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000
FXUS66 KSTO 202141
AFDSTO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
141 PM PST Sat Dec 20 2014

.Synopsis...
Mainly light Rain and light amounts of high elevation mountain
snow continue tonight, diminishing on Sunday. Dry Monday and
Tuesday under high pressure ridge. There is a chance another
system may impact the region Wednesday into Christmas Day.

&&

.Discussion...

A weak warm front is moving through the region. The atmosphere is
very moist so there is a chance of showers. Any showers should be
light for most areas other than in the far north where there is a
greater chance of seeing some moderate rain. Snow levels will be
rising throughout the evening so expect them to remain above
major trans-sierra pass levels.

Moisture will continue to stream into the region through Sunday
evening before a strong ridge of high pressure builds over the
interior to keep things dry for several days. Fog may become an
issue each night and morning starting Monday morning.

Today`s chilly temperatures are actually around normal for us this
time of year. As the ridge builds expect most temperatures to warm
well above normal...10 to 15 degrees above normal. Redding could
be flirting with reaching 70 degrees on Tuesday. Further south in
the valley moist air and morning fog and a temperature inversion
may limit the amount of warm up. I expect adjacent foothills to
end up being warmer.


.Extended Discussion (Wednesday through Saturday)

Models continue to struggle with the evolution of the Christmas
Eve system, although they are in slightly better agreement than 12
hours ago. The ECMWF remains to be the most bullish, bringing
potentially moderate snow and modest Valley rain to the area. The
operational GFS brushes by the northeastern portion of the state,
bringing Lassen Park some light snow. The Parallel (Hi-Res) GFS is
a blend of the two. The GEM has the farthest north storm track and
would be dry altogether for NorCal. With a majority of models now
showing at least some precipitation, we`ve increased our PoP
forecast accordingly.

Drier northwesterly flow moves over the area in the wake of the
system heading into next weekend. This could bring colder
overnight temperatures.

Dang


&&

.Aviation...

Widespread IFR/MVFR conditions continue across Valley TAF sites as
abundant moisture remains over the region. IFR/LIFR conditions
will continue over the mountains. Scattered showers will move
through the area today, and patchy fog may develop across parts of
the Valley tonight. Snow levels 060-070 will rise to above 080 by
early Sunday. SE winds 8-16 kt will continue across the Valley
today.

Dang


&&

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

$$








000
FXUS66 KSTO 202141
AFDSTO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
141 PM PST Sat Dec 20 2014

.Synopsis...
Mainly light Rain and light amounts of high elevation mountain
snow continue tonight, diminishing on Sunday. Dry Monday and
Tuesday under high pressure ridge. There is a chance another
system may impact the region Wednesday into Christmas Day.

&&

.Discussion...

A weak warm front is moving through the region. The atmosphere is
very moist so there is a chance of showers. Any showers should be
light for most areas other than in the far north where there is a
greater chance of seeing some moderate rain. Snow levels will be
rising throughout the evening so expect them to remain above
major trans-sierra pass levels.

Moisture will continue to stream into the region through Sunday
evening before a strong ridge of high pressure builds over the
interior to keep things dry for several days. Fog may become an
issue each night and morning starting Monday morning.

Today`s chilly temperatures are actually around normal for us this
time of year. As the ridge builds expect most temperatures to warm
well above normal...10 to 15 degrees above normal. Redding could
be flirting with reaching 70 degrees on Tuesday. Further south in
the valley moist air and morning fog and a temperature inversion
may limit the amount of warm up. I expect adjacent foothills to
end up being warmer.


.Extended Discussion (Wednesday through Saturday)

Models continue to struggle with the evolution of the Christmas
Eve system, although they are in slightly better agreement than 12
hours ago. The ECMWF remains to be the most bullish, bringing
potentially moderate snow and modest Valley rain to the area. The
operational GFS brushes by the northeastern portion of the state,
bringing Lassen Park some light snow. The Parallel (Hi-Res) GFS is
a blend of the two. The GEM has the farthest north storm track and
would be dry altogether for NorCal. With a majority of models now
showing at least some precipitation, we`ve increased our PoP
forecast accordingly.

Drier northwesterly flow moves over the area in the wake of the
system heading into next weekend. This could bring colder
overnight temperatures.

Dang


&&

.Aviation...

Widespread IFR/MVFR conditions continue across Valley TAF sites as
abundant moisture remains over the region. IFR/LIFR conditions
will continue over the mountains. Scattered showers will move
through the area today, and patchy fog may develop across parts of
the Valley tonight. Snow levels 060-070 will rise to above 080 by
early Sunday. SE winds 8-16 kt will continue across the Valley
today.

Dang


&&

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

$$









000
FXUS66 KSTO 201708
AFDSTO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
908 AM PST Sat Dec 20 2014

.Synopsis...
Light Rain and light mountain snow continue today, diminishing on
Sunday. Dry Monday and Tuesday under high pressure ridge. There is
a chance another system may impact the region Wednesday into
Christmas Day.

&&

.Discussion...
A weak warm front is moving through the region. The atmosphere is
very moist so there is a chance of showers. Any showers should be
light for most areas other than in the far north where there is a
greater chance of seeing some moderate rain. Snow levels will be
rising throughout the day so by early afternoon expect them to be
above major trans-sierra pass levels. Skies should remain cloudy
today over the interior.

Moisture will continue to stream into the region through Sunday
evening before a strong ridge of high pressure builds over the
interior to keep things dry for several days. Fog may becone an
issue each night and morning.


.Extended Discussion (Wednesday through Saturday)

Models continue to be all over the place with solutions on the
Christmas Eve system lending poor confidence to the forecast. EC
continues to be the most bullish spreading precipitation southward
into Central CA while both the latest GEM and GFS operational runs
only slightly dent the ridge over the area and spread
precipitation only as far south as the northern mountains. We`ll
continue to monitor trends with this system. Drier northwesterly
flow forecast over the area in the wake of the system heading into
next weekend.

&&

.Aviation...

Widespread IFR/MVFR conditions continue across Valley TAF sites as
abundant moisture remains over the region. IFR/LIFR conditions
will continue over the mountains. Scattered showers will move
through the area today. Snow levels 050-060 will rise to above
080 by early Sunday. SE winds 8-16 kt will continue across the
Valley today.

Dang


&&

.STO Watches/Warnings/Advisories...
winter weather advisory until 10 am pst this morning above 6000
feet in the west slope northern sierra nevada.

&&

$$









000
FXUS66 KSTO 201708
AFDSTO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
908 AM PST Sat Dec 20 2014

.Synopsis...
Light Rain and light mountain snow continue today, diminishing on
Sunday. Dry Monday and Tuesday under high pressure ridge. There is
a chance another system may impact the region Wednesday into
Christmas Day.

&&

.Discussion...
A weak warm front is moving through the region. The atmosphere is
very moist so there is a chance of showers. Any showers should be
light for most areas other than in the far north where there is a
greater chance of seeing some moderate rain. Snow levels will be
rising throughout the day so by early afternoon expect them to be
above major trans-sierra pass levels. Skies should remain cloudy
today over the interior.

Moisture will continue to stream into the region through Sunday
evening before a strong ridge of high pressure builds over the
interior to keep things dry for several days. Fog may becone an
issue each night and morning.


.Extended Discussion (Wednesday through Saturday)

Models continue to be all over the place with solutions on the
Christmas Eve system lending poor confidence to the forecast. EC
continues to be the most bullish spreading precipitation southward
into Central CA while both the latest GEM and GFS operational runs
only slightly dent the ridge over the area and spread
precipitation only as far south as the northern mountains. We`ll
continue to monitor trends with this system. Drier northwesterly
flow forecast over the area in the wake of the system heading into
next weekend.

&&

.Aviation...

Widespread IFR/MVFR conditions continue across Valley TAF sites as
abundant moisture remains over the region. IFR/LIFR conditions
will continue over the mountains. Scattered showers will move
through the area today. Snow levels 050-060 will rise to above
080 by early Sunday. SE winds 8-16 kt will continue across the
Valley today.

Dang


&&

.STO Watches/Warnings/Advisories...
winter weather advisory until 10 am pst this morning above 6000
feet in the west slope northern sierra nevada.

&&

$$








000
FXUS66 KSTO 201227
AFDSTO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
427 AM PST Sat Dec 20 2014

.Synopsis...
Rain and mountain snow continue today, gradually diminishing
through the day, with some mainly mountain showers lingering into Sunday.
Dry Monday and Tuesday under high pressure ridging. Another
potentially wet system may impact the region Wednesday into
Christmas Day.

&&

.Discussion...
Lingering cold frontal showers exiting eastward this morning while
abundant moisture and warm advection are spreading inland into the
area from a Pacific plume. While dynamics are limited, PW amounts
over an inch will bring additional rain, especially into the
Coastal Range and Shasta County.

Rain and snow continue to be an issue early this morning with a
batch of lingering showers over the Sierra. Sensors show
temperatures on I80 generally in the mid 30s, while webcams show some
rain showers and wet road surfaces. Caltrans reports a mix of
rain and snow over Highway 50 from Twin Bridges eastward with
chain controls in effect. Have continued the Winter Weather
Advisory through 10 am mainly for that area southward with an
additional inch of snow possible keeping roads slippery. Snow
levels will continue to rise through the day with warm advection,
with limited additional accumulation for the afternoon.

High resolution models show precipitation this morning across the
Coastal range into portions of the Valley. Valley rain will taper
off from the afternoon into evening (south to north), but the
moisture in the Sierra should keep lingering light snow showers
into Sunday.

Upper level ridging begins to build over the Eastern Pacific on
Sunday. Enough moisture remains to keep some lingering showers over
the northern mountains and possibly into the northern Sacramento
Valley. Skies over the northern San Joaquin Valley may clear
enough to allow some patchy fog to develop.

Warmer airmass under the ridge and a little less cloud cover will
allow daytime highs on Sunday to climb to above normal for this
time of year. The ridge strengthens and builds farther inland on
Monday and Tuesday which means clear skies, the redevelopment of
patchy morning fog and warmer daytime highs. Areas in fog may see
less warming, so temperatures could be tricky in those areas.


.Extended Discussion (Wednesday through Saturday)

Models continue to be all over the place with solutions on the
Christmas Eve system lending poor confidence to the forecast. EC
continues to be the most bullish spreading precipitation southward
into Central CA while both the latest GEM and GFS operational runs
only slightly dent the ridge over the area and spread
precipitation only as far south as the northern mountains. We`ll
continue to monitor trends with this system. Drier northwesterly
flow forecast over the area in the wake of the system heading into
next weekend.

