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000
FXUS66 KSTO 210439
AFDSTO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
935 PM PDT Sun Apr 20 2014

.Synopsis...
A Pacific trough will approach the coast Monday bringing
increasing clouds and a chance of rain and higher elevation snow
Monday night and Tuesday. Another trough will bring unsettled
conditions Friday and Saturday.

&&

.Discussion...

Darkening in the water vapor imagery this evening indicative of a
well defined vort max rotating Ewd with the Ern Pac trof. This trof
is tapping into a modest PW plume of about six to seven tenths of an
inch north of 35N...with the higher PWs to the south. Thus...the
potential for a modest precip event will be challenged by the lower
PW air off the coast which the frontal band must navigate on MON
likely eroding the plume to some degree...and the forecast splitting
of the vort max as the trof approaches/nears Norcal. The apparent
timing of the precip seems to indicate that interior Norcal will
remain dry until the late afternoon and evening hours when some
scattered showers should develop...per the WRF.

Most of the rain is likely to hold off until the Mon nite (after
midnite)/Tue morning period...with widespread showers over the
Siernev Tue afternoon...and decreasing activity in the Valley. Looks
as if the WRF indicates (forecasts) a decent band of convective
precip along the I-80/Hwy 50 corridor early Tue afternoon
corresponding to the passage of the upper trof axis.

This weekend`s Bufkit forecast hodographs for the valley on Tue
mainly showed straight line hodographs indicative of more
multicellular convection than supercellular convection. Generally...
some of the storms may contain small hail rather than rotating
updrafts this time around.

A much cooler day on Tue with 850 mbs temps and low to mid level
thicknesses some 13 deg/20 dam lower than Sun. Max temps in the
valley should only reach into the 60s.    JHM

.Previous Discussion...

Upper trough will move east towards the coast late tonight with
increasing clouds after midnight...but no precip. Trough will
deepen as it moves along the coast tomorrow. Scattered showers will
move over the coastal range and northern Shasta county during the
afternoon. High temperatures will cool into the mid to upper
70`s at most valley spots...due to the increased cloud cover.
These readings are still about 5 degrees above normal.

Band of showers with frontal system will move across Norcal after
midnight. Sufficient instability is indicated by modified
totals/totals over the northern and central Sacramento valley for
thunderstorms and decided to add slight thunderstorm chances for
these areas. Lift will also be aided by initial vort lobe swinging
through the area.

Skies will turn partly cloudy Tuesday morning behind leading
moisture band. Models prog best instability over the valley 11am-
4pm Tuesday and showers and isolated thunderstorm should develop
with surface heating. Snow levels will drop to 4500 feet during
the afternoon. Up to 2 inches of snow will be possible at pass
levels during the afternoon and evening. Qpf`s will generally be
light outside of thunderstorms with this system as most valley
locations receive 0.10 inches or less. High temperatures will
cool into the mid and upper 60`s for valleys.

Trough will move into the great basin region on Wednesday...but an
unsettled northwest flow will keep shower chances over the
northern mountains and Shasta county. Temperatures will warm into
low 70`s at most valley locations. Another trough will approach
the area Thursday increasing the shower chances over northern and
western areas.

.Extended Discussion (Thursday through Sunday)

Ridging Thursday will bring a brief return to above normal highs,
before a cool shortwave from the Gulf of Alaska begins edging into
the area late afternoon/evening. Showers will begin to spread into
the northern and Coastal Mountains, then into most of area by
Friday. Peak precipitation over the north is expected Friday
afternoon, over the Sierra Friday evening (snow levels around 6000
ft). Lingering showers continue int Saturday. Precipitation totals
of an inch or possibly 2 possible for the higher mountains.

Another wave may arrive Saturday night/Sunday across most of the
area (ECMWF) or weak ridging with some moisture over the northern
mountains. Will lean towards the wetter ECMWF for now, with the
weekend remaining relatively wet and with below normal
temperatures. EK

&&

.Aviation...

VFR conditions will continue through Monday afternoon across
interior Northern California. Generally light Valley winds will
become southerly 5-15 kt across the Valley ahead of a low pressure
system Monday. Near KRDD-KRBL, south winds 15-20 kt with gusts to 35
kt possible Monday afternoon. Look for precipitation to spread into
Northern Interior CA after 00z Tuesday, with IFR/LIFR conditions
possible over the mountains.

Dang

&&

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

$$







000
FXUS66 KSTO 202246
AFDSTO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
346 PM PDT Sun Apr 20 2014

.Synopsis...
A Pacific trough will approach the coast Monday bringing
increasing clouds and a chance of rain and higher elevation snow
Monday night and Tuesday. Another trough will bring unsettled
conditions Friday and Saturday.

&&

.Discussion...

Upper trough will move west towards the coast late tonight with
increasing clouds after midnight...but no precip. Trough will
deepen as it moves along the coast tomorrow. Scattered showers will
move over the coastal range and northern Shasta county during the
afternoon. High temperatures will cool into the mid to upper
70`s at most valley spots...due to the increased cloud cover.
These readings are still about 5 degrees above normal.

Band of showers with frontal system will move across Norcal after
midnight. Sufficient instability is indicated by modified
totals/totals over the northern and central Sacramento valley for
thunderstorms and decided to add slight thunderstorm chances for
these areas. Lift will also be aided by initial vort lobe swinging
through the area.

