Area Forecast Discussion
Issued by NWS Sacramento, CA

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FXUS66 KSTO 161109
AFDSTO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
409 AM PDT Thu Apr 16 2015

.Synopsis...
High pressure over the west coast for mainly fair skies and
warmer than normal tempertures through the weekend. A weak low
forms over the north state for a slight threat of mountain showers
over the weekend and early next week.

&&

.Discussion...
High pressure aloft over the west coast for fair skies this
morning. Northerly surface gradient of about 10 mb from MFR to SAC
holding fairly steady this morning for breezy north winds most
areas. Models show a fairly quick drop off by 18z today so should
see a gradual drop off in winds late this morning and into the
afternoon. Drop off in winds and increased subsidence under the
ridge will bring several degrees of warming today. Daytime highs
are forecast to come in 10 to 15 degrees above normal. Overall
airmass warms a bit more on Friday for another slight increase in
temperatures. Mid range models in fair agreement in digging a weak
trough over the Pacific Northwest southward into the Great Basin
over the weekend. The weak low that forms over Norcal along the
tail end of this trough may produce enough instability for some
isolated mountain showers or thunderstorms afternoon and evening
hours over the weekend. Otherwise...warm conditions continue under
mainly fair skies and light northerly winds.


.Extended Discussion (Monday through Thursday)

Warm, above normal temperatures continue on Monday with highs
generally in the mid to upper 80s in the Valley and mid 50s to mid
70s in the mountains. Upper level disturbance will be off the Nor
Cal Coast bringing some instability for a slight chance of showers
and possibly thunderstorms over the mountains Monday. By Tuesday,
a cold and deep trough is expected to dig down along the West
Coast bringing a more widespread threat of precipitation to
NorCal. Although details are not consistent, both the ECMWF and
GFS indicate that this trough will impact our region with cooler
and wetter weather Tuesday into Thursday. The most notable change
in temperatures will occur between Monday and Tuesday when daytime
highs will drop about 6-10 degrees. This will make our
temperatures much more seasonal on Tuesday and the cooling trend
will continue through Thursday as the daytime highs lower each day
by a few degrees so that temperatures become 5-10 degrees below
normal. JBB


&&

.Aviation...

VFR conditions continue today. Northerly winds gusts will pick up
again around sunrise 10-20 kts with gusts up to 30 kts primarily
between 16-21z at TAF sites. NE winds will strengthen across the
Sierra, with local gusts above 35 kt possible this morning. Winds
will lighten later this afternoon and evening becoming light
around 10 kts or less. JBB


&&

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

$$







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