&&

.Aviation...

Widespread IFR/MVFR conditions in -RA/-SN BR will continue as warm
front remains draped across the region. Snow levels 050-060 will
rise to above 080 by early Sunday. Conditions improve gradually by
08Z Sunday.

&&

.STO Watches/Warnings/Advisories...
winter weather advisory until 10 am pst this morning above 6000
feet in the west slope northern sierra nevada.

&&

$$









000
FXUS66 KSTO 201227
AFDSTO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
427 AM PST Sat Dec 20 2014

.Synopsis...
Rain and mountain snow continue today, gradually diminishing
through the day, with some mainly mountain showers lingering into Sunday.
Dry Monday and Tuesday under high pressure ridging. Another
potentially wet system may impact the region Wednesday into
Christmas Day.

&&

.Discussion...
Lingering cold frontal showers exiting eastward this morning while
abundant moisture and warm advection are spreading inland into the
area from a Pacific plume. While dynamics are limited, PW amounts
over an inch will bring additional rain, especially into the
Coastal Range and Shasta County.

Rain and snow continue to be an issue early this morning with a
batch of lingering showers over the Sierra. Sensors show
temperatures on I80 generally in the mid 30s, while webcams show some
rain showers and wet road surfaces. Caltrans reports a mix of
rain and snow over Highway 50 from Twin Bridges eastward with
chain controls in effect. Have continued the Winter Weather
Advisory through 10 am mainly for that area southward with an
additional inch of snow possible keeping roads slippery. Snow
levels will continue to rise through the day with warm advection,
with limited additional accumulation for the afternoon.

High resolution models show precipitation this morning across the
Coastal range into portions of the Valley. Valley rain will taper
off from the afternoon into evening (south to north), but the
moisture in the Sierra should keep lingering light snow showers
into Sunday.

Upper level ridging begins to build over the Eastern Pacific on
Sunday. Enough moisture remains to keep some lingering showers over
the northern mountains and possibly into the northern Sacramento
Valley. Skies over the northern San Joaquin Valley may clear
enough to allow some patchy fog to develop.

Warmer airmass under the ridge and a little less cloud cover will
allow daytime highs on Sunday to climb to above normal for this
time of year. The ridge strengthens and builds farther inland on
Monday and Tuesday which means clear skies, the redevelopment of
patchy morning fog and warmer daytime highs. Areas in fog may see
less warming, so temperatures could be tricky in those areas.


.Extended Discussion (Wednesday through Saturday)

Models continue to be all over the place with solutions on the
Christmas Eve system lending poor confidence to the forecast. EC
continues to be the most bullish spreading precipitation southward
into Central CA while both the latest GEM and GFS operational runs
only slightly dent the ridge over the area and spread
precipitation only as far south as the northern mountains. We`ll
continue to monitor trends with this system. Drier northwesterly
flow forecast over the area in the wake of the system heading into
next weekend.

&&

.Aviation...

Widespread IFR/MVFR conditions in -RA/-SN BR will continue as warm
front remains draped across the region. Snow levels 050-060 will
rise to above 080 by early Sunday. Conditions improve gradually by
08Z Sunday.

&&

.STO Watches/Warnings/Advisories...
winter weather advisory until 10 am pst this morning above 6000
feet in the west slope northern sierra nevada.

&&

$$








000
FXUS66 KSTO 200600
AFDSTO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
955 PM PST Fri Dec 19 2014

.Synopsis...
Rain and mountain snow this evening as a Pacific cold front moves
through the region. Lingering showers on Saturday for the valley
and through Sunday over the mountains. Dry all areas
Monday/Tuesday under high pressure ridge. Another system may
impact the region Wednesday evening into Christmas Day.

&&

.Discussion...
Frontal band remnants over the far SErn portion of the CWA will
linger for a few more hours...but generally should be waning.
Extended the WSW til 4 am to account for the snowy conditions from
Hwy 50 Swd. The WAA precip is showing-up on the radars over the S
Bay area ahead of the warm front which will traverse the CWA on SAT
with the gradually building ridge. Normally the ridge would preclude
precip...but the exceeding wet plume over 200 pct of normal along
40N poised to reach the Nrn CA coast...and strong WAA will defy
meteorological science and rain will overspread most of the
CWA...especially N of SAC and over the mtns as well. The WAA will
account for relatively high snow levels...perhaps rising to near or
above the passes Sat evening as the precip finally winds down or
ends.  JHM

Upper ridge will amplify on Sunday. If skies clear enough early
Sunday morning, then patchy fog development in the valley is
possible. Sunday looks dry over much of the north state but models
continue to show moisture moving over the ridge Sunday afternoon.
Therefore...have kept shower threat over the mountains although
precipitation amounts will be light. Warmer airmass under the ridge
and a little less cloud cover will allow daytime highs on Sunday to
climb to above normal for this time of year. The ridge strengthens
and builds farther inland on Monday which means clear skies, the
redevelopment of patchy morning fog and warmer daytime highs. JBB


.Extended Discussion (Tuesday through Friday)

High pressure will remain in control for Tuesday into early
Wednesday. Patchy morning fog possible mainly in the Valley each
morning. The main system of interest is still progged to move
through later on Christmas Eve into Christmas Day. Models continue
to be all over the place with solutions with the only agreement
being the appearance of a trough. 12Z ECMWF wettest of solutions
with deep low dropping ESE into So Cal and precip across the entire
area. GEM also depicts closed low into So Cal but results in split
flow to the north and south of local area, leaving us dry. GFS
weakest and furthest north of the bunch with only light precip
brushing far northern portions of the state. Thus, confidence
continues to be low regarding holiday forecast unfortunately. Have
continued with slight to low chance of rain/snow mainly late Weds
morning into Weds night north of I-80 until details are better
resolved. If precip does occur, could cause some travel headaches
across the Sierra as snow levels look to fall to around 4000 feet.
Will continue to highlight uncertainty and will continue to watch
as the holiday week draws near. High pressure will build in behind
this pesky system for Friday into the weekend, resulting in dry
weather.

CEO


&&

.Aviation...

Frontal system lingering over the far Srn portion of the CWA where
light precip will continue. Warm frontal rain/showers will begin to
move into Nrn SJ valley after midnight. Next wx system along the Nrn
CA coast will overspread the Nrn portion of the CWA and TAF sites
after 10z or so. Mostly MVFR with local IFR conditions in the
Valley, with IFR/LIFR conditions in the mountains. Periodic -SHRA
will continue through tonight and into Saturday. Freezing levels
will be between 5000-6000 ft. SE Valley winds 10-15 kt this
afternoon will decrease to below 10 kt tonight.

&&

.STO Watches/Warnings/Advisories...
winter weather advisory until 10 pm pst this evening above 6000 feet
in the west slope northern sierra nevada.

&&

$$










000
FXUS66 KSTO 200600
AFDSTO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
955 PM PST Fri Dec 19 2014

.Synopsis...
Rain and mountain snow this evening as a Pacific cold front moves
through the region. Lingering showers on Saturday for the valley
and through Sunday over the mountains. Dry all areas
Monday/Tuesday under high pressure ridge. Another system may
impact the region Wednesday evening into Christmas Day.

&&

.Discussion...
Frontal band remnants over the far SErn portion of the CWA will
linger for a few more hours...but generally should be waning.
Extended the WSW til 4 am to account for the snowy conditions from
Hwy 50 Swd. The WAA precip is showing-up on the radars over the S
Bay area ahead of the warm front which will traverse the CWA on SAT
with the gradually building ridge. Normally the ridge would preclude
precip...but the exceeding wet plume over 200 pct of normal along
40N poised to reach the Nrn CA coast...and strong WAA will defy
meteorological science and rain will overspread most of the
CWA...especially N of SAC and over the mtns as well. The WAA will
account for relatively high snow levels...perhaps rising to near or
above the passes Sat evening as the precip finally winds down or
ends.  JHM

Upper ridge will amplify on Sunday. If skies clear enough early
Sunday morning, then patchy fog development in the valley is
possible. Sunday looks dry over much of the north state but models
continue to show moisture moving over the ridge Sunday afternoon.
Therefore...have kept shower threat over the mountains although
precipitation amounts will be light. Warmer airmass under the ridge
and a little less cloud cover will allow daytime highs on Sunday to
climb to above normal for this time of year. The ridge strengthens
and builds farther inland on Monday which means clear skies, the
redevelopment of patchy morning fog and warmer daytime highs. JBB


.Extended Discussion (Tuesday through Friday)

High pressure will remain in control for Tuesday into early
Wednesday. Patchy morning fog possible mainly in the Valley each
morning. The main system of interest is still progged to move
through later on Christmas Eve into Christmas Day. Models continue
to be all over the place with solutions with the only agreement
being the appearance of a trough. 12Z ECMWF wettest of solutions
with deep low dropping ESE into So Cal and precip across the entire
area. GEM also depicts closed low into So Cal but results in split
flow to the north and south of local area, leaving us dry. GFS
weakest and furthest north of the bunch with only light precip
brushing far northern portions of the state. Thus, confidence
continues to be low regarding holiday forecast unfortunately. Have
continued with slight to low chance of rain/snow mainly late Weds
morning into Weds night north of I-80 until details are better
resolved. If precip does occur, could cause some travel headaches
across the Sierra as snow levels look to fall to around 4000 feet.
Will continue to highlight uncertainty and will continue to watch
as the holiday week draws near. High pressure will build in behind
this pesky system for Friday into the weekend, resulting in dry
weather.

CEO


&&

.Aviation...

Frontal system lingering over the far Srn portion of the CWA where
light precip will continue. Warm frontal rain/showers will begin to
move into Nrn SJ valley after midnight. Next wx system along the Nrn
CA coast will overspread the Nrn portion of the CWA and TAF sites
after 10z or so. Mostly MVFR with local IFR conditions in the
Valley, with IFR/LIFR conditions in the mountains. Periodic -SHRA
will continue through tonight and into Saturday. Freezing levels
will be between 5000-6000 ft. SE Valley winds 10-15 kt this
afternoon will decrease to below 10 kt tonight.

&&

.STO Watches/Warnings/Advisories...
winter weather advisory until 10 pm pst this evening above 6000 feet
in the west slope northern sierra nevada.

