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000
FXUS66 KSTO 222156
AFDSTO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
256 PM PDT Fri May 22 2015

.Synopsis...
Mild weather with mainly mountain showers and thunderstorms will
continue today. Warmer temperatures with scattered mountain showers
expected this weekend into next week.

&&

.Discussion...
A longwave trough remains situated along the West Coast, with
embedded closed upper low now over the Desert Southwest. Showers
and a few thunderstorms have again developed across the interior
northern mountains. Low clouds and fog blanketed the mountains
today, which limited surface instability. Coupled with the fact
that forcing isnt as strong as yesterday, we`re not seeing the
level of convective activity as we`ve seen the last several days.

The short-range, Hi-Res models (ARW, NMM, and HRRR), all suggest a
possibility of showers from the Shasta-Trinitys and Mendocino
reaching the Sacramento Valley floor this evening. Otherwise, dry
weather is in store for the lower elevations the next several days
as a more stable airmass comes into place. The mountains will
continue to see showery activity, although Sunday and Memorial Day
may not be quite as widespread as Saturday.

Seasonably cool temperatures will continue today under a moist
airmass. However, a slow and gradual warming trend is expected
through the holiday weekend. Temperatures should generally be
within a few degrees of normal for the weekend.

Dang

&&


.Extended Discussion (Tuesday through Friday)

The unsettled weather pattern continues into the extended period,
though there are signs of a break late Thursday and Friday as
shortwave ridging builds in. There is just a slight chance of
showers and afternoon/evening thunderstorms along the crest
through Thursday, with mainly dry conditions on Friday.

High temperatures are expected to warm from near normal levels on
Tuesday to several degrees above normal by Fhursday and Friday.
This means locations in the northern Sacramento Valley could be in
the low 90s, with the rest of the Valley in the upper 80s. Whether
the ridging can hold into next weekend is uncertain. EK


&&

.Aviation...

General VFR conditions expected next 24 hours except areas of MVFR
with local IFR conditions over the mountains in the vicinity
showers and isolated thunderstorms...through around 04Z. Local
westerly wind gusts 20-25 kts in the Delta and northern San
Joaquin Valley through around 12z Saturday, and again returning
after 20z. EK

&&

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

$$








000
FXUS66 KSTO 222156
AFDSTO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
256 PM PDT Fri May 22 2015

.Synopsis...
Mild weather with mainly mountain showers and thunderstorms will
continue today. Warmer temperatures with scattered mountain showers
expected this weekend into next week.

&&

.Discussion...
A longwave trough remains situated along the West Coast, with
embedded closed upper low now over the Desert Southwest. Showers
and a few thunderstorms have again developed across the interior
northern mountains. Low clouds and fog blanketed the mountains
today, which limited surface instability. Coupled with the fact
that forcing isnt as strong as yesterday, we`re not seeing the
level of convective activity as we`ve seen the last several days.

The short-range, Hi-Res models (ARW, NMM, and HRRR), all suggest a
possibility of showers from the Shasta-Trinitys and Mendocino
reaching the Sacramento Valley floor this evening. Otherwise, dry
weather is in store for the lower elevations the next several days
as a more stable airmass comes into place. The mountains will
continue to see showery activity, although Sunday and Memorial Day
may not be quite as widespread as Saturday.

Seasonably cool temperatures will continue today under a moist
airmass. However, a slow and gradual warming trend is expected
through the holiday weekend. Temperatures should generally be
within a few degrees of normal for the weekend.

Dang

&&


.Extended Discussion (Tuesday through Friday)

The unsettled weather pattern continues into the extended period,
though there are signs of a break late Thursday and Friday as
shortwave ridging builds in. There is just a slight chance of
showers and afternoon/evening thunderstorms along the crest
through Thursday, with mainly dry conditions on Friday.

High temperatures are expected to warm from near normal levels on
Tuesday to several degrees above normal by Fhursday and Friday.
This means locations in the northern Sacramento Valley could be in
the low 90s, with the rest of the Valley in the upper 80s. Whether
the ridging can hold into next weekend is uncertain. EK


&&

.Aviation...

General VFR conditions expected next 24 hours except areas of MVFR
with local IFR conditions over the mountains in the vicinity
showers and isolated thunderstorms...through around 04Z. Local
westerly wind gusts 20-25 kts in the Delta and northern San
Joaquin Valley through around 12z Saturday, and again returning
after 20z. EK

&&

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

$$









000
FXUS66 KSTO 221602
AFDSTO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
902 AM PDT Fri May 22 2015

.Synopsis...
Mild weather with mainly mountain showers and thunderstorms will
continue today. Warmer temperatures with scattered mountain showers
expected this weekend into next week.

&&

.Discussion...
A longwave trough remains situated along the West Coast, with
embedded closed upper low moving inland over Southern California.
Easterly flow off the Sierra this morning brought a few sprinkles
down into the southern Sacramento and northern San Joaquin
Valleys. Otherwise, weather is relatively quiet early this
morning with some reports of low clouds and locally dense fog
along the mountains.

