FXUS66 KSTO 221036
AFDSTO
Area Forecast Discussion
National Weather Service Sacramento CA
336 AM PDT Mon Apr 22 2019
SYNOPSIS...
High pressure will build over the region with warm temperatures
and dry conditions. High temperatures will peak near the middle
of the week.
.DISCUSSION
...
Upper level ridge will build across NorCal today behind departing
trough over the Great Basin region. This will provide dry
conditions with warmer temperatures. Surface gradient will also
become enhanced between the ridge and trough with breezy north
winds developing. A few gusts to 25 mph will be possible
throughout the Sacramento Valley. Afternoon highs in the mid to
upper 80`s over the Valley will be 10 to 15 degrees above normal.
Ridge will remain in place through the week providing the warmest
weather of the year thus far. Most Valley locations will reach
the first 90 degrees of the season Tuesday and Wednesday. A system
passing north of the area Thursday may bring a few showers or
thunderstorms to the Southern Cascades and Shasta county.
.EXTENDED DISCUSSION
(Friday THROUGH Monday)
The broad upper ridge situated over the southwestern U.S. through
Thursday will have advanced into the Rockies by Friday. This will
give way to a split in the jet streams as a potent upper low is
expected to dig toward extreme Southern California by late in the
weekend. The more southward trajectory should keep the primary
impacts down over the southern half of the state. However, did
keep the chance for precipitation over Tuolumne County during the
weekend. Any northward adjustment of this upper low would allow
for impacts over additional counties.
Where the guidance has struggled is with resolving the amplified
northern stream flow. Operational models which include the GFS and
ECMWF solutions show a variety of scenarios indicative of the
uncertainty at hand. Ensemble means are more clustered and keep
the primary storm track well to the north up toward Washington and
Oregon. Based on the idea of lower heights infiltrating the West
Coast, expect temperatures to drop Sunday into next Monday (April
29). At this point, Valley temperatures should fall back into the
mid 70s while mountain locations stay in the upper 40s to lower
50s. ~BRO
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