Skies will turn partly cloudy Tuesday morning behind leading
moisture band. Models prog best instability over the valley 11am-
4pm Tuesday and showers and isolated thunderstorm should develop
with surface heating. Snow levels will drop to 4500 feet during
the afternoon. Up to 2 inches of snow will be possible at pass
levels during the afternoon and evening. Qpf`s will generally be
light outside of thunderstorms with this system as most valley
locations receive 0.10 inches or less. High temperatures will
cool into the mid and upper 60`s for valleys.

Trough will move into the great basin region on Wednesday...but an
unsettled northwest flow will keep shower chances over the
northern mountains and Shasta county. Temperatures will warm into
low 70`s at most valley locations. Another trough will approach
the area Thursday increasing the shower chances over northern and
western areas.

.Extended Discussion (Thursday through Sunday)

Ridging Thursday will bring a brief return to above normal highs,
before a cool shortave from the Gulf of Alaska begins edging into
the area late afternoon/evening. Showers will begin to spread into
the northern and Coastal Mountains, then into most of area by
Friday. Peak precipitation over the north is expected Friday
afternoon, over the Sierra Friday evening (snow levels around 6000
ft). Lingering showers continue int Saturday. Precipitation totals
of an inch or possibly 2 possible for the higher mountains.

Another wave may arrive Saturday night/Sunday across most of the
area (ECMWF) or weak ridging with some moisture over the northern
mountains. Will lean towards the wetter ECMWF for now, with the
weekend remaining relatively wet and with below normal
temperatures. EK

&&

.Aviation...

VFR conditions will continue the next 24 hours across interior
Northern California. Northwest winds 5-15 kt across the Valley
will become light tonight, except local breezy southwest winds
near the Delta. Winds will become southerly 5-15 kt across the
Valley ahead of a low pressure system Monday. Near KRDD-KRBL,
south winds 15-20 kt with gusts to 35 kt possible Monday
afternoon.

Dang


&&

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

$$









000
FXUS66 KSTO 202236
AFDSTO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
336 PM PDT Sun Apr 20 2014

.Synopsis...
A Pacific trough will approach the coast Monday bringing
increasing clouds and a chance of rain and higher elevation snow
Monday night and Tuesday. Another trough will bring unsettled
conditions Friday and Saturday.

&&

.Discussion...

Upper trough will move west towards the coast late tonight with
increasing clouds after midnight...but no precip. Trough will
deepen as it moves along the coast tomorrow. Scattered showers will
move over the coastal range and northern Shasta county during the
afternoon. High temperatures will cool into the mid to upper
70`s at most valley spots...due to the increased cloud cover.
These readings are still about 5 degrees above normal.

Band of showers with frontal system will move across Norcal after
midnight. Sufficient instability is indicated by modified
totals/totals over the northern and central Sacramento valley for
thunderstorms and decided to add slight thunderstorm chances for
these areas. Lift will also be aided by initial vort lobe swinging
through the area.

Skies will turn partly cloudy Tuesday morning behind leading
moisture band. Models prog best instability over the valley 11am-
4pm Tuesday and showers and isolated thunderstorm should develop
with surface heating. Snow levels will drop to 4500 feet during
the afternoon. Up to 2 inches of snow will be possible at pass
levels during the afternoon and evening. Qpf`s will generally be
light outside of thunderstorms with this system as most valley
locations receive 0.10 inches or less. High temperatures will
cool into the mid and upper 60`s for valleys.

Trough will move into the great basin region on Wednesday...but an
unsettled northwest flow will keep shower chances over the
northern mountains and Shasta county.

.Extended Discussion (Thursday through Sunday)

Mostly dry conditions on Thursday with above normal daytime highs.
Could see a few lingering showers over the northern mountains,
though. Valley highs in the mid to upper 70s with some isolated
spots reaching 80. By Friday, NorCal will transition back to a
cooler, wetter pattern as a cold front brings chances of
precipitation over much of the area by afternoon. Additional
storm waves will continue through the weekend, with continued wet periods
and below normal temperatures. However, models are out of synch
for the details over the weekend. The GFS & GEM show another wet
storm impacting NorCal on Saturday but the ECMWF shows less
precipitation for that system. Then on Sunday, the ECMWF shows a
wetter storm wave moving into NorCal while the GFS & GEM trend towards
a weak ridge over the region. Have generally kept a mention of
precipitation through the weekend until details become more clear.

&&

.Aviation...

VFR conditions will continue the next 24 hours across interior
Northern California. Northwest winds 5-15 kt across the Valley
will become light tonight, except local breezy southwest winds
near the Delta. Winds will become southerly 5-15 kt across the
Valley ahead of a low pressure system Monday. Near KRDD-KRBL,
south winds 15-20 kt with gusts to 35 kt possible Monday
afternoon.

Dang


&&

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

$$









000
FXUS66 KSTO 201656
AFDSTO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
956 AM PDT Sun Apr 20 2014

.Synopsis...
Warm temperatures under high pressure ridge this afternoon. A
Pacific trough will approach the coast Monday bringing increasing
clouds and a chance of rain and higher elevation snow Monday
night and Tuesday. Another trough will bring unsettled conditions
Friday and Saturday.

&&

.Discussion...
Temperatures are running 5 to 10 degrees warmer versus 24 hours at
most valley locations. Have updated forecast to raise high temps
a few degrees to match better with short term guidance. This gives
high temperatures in the low to mid 80`s for valley areas.
Otherwise...dry conditions with generally light winds. A weak
delta breeze will develop through the delta...but not move farther
east than about Davis.

