Area Forecast Discussion
Issued by NWS Sacramento, CA

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000
FXUS66 KSTO 300426
AFDSTO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
926 PM PDT Wed Apr 29 2015

.Synopsis...
Mainly dry and warm weather with above normal temperatures through
early next week. A weak trof will bring a chance of showers or
thunderstorms near the Sierra crest Thursday...and into the
weekend. Breezy north winds are expected later tonight and
Thursday mainly on the west side of the Sacramento Valley. Low
pressure will bring an increased threat of mountain showers or
thunderstorms during the middle of next week.

&&

.Discussion...
High pressure is bringing clear skies to the region tonight.
Northerly flow will increase overnight over the north and then
spread south during the day. Breezy conditions are expected
Thursday as surface high pressure builds into the Great Basin
overnight into Thursday. Easterly winds will increase over the
mountains tonight with the strongest wind gusts around 35 mph for
some of the favored areas. Valley winds look to be in the 15 to
25 mph range on Thursday with some higher gusts up to 35 mph along
the west side of the Sacramento valley. Lighter winds are forecast
in the San Joaquin Valley.

Many temperatures should warm into lower 90s in the valley on
Thursday and Friday. Isolated thunderstorms look possible in the
Sierra for both of those days...mainly from around Tahoe
southward.

On Saturday there will be a very weak through off the northwest
coast that may interact with some moisture coming up from the
south. Models vary on placement and extent of showers and
thunderstorms. The GFS is indicating a little more potential than
the NAM model this evening. Temperatures should start to cool a
little over Friday`s highs and for the most part bring
temperatures back down into the 80s.


.Extended Discussion (Sunday through Wednesday)

Temperatures may cool a little on Sunday with highs generally in
the 80s in the Valley and low 50s to low 70s in the mountains. The
most cooling is expected to be around the delta region with an
increase in onshore flow along with a little cooler airmass.
Temperatures are expected to be similar for Monday.
There is a slight chance of thunderstorms near the Sierra crest
around Tahoe and south on Sunday afternoon and evening as a weak
disturbance moves through the area. A weak disturbance over the
North with a low over Southern California for Monday will expand
the threat of thunderstorms to all of the mountains of interior
Northern California. A low pressure system may move into the
Pacific Northwest coast on Tuesday with some brushing Northern
California for a continued threat of thunderstorms over the
mountains. The 12z GFS deepens this system over Northern
California on Wednesday but the 12z ECMWF is more progressive and
shifts it to the east with a high pressure building in over
Northern California from the Eastern Pacific behind it on
Wednesday. Although the 00z ECMWF had a solution more like the 12Z
GFS with the trough digging south so kept showers and
thunderstorms to the Northern Sac Valley and mountains for
Wednesday and temperatures cooling into the upper 70s to low 80s in
Valley and upper 40s to lower 60s in the mountains.


&&

.Aviation...

VFR conditions expected across interior NorCal the next 24 hrs.
Northerly winds will increase aft 08z with speeds of 10-25 kt with gusts
up to 32 kts after 15z. The strongest winds are expected at KRDD
and KRBL and along the west side of the Sacramento Valley. No
airport weather advisories have been issued, with Redding
approaching criteria but not expected to reach it. Winds are
expected to decrease 00z.

&&

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

$$







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