weekend as high pressure builds into the region.
.EXTENDED DISCUSSION (Sunday THROUGH Wednesday)
High amplitude upper ridging in the EPAC extends over Interior
NorCal through the weekend resulting in dry conditions with above
normal temperatures. Ridging may weaken some over northern
portions of CA Monday as a short wave trough digs through the
PACNW into the Great Basin. This could bring minor cooling over
northern portions of the forecast area Monday. High pressure
rebuilds behind the wave Monday night into Tuesday resulting in a
return of gusty northerly wind. Breezy conditions continue into
Wednesday as ridge axis shifts inland and temperatures increase to
upwards of 15+ degrees above normal.
Moist NWly flow alf with lcl MVFR/IFR poss in pcpn, mnly omtns til
arnd 09z Thu. Lcl Sly sfc wnd gsts up to 25 kts poss in the Cntrl
Vly tda and lcl SW-W sfc wnd gsts up to 35 kts poss ovr hyr trrn.