.Previous Discussion...
Weak high pressure building over the region today will produce
light northerly winds and warmer temperatures. Highs today will be
in the low to mid 80s in the central valley with 60s to lower 70s
for the mountains.

On Monday a stronger shortwave will approach the interior and may
be able to produce a few mountains showers for the afternoon over
the far northern sections ahead of the front. At this time the
system looks to start to move inland Monday night. Cooler air
filtering into the region will cool valley temperatures back into
the 70s.

The system will still be impacting the interior on Tuesday with
showers and isolated thunderstorms expected over most of the
interior. Snow levels will remain above pass level through Monday
but lower Monday night and Tuesday below major pass levels in the
Sierra Nevada. Not a lot of snow or precipitation is forecast at
this time but several inches of snow near pass levels look
possible. Temperatures will continue to cool on Tuesday which
looks like the coldest day this week. Highs will be in the 60s for
the central valley.

On Wednesday the system will have moved well to the northeast of
the area to keep most areas dry. Zonal flow into the far northern
part of the state may produce a few showers over the southern
Cascades otherwise expect dry and warmer conditions to prevail.


.Extended Discussion (Thursday through Sunday)

Mostly dry conditions on Thursday with above normal daytime highs.
Could see a few lingering showers over the northern mountains,
though. Valley highs in the mid to upper 70s with some isolated
spots reaching 80. By Friday, NorCal will transition back to a
cooler, wetter pattern as a cold front brings chances of
precipitation over much of the area by afternoon. Additional
storm waves will continue through the weekend, with continued wet periods
and below normal temperatures. However, models are out of synch
for the details over the weekend. The GFS & GEM show another wet
storm impacting NorCal on Saturday but the ECMWF shows less
precipitation for that system. Then on Sunday, the ECMWF shows a
wetter storm wave moving into NorCal while the GFS & GEM trend towards
a weak ridge over the region. Have generally kept a mention of
precipitation through the weekend until details become more clear.

&&

.Aviation...

VFR conditions will continue the next 24 hours across interior
Northern California. North to Northwest winds 5-15 kt for TAF
sites. Stronger winds will develop again in the delta region with
gusts up to 25 kt.

&&

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

$$









000
FXUS66 KSTO 201023
AFDSTO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
323 AM PDT Sun Apr 20 2014

.Synopsis...
Building high pressure today will result in light northerly winds
and warmer temperatures. A stronger Pacific trough will approach
the coast Monday bringing increasing clouds and a chance of rain
and higher elevation snow on Monday night and Tuesday. Some areas
may also see isolated thunderstorms. Weak high pressure will dry
things out for most areas Wednesday and Thursday with a threat of
precipitation continuing across the far northern sections of the
state. Another trough will bring a chance of rain to all of
interior Northern California Friday into Saturday.

&&

.Short Term Discussion...
Weak high pressure building over the region today will produce
light northerly winds and warmer temperatures. Highs today will be
in the low to mid 80s in the central valley with 60s to lower 70s
for the mountains.

On Monday a stronger shortwave will approach the interior and may
be able to produce a few mountains showers for the afternoon over
the far northern sections ahead of the front. At this time the
system looks to start to move inland Monday night. Cooler air
filtering into the region will cool valley temperatures back into
the 70s.

The system will still be impacting the interior on Tuesday with
showers and isolated thunderstorms expected over most of the
interior. Snow levels will remain above pass level through Monday
but lower Monday night and Tuesday below major pass levels in the
Sierra Nevada. Not a lot of snow or precipitation is forecast at
this time but several inches of snow near pass levels look
possible. Temperatures will continue to cool on Tuesday which
looks like the coldest day this week. Highs will be in the 60s for
the central valley.

On Wednesday the system will have moved well to the northeast of
the area to keep most areas dry. Zonal flow into the far northern
part of the state may produce a few showers over the southern
Cascades otherwise expect dry and warmer conditions to prevail.


.Extended Discussion (Thursday through Sunday)

Mostly dry conditions on Thursday with above normal daytime highs.
Could see a few lingering showers over the northern mountains,
though. Valley highs in the mid to upper 70s with some isolated
spots reaching 80. By Friday, NorCal will transition back to a
cooler, wetter pattern as a cold front brings chances of
precipitation over much of the area by afternoon. Additional
storm waves will continue through the weekend, with continued wet periods
and below normal temperatures. However, models are out of synch
for the details over the weekend. The GFS & GEM show another wet
storm impacting NorCal on Saturday but the ECMWF shows less
precipitation for that system. Then on Sunday, the ECMWF shows a
wetter storm wave moving into NorCal while the GFS & GEM trend towards
a weak ridge over the region. Have generally kept a mention of
precipitation through the weekend until details become more clear.

&&

.Aviation...

VFR conditions will continue the next 24 hours across interior
Northern California. North to Northwest winds 5-15 kt for TAF
sites. Stronger winds will develop again in the delta region with
gusts up to 30 kt.


&&

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

$$









000
FXUS66 KSTO 200431
AFDSTO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
930 PM PDT Sat Apr 19 2014

.Synopsis...
Building high pressure on Sunday will result in warmer temperatures.
A stronger Pacific trough will approach the coast Monday bringing
increasing clouds and a chance of rain and higher elevation snow on
Monday night and Tuesday. Some areas may also see isolated
thunderstorms. Weak high pressure will dry things out some Wednesday
and Thursday but a threat of precipitation will continue across the
far northern sections of the state. Another trough will bring
another chance of rain to all of interior Northern California Friday
into Saturday.

