Scientific Forecaster Discussion
fxus66 ksto 231017
Area forecast discussion
National Weather Service Sacramento California
317 am PDT Wed Oct 23 2019
strong northerly winds into Thursday with elevated fire weather
concerns. Dry weather with above average temperatures forecast
through the remainder of the week.
a few high clouds are brushing across interior norcal early this
morning associated with short-wave energy passing in northwest
flow aloft. Otherwise, skies are clear. Northerly surface pressure
gradients have increased (kmfr-ksac now over 11 mbs) and gusts of
15-30 mph are occurring over the northern Sacramento Valley with a
few gusts approaching 40 mph over the foothills.
Current temperatures are running 10-15 degrees milder compared to
24 hours ago across the breezy northern Sacramento Valley, while
temperatures elsewhere are running pretty similar to early
Tuesday. Readings range from the upper 20s in the mountain valleys
to the mid 70s across milder portions of the Sacramento Valley.
Warm and dry conditions continue through the remainder of the
week as an upper level ridge remains centered over the eastern
Pacific and norcal. Highs will be around 10 to 15 degrees above
average for late-October. Overnight lows will be mild across
windier portions of the valley and in the foothills thermal belts,
but will be close to normal elsewhere.
The main concern this week is critical fire weather conditions
today and Thursday as an upper level shortwave digs into the
Great Basin and dry conditions persist. The kmfr-ksac gradient is
expected to remain around 10 mbs. Winds will increase and spread
south today as mixing develops and upper level northerly flow
becomes aligned with terrain of the Central Valley. Wind Advisory
is in effect from late-morning until this evening.
Winds will continue tonight along the western edge of the
Sacramento Valley, but will increase across the west slopes of the
northern Sierra Nevada as the easterly surface pressure gradient
tightens (krno-ksac forecast to rise to around 10 mbs).
Breezy northerly winds continue Thursday, but won't be as strong
as today, as upper ridging moves overhead and surface gradients
begin to relax.
Extended discussion (sunday through wednesday)...
while some model differences continue, there is general agreement
with them and ensembles that an upper level trough will drop
southward through the Great Basin on Sunday. Moisture will be
limited and expect weather at this point to be dry. Will have to
watch this, though, as a few ensemble members try to bring light
showers over the Sierra in Tuolumne County.
Temperatures trend down early next week, with near normal highs
expected Sunday then dropping below normal by Monday and
continuing cool into mid week. North to east winds are forecast to
return, strongest Sunday afternoon and evening. This would bring
enhanced fire weather concerns into early Monday. Humidity levels
might be a little higher and winds a little less strong, though,
than in the current event. Light north winds continue into
VFR conditions continue over the next 24 hours at taf sites.
Generally northerly sustained winds 10 to 20 kts today. Gusts up
to 25 to 35 kts possible for Sacramento Valley. After 18z.
red flag warning from 8 am this morning to 4 PM PDT Thursday for
Carquinez Strait and Delta-central Sacramento Valley in Glenn,
Colusa, Yuba, northern Sutter, and Butte County below 1000 ft-
eastern Mendocino nf-eastern portion of Shasta/Trinity nf-Lake
County portion of lake-Napa-Sonoma unit-northern motherlode from
1000 to 3000 ft. Includes portions of Nevada-Yuba-Placer-Amador
and Eldorado units-northern Sacramento Valley to southern Tehama
County line below 1000 ft-northern San Joaquin Valley in San
Joaquin and Stanislaus counties below 1000 ft-northern Sierra
foothills from 1000 to 3000 ft. Includes portions of Shasta-
Trinity and Butte units-northern Sierra including Lassen np and
Plumas and Lassen nf/S west of the Sierra crest (west of Evans
Peak-Grizzly Peak-beckworth peak)-northern Sierra including the
Tahoe and Eldorado nf/S west of the Sierra crest-southeast edge
Shasta-Trinity nf and western portions of Tehama-Glenn unit-
southern Sacramento Valley in Yolo-Sacramento far western
Placer, southern Sutter and Solano County below 1000 ft-
Stanislaus nf west of the Sierra crest.
Wind Advisory from 11 am this morning to 8 PM PDT this evening