&&

$$











000
FXUS66 KSTO 192329
AFDSTO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
329 PM PST Fri Dec 19 2014

.Synopsis...
Rain and mountain snow this evening as a Pacific cold front moves
through the region. Lingering showers on Saturday for the valley
and through Sunday over the mountains. Dry all areas
Monday/Tuesday under high pressure ridge. Another system may
impact the region Wednesday evening into Christmas Day.

&&

.Discussion...
Rain and snow impacted the southern half of our CWA for much of
the day. The main band of precipitation was essentially parallel
to the Interstate 80 corridor this morning and afternoon causing
localized urban and small stream flooding as well as many traffic
issues up in the mountains. Latest radar imagery shows that this main
band is now just south of the I-80 corridor so conditions will
improve for a few hours. However, additional precipitation is
expected generally from the I-80 corridor and southward later
tonight between 6-10 pm. Have kept the Snow Advisory in effect
through 10 pm tonight. Snow levels have been as low as around 5000
ft elevation, but the bulk of snow accumulation is at 6000 ft and above.

The high resolution models show another dose of precipitation
arriving early Saturday morning across the Coastal range into
portions of the valley. Valley rain will taper off from afternoon
into evening (south to north), but the moisture in the Sierra should
keep lingering light snow showers into Sunday. Sierra travelers
should be prepared for continuing light snow through the weekend.

An upper ridge begins to build over the Eastern Pacific on
Saturday and will amplify on Sunday. If skies clear enough early
Sunday morning, then patchy fog development in the valley is
possible. Sunday looks dry over much of the north state but models
continue to show moisture moving over the ridge Sunday afternoon.
Therefore...have kept shower threat over the mountains although
precipitation amounts will be light. Warmer airmass under the
ridge and a little less cloud cover will allow daytime highs on
Sunday to climb to above normal for this time of year. The ridge
strengthens and builds farther inland on Monday which means clear
skies, the redevelopment of patchy morning fog and warmer daytime
highs. JBB


.Extended Discussion (Tuesday through Friday)

High pressure will remain in control for Tuesday into early
Wednesday. Patchy morning fog possible mainly in the Valley each
morning. The main system of interest is still progged to move
through later on Christmas Eve into Christmas Day. Models continue
to be all over the place with solutions with the only agreement
being the appearance of a trough. 12Z ECMWF wettest of solutions
with deep low dropping ESE into So Cal and precip across the entire
area. GEM also depicts closed low into So Cal but results in split
flow to the north and south of local area, leaving us dry. GFS
weakest and furthest north of the bunch with only light precip
brushing far northern portions of the state. Thus, confidence
continues to be low regarding holiday forecast unfortunately. Have
continued with slight to low chance of rain/snow mainly late Weds
morning into Weds night north of I-80 until details are better
resolved. If precip does occur, could cause some travel headaches
across the Sierra as snow levels look to fall to around 4000 feet.
Will continue to highlight uncertainty and will continue to watch
as the holiday week draws near. High pressure will build in behind
this pesky system for Friday into the weekend, resulting in dry
weather.

CEO


&&

.Aviation...

Frontal system is moving through Northern California this
afternoon, with the bulk of precipitation south of I80. Mainly
MVFR with local IFR conditions are accompanying this system in the
Valley, with IFR/LIFR conditions in the mountains. Periodic -SHRA
will continue through tonight and into Saturday. Freezing levels
will be between 5000-6000 ft. SE Valley winds 10-15 kt this
afternoon will decrease to below 10 kt tonight.

Dang


&&

.STO Watches/Warnings/Advisories...
winter weather advisory until 10 pm pst this evening above 6000
feet in the west slope northern sierra nevada...western plumas
county/lassen park.

&&

$$








000
FXUS66 KSTO 192329
AFDSTO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
329 PM PST Fri Dec 19 2014

.Synopsis...
Rain and mountain snow this evening as a Pacific cold front moves
through the region. Lingering showers on Saturday for the valley
and through Sunday over the mountains. Dry all areas
Monday/Tuesday under high pressure ridge. Another system may
impact the region Wednesday evening into Christmas Day.

&&

.Discussion...
Rain and snow impacted the southern half of our CWA for much of
the day. The main band of precipitation was essentially parallel
to the Interstate 80 corridor this morning and afternoon causing
localized urban and small stream flooding as well as many traffic
issues up in the mountains. Latest radar imagery shows that this main
band is now just south of the I-80 corridor so conditions will
improve for a few hours. However, additional precipitation is
expected generally from the I-80 corridor and southward later
tonight between 6-10 pm. Have kept the Snow Advisory in effect
through 10 pm tonight. Snow levels have been as low as around 5000
ft elevation, but the bulk of snow accumulation is at 6000 ft and above.

The high resolution models show another dose of precipitation
arriving early Saturday morning across the Coastal range into
portions of the valley. Valley rain will taper off from afternoon
into evening (south to north), but the moisture in the Sierra should
keep lingering light snow showers into Sunday. Sierra travelers
should be prepared for continuing light snow through the weekend.

An upper ridge begins to build over the Eastern Pacific on
Saturday and will amplify on Sunday. If skies clear enough early
Sunday morning, then patchy fog development in the valley is
possible. Sunday looks dry over much of the north state but models
continue to show moisture moving over the ridge Sunday afternoon.
Therefore...have kept shower threat over the mountains although
precipitation amounts will be light. Warmer airmass under the
ridge and a little less cloud cover will allow daytime highs on
Sunday to climb to above normal for this time of year. The ridge
strengthens and builds farther inland on Monday which means clear
skies, the redevelopment of patchy morning fog and warmer daytime
highs. JBB


.Extended Discussion (Tuesday through Friday)

High pressure will remain in control for Tuesday into early
Wednesday. Patchy morning fog possible mainly in the Valley each
morning. The main system of interest is still progged to move
through later on Christmas Eve into Christmas Day. Models continue
to be all over the place with solutions with the only agreement
being the appearance of a trough. 12Z ECMWF wettest of solutions
with deep low dropping ESE into So Cal and precip across the entire
area. GEM also depicts closed low into So Cal but results in split
flow to the north and south of local area, leaving us dry. GFS
weakest and furthest north of the bunch with only light precip
brushing far northern portions of the state. Thus, confidence
continues to be low regarding holiday forecast unfortunately. Have
continued with slight to low chance of rain/snow mainly late Weds
morning into Weds night north of I-80 until details are better
resolved. If precip does occur, could cause some travel headaches
across the Sierra as snow levels look to fall to around 4000 feet.
Will continue to highlight uncertainty and will continue to watch
as the holiday week draws near. High pressure will build in behind
this pesky system for Friday into the weekend, resulting in dry
weather.

CEO


&&

.Aviation...

Frontal system is moving through Northern California this
afternoon, with the bulk of precipitation south of I80. Mainly
MVFR with local IFR conditions are accompanying this system in the
Valley, with IFR/LIFR conditions in the mountains. Periodic -SHRA
will continue through tonight and into Saturday. Freezing levels
will be between 5000-6000 ft. SE Valley winds 10-15 kt this
afternoon will decrease to below 10 kt tonight.

Dang


&&

.STO Watches/Warnings/Advisories...
winter weather advisory until 10 pm pst this evening above 6000
feet in the west slope northern sierra nevada...western plumas
county/lassen park.

&&

$$









000
FXUS66 KSTO 191720
AFDSTO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
920 AM PST Fri Dec 19 2014

.Synopsis...
Rain and mountain snow today as a Pacific cold front moves through
the region. Drying south on Saturday with a few showers north
especially over the mountains. Precipitation threat pushing
northward on Sunday as high pressure begins pushing northward over
the west coast. Dry all areas Monday/Tuesday under high pressure
ridge. Another system may impact the region Wedneseday evening
into Christmas Day.

&&

.Discussion...
Have made a slight update to the forecast this morning. Radar is
showing a swath of precipitation from the Bay Area into the Delta
region into the Sac Metro area and up towards Blue Canyon in the
Sierra. This system has areas of moderate rainfall (snowfall above
5000 ft) and is moving slowly across this region. Have increased
the chance of precipitation for our CWA from the Delta region into
the valley and up into the Sierra where that band is and southward
for late morning into afternoon. Another wave of precipitation
should move in tonight, but a look at hi-res models suggest that
it may arrive later than expected. Will take a look at the timing
and fine-tune details for this afternoon`s package. May need to
consider whether the snow advisory needs to extend into Saturday
morning. JBB

.Previous Discussion...
A Pacific frontal system now moving into northwest California will
be moving across the north state today. Radar is currently showing
light precipitation out ahead of the from from about Red Bluff
westward. Current timing has the main frontal band hitting the
Sacramento valley around 18z then moving into the Sierra by 00z
this afternoon. The frontal system should be mainly south and east
of the forecast area by 12z Saturday morning. Main impact of this
system will be snowfall over the Sierra passes with snow levels
between about 5000 and 5500 feet. Models still put snow amounts at
about 3 to 6 inches with up to about 10 inches at the highest
elevations or enough to cause travel difficulties getting over the
Sierra on a weekend. Flat ridging begins to push up over the west
coast on Saturday but a weak disturbance riding over this ridge
with bring a continued threat of showers over the mountains and in
the valley from about Sacramento northward. Precipitation from
this disturbance should be quite light. Upper ridge continues to
amplify on Sunday and may just see enough clearing over the
southern portions of the CWA to allow for some patchy fog in the
valleys. Some cloud cover is likely though so fog does not look
like it will become too extensive. Sunday looks dry over much of
the north state but all models showing yet another shortwave
disturbance tracking over the ridge Sunday afternoon.
Therefore...have kept shower threat over the northern mountains
and Shasta county although again...precip amounts will remain
quite light. Warmer airmass under the ridge and a little less
cloud cover will allow daytime highs on Sunday to climb to above
normal for this time of year. Upper ridge finally amplifies enough
on Monday to push any precip threat north of the CWA. Morning
valley fog is likely again in the morning Monday burning away in
the afternoon with daytime highs warming to several degrees above
normal.

.Extended Discussion (Tuesday through Friday)

Dry weather will continue Monday and Tuesday as high pressure
ridge remains in control across the region. Only impact in this
period will be areas of valley fog each morning with lingering
surface moisture.