&&

.Short Term Discussion...
Onshore flow and the Delta Breeze will be decreasing overnight and
into Sun as 5H heights rise over Norcal in advance of the deepening
Ern Pac trof that will affect Norcal wx early next week. After the
good Delta push into the Valley today (Sat) and only a minor 20m
height rises on Sun...the Nly pressure gradients will not be as
impactful for a good katabatic wind effect. The NAMGRAD shows the
RDD-SAC gradient only up to 1 mb by 12z...decreasing after that to
near zero. In fact the SFO-SAC gradient increases to 2+ mbs Sun
afternoon and a modest Delta Breeze should return by evening. We
updated the Sun Max T grids/forecasts to reflect this...with the
maxes correlating more closely to the 850-1000mb dry adiabatic lapse
rate...generally low to mid 80s in the valley.   JHM

.Previous Discussion...

Cooler and possibly wet weather Monday into Tuesday with a
stronger trough affecting Northern California. The timing of
trough has been varying some between the models and model runs.
The 18z NAM is a little slower than the 12z NAM but the 18z GFS
is a little faster than 12Z. The quicker timing may bring
precipitation into the Coastal range and Shasta County during the
day on Monday. The best chance of precipitation will be Monday
night into early Tuesday. The trough moving through Tuesday
morning makes convection less favorable than moving through
in afternoon.  Slight chance of thunderstorms Tuesday morning then
the best instability spreads east Tuesday afternoon for a threat of
thunderstorms over the east side of Sacramento Valley and into
Western Plumas County as trough shifts east. Snow levels will
start out around 7000 ft Monday night and lowering to around 5000
ft Tuesday morning. Snow accumulations generally expected to be
less than 4 inches near pass levels.


.Extended Discussion (Wednesday through Saturday)

The upper level trough will be exiting to the east on Wednesday,
with drying conditions and high temperatures warming to near
normal levels. Could see a few lingering showers over the northern
mountains, with dry weather elsewhere. Ridging on Thursday will
bring a return to above normal highs, with Valley highs in the mid
to upper 70s to near 80. A shortwave with a surface cold front is
expected to move into the area on Friday, spreading chances of
precipitation over much of the area by afternoon. Although there
are timing differences, models continue to show a trough pattern
with unsettled and cool conditions for the end of the week.
Additional shortwaves will continue through the weekend, with more
widespread precipitation and below normal temperatures. Models are
hinting that late Saturday and Sunday could be potentially quite
wet, with a significant moisture plume. A caveat to this is the
12z GFS, which, contrary to earlier runs, is trying to build in
some weak ridging in by late Sunday. Will be watching this system
closely to see how it evolves over the coming days. EK

&&

.Aviation...

VFR conditions will continue the next 24 hours across interior
Northern California. South to west winds 5-15 kt with local gusts to
30 kt near the Delta will gradually weaken overnight. Winds will
shift to the north 5-15 kt across the Valley on Sunday.

Dang

&&

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

$$







000
FXUS66 KSTO 192230
AFDSTO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
330 PM PDT Sat Apr 19 2014

.Synopsis...
A weak system well to the north will bring slightly cooler
temperatures today. Building high pressure on Sunday will result
in northerly winds and warmer temperatures. A stronger Pacific
trough will approach the coast Monday bringing increasing clouds
and a chance of rain and higher elevation snow on Monday night and
Tuesday. Some areas may also see isolated thunderstorms. Weak high
pressure will dry things out some Wednesday and Thursday but a
threat of precipitation will continue across the far northern
sections of the state. Another trough will bring another chance of
rain to all of interior Northern California Friday into Saturday.

&&

.Short Term Discussion...
Temperatures running a few degrees cooler this afternoon in most
locations compared to yesterday due to synoptic cooling and
onshore flow with a system moving through the Pacific Northwest
Onshore flow with delta breeze with SUU winds around 20 mph and
southerly winds in the Sacramento Valley. The onshore flow will
decrease and flow will become Northerly tonight as surface high
pressure moves into the Pacific Northwest. Although the MFR-SAC
gradient expected to be about 7 MB and 925 MB winds about 20 kts
tomorrow morning so Northerly winds not expected to be very
strong. The Northerly downslope winds will locally keep some
overnight temperatures warmer tonight than last night. Weak ridge
over the area tomorrow as the system shifts east and a stronger
system approaches the west coast. This will bring warmer
temperates in the mid 80s in the valley and around 80 in the
delta and 60s and 70s in the mountains Sunday afternoon. Temperatures
cool down on Monday into the mid to upper 70s in the Valley and
50s and 60s in the mountains with the trough off the California
coast bringing synoptic cooling and onshore flow. Temperatures
cool down to below normal for this time of the year on Tuesday
with highs in the mid 60s to around 70 in the valley and 40s and
50s in the mountains as the trough moves through the area.

