Area Forecast Discussion
Issued by NWS Sacramento, CA

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FXUS66 KSTO 201109
AFDSTO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
409 AM PDT Mon Oct 20 2014

.Synopsis...
Frontal system will provide cooler temperatures and precipitation
chances from this morning through tonight. Another storm system
will cause shower chances from Wednesday into the weekend.

&&

.Discussion...
At 3 am, radar was showing the main rainband of the incoming front
impacting the NorCal coastline. This rainband has a fairly north
to south orientation with the leading edge along the
Humboldt/Trinity county border and extending northward past Medford,
OR.

For our CWA, expect precipitation to cover the Coastal Range early
this morning (by 5-6 am). The front will continue to track
eastward today spreading chances of precipitation east and
south across interior NorCal. Redding area should start to get rain
around 10-11 am and the Sac metro region around 11 am to noon.
Valley rain amounts won`t amount to much with the Sacramento area
getting a few hundredths and the Northern Sacramento valley
(Redding/Red Bluff vicinity) ranging 0.05" to 0.15". Higher
terrain surrounding the Northern Sac Valley will see higher
amounts of rain measuring around 0.25-0.5"...not "drought-busting"
rain totals, but still helpful.

Once the main rain band passes there could be a slight chance of
convection this afternoon into early evening. Infrared satellite
imagery shows the typical "popcorn" clouds behind the front. This
colder airmass aloft will move over our CWA later today and
enhance instability which could trigger a few thunderstorms. With
the colder air moving inland, daytime highs will range about 3 to
10 degrees below normal. Expect valley highs in the upper 60s to
mid 70s and mountain highs in the 50s & 60s.

Zonal flow aloft over the region for Tuesday with light northerly
winds. Cooler air will remain over the area to keep temperatures
in the lower to mid 70s for another day for the valley to the 50s
for the mountains. Some high cloudiness should be over the area as
well.  JBB



.Extended Discussion (Friday through Monday)

The next main weather impact will be a large low that develops in
the Gulf of Alaska by Wednesday and impacts our region into the
weekend. Rain chances should nudge into the Coastal Range late
Wednesday night with light rain that will spread farther inland at
times for the rest of the week. For Thursday, rain chances will
stay generally north of Interstate 80. Main change from previous
forecasts is that the models are in better agreement as to our wet
weather outlook for the end of the week. From Friday into
Saturday, that low in the Gulf of Alaska will dig southward and
move into the west coast which should spread chances of rain
across all of our CWA into the San Joaquin valley so have
increased PoPs to reflect this. This trough will push eastward on
Sunday and Monday. There will still be lingering chances of rain,
but they will be diminished in areal coverage and be limited to
areas north of I-80 and mainly across higher terrain. Daytime
highs in the extended period will be fairly consistent at near
seasonal to about 5 degrees below normal. JBB


&&

.Aviation...

Generally VFR conditions today with lowering clouds and stronger
southerly winds as a cold front moves through the area today.
Precipitation and lower clouds over the coastal mountains will
spread inland extending over the northern Sacramento Valley by
around 15 z, bringing local MVFR conditions there. MVFR
conditions with local IFR are possible over the Mountains. ISOLD
TSRA possible this afternoon and evening. EK


&&

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

$$







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