The next system of interest is progged to move through late
Christmas Eve into Christmas Day as it drops ESE from the Pac NW into
the Great Basin. The eastern Pac high center placement has
trended a bit farther south. This shift in the high center has
allowed the incoming trough to progress through NorCal rather than
deflect it to the northeast into the Great Basin. These previous
runs hadn`t looked that wet; instead, they looked colder and
drier. Now with this more progressive trough from a moister/less
cold source region, snow levels should stay around 4500-5000 ft
with potentially more snowfall Christmas Eve into early Christmas.
The timing of this system could pose some travel headaches.

High pressure builds in late Christmas Day into Friday with a NNW
jetstream overhead, resulting in increased northerly to
northeasterly low level winds. The warming wind speeds should keep
overnight temps from dropping too low Friday. But once the winds
subside, be prepared for some patches of frost for the Sac
Valley...maybe over the weekend.
JClapp

&&

.Aviation...

Frontal system moving through Northern California this morning.
MVFR/IFR conditions across the Valley in SHRA today, with IFR/LIFR
conditions in the mountains. Freezing levels will be between
5000-6000 ft. SE Valley winds will be 10-20 kt today, decreasing
to below 10 kt tonight.

Dang


&&

.STO Watches/Warnings/Advisories...
winter weather advisory until 10 pm pst this evening above 6000
feet in the west slope northern sierra nevada...western plumas
county/lassen park.

&&

$$








000
FXUS66 KSTO 191720
AFDSTO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
920 AM PST Fri Dec 19 2014

.Synopsis...
Rain and mountain snow today as a Pacific cold front moves through
the region. Drying south on Saturday with a few showers north
especially over the mountains. Precipitation threat pushing
northward on Sunday as high pressure begins pushing northward over
the west coast. Dry all areas Monday/Tuesday under high pressure
ridge. Another system may impact the region Wedneseday evening
into Christmas Day.

&&

.Discussion...
Have made a slight update to the forecast this morning. Radar is
showing a swath of precipitation from the Bay Area into the Delta
region into the Sac Metro area and up towards Blue Canyon in the
Sierra. This system has areas of moderate rainfall (snowfall above
5000 ft) and is moving slowly across this region. Have increased
the chance of precipitation for our CWA from the Delta region into
the valley and up into the Sierra where that band is and southward
for late morning into afternoon. Another wave of precipitation
should move in tonight, but a look at hi-res models suggest that
it may arrive later than expected. Will take a look at the timing
and fine-tune details for this afternoon`s package. May need to
consider whether the snow advisory needs to extend into Saturday
morning. JBB

.Previous Discussion...
A Pacific frontal system now moving into northwest California will
be moving across the north state today. Radar is currently showing
light precipitation out ahead of the from from about Red Bluff
westward. Current timing has the main frontal band hitting the
Sacramento valley around 18z then moving into the Sierra by 00z
this afternoon. The frontal system should be mainly south and east
of the forecast area by 12z Saturday morning. Main impact of this
system will be snowfall over the Sierra passes with snow levels
between about 5000 and 5500 feet. Models still put snow amounts at
about 3 to 6 inches with up to about 10 inches at the highest
elevations or enough to cause travel difficulties getting over the
Sierra on a weekend. Flat ridging begins to push up over the west
coast on Saturday but a weak disturbance riding over this ridge
with bring a continued threat of showers over the mountains and in
the valley from about Sacramento northward. Precipitation from
this disturbance should be quite light. Upper ridge continues to
amplify on Sunday and may just see enough clearing over the
southern portions of the CWA to allow for some patchy fog in the
valleys. Some cloud cover is likely though so fog does not look
like it will become too extensive. Sunday looks dry over much of
the north state but all models showing yet another shortwave
disturbance tracking over the ridge Sunday afternoon.
Therefore...have kept shower threat over the northern mountains
and Shasta county although again...precip amounts will remain
quite light. Warmer airmass under the ridge and a little less
cloud cover will allow daytime highs on Sunday to climb to above
normal for this time of year. Upper ridge finally amplifies enough
on Monday to push any precip threat north of the CWA. Morning
valley fog is likely again in the morning Monday burning away in
the afternoon with daytime highs warming to several degrees above
normal.

.Extended Discussion (Tuesday through Friday)

Dry weather will continue Monday and Tuesday as high pressure
ridge remains in control across the region. Only impact in this
period will be areas of valley fog each morning with lingering
surface moisture.

The next system of interest is progged to move through late
Christmas Eve into Christmas Day as it drops ESE from the Pac NW into
the Great Basin. The eastern Pac high center placement has
trended a bit farther south. This shift in the high center has
allowed the incoming trough to progress through NorCal rather than
deflect it to the northeast into the Great Basin. These previous
runs hadn`t looked that wet; instead, they looked colder and
drier. Now with this more progressive trough from a moister/less
cold source region, snow levels should stay around 4500-5000 ft
with potentially more snowfall Christmas Eve into early Christmas.
The timing of this system could pose some travel headaches.

High pressure builds in late Christmas Day into Friday with a NNW
jetstream overhead, resulting in increased northerly to
northeasterly low level winds. The warming wind speeds should keep
overnight temps from dropping too low Friday. But once the winds
subside, be prepared for some patches of frost for the Sac
Valley...maybe over the weekend.
JClapp

&&

.Aviation...

Frontal system moving through Northern California this morning.
MVFR/IFR conditions across the Valley in SHRA today, with IFR/LIFR
conditions in the mountains. Freezing levels will be between
5000-6000 ft. SE Valley winds will be 10-20 kt today, decreasing
to below 10 kt tonight.

Dang


&&

.STO Watches/Warnings/Advisories...
winter weather advisory until 10 pm pst this evening above 6000
feet in the west slope northern sierra nevada...western plumas
county/lassen park.

&&

$$









000
FXUS66 KSTO 191151
AFDSTO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
351 AM PST Fri Dec 19 2014

.Synopsis...
Rain and mountain snow today as a Pacific cold front moves through
the region. Drying south on Saturday with a few showers north
especially over the mountains. Precipitation threat pushing
northward on Sunday as high pressure begins pushing northward over
the west coast. Dry all areas Monday/Tuesday under high pressure
ridge. Slight chance of mainly mountain showers on Wednesday.
Forecast looks mainly dry on Christmas day except showers over
Sierra.

&&

.Discussion...
A Pacific frontal system now moving into northwest California will
be moving across the north state today. Radar is currently showing
light precipitation out ahead of the from from about Red bluff
westward. Current timing has the main frontal band hitting the
Sacramento valley around 18z then moving into the Sierra by 00z
this afternoon. The frontal system should be mainly south and east
of the forecast area by 12z Saturday morning. Main impact of this
system will be snowfall over the Sierra passes with snow levels
between about 5000 and 5500 feet. Models still put snow amounts at
about 3 to 5 inches with up to about 10 inches at the highest
elevations or enough to cause travel difficulties getting over the
Sierra on a weekend. Flat ridging begins to push up over the west
coast on Saturday but a weak disturbance riding over this ridge
with bring a continued threat of showers over the mountains and
in the valley from about Sacramento northward. Precipitation from
this disturbance should be quite light. Upper ridge continues to
amplify on Sunday and may just see enough clearing over the
southern portions of the CWA to allow for some patchy fog in the
valleys. Some cloud cover is likely though so fog does not look
like it will become too extensive. Sunday looks dry over much of
the north state but all models showing yet another shortwave
disturbance tracking over the ridge Sunday afternoon.
Therefore...have kept shower threat over the northern mountains
and Shasta county although again...precip amounts will remain
quite light. Warmer airmass under the ridge and a little less
cloud cover will allow daytime highs on Sunday to climb to above
normal for this time of year. Upper ridge finally amplifies enough
on Monday to push any precip threat north of the CWA. Morning
valley fog is likely again in the morning Monday burning away in
the afternoon with daytime highs warming to several degrees above
normal.

.Extended Discussion (Tuesday through Friday)

Dry weather will continue Tuesday as high pressure ridge remains
in control across the region. Only impact in this period will be
areas of valley fog each morning with lingering surface moisture.

The next system of interest is progged to move through late
Christmas Eve into Christmas Day as it drops ESE from the Pac NW into
the Great Basin. The eastern Pac high center placement has
trended a bit farther south. This shift in the high center has
allowed the incoming trough to progress through NorCal rather than
deflect it to the northeast into the Great Basin. These previous
runs hadn`t looked that wet; instead, they looked colder and
drier. Now with this more progressive trough from a moister/less
cold source region, snow levels should stay around 4500-5000 ft
with potentially more snowfall Christmas Eve into early Christmas.
The timing of this system could pose some travel headaches.

High pressure builds in late Christmas Day into Friday with a NNW
jetstream overhead, resulting in increased northerly to
northeasterly low level winds. The warming wind speeds should keep
overnight temps from dropping too low Friday. But once the winds
subside, be prepared for some patches of frost for the Sac
Valley...maybe over the weekend.
JClapp

&&

.Aviation...

Rain spreading SEward this morning. MVFR/IFR conditions in vcty of
rain in valley, with IFR/LIFR conditions in the mountains.
Freezing levels will be between 5000-6000 ft. SE valley surface
winds will increase to 15-25 kts today with SSE-SW flight level winds
020-040 25-35 kts.       JClapp


&&

.STO Watches/Warnings/Advisories...
winter weather advisory until 10 pm pst this evening above 6000
feet in the west slope northern sierra nevada...western plumas
county/lassen park.

&&

$$









000
FXUS66 KSTO 191151
AFDSTO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
351 AM PST Fri Dec 19 2014

.Synopsis...
Rain and mountain snow today as a Pacific cold front moves through
the region. Drying south on Saturday with a few showers north
especially over the mountains. Precipitation threat pushing
northward on Sunday as high pressure begins pushing northward over
the west coast. Dry all areas Monday/Tuesday under high pressure
ridge. Slight chance of mainly mountain showers on Wednesday.
Forecast looks mainly dry on Christmas day except showers over
Sierra.