Cooler and possibly wet weather Monday into Tuesday with a
stronger trough affecting Northern California. The timing of
trough has been varying some between the models and model runs.
the 18z NAM is a little slower than the 12z NAM but the 18z GFS
is a little faster than 12Z. The quicker timing may bring
precipitation into the Coastal range and Shasta County during the
day on Monday. The best chance of precipitation will be Monday
night into early Tuesday. The trough moving through Tuesday
morning makes convection less favorable than moving through
in afternoon.  Slight chance of thunderstorms Tuesday morning then
the best instability spreads east Tuesday afternoon for a threat of
thunderstorms over the east side of Sacramento Valley and into
Western Plumas County as trough shifts east. Snow levels will
start out around 7000 ft Monday night and lowering to around 5000
ft Tuesday morning. Snow accumulations generally expected to be
less than 4 inches near pass levels.


.Extended Discussion (Wednesday through Saturday)

The upper level trough will be exiting to the east on Wednesday,
with drying conditions and high temperatures warming to near
normal levels. Could see a few lingering showers over the northern
mountains, with dry weather elsewhere. Ridging on Thursday will
bring a return to above normal highs, with Valley highs in the mid
to upper 70s to near 80. A shortwave with a surface cold front is
expected to move into the area on Friday, spreading chances of
precipitation over much of the area by afternoon. Although there
are timing differences, models continue to show a trough pattern
with unsettled and cool conditions for the end of the week.
Additional shortwaves will continue through the weekend, with more
widespread precipitation and below normal temperatures. Models are
hinting that late Saturday and Sunday could be potentially quite
wet, with a significant moisture plume. A caveat to this is the
12z GFS, which, contrary to earlier runs, is trying to build in
some weak ridging in by late Sunday. Will be watching this system
closely to see how it evolves over the coming days. EK

&&

.Aviation...

VFR conditions will continue the next 24 hours across interior
Northern California. South to west winds 5-15 kt with local gusts
to 30 kt near the Delta will become light tonight. Winds will
shift around to the north 5-15 kt with local gusts to 25 kt across
the Valley on Sunday.

Dang


&&

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

$$









000
FXUS66 KSTO 191703
AFDSTO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
958 AM PDT Sat Apr 19 2014

.Synopsis...
A weak system well to the north will bring slightly cooler
temperatures today. Building high pressure on Sunday will result
in northerly winds and warmer temperatures. A stronger Pacific
trough will approach the coast Monday bringing increasing clouds
and a chance of rain and higher elevation snow on Monday night and
Tuesday. Some areas may also see a chance of thunderstorms. Weak
high pressure will dry things out some Wednesday and Thursday but a
threat of precipitation will continue across the far northern
sections of the state. Another trough will bring another chance of
rain to all of interior Northern California Friday into Saturday.

&&

.Short Term Discussion...
A system is moving through the Pacific Northwest today bringing
some clouds and cooler temperatures today with synoptic cooling and
onshore flow. The Delta Breeze is blowing this morning with SF0-SAC
gradient around 3 mb and SUU winds SW around 30 mph. Temperatures
today will warm up into the upper 70s to low 80s in the valley and
low 70s in the delta and 50s and 60s in the mountains. Weak ridge
over the area tomorrow as this systems shifts east and a stronger
system approaches the west coast. This will bring warmer
temperatures and some northerly winds Sunday. The onshore flow will
turn Northerly tonight as surface high pressure moves into the
Pacific Northwest. Although the MFR-SAC gradient expected to only be
about 7 MB and 925 MB winds only about 20 kts so Northerly winds not
expected to be very strong. The Northerly downslope winds will keep
some overnight temperatures warmer tonight than last night.
Temperatures Sunday afternoon will warm into the mid 80s in the
valley and around 80 in the delta and 60s and 70s in the mountains.
Temperatures cool down on Monday into the mid to upper 70s in the
Valley and 50s and 60s in the mountains with the trough off the
California coast bringing synoptic cooling and onshore flow.
Temperatures cool down to below normal for this time of the year on
Tuesday with highs in the mid 60s to around 70 in the valley and 40s
and 50s in the mountains as the trough moves through the area.
Precipitation may begin over the Coastal range and Shasta county
Monday afternoon and spread southeast across the area by Tuesday
morning. The 12z NAM is much quicker with the trough and moves it
east of the area by Tuesday afternoon making convection less
favorable. The GFS is a little slower with a piece of energy moving
through Northern California Tuesday afternoon. The current forecast
goes with the GFS solution but may decrease precipitation amounts
and pops for afternoon forecast with drier NAM. Snow levels will
start out around 7000 ft Monday night and lowering to around 5000 ft
Tuesday morning. Not a lot of snow or precipitation is forecast at
this time but a couple of inches of snow near pass level look
possible.


.Extended Discussion (Wednesday through Saturday)

Slight warming trend begins on Wednesday as the upper low from
Monday and Tuesday moves east of our region and ridging re-
develops along the west coast. This ridge is not forecast to be
strong so lingering light showers are possible over the northern
mountains Wed & Thurs. Additional warming on Thursday as valley highs
return to the mid-upper 70s. However, by Friday and into the
weekend, another upper trough will move across our CWA bringing a
return of more widespread precipitation and cooler temperatures.
JBB

&&

.Aviation...

VFR conditions will continue next 24 hours for Central Valley TAF
sites. Generally light winds over the northern Sacramento Valley,
with winds 12-15 kt with local gusts to 21 kt expected from KSMF
southward through this afternoon. Breezy/windy in the Delta region
WS winds 15-25 kt gusting to around 35 kt.

