Area Forecast Discussion
Issued by NWS Sacramento, CA

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FXUS66 KSTO 142143
AFDSTO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
243 PM PDT Sun Sep 14 2014

.Synopsis...
Cooler temperatures for much of this work week. Valley sprinkles
and mountain showers and isolated thunderstorms will be possible
for parts of the area Monday, and again Wednesday through
Thursday.

&&

.Discussion...(Tonight through Wednesday)
Today max temperatures will be close to 100 for Sacramento and top
100 degrees over the far northern end of the valley. The delta
breeze weakened for a few hours allowing for temperatures to make
a run at one more 100 degree day for the Sacramento region. The
delta breeze is starting to increase again and should be breezy by
this evening.

Late tonight through early Monday afternoon some moisture will
move north from the south. Sprinkles may be possible as it passes
through the area. A low pressure area will be off the coast and
lift northward staying off the coast. The better dynamics will
remain with the low but the NAM and GFS model is indicating some
instability over the interior. Have added a slight chance of
showers or thunderstorms over the mountains for Monday afternoon
north of I-80 through the Burney Basin.

Cyclonic flow will remain over the area on Tuesday as a much
stronger low forms off the west coast. A decent delta breeze
should continue on Tuesday as well with some cooling over most of
the interior expected. The mountains may not have much change in
temperatures from Monday`s highs.

On Wednesday decent low will approach from the west and continued
cooling is expected. Late in the day some showers may be possible
along the coastal range per the European model but the GFS is
delaying any showers until Wednesday night.

&&


.Extended Discussion (Thursday through Sunday)

Medium range models similar in dropping 568ish DM upper low south
along the California coast Thursday and slowly filling it.
Forecast PWS upwards of around 1.4 inches over Interior NorCal
Thursday to keep a threat of showers in portions of the lower
elevations with enough instability to support possible afternoon
mountain thunderstorms. Additional cooling Thursday will result in
below normal temperatures with mid 80s in the Central Valley and
mainly 60s to 70s for the mountains and foothills.

Models then diverge Friday into the weekend with placement of
omega upper ridge and associated trapped low. 12z GFS is more
progressive keeping the ridge axis farther downstream while 12z GEM
and ECMWF-HiRes keep it close to the West Coast. Forecast becomes
increasingly difficult as models handle placement of trapped
closed low poorly. NAEFS probability QPF keeps a dry forecast for
Interior NorCal through the remainder of the extended so will lean
towards this for now but confidence low. Will continue
advertising a warming trend with high temps rising to around 5
degrees or so above normal through next weekend.

PCH

&&

.Aviation...

SWly flow alf as upr low in EPAC apchs far NW ptn of CA Mon aftn.
VFR conds ovr Intr NorCal nxt 24 hrs with isold tstms poss ovr Nrn
intr mtns Mon aftn. Lcl SWly sfc wnd gsts to 30 kts poss ovr hyr
mtn trrn aftns into eves and in the Delta tngt into Mon mrng.

&&

.STO Watches/Warnings/Advisories...
None.
&&

$$






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