Area Forecast Discussion
Issued by NWS Sacramento, CA

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FXUS66 KSTO 011649
AFDSTO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
849 AM PST Sun Feb 1 2015

.Synopsis...
Light precipitation possible in far northern portions late today
through Tuesday night. Above normal temperatures still expected
next week. Night and morning fog possible in the Central Valley
today into early next week. Increasing confidence in wet pattern
returning late in the week.

&&

.Short Term Discussion (Today through Wednesday)...
Patchy Dense Fog in the Northern San Joaquin and Delta area
and West of Sacramento this morning. Dense Fog reported at Davis,
Vacaville and Fairfield and Stockton with visibilities less than a
quarter of a mile at 8 am. Dense fog advisory out until 10 am this
morning. Visibilities should start increasing around 10 am as the
fog and low clouds dissipate. Patchy fog is expected to return to
areas around Sacramento, Delta and the Northern San Joaquin Valley
again the next few mornings.

High pressure weakens over the area with flattening ridge the next few
days bringing cooler temperatures (but still generally 5 to 10
degrees above normal) and possibly some precipitation to the
Northern portion of the Sacramento Valley and surrounding
mountains. The most cooling will be today with temperatures around
5 to 10 degrees cooler than yesterday due to high clouds and a
cooler air mass (850 mb temps drop around 3 degrees C). This will
bring afternoon temperatures down into the 60s in the Valley and
50s in the mountains which is still around 6 to 12 degrees above
normal for the beginning of February. Weak systems moving through
the fairly flat ridge will brush by the north bringing a chance of
precipitation this afternoon into Tuesday for the Northern
Sacramento Valley and surrounding mountains. Precipitation amounts
will be light with a quarter to half inch around Mt. Lassen and Shasta
County mountains, around 0.15 inches around Redding and less then
a tenth of an inch south of Redding in the Valley to around Chico.
Ridge builds up some on Wednesday ahead of a trough. The ridge
will bring a dry day and warmer temperatures up north with less
cloud cover. Patchy Valley fog is expected again in the morning.
The approaching trough may bring wet weather Thursday into the
weekend for Northern California.

.Extended Discussion (Thursday through Sunday)

No major changes in the models for the extended period continues
to lend confidence toward a return of wet weather for much of the
region later this week.

Ridge of high pressure still forecast to shift east into the
Rockies late this week as trough over the Gulf of Alaska edges a
bit closer. Models continue to forecast a period of very moist
southwesterly flow into NorCal late in the week and next weekend
(TPW plume in excess of 1.5 inches).

Heaviest QPF still forecast over northwest California with a shot
of decent precipitation likely extending south to around I-80
Friday into Saturday as strong upper jet noses onto the west coast
and IVT increases to well above normal.

&&

.Aviation...

VFR conditions across interior NorCal except for a band of dense
fog located along waterways. This is mainly impacting the Delta,
just west of KSMF and extending southward into the northern San
Joaquin Valley impacting KMOD with LIFR/IFR conditions. This is
dispersing by around 17-18Z, with lingering BR/HZ. Light
northerly winds this morning shifting to light southerly in the
afternoon. Disturbances passing to the north will bring increasing
mid and high clouds with shower chances limited to the northern
mountains.

&&

.STO Watches/Warnings/Advisories...
dense fog advisory until 10 am pst this morning carquinez strait
and delta...northern san joaquin valley...southern sacramento
valley.

&&

$$







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