&&

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

$$











000
FXUS66 KSTO 191658
AFDSTO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
958 AM PDT Sat Apr 19 2014

.Synopsis...
A weak system well to the north will bring slightly cooler
temperatures today. Building high pressure on Sunday will result
in northerly winds and warmer temperatures. A stronger Pacific
trough will approach the coast Monday bringing increasing clouds
and a chance of rain and higher elevation snow on Monday night and
Tuesday. Some areas may also see a chance of thunderstorms. Weak
high pressure will dry things out some Wednesday and Thursday but a
threat of precipitation will continue across the far northern
sections of the state. Another trough will bring another chance of
rain to all of interior Northern California Friday into Saturday.

&&

.Short Term Discussion...
A system is moving through the Pacific Northwest today bringing
some clouds and cooler temperatures today with synoptic cooling
and onshore flow. The Delta Breeze is blowing this morning with SF0-SAC
gradient around 3 mb and SUU winds SW around 30 mph. Temperatures
today will warm up into the upper 70s to low 80s in the valley and
low 70s in the delta and 50s and 60s in the mountains. Weak ridge
over the area tomorrow as this systems shifts east and a stronger
system approaches the west coast. This will bring warmer
temperatures and some northerly winds Sunday. The onshore flow
will turn Northerly tonight as surface high pressure moves into
the Pacific Northwest. Although the MFR-SAC gradient expected to
only be about 7 MB and 925 MB winds only about 20 kts so Northerly
winds not expected to be very strong. The Northerly downslope winds
will keep some overnight temperatures warmer tonight than last
night. Temperatures Sunday afternoon will warm into the mid 80s in
the valley and around 80 in the delta and 60s and 70s in the
mountains. Temperatures cool down on Monday into the mid to upper
70s in the Valley and 50s and 60s in the mountains with the
trough off the California coast bringing synoptic cooling and
onshore flow. Temperatures cool down to below normal for this time
of the year on Tuesday with highs in the mid 60s to around 70 in
the valley and 40s and 50s in the mountains as the trough moves
through the area. Precipitation may begin over the Coastal range
and Shasta county Monday afternoon and spread southeast across the
area by Tuesday morning. The 12z NAM is much quicker with the
trough and moves it east of the area by Tuesday afternoon making
convection less favorable. The GFS is a little slower with a
piece of energy moving through Northern California Tuesday
afternoon. The current forecast goes with the GFS solution but may
decrease precipitation amounts and pops for afternoon forecast with
drier NAM. Snow levels will start out around 7000 ft Monday night
and lowering to around 5000 ft Tuesday morning. Not a lot of snow
or precipitation is forecast at this time but a couple of inches
of snow near pass level look possible.


.Extended Discussion (Wednesday through Saturday)

Slight warming trend begins on Wednesday as the upper low from
Monday and Tuesday moves east of our region and ridging re-
develops along the west coast. This ridge is not forecast to be
strong so lingering light showers are possible over the northern
mountains Wed & Thurs. Additional warming on Thursday as valley highs
return to the mid-upper 70s. However, by Friday and into the
weekend, another upper trough will move across our CWA bringing a
return of more widespread precipitation and cooler temperatures.
JBB

&&

.Aviation...

VFR conditions will continue next 24 hours for Central Valley TAF sites.
Generally light winds up to 12-15 kt with local gusts to 21 kt
expected at from KSMF southward through today. Breezy/windy in the Delta
region WS winds 15-25 kt gusting to around 35 kt.

&&

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

$$









000
FXUS66 KSTO 190946
AFDSTO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
246 AM PDT Sat Apr 19 2014

.Synopsis...
A weak system well to the north will bring slightly cooler
temperatures today. Building high pressure on Sunday will result
in northerly winds and warmer temperatures. A stronger Pacific
trough will approach the coast Monday bringing increasing clouds
and a chance of rain and higher elevation snow on Monday night and
Tuesday. Some areas may also see a chance of thunderstorms. Weak
high pressure will dry things out over the interior by Thursday
but a threat of precipitation will continue across the far
northern sections of the state.

&&

.Short Term Discussion...
A weak shortwave well to the north will produce zonal flow over
the region today and help to bring slightly cooler temperatures.
Weak high pressure will build behind the shortwave to the north to
help produce northerly winds for Sunday and warmer temperatures.
On Monday a stronger shortwave will approach the interior and may
be able to produce a few mountains showers for the afternoon over
the northern sections but at this time the system looks to start
to move inland Monday evening. Have added a slight chance of
thunderstorms for the north end of the valley Monday evening as
better dynamics move over interior.

The system will still be impacting the interior on Tuesday with
showers and thunderstorms expected over most of the interior. Snow
levels will remain above pass level through Monday but lower
Monday night and Tuesday below major pass levels in the Sierra
Nevada. Not a lot of snow or precipitation is forecast at this
time but a couple of inches of snow near pass level look
possible.

.Extended Discussion (Wednesday through Saturday)

Slight warming trend begins on Wednesday as the upper low from
Monday and Tuesday moves east of our region and ridging re-
develops along the west coast. This ridge is not forecast to be
strong so lingering light showers are possible over the northern mountains.
Additional warming on Thursday as valley highs return to the mid-
upper 70s. However, by Friday and into the weekend, another upper
trough will move across our CWA bringing a return of more
widespread precipitation and cooler temperatures. JBB

&&

.Aviation...

VFR conditions will continue next 24 hours for Central Valley TAF sites.
Generally light winds up to 12 knots expected at TAF sites today.
Breezy winds in the Delta region with 15-25 knot SW winds.