&&

.Discussion...
A Pacific frontal system now moving into northwest California will
be moving across the north state today. Radar is currently showing
light precipitation out ahead of the from from about Red bluff
westward. Current timing has the main frontal band hitting the
Sacramento valley around 18z then moving into the Sierra by 00z
this afternoon. The frontal system should be mainly south and east
of the forecast area by 12z Saturday morning. Main impact of this
system will be snowfall over the Sierra passes with snow levels
between about 5000 and 5500 feet. Models still put snow amounts at
about 3 to 5 inches with up to about 10 inches at the highest
elevations or enough to cause travel difficulties getting over the
Sierra on a weekend. Flat ridging begins to push up over the west
coast on Saturday but a weak disturbance riding over this ridge
with bring a continued threat of showers over the mountains and
in the valley from about Sacramento northward. Precipitation from
this disturbance should be quite light. Upper ridge continues to
amplify on Sunday and may just see enough clearing over the
southern portions of the CWA to allow for some patchy fog in the
valleys. Some cloud cover is likely though so fog does not look
like it will become too extensive. Sunday looks dry over much of
the north state but all models showing yet another shortwave
disturbance tracking over the ridge Sunday afternoon.
Therefore...have kept shower threat over the northern mountains
and Shasta county although again...precip amounts will remain
quite light. Warmer airmass under the ridge and a little less
cloud cover will allow daytime highs on Sunday to climb to above
normal for this time of year. Upper ridge finally amplifies enough
on Monday to push any precip threat north of the CWA. Morning
valley fog is likely again in the morning Monday burning away in
the afternoon with daytime highs warming to several degrees above
normal.

.Extended Discussion (Tuesday through Friday)

Dry weather will continue Tuesday as high pressure ridge remains
in control across the region. Only impact in this period will be
areas of valley fog each morning with lingering surface moisture.

The next system of interest is progged to move through late
Christmas Eve into Christmas Day as it drops ESE from the Pac NW into
the Great Basin. The eastern Pac high center placement has
trended a bit farther south. This shift in the high center has
allowed the incoming trough to progress through NorCal rather than
deflect it to the northeast into the Great Basin. These previous
runs hadn`t looked that wet; instead, they looked colder and
drier. Now with this more progressive trough from a moister/less
cold source region, snow levels should stay around 4500-5000 ft
with potentially more snowfall Christmas Eve into early Christmas.
The timing of this system could pose some travel headaches.

High pressure builds in late Christmas Day into Friday with a NNW
jetstream overhead, resulting in increased northerly to
northeasterly low level winds. The warming wind speeds should keep
overnight temps from dropping too low Friday. But once the winds
subside, be prepared for some patches of frost for the Sac
Valley...maybe over the weekend.
JClapp

&&

.Aviation...

Rain spreading SEward this morning. MVFR/IFR conditions in vcty of
rain in valley, with IFR/LIFR conditions in the mountains.
Freezing levels will be between 5000-6000 ft. SE valley surface
winds will increase to 15-25 kts today with SSE-SW flight level winds
020-040 25-35 kts.       JClapp


&&

.STO Watches/Warnings/Advisories...
winter weather advisory until 10 pm pst this evening above 6000
feet in the west slope northern sierra nevada...western plumas
county/lassen park.

&&

$$








000
FXUS66 KSTO 190537
AFDSTO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
935 PM PST Thu Dec 18 2014

.Synopsis...
Fairly dry today for the region. Next frontal system moves through
NORCAL Friday bringing rain and mountain snow. Drying south on
Saturday with a few showers north especially over the mountains.
All areas dry on Sunday except far northern Shasta county
mountains. Dry Monday/Tuesday under high pressure ridge. Slight
chance of mainly mountain showers on Wednesday.

&&

.Discussion...
Main short wave energy with the incoming trof is N of 40N and moving
towards/into the Pac NW brushing by N of the CA/OR border on Fri.
Just to the S...and along 130W...weaker short wave energy is
enhancing a small area of moisture behind a well defined frontal
band now moving inland with the leading edge near the Wrn Shasta Co
border. This frontal band should zip across Norcal tonite...with
another area of enhanced moisture moving inland during the day on
Fri.

Light rain has been lingering over Wrn Shasta Co this afternoon and
will soon be overrun by the frontal band by around midnite. Rainfall
rates should increase there with the frontal band moving into the
Siernev mainly after 12z...as well as the SAC-SCK areas.   JHM


.Previous Discussion...

The forecast shows valley rain totals ranging 0.10" to 0.50" with
the higher amounts in the Redding and Red Bluff vicinity. The
Sacramento Metro region should get around a quarter of an inch and
areas southward will be closer to a tenth. Primary concern with this
system is snow impacting travel along the Sierra on Friday. Have
issued a Winter Storm Advisory for snow above 6000 ft along the
Western Sierra slopes from Friday 4 am to 10 pm. Sierra traffic
tends to be heavier on Fridays and we`re expecting 3-6 inches of
snow near pass levels which will likely cause traffic delays and
chain restrictions. Mountain snow showers are expected to linger
into Saturday, but any additional snow accumulation will be light.

Ridging builds over the Eastern Pacific on Saturday and nudges into
the west coast late Sat/early Sun. Lingering showers may continue
to slide over the top of the ridge and impact far NorCal through the
weekend due to strong WAA, otherwise, most of our CWA will be dry.
Clearer skies and a warming airmass under the ridge will allow
daytime highs to warm to near normal on Saturday and to a few to
several degrees above normal on Sunday. JBB


.Extended Discussion (Monday through Thursday)

Main concern in long term is around potential system for Christmas
Eve/Christmas Day.

Dry weather will continue Monday into early Wednesday as high
pressure ridge remains in control across the region. Daytime temps
will max out around 60 in the valley and upper 40s to 50s in the
foothill/mountains. Only impact in this period will be areas of
valley fog each morning with lingering surface moisture. High
confidence for this period and it will lead to a few good travel
days.

The next system of interest is progged to move through late
Christmas Eve into Christmas Day as it drops SE from the Pac NW into
the Great Basin. Model solutions continue to be all over the place
as previously advertised. 12Z run of the ECMWF...which was the
strongest and wettest of the bunch and mirrored the latest GEM and
parallel 13km GFS...has flip flopped from previous run and now
mirrors the weaker, more progressive GFS solution. This would lead
to a mainly dry holiday period, especially in most locations in
the Valley. Of bigger note would be infiltration of colder air and
lower snow levels. Snow levels could drop to 3000-3500 feet by
Thursday with accumulating snow and travel headaches likely if
a stronger system does materialize. Overnight temps late in the week
could also drop into the 30s in some spots in the valley leading
to frost. Confidence is low in details and chances for
precipitation at this point so have not made major changes to the
going forecast. Will need to be monitored as we get closer. CEO

&&

.Aviation...

Next low pressure system approaching California, with -RA developing
along the Northern Valley between 09-12z, and Sacramento TAF sites
by 15-18z. MVFR/IFR conditions in the Valley, with IFR/LIFR
conditions in the mountains. Snow levels will be between 5000-6000
ft. Southeast winds will increase to 10-18 kt late tonight into
Friday.

&&

.STO Watches/Warnings/Advisories...
winter weather advisory from 4 am to 10 pm pst friday above 6000
feet in the west slope northern sierra nevada...western plumas
county/lassen park.

&&

$$








000
FXUS66 KSTO 190537
AFDSTO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
935 PM PST Thu Dec 18 2014

.Synopsis...
Fairly dry today for the region. Next frontal system moves through
NORCAL Friday bringing rain and mountain snow. Drying south on
Saturday with a few showers north especially over the mountains.
All areas dry on Sunday except far northern Shasta county
mountains. Dry Monday/Tuesday under high pressure ridge. Slight
chance of mainly mountain showers on Wednesday.

&&

.Discussion...
Main short wave energy with the incoming trof is N of 40N and moving
towards/into the Pac NW brushing by N of the CA/OR border on Fri.
Just to the S...and along 130W...weaker short wave energy is
enhancing a small area of moisture behind a well defined frontal
band now moving inland with the leading edge near the Wrn Shasta Co
border. This frontal band should zip across Norcal tonite...with
another area of enhanced moisture moving inland during the day on
Fri.

Light rain has been lingering over Wrn Shasta Co this afternoon and
will soon be overrun by the frontal band by around midnite. Rainfall
rates should increase there with the frontal band moving into the
Siernev mainly after 12z...as well as the SAC-SCK areas.   JHM


.Previous Discussion...

The forecast shows valley rain totals ranging 0.10" to 0.50" with
the higher amounts in the Redding and Red Bluff vicinity. The
Sacramento Metro region should get around a quarter of an inch and
areas southward will be closer to a tenth. Primary concern with this
system is snow impacting travel along the Sierra on Friday. Have
issued a Winter Storm Advisory for snow above 6000 ft along the
Western Sierra slopes from Friday 4 am to 10 pm. Sierra traffic
tends to be heavier on Fridays and we`re expecting 3-6 inches of
snow near pass levels which will likely cause traffic delays and
chain restrictions. Mountain snow showers are expected to linger
into Saturday, but any additional snow accumulation will be light.

Ridging builds over the Eastern Pacific on Saturday and nudges into
the west coast late Sat/early Sun. Lingering showers may continue
to slide over the top of the ridge and impact far NorCal through the
weekend due to strong WAA, otherwise, most of our CWA will be dry.
Clearer skies and a warming airmass under the ridge will allow
daytime highs to warm to near normal on Saturday and to a few to
several degrees above normal on Sunday. JBB


.Extended Discussion (Monday through Thursday)

Main concern in long term is around potential system for Christmas
Eve/Christmas Day.

Dry weather will continue Monday into early Wednesday as high
pressure ridge remains in control across the region. Daytime temps
will max out around 60 in the valley and upper 40s to 50s in the
foothill/mountains. Only impact in this period will be areas of
valley fog each morning with lingering surface moisture. High
confidence for this period and it will lead to a few good travel
days.

The next system of interest is progged to move through late
Christmas Eve into Christmas Day as it drops SE from the Pac NW into
the Great Basin. Model solutions continue to be all over the place
as previously advertised. 12Z run of the ECMWF...which was the
strongest and wettest of the bunch and mirrored the latest GEM and
parallel 13km GFS...has flip flopped from previous run and now
mirrors the weaker, more progressive GFS solution. This would lead
to a mainly dry holiday period, especially in most locations in
the Valley. Of bigger note would be infiltration of colder air and
lower snow levels. Snow levels could drop to 3000-3500 feet by
Thursday with accumulating snow and travel headaches likely if
a stronger system does materialize. Overnight temps late in the week
could also drop into the 30s in some spots in the valley leading
to frost. Confidence is low in details and chances for
precipitation at this point so have not made major changes to the
going forecast. Will need to be monitored as we get closer. CEO

&&

.Aviation...

