FXUS66 KSTO 102143
AFDSTO
Area Forecast Discussion
National Weather Service Sacramento CA
243 PM PDT Mon Aug 10 2020
SYNOPSIS...
Cooling trend expected tonight into Tuesday, with below normal
high temperatures Tuesday afternoon. Afternoon and evening thunderstorms
possible over Sierra Nevada through Tuesday. Near normal
temperatures midweek, then warming up again by next weekend.
.DISCUSSION
...
Current temperatures are running slightly hotter across the
northern Sacramento Valley this afternoon. Redding Airport hit 110
yesterday, and has been running 3 degrees warmer for much of
today. This could see Redding with a high close to the record of
15, set in 1978.
The Delta Breeze has spread a little cooling into the Delta
region today (1 to 4 degrees), and this will strengthen overnight
bringing and more significant cooling into the Sacramento and
Stockton areas.
Weak trough develops along the West Coast on Tuesday and
Wednesday, pushing most of the late day thunderstorm activity
back well to the east of the forecast area by Wednesday. Some
lingering isolated storms are possible over the Sierra Crest,
mainly south of I-80. The trough will also result in
strengthening onshore flow by this evening which will bring cooler
temperatures (back to around average for this time of years for a
couple of days.
Trough forecast to weaken by Thursday leading to slight warming as
onshore flow slackens.
.EXTENDED DISCUSSION
(Friday THROUGH Monday)...
To conclude the work week, a broad elongated trough off the
California coast is expected to retrograde toward the west in
time. Ensembles show the longstanding ridge over the Four Corners
will translate toward the southwestern U.S. The resultant rise in
mid/upper-level heights should bring another bout of heat to the
region over the weekend and to start the following week. Valley
temperatures are likely to return to the triple digits with
ensembles showing the potential for 100 to 105 degree readings
over the southern Sacramento/northern San Joaquin Valleys. Daily
highs will likely be at least 10 degrees above climatology over
these regions given the northward expansion of the ridge. Dry
weather is expected during the extended period. ~BRO
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