&&

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

$$









000
FXUS66 KSTO 190405
AFDSTO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
905 PM PDT Fri Apr 18 2014

.Synopsis...A weak frontal passage will bring a isolated showers
and thunderstorms to the Sierra this afternoon and evening.
Otherwise...building high pressure will bring fair skies and above
normal temperatures through the remainder of the weekend. A
stronger Pacific trough will approach the coast early next week
bringing increasing clouds on Monday and a chance of rain and
higher elevation snow on Tuesday. Some areas may also see a chance
of thunderstorms on Tuesday. Weak high pressure will dry things
out over the central state by Thursday but a threat of
precipitation will continue across the north state.

&&

.Short Term Discussion...
Sierra Nevada showers are winding down this evening as ams
stabilizes. Upper low to the south will continue to slowly progress
towards the Desert Southwest as upstream weak upper ridging builds
over Interior NorCal. Baroclinic cirrus associated with weak
approaching Pacific front will move through ridging into the CWA
overnight. Onshore flow has picked up this evening with moderate
wind through the Delta into the Southern Sac valley where KSFO-KSAC
surface pressure gradient is a little above 3 mb. MOS guidance
suggests flow strength will remain nearly the same overnight with
overnight low temps from the upper 40s to low 50s in the
Delta/Central Valley.

Remnants of weak Pacific cold front move onshore by early Saturday
and undergoes frontolysis over far northern interior CA. Upper ridge
weakens as a result with minor synoptic cooling. Despite this, high
temps tomorrow will continue above normal with upper 70s to low 80s
in the Central Valley and 50s to 70s for the mountains and
foothills.  Some cumulus clouds may develop near the Sierra Crest
tomorrow afternoon, especially in Alpine and Tuolumne counties, but
the stronger instability for any shower/thunderstorm activity is
expected to remain further to the southeast of the forecast area.
Heights and thicknesses increases slightly on Sunday for minor
warming over the CWA.

Upstream deepening trough in the Pacific approaches the West Coast
Monday resulting in increased onshore flow and the beginning of a
cooler unsettled weather pattern. Differences exist in model timing
for onset of precip with the GEM/ECMWF-HiRes spreading some frontal
precip into the forecast area by Monday afternoon while the Oper GFS
holds off more towards Monday evening. High temps on Monday forecast
about 5 to 10 degrees cooler than Sunday.

PCH


.Extended Discussion (Tuesday through Friday)

Showers and a slight chance of thunderstorms in the valley on
Tuesday as models indicate some instability with the passage of
the upper low. Cooler temperatures will be noticeable as valley
highs lower into the mid to upper 60s on Tuesday. Slight warming
trend begins on Wednesday and continues into Thursday as the upper
low passes eastward and ridging re-develops. Could still have some
lingering showers on Wed & Thurs...primarily over higher
elevations. Yet...another system will approach the area Friday
with shower chances increasing mainly over the mountains.

&&

.Aviation...

VFR conditions will continue for the next 24 hours with
generally light winds. A few wind gusts to 25 kts will be possible
through the delta during the evening.

&&

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

$$











000
FXUS66 KSTO 182204
AFDSTO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
304 PM PDT Fri Apr 18 2014

.Synopsis...A weak frontal passage will bring a isolated showers
and thunderstorms to the Sierra this afternoon and evening.
Otherwise...building high pressure will bring fair skies and above
normal temperatures through the remainder of the weekend. A
stronger Pacific trough will approach the coast early next week
bringing increasing clouds on Monday and a chance of rain and
higher elevation snow on Tuesday. Some areas may also see a chance
of thunderstorms on Tuesday. Weak high pressure will dry things
out over the central state by Thursday but a threat of
precipitation will continue across the north state.

&&

.Short Term Discussion...
Temperatures this afternoon are running similar to a little cooler
than yesterday with high clouds moving through Northern
California. Cumulus developing over the Sierra with some mid level
moisture and instability this afternoon for isolated to scattered showers
and isolated thunderstorms through this evening.

A trough moves through the Pacific Northwest on Saturday but
interior Northern California should stay dry with above normal
temperatures. Although some cumulus clouds may develop near the
Sierra Crest especially in Alpine and Tuolumne counties in the
afternoon and evening but most of instability is to the southeast
so do not expect showers or thunderstorms at this time.
Temperatures are expected to be in the upper 70s to low 80s in the
valley and 50s and 60s in the mountains, which is about 5 to 10 degrees
above normal for mid April. Temperatures warm up a little with
weak ridging ahead of a stronger system off the West Coast on Sunday.
Temperatures will warm into the low to mid 80s in the Valley and
mid 50s to mid 70s in the mountains.

Temperatures will cool on Monday as the trough approaches the
coast bringing synoptic cooling and onshore flow along with cloud
cover. Temperatures are expected to be in the mid to upper 70s in
the Valley and 50s and 60s in the mountains. Precipitation may
move into Shasta County and the Coastal Range on Monday afternoon
and then spread across most of the area by Tuesday morning.


.Extended Discussion (Tuesday through Friday)

Showers and a slight chance of thunderstorms in the valley on
Tuesday as models indicate some instability with the passage of
the upper low. Cooler temperatures will be noticeable as valley
highs lower into the mid to upper 60s on Tuesday. Slight warming
trend begins on Wednesday and continues into Thursday as the upper
low passes eastward and ridging re-develops. Could still have some
lingering showers on Wed & Thurs...primarily over higher
elevations. Yet...another system will approach the area Friday
with shower chances increasing mainly over the mountains.