Next low pressure system approaching California, with -RA developing
along the Northern Valley between 09-12z, and Sacramento TAF sites
by 15-18z. MVFR/IFR conditions in the Valley, with IFR/LIFR
conditions in the mountains. Snow levels will be between 5000-6000
ft. Southeast winds will increase to 10-18 kt late tonight into
Friday.

&&

.STO Watches/Warnings/Advisories...
winter weather advisory from 4 am to 10 pm pst friday above 6000
feet in the west slope northern sierra nevada...western plumas
county/lassen park.

&&

$$







000
FXUS66 KSTO 182331
AFDSTO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
331 PM PST Thu Dec 18 2014

.Synopsis...
Fairly dry today for the region. Next frontal system moves through
NORCAL Friday bringing rain and mountain snow. Drying south on
Saturday with a few showers north especially over the mountains.
All areas dry on Sunday except far northern Shasta county
mountains. Dry Monday/Tuesday under high pressure ridge. Slight
chance of mainly mountain showers on Wednesday.

&&

.Discussion...
Both Beale and the Davis radars are back up from maintenance
earlier today. We did hear reports of light rain in parts of Shasta
County when the radar was down and current radar imagery does
verify light showers in that region. Otherwise, the rest of our
CWA remains fairly dry. However, one more round of rain and snow
is on its way. A storm offshore is already moving into the far
northern CA coastline and will bring the next notable wave of rain
and snow to interior NorCal on Friday. More widespread
precipitation will move into the Coastal Range late tonight and
then spread into the Central valley and Sierra on Friday. Forecast
shows valley rain totals ranging 0.10" to 0.50" with the higher
amounts in the Redding and Red Bluff vicinity. The Sacramento
Metro region should get around a quarter of an inch and areas
southward will be closer to a tenth. Primary concern with this
system is snow impacting travel along the Sierra on Friday. Have
issued a Winter Storm Advisory for snow above 6000 ft along the
Western Sierra slopes from Friday 4 am to 10 pm. Sierra traffic
tends to be heavier on Fridays and we`re expecting 3-6 inches of
snow near pass levels which will likely cause traffic delays and
chain restrictions. Mountain snow showers are expected to linger
into Saturday, but any additional snow accumulation will be
light.

Ridging builds over the Eastern Pacific on Saturday and nudge into
the west coast late Sat/early Sun. Lingering showers may continue
to slide over the top of the ridge and impact far NorCal through
the weekend, otherwise, most of our CWA will be dry. Clearer
skies and a warming airmass under the ridge will allow daytime
highs to warm to near normal on Saturday and to a few to several
degrees above normal on Sunday. JBB


.Extended Discussion (Monday through Thursday)

Main concern in long term is around potential system for Christmas
Eve/Christmas Day.

Dry weather will continue Monday into early Wednesday as high
pressure ridge remains in control across the region. Daytime temps
will max out around 60 in the valley and upper 40s to 50s in the
foothill/mountains. Only impact in this period will be areas of
valley fog each morning with lingering surface moisture. High
confidence for this period and it will lead to a few good travel days.

The next system of interest is progged to move through late
Christmas Eve into Christmas Day as it drops SE from the Pac NW into
the Great Basin. Model solutions continue to be all over the place
as previously advertised. 12Z run of the ECMWF...which was the
strongest and wettest of the bunch and mirrored the latest GEM and
parallel 13km GFS...has flip flopped from previous run and now
mirrors the weaker, more progressive GFS solution. This would lead
to a mainly dry holiday period, especially in most locations in
the Valley. Of bigger note would be infiltration of colder air and
lower snow levels. Snow levels could drop to 3000-3500 feet by
Thursday with accumulating snow and travel headaches likely if
a stronger system does materialize. Overnight temps late in the week
could also drop into the 30s in some spots in the valley leading
to frost. Confidence is low in details and chances for
precipitation at this point so have not made major changes to the
going forecast. Will need to be monitored as we get closer. CEO

&&

.Aviation...

Mainly VFR conditions across the area this afternoon, except local
MVFR along the west side of the Valley. Next low pressure system
is approaching California, with -RA developing along the Northern
Valley between 09-12z, and Sacramento TAF sites by 15-18z.
MVFR/IFR conditions possible in the Valley, with IFR/LIFR
conditions in the mountains. Snow levels will be between 5000-6000
ft. Southeast winds will increase to 10-18 kt late tonight into
Friday.

Dang


&&

.STO Watches/Warnings/Advisories...
winter weather advisory from 4 am to 10 pm pst friday above 6000
feet in the west slope northern sierra nevada...western plumas
county/lassen park.

&&

$$









000
FXUS66 KSTO 182331
AFDSTO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
331 PM PST Thu Dec 18 2014

.Synopsis...
Fairly dry today for the region. Next frontal system moves through
NORCAL Friday bringing rain and mountain snow. Drying south on
Saturday with a few showers north especially over the mountains.
All areas dry on Sunday except far northern Shasta county
mountains. Dry Monday/Tuesday under high pressure ridge. Slight
chance of mainly mountain showers on Wednesday.

&&

.Discussion...
Both Beale and the Davis radars are back up from maintenance
earlier today. We did hear reports of light rain in parts of Shasta
County when the radar was down and current radar imagery does
verify light showers in that region. Otherwise, the rest of our
CWA remains fairly dry. However, one more round of rain and snow
is on its way. A storm offshore is already moving into the far
northern CA coastline and will bring the next notable wave of rain
and snow to interior NorCal on Friday. More widespread
precipitation will move into the Coastal Range late tonight and
then spread into the Central valley and Sierra on Friday. Forecast
shows valley rain totals ranging 0.10" to 0.50" with the higher
amounts in the Redding and Red Bluff vicinity. The Sacramento
Metro region should get around a quarter of an inch and areas
southward will be closer to a tenth. Primary concern with this
system is snow impacting travel along the Sierra on Friday. Have
issued a Winter Storm Advisory for snow above 6000 ft along the
Western Sierra slopes from Friday 4 am to 10 pm. Sierra traffic
tends to be heavier on Fridays and we`re expecting 3-6 inches of
snow near pass levels which will likely cause traffic delays and
chain restrictions. Mountain snow showers are expected to linger
into Saturday, but any additional snow accumulation will be
light.

Ridging builds over the Eastern Pacific on Saturday and nudge into
the west coast late Sat/early Sun. Lingering showers may continue
to slide over the top of the ridge and impact far NorCal through
the weekend, otherwise, most of our CWA will be dry. Clearer
skies and a warming airmass under the ridge will allow daytime
highs to warm to near normal on Saturday and to a few to several
degrees above normal on Sunday. JBB


.Extended Discussion (Monday through Thursday)

Main concern in long term is around potential system for Christmas
Eve/Christmas Day.

Dry weather will continue Monday into early Wednesday as high
pressure ridge remains in control across the region. Daytime temps
will max out around 60 in the valley and upper 40s to 50s in the
foothill/mountains. Only impact in this period will be areas of
valley fog each morning with lingering surface moisture. High
confidence for this period and it will lead to a few good travel days.

The next system of interest is progged to move through late
Christmas Eve into Christmas Day as it drops SE from the Pac NW into
the Great Basin. Model solutions continue to be all over the place
as previously advertised. 12Z run of the ECMWF...which was the
strongest and wettest of the bunch and mirrored the latest GEM and
parallel 13km GFS...has flip flopped from previous run and now
mirrors the weaker, more progressive GFS solution. This would lead
to a mainly dry holiday period, especially in most locations in
the Valley. Of bigger note would be infiltration of colder air and
lower snow levels. Snow levels could drop to 3000-3500 feet by
Thursday with accumulating snow and travel headaches likely if
a stronger system does materialize. Overnight temps late in the week
could also drop into the 30s in some spots in the valley leading
to frost. Confidence is low in details and chances for
precipitation at this point so have not made major changes to the
going forecast. Will need to be monitored as we get closer. CEO

&&

.Aviation...

Mainly VFR conditions across the area this afternoon, except local
MVFR along the west side of the Valley. Next low pressure system
is approaching California, with -RA developing along the Northern
Valley between 09-12z, and Sacramento TAF sites by 15-18z.
MVFR/IFR conditions possible in the Valley, with IFR/LIFR
conditions in the mountains. Snow levels will be between 5000-6000
ft. Southeast winds will increase to 10-18 kt late tonight into
Friday.

Dang


&&

.STO Watches/Warnings/Advisories...
winter weather advisory from 4 am to 10 pm pst friday above 6000
feet in the west slope northern sierra nevada...western plumas
county/lassen park.

&&

$$








000
FXUS66 KSTO 181722
AFDSTO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
922 AM PST Thu Dec 18 2014

.Synopsis...
Fairly dry today for the region. Next frontal system moves through
NORCAL Friday bringing relatively light rain and mountain snow.
Drying south on Saturday with a few showers north especially over
the mountains. All areas dry on Sunday except far northern Shasta
county mountains. Dry Monday/Tuesday under high pressure ridge.
Slight chance of mainly mountain showers on Wednesday.

&&

.Discussion...
No updates needed this morning. Dry forecast for NorCal today. The next
front which will impact us Friday into Saturday and we will focus
on reviewing snow amounts since the CNRFC has slightly increased
the amount of precipitation this morning. JBB

.Previous Discussion...Northern California should be mainly dry today as a
small scale ridge slides across the west coast. This fairly dirty
ridge will allow plenty of clouds to spill over the area today and
can not rule out a few light showers over the mountains where
orographics may squeeze out a light shower or snow flurry. The
next Pacific storm system to impact the region has now crossed 130
west and is forecast to move into northwest California early
Friday morning. The bulk of the moisture associated with this
system is forecast to drop southward into north central California
so is not expected to be a major precipitation producer over
NORCAL. Most valley locations should only see a few tenths of an
inch of rain with locations above about 5000 feet seeing a few to
several inches of snow or enough for some minor travel impacts.
Upper ridging slowly rebuilds along the west coast Saturday and
Sunday with the precip threat retreating northward. On
Saturday...areas north of about Sacramento will see a threat of
light showers but by Sunday afternoon only Shasta county is likely
to see any precipitation threat at all. Clearer skies and a
warming airmass under the ridge will allow daytime highs to warm
to near normal on Saturday and to a few to several degrees above
normal on Sunday.


