Area Forecast Discussion
Issued by NWS Sacramento, CA

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551
FXUS66 KSTO 261035
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
335 AM PDT Tue Sep 26 2017


.SYNOPSIS...
Breezy north winds today through early Wednesday for increased
fire danger. Remaining warmer than normal through the end of the
week with lighter winds. A little cooler over the weekend.

&&

.DISCUSSION...
Temperatures running a few to several degrees warmer than 24 hours
ago as high pressure continues to build over the eastern Pacific.
Overall airmass warms a few degrees today so expect daytime highs
to come in a few degrees above Monday and about 5 degrees above
normal for this time of year. Combination of northerly flow aloft
and moderately tight surface gradient will bring another day of
breezy north winds. RDD to SAC gradient also higher than 24 hours
ago so expect the north winds to be a little higher today.
Combination of breezy north winds and low RH continue to bring
increased fire danger so Red Flag warning will remain in place
through Wednesday morning. Upper level ridge is forecast to center
over the west coast by Wednesday afternoon bringing a slight
warming trend and lighter surface gradients so should see lighter
winds by the afternoon hours. Weather pattern changes little on
Thursday as the upper ridge slides slowly eastward over the
region. An upper low pushing into the Pacific Northwest is
forecast to displace the upper ridge into the Rockies on Friday.
This will bring daytime highs Friday down to near normal. At this
time, it appears any precipitation associated with this low
pressure system will remain north of the forecast area.

&&
.EXTENDED DISCUSSION (Saturday THROUGH Tuesday)

The extended forecast is now trending cooler for the weekend as a
trough moves through Saturday, potentially followed by a deeper
trough early next week. Extended models have struggled with
consistency, so confidence has lowered. Current forecast now
projects below normal temperatures for Sunday into Monday, with
Valley highs in the low 80s, along with breezy northerly winds. Have
introduced a slight chance of rain Monday and Tuesday, mainly for
northern Shasta County. May need to expand this further if deeper
trough solution trend continues. EK


&&

.AVIATION...

VFR conditions expected for Valley TAF sites for the next 24
hours. Northerly gusts up to 20kts possible in the Sacramento
Valley today 18-02z. Easterly gusts up to 30kt possible over the
Sierra crest and foothills this morning.

&&

.STO WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning until 7 AM PDT Wednesday 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 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 Motherlode
From 1000 to 3000 Ft. Includes portions of Calaveras-Tuolumne
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.

&&

$$



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