&&

.Aviation...

VFR conditions will continue for the next 24 hours with
generally light winds. A few wind gusts to 25 kts will be possible
through the delta during the evening. Isolated thunderstorms
along the Sierra Crest through 03z.

&&

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

$$









000
FXUS66 KSTO 181647
AFDSTO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
947 AM PDT Fri Apr 18 2014

.Synopsis...A weak frontal passage will bring a isolated showers
and thunderstorms to the Sierra today. Otherwise...building high
pressure will bring fair skies and well above normal temperatures
through the remainder of the weekend. A stronger Pacific trough
will approach the coast early next week bringing increasing clouds
on Monday and a chance of rain and higher elevation snow on
Tuesday. Some areas may also see a chance of thunderstorms on
Tuesday. Weak high pressure will dry things out over the central
state by Thursday but a threat of precipitation will continue
across the north state.

&&

.Short Term Discussion...
Another mostly sunny spring day with above normal temperatures for
Interior California today. Although with some mid level moisture
and instability over the Sierra this afternoon and evening could
see some showers and possibly isolated thunderstorms...especially
south of highway 50. Another trough moves through the Pacific
Northwest on Saturday but interior Northern California should
stay dry with above normal temperatures. Some cumulus clouds may
develop near the Sierra Crest in Alpine and Tuolumne counties in
the afternoon and evening but most of instability is to the
southeast so do not expect showers or thunderstorms at this time.
Temperatures are expected to be in the upper 70s to low 80s in the
valley and 50s and 60s in the mountains, which is about 3 to 9
degrees above normal for mid April. Temperatures warm up a little
with weak ridging ahead of a stronger system on Sunday.
Temperatures will warm into the low to mid 80s in the Valley and
mid 50s to mid 70s in the mountains. Temperatures will cool on
Monday as the trough approaches the coast bringing synoptic
cooling and onshore flow and some clouds. Temperatures are expected to
be in the mid to upper 70s in the Valley and 50s and 60s in the
mountains. Precipitation may move into the far north Monday
afternoon and then spread across the area by Tuesday morning.


.Extended Discussion (Tuesday through Friday)

Showers will continue across our CWA on Tuesday. Slight chance of
thunderstorms in the valley on Tuesday as models indicate some
instability with the passage of the upper low. Cooler temperatures
will be noticeable as valley highs lower into the mid to upper 60s
on Tuesday. Slight warming trend begins on Wednesday and continues
into Thursday as the upper low passes eastward and ridging re-
develops. Could still have some lingering showers on Wed &
Thurs...primarily over higher elevations. JBB

&&

.Aviation...

VFR conditions will continue today and winds will generally be
light north to northwesterly across the valley (around 10 kts).
Fairly dry weather today except for the possibility of
thunderstorms along the Sierra Crest.

&&

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

$$









000
FXUS66 KSTO 181153
AFDSTO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
453 AM PDT Fri Apr 18 2014

.Synopsis...A weak frontal passage will bring a slight chance of
showers to the Sierra today. Otherwise...building high pressure
will bring fair skies and well above normal temperatures through
the remainder of the weekend. A stronger Pacific trough will
approach the coast early next week bringing increasing clouds on
Monday and a chance of rain and higher elevation snow on Tuesday.
Some areas may also see a chance of thunderstorms on Tuesday. Weak
high pressure will dry things out over the central state by
Thursday but a threat of precipitation will continue across the
north state.

&&

.Short Term Discussion...
A weak frontal band moving through northern California brought
isolated light showers and a few thunderstorms to northern
California last evening. This system has now moved into northeast
California. As this system continues to the southeast it may
combine with the instability of a low moving through southern
California to produce a threat of showers or thunderstorms over
the northern Sierra this afternoon. Elsewhere...clearing skies
will allow daytime highs to again climb to well above normal for
this time of year. a flattened high pressure ridge over northern
California will bring dry conditions over the weekend. Although
daytime temperatures will be a little cooler, they will still
remain several degrees above normal for this time of year.

A stronger Pacific frontal system is forecast to approach the
coast on Monday bringing increasing cloudiness and a little cooler
temperatures on Monday with a slight threat of showers to the
Shasta county mountains. As this frontal band pushes inland late
Monday it may bring a good threat of precipitation to nearly all of
the CWA.


.Extended Discussion (Tuesday through Friday)

Showers will continue across our CWA on Tuesday. Slight chance of
thunderstorms in the valley on Tuesday as models indicate some
instability with the passage of the upper low. Cooler temperatures
will be noticeable as valley highs lower into the mid to upper 60s
on Tuesday. Slight warming trend begins on Wednesday and continues
into Thursday as the upper low passes eastward and ridging re-
develops. Could still have some lingering showers on Wed &
Thurs...primarily over higher elevations. JBB

&&

.Aviation...

VFR conditions will continue today and winds will generally be
light north to northwesterly across the valley (around 10 kts).
However, this morning will bring locally moderate gusts to the
Northern Sacramento Valley for KRDD and KRBL vicinity with gusts
up to around 18 kts possible through 18z. Fairly dry weather today
except for the possibility of thunderstorms along the Sierra
Crest. JBB

&&

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

$$









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