.Extended Discussion (Monday through Thursday)

Medium range models continue the transition to a drier weather
pattern into early next week. The main weather impact will be
valley and adjacent lower foothill stratus/fog nights and
mornings.

Longer range models are coming more inline with the evolution of
a deepening trough over the Pacific Northwest and into the Great
Basin toward the middle of next week. The ECMWF and GFS offer a
solution that would squeeze the bubble high westward and bring in
colder air with some lower elevation snow to the Sierra. The
colder ECMWF has the deeper low farther southwest over NV, while
the GFS is farther northeast over ID/MT. The pattern doesn`t look
to be a big rain/snow producer, but we have included a limited
mention of mountain precip focusing on the Sierra. Northerly winds
are likely to develop behind this front late in the week.
Depending on the winds, this pattern could bring widespread
minimum temperatures well into the 30s across the valley with some
areas of frost.     JClapp


&&

.Aviation...

Upper ridge moving in today with fairly light winds. Areas of
valley MVFR this morn with local IFR near valley edge and over
mountains. Next trough over area late tonight into Friday with
showers. Enough cloudiness will limit fog production.
JClapp


&&

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

$$








000
FXUS66 KSTO 181722
AFDSTO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
922 AM PST Thu Dec 18 2014

.Synopsis...
Fairly dry today for the region. Next frontal system moves through
NORCAL Friday bringing relatively light rain and mountain snow.
Drying south on Saturday with a few showers north especially over
the mountains. All areas dry on Sunday except far northern Shasta
county mountains. Dry Monday/Tuesday under high pressure ridge.
Slight chance of mainly mountain showers on Wednesday.

&&

.Discussion...
No updates needed this morning. Dry forecast for NorCal today. The next
front which will impact us Friday into Saturday and we will focus
on reviewing snow amounts since the CNRFC has slightly increased
the amount of precipitation this morning. JBB

.Previous Discussion...Northern California should be mainly dry today as a
small scale ridge slides across the west coast. This fairly dirty
ridge will allow plenty of clouds to spill over the area today and
can not rule out a few light showers over the mountains where
orographics may squeeze out a light shower or snow flurry. The
next Pacific storm system to impact the region has now crossed 130
west and is forecast to move into northwest California early
Friday morning. The bulk of the moisture associated with this
system is forecast to drop southward into north central California
so is not expected to be a major precipitation producer over
NORCAL. Most valley locations should only see a few tenths of an
inch of rain with locations above about 5000 feet seeing a few to
several inches of snow or enough for some minor travel impacts.
Upper ridging slowly rebuilds along the west coast Saturday and
Sunday with the precip threat retreating northward. On
Saturday...areas north of about Sacramento will see a threat of
light showers but by Sunday afternoon only Shasta county is likely
to see any precipitation threat at all. Clearer skies and a
warming airmass under the ridge will allow daytime highs to warm
to near normal on Saturday and to a few to several degrees above
normal on Sunday.


.Extended Discussion (Monday through Thursday)

Medium range models continue the transition to a drier weather
pattern into early next week. The main weather impact will be
valley and adjacent lower foothill stratus/fog nights and
mornings.

Longer range models are coming more inline with the evolution of
a deepening trough over the Pacific Northwest and into the Great
Basin toward the middle of next week. The ECMWF and GFS offer a
solution that would squeeze the bubble high westward and bring in
colder air with some lower elevation snow to the Sierra. The
colder ECMWF has the deeper low farther southwest over NV, while
the GFS is farther northeast over ID/MT. The pattern doesn`t look
to be a big rain/snow producer, but we have included a limited
mention of mountain precip focusing on the Sierra. Northerly winds
are likely to develop behind this front late in the week.
Depending on the winds, this pattern could bring widespread
minimum temperatures well into the 30s across the valley with some
areas of frost.     JClapp


&&

.Aviation...

Upper ridge moving in today with fairly light winds. Areas of
valley MVFR this morn with local IFR near valley edge and over
mountains. Next trough over area late tonight into Friday with
showers. Enough cloudiness will limit fog production.
JClapp


&&

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

$$









000
FXUS66 KSTO 181219
AFDSTO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
419 AM PST Thu Dec 18 2014

.Synopsis...
A few light showers over the mountains today...otherwise dry. Next
frontal system moves through NORCAL Friday bringing relatively
light rain and mountain snow. Drying south on Saturday with a few
showers north especially over the mountains. All areas dry on
Sunday except far northern Shasta county mountains. Dry
Monday/Tuesday under high pressure ridge. Slight chance of mainly
mountain showers on Wednesday.

&&

.Discussion...
A weak shortwave trough which moved through NORCAL overnight has now
moved south and east or the region. Showers are diminishing to the
south and east at this time and will allow winter weather advisory
over the Sierra to expire shortly. Once these few lingering
showers clear out...Northern California should be mainly dry today
as a small scale ridge slides across the west coast. This fairly
dirty ridge will allow plenty of clouds to spill over the area
today and can not rule out a few light showers over the mountains
where orographics may squeeze out a light shower or snow flurry.
The next Pacific storm system to impact the region has now crossed
130 west and is forecast to move into northwest California early
Friday morning. The bulk of the moisture associated with this
system is forecast to drop southward into north central California
so is not expected to be a major precipitation producer over
NORCAL. Most valley locations should only see a few tenths of an
inch of rain with locations above about 5000 feet seeing a few to
several inches of snow or enough for some minor travel impacts.
Upper ridging slowly rebuilds along the west coast Saturday and
Sunday with the precip threat retreating northward. On
Saturday...areas north of about Sacramento will see a threat of
light showers but by Sunday afternoon only Shasta county is likely
to see any precipitation threat at all. Clearer skies and a
warming airmass under the ridge will allow daytime highs to warm
to near normal on Saturday and to a few to several degrees above
normal on Sunday.


.Extended Discussion (Monday through Thursday)

Medium range models continue the transition to a drier weather
pattern into early next week. The main weather impact will be
valley and adjacent lower foothill stratus/fog nights and
mornings.

Longer range models are coming more inline with the evolution of
a deepening trough over the Pacific Northwest and into the Great
Basin toward the middle of next week. The ECMWF and GFS offer a
solution that would squeeze the bubble high westward and bring in
colder air with some lower elevation snow to the Sierra. The
colder ECMWF has the deeper low farther southwest over NV, while
the GFS is farther northeast over ID/MT. The pattern doesn`t look
to be a big rain/snow producer, but we have included a limited
mention of mountain precip focusing on the Sierra. Northerly winds
are likely to develop behind this front late in the week.
Depending on the winds, this pattern could bring widespread
minimum temperatures well into the 30s across the valley with some
areas of frost.     JClapp


&&

.Aviation...

Upper ridge moving in today with fairly light winds. Areas of
valley MVFR this morn with local IFR near valley edge and over
mountains. Next trough over area late tonight into Friday with
showers. Enough cloudiness will limit fog production.
JClapp


&&

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

$$








000
FXUS66 KSTO 181219
AFDSTO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
419 AM PST Thu Dec 18 2014

.Synopsis...
A few light showers over the mountains today...otherwise dry. Next
frontal system moves through NORCAL Friday bringing relatively
light rain and mountain snow. Drying south on Saturday with a few
showers north especially over the mountains. All areas dry on
Sunday except far northern Shasta county mountains. Dry
Monday/Tuesday under high pressure ridge. Slight chance of mainly
mountain showers on Wednesday.

&&

.Discussion...
A weak shortwave trough which moved through NORCAL overnight has now
moved south and east or the region. Showers are diminishing to the
south and east at this time and will allow winter weather advisory
over the Sierra to expire shortly. Once these few lingering
showers clear out...Northern California should be mainly dry today
as a small scale ridge slides across the west coast. This fairly
dirty ridge will allow plenty of clouds to spill over the area
today and can not rule out a few light showers over the mountains
where orographics may squeeze out a light shower or snow flurry.
The next Pacific storm system to impact the region has now crossed
130 west and is forecast to move into northwest California early
Friday morning. The bulk of the moisture associated with this
system is forecast to drop southward into north central California
so is not expected to be a major precipitation producer over
NORCAL. Most valley locations should only see a few tenths of an
inch of rain with locations above about 5000 feet seeing a few to
several inches of snow or enough for some minor travel impacts.
Upper ridging slowly rebuilds along the west coast Saturday and
Sunday with the precip threat retreating northward. On
Saturday...areas north of about Sacramento will see a threat of
light showers but by Sunday afternoon only Shasta county is likely
to see any precipitation threat at all. Clearer skies and a
warming airmass under the ridge will allow daytime highs to warm
to near normal on Saturday and to a few to several degrees above
normal on Sunday.


.Extended Discussion (Monday through Thursday)

Medium range models continue the transition to a drier weather
pattern into early next week. The main weather impact will be
valley and adjacent lower foothill stratus/fog nights and
mornings.

Longer range models are coming more inline with the evolution of
a deepening trough over the Pacific Northwest and into the Great
Basin toward the middle of next week. The ECMWF and GFS offer a
solution that would squeeze the bubble high westward and bring in
colder air with some lower elevation snow to the Sierra. The
colder ECMWF has the deeper low farther southwest over NV, while
the GFS is farther northeast over ID/MT. The pattern doesn`t look
to be a big rain/snow producer, but we have included a limited
mention of mountain precip focusing on the Sierra. Northerly winds
are likely to develop behind this front late in the week.
Depending on the winds, this pattern could bring widespread
minimum temperatures well into the 30s across the valley with some
areas of frost.     JClapp


&&

.Aviation...

Upper ridge moving in today with fairly light winds. Areas of
valley MVFR this morn with local IFR near valley edge and over
mountains. Next trough over area late tonight into Friday with
showers. Enough cloudiness will limit fog production.
JClapp


&&

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

$$









000
FXUS66 KSTO 181219
AFDSTO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
419 AM PST Thu Dec 18 2014

.Synopsis...
A few light showers over the mountains today...otherwise dry. Next
frontal system moves through NORCAL Friday bringing relatively
light rain and mountain snow. Drying south on Saturday with a few
showers north especially over the mountains. All areas dry on
Sunday except far northern Shasta county mountains. Dry
Monday/Tuesday under high pressure ridge. Slight chance of mainly
mountain showers on Wednesday.

&&

.Discussion...
A weak shortwave trough which moved through NORCAL overnight has now
moved south and east or the region. Showers are diminishing to the
south and east at this time and will allow winter weather advisory
over the Sierra to expire shortly. Once these few lingering
showers clear out...Northern California should be mainly dry today
as a small scale ridge slides across the west coast. This fairly
dirty ridge will allow plenty of clouds to spill over the area
today and can not rule out a few light showers over the mountains
where orographics may squeeze out a light shower or snow flurry.
The next Pacific storm system to impact the region has now crossed
130 west and is forecast to move into northwest California early
Friday morning. The bulk of the moisture associated with this
system is forecast to drop southward into north central California
so is not expected to be a major precipitation producer over
NORCAL. Most valley locations should only see a few tenths of an
inch of rain with locations above about 5000 feet seeing a few to
several inches of snow or enough for some minor travel impacts.
Upper ridging slowly rebuilds along the west coast Saturday and
Sunday with the precip threat retreating northward. On
Saturday...areas north of about Sacramento will see a threat of
light showers but by Sunday afternoon only Shasta county is likely
to see any precipitation threat at all. Clearer skies and a
warming airmass under the ridge will allow daytime highs to warm
to near normal on Saturday and to a few to several degrees above
normal on Sunday.


.Extended Discussion (Monday through Thursday)

Medium range models continue the transition to a drier weather
pattern into early next week. The main weather impact will be
valley and adjacent lower foothill stratus/fog nights and
mornings.

Longer range models are coming more inline with the evolution of
a deepening trough over the Pacific Northwest and into the Great
Basin toward the middle of next week. The ECMWF and GFS offer a
solution that would squeeze the bubble high westward and bring in
colder air with some lower elevation snow to the Sierra. The
colder ECMWF has the deeper low farther southwest over NV, while
the GFS is farther northeast over ID/MT. The pattern doesn`t look
to be a big rain/snow producer, but we have included a limited
mention of mountain precip focusing on the Sierra. Northerly winds
are likely to develop behind this front late in the week.
Depending on the winds, this pattern could bring widespread
minimum temperatures well into the 30s across the valley with some
areas of frost.     JClapp


&&

.Aviation...

Upper ridge moving in today with fairly light winds. Areas of
valley MVFR this morn with local IFR near valley edge and over
mountains. Next trough over area late tonight into Friday with
showers. Enough cloudiness will limit fog production.
JClapp


&&

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

$$









000
FXUS66 KSTO 181219
AFDSTO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
419 AM PST Thu Dec 18 2014

.Synopsis...
A few light showers over the mountains today...otherwise dry. Next
frontal system moves through NORCAL Friday bringing relatively
light rain and mountain snow. Drying south on Saturday with a few
showers north especially over the mountains. All areas dry on
Sunday except far northern Shasta county mountains. Dry
Monday/Tuesday under high pressure ridge. Slight chance of mainly
mountain showers on Wednesday.

&&

.Discussion...
A weak shortwave trough which moved through NORCAL overnight has now
moved south and east or the region. Showers are diminishing to the
south and east at this time and will allow winter weather advisory
over the Sierra to expire shortly. Once these few lingering
showers clear out...Northern California should be mainly dry today
as a small scale ridge slides across the west coast. This fairly
dirty ridge will allow plenty of clouds to spill over the area
today and can not rule out a few light showers over the mountains
where orographics may squeeze out a light shower or snow flurry.
The next Pacific storm system to impact the region has now crossed
130 west and is forecast to move into northwest California early
Friday morning. The bulk of the moisture associated with this
system is forecast to drop southward into north central California
so is not expected to be a major precipitation producer over
NORCAL. Most valley locations should only see a few tenths of an
inch of rain with locations above about 5000 feet seeing a few to
several inches of snow or enough for some minor travel impacts.
Upper ridging slowly rebuilds along the west coast Saturday and
Sunday with the precip threat retreating northward. On
Saturday...areas north of about Sacramento will see a threat of
light showers but by Sunday afternoon only Shasta county is likely
to see any precipitation threat at all. Clearer skies and a
warming airmass under the ridge will allow daytime highs to warm
to near normal on Saturday and to a few to several degrees above
normal on Sunday.


.Extended Discussion (Monday through Thursday)

Medium range models continue the transition to a drier weather
pattern into early next week. The main weather impact will be
valley and adjacent lower foothill stratus/fog nights and
mornings.

Longer range models are coming more inline with the evolution of
a deepening trough over the Pacific Northwest and into the Great
Basin toward the middle of next week. The ECMWF and GFS offer a
solution that would squeeze the bubble high westward and bring in
colder air with some lower elevation snow to the Sierra. The
colder ECMWF has the deeper low farther southwest over NV, while
the GFS is farther northeast over ID/MT. The pattern doesn`t look
to be a big rain/snow producer, but we have included a limited
mention of mountain precip focusing on the Sierra. Northerly winds
are likely to develop behind this front late in the week.
Depending on the winds, this pattern could bring widespread
minimum temperatures well into the 30s across the valley with some
areas of frost.     JClapp


&&

.Aviation...

Upper ridge moving in today with fairly light winds. Areas of
valley MVFR this morn with local IFR near valley edge and over
mountains. Next trough over area late tonight into Friday with
showers. Enough cloudiness will limit fog production.
JClapp


&&

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

$$








000
FXUS66 KSTO 180500
AFDSTO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
900 PM PST Wed Dec 17 2014

.Synopsis...
Yet another wave of rain/snow moving in tonight. A brief break in
precipitation some areas on Thursday. Next frontal passage on
Friday with light to moderate rain and higher elevation snow into
Saturday morning. Mountain showers possible over the weekend but mainly
dry in the valley. Dry all areas Monday through mid week under
west coast high pressure ridge.

&&

.Discussion...
A weak cold front is moving through the interior this evening.
Light amounts of precipitation are spreading through the
interior. Amounts will generally be less than a quarter
inch for all areas.

Snowfall will be picking up after about 11 pm. Models indicate the
intensity of precipitation decreasing again as it moves over the
Sierra and will generally bring less than 3 inches of snow during
the overnight hours. Snow levels are generally above 4500 feet but
may get down locally to around 4000 feet overnight. Some patches
of fog will likely develop in the late night and morning hours but
it may not be too bad in the morning with some cloud cover moving
into the region behind this front. Most areas will be drying out on
Thursday with some lingering showers over the mountains and north
end of the valley.

Another weak system for the area will move through on Friday
followed by a building ridge of high pressure for the weekend.
The GFS is the deepest with the weekend wave keeping precipitation
mainly north of I-80 while the NAM does the same but in the
mountains and limits any valley precipitation to the north end of
the Sacramento Valley. The rest of California will be drying out.

.Extended Discussion (Sunday through Wednesday)

Medium range models similar in transitioning to a drier weather
pattern over the weekend into early next week. Some light precip
continues to be depicted over the Shasta mountains Sunday,
otherwise dry weather with the main weather concern being impact
of valley stratus and/or fog nights and mornings. Models
strengthen upper high in EPAC with associated upper ridge building
over Interior NorCal.

Longer range models are struggling with the evolution of a
deepening trough over the Pacific Northwest toward the middle of
next week. The ECMWF and Parallel-GFS offer a solution that brings
the system farther westward, which could bring some low elevation
snow to the Sierra. The lo-res GFS and GEM swing the trough through
the Rockies, which would be a drier solution for Northern
California. For now, we`ve included "chance" wording in the
forecast focusing on the Sierra.

Dang / JClapp


&&

.Aviation...

Trof movg E tngt then upr rdg Thu. For Intr NorCal, areas
MVFR/IFR tda into Thu mrng in prec with lcl LIFR omtns. Sn lvls
040-045 ft AMSL.


&&

.STO Watches/Warnings/Advisories...
winter weather advisory until 4 am pst thursday above 4000 feet
in the west slope northern sierra nevada...western plumas
county/lassen park.

&&

$$








000
FXUS66 KSTO 180500
AFDSTO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
900 PM PST Wed Dec 17 2014

.Synopsis...
Yet another wave of rain/snow moving in tonight. A brief break in
precipitation some areas on Thursday. Next frontal passage on
Friday with light to moderate rain and higher elevation snow into
Saturday morning. Mountain showers possible over the weekend but mainly
dry in the valley. Dry all areas Monday through mid week under
west coast high pressure ridge.

&&

.Discussion...
A weak cold front is moving through the interior this evening.
Light amounts of precipitation are spreading through the
interior. Amounts will generally be less than a quarter
inch for all areas.

Snowfall will be picking up after about 11 pm. Models indicate the
intensity of precipitation decreasing again as it moves over the
Sierra and will generally bring less than 3 inches of snow during
the overnight hours. Snow levels are generally above 4500 feet but
may get down locally to around 4000 feet overnight. Some patches
of fog will likely develop in the late night and morning hours but
it may not be too bad in the morning with some cloud cover moving
into the region behind this front. Most areas will be drying out on
Thursday with some lingering showers over the mountains and north
end of the valley.

Another weak system for the area will move through on Friday
followed by a building ridge of high pressure for the weekend.
The GFS is the deepest with the weekend wave keeping precipitation
mainly north of I-80 while the NAM does the same but in the
mountains and limits any valley precipitation to the north end of
the Sacramento Valley. The rest of California will be drying out.

.Extended Discussion (Sunday through Wednesday)

Medium range models similar in transitioning to a drier weather
pattern over the weekend into early next week. Some light precip
continues to be depicted over the Shasta mountains Sunday,
otherwise dry weather with the main weather concern being impact
of valley stratus and/or fog nights and mornings. Models
strengthen upper high in EPAC with associated upper ridge building
over Interior NorCal.

Longer range models are struggling with the evolution of a
deepening trough over the Pacific Northwest toward the middle of
next week. The ECMWF and Parallel-GFS offer a solution that brings
the system farther westward, which could bring some low elevation
snow to the Sierra. The lo-res GFS and GEM swing the trough through
the Rockies, which would be a drier solution for Northern
California. For now, we`ve included "chance" wording in the
forecast focusing on the Sierra.

Dang / JClapp


&&

.Aviation...

Trof movg E tngt then upr rdg Thu. For Intr NorCal, areas
MVFR/IFR tda into Thu mrng in prec with lcl LIFR omtns. Sn lvls
040-045 ft AMSL.


&&

.STO Watches/Warnings/Advisories...
winter weather advisory until 4 am pst thursday above 4000 feet
in the west slope northern sierra nevada...western plumas
county/lassen park.

&&

$$









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