Scattered afternoon and evening showers and thunderstorms will
continue over the mountains today and through the Memorial Day
Weekend. Upper level flow will be shifting to a northerly
direction today and through the weekend. Interestingly, the HRRR
is showing some showery development over the Shasta-Trinitys
advecting over the northern Valley later today. Otherwise, most of
the convection is likely to remain confined over the mountains
through the holiday weekend.

Seasonably cool temperatures will continue today under a moist
airmass. However, a slow and gradual warming trend is expected
through the holiday weekend. Temperatures should generally be
within a few degrees of normal for the weekend.

Dang

&&


.Extended Discussion (Tuesday through Friday)

Trough pattern forecast to linger, albeit weaker, through the
extended period continuing a chance of daily diurnal deep
convection over the mountains while temperatures return to near
normal.

&&

.Aviation...

General VFR conditions expected next 24 hours except areas of MVFR
with local IFR conditions over the northern Sierra Nevada vicinity
showers. Scattered thunderstorms over the mountains 20Z-02Z.
Chance for MVFR ceilings in the Delta through about 17Z. Local
westerly wind gusts 20-25 kts after 20Z in the Delta and northern
San Joaquin Valley.

&&

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

$$









000
FXUS66 KSTO 221602
AFDSTO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
902 AM PDT Fri May 22 2015

.Synopsis...
Mild weather with mainly mountain showers and thunderstorms will
continue today. Warmer temperatures with scattered mountain showers
expected this weekend into next week.

&&

.Discussion...
A longwave trough remains situated along the West Coast, with
embedded closed upper low moving inland over Southern California.
Easterly flow off the Sierra this morning brought a few sprinkles
down into the southern Sacramento and northern San Joaquin
Valleys. Otherwise, weather is relatively quiet early this
morning with some reports of low clouds and locally dense fog
along the mountains.

Scattered afternoon and evening showers and thunderstorms will
continue over the mountains today and through the Memorial Day
Weekend. Upper level flow will be shifting to a northerly
direction today and through the weekend. Interestingly, the HRRR
is showing some showery development over the Shasta-Trinitys
advecting over the northern Valley later today. Otherwise, most of
the convection is likely to remain confined over the mountains
through the holiday weekend.

Seasonably cool temperatures will continue today under a moist
airmass. However, a slow and gradual warming trend is expected
through the holiday weekend. Temperatures should generally be
within a few degrees of normal for the weekend.

Dang

&&


.Extended Discussion (Tuesday through Friday)

Trough pattern forecast to linger, albeit weaker, through the
extended period continuing a chance of daily diurnal deep
convection over the mountains while temperatures return to near
normal.

&&

.Aviation...

General VFR conditions expected next 24 hours except areas of MVFR
with local IFR conditions over the northern Sierra Nevada vicinity
showers. Scattered thunderstorms over the mountains 20Z-02Z.
Chance for MVFR ceilings in the Delta through about 17Z. Local
westerly wind gusts 20-25 kts after 20Z in the Delta and northern
San Joaquin Valley.

&&

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

$$










000
FXUS66 KSTO 221023
AFDSTO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
323 AM PDT Fri May 22 2015

.Synopsis...
Mild weather with mainly mountain showers and thunderstorms will
continue today. Warmer temperatures with fewer mountain showers
expected this weekend into next week.

&&

.Discussion...
Upper low center just off the coast of point Concepcion this
morning and moving to the southeast. Upper level deformation zone
over the Great Basin contained numerous showers during the day on
Thursday but most of these showers had dissipated by the early
morning hours this morning. As for our CWA this morning...a few
dissipating showers have drifted southwestward into the Northern
Sierra with remnant clouds and partly cloudy skies elsewhere. Main
upper low center is forecast to track through southern California
today. Stability proggs show slightly unstable conditions over the
mountain areas today under broad upper trough and cyclonic flow.
Scattered mountain thunderstorms are a likely occurrence again
today. Steering current today will be out of the northeast so not
out of the question that some of these showers will make it into
the valley at least in the form of dissipating showers or
thunderstorms. Cool airmass and variable cloud cover will keep
temperatures down a little below normal today. Upper trough axis
shifts to the eastern Great Basin on Saturday with Eastern Pacific
ridging starting to push inland over the area for a slight
warming. Still a threat of showers or thunderstorms over the
Sierra however as wrap around moisture pushes over the Sierra
crest. Still a bit more warming on Sunday with daytime highs
most areas pushing above normal for the first time in a few
weeks. With only slight movement of Great Basin trough...wrap
around moisture and Sierra crest showers or Thunderstorms remain a
possibility Sunday afternoon. Mid range models now in better
agreement in placing a weak low center over Washington state by
Monday afternoon with a trough sagging down over Northwest
California. This system showing enough instability and upward
motion for a threat of showers over the northern mountains and
Sierra. Otherwise...mainly fair skies and slightly above normal
temperatures continue.
&&

.Extended Discussion (Tuesday through Friday)

Trough pattern forecast to linger, albeit weaker, through the
extended period continuing a chance of daily diurnal deep
convection over the mountains while temperatures return to near
normal.

&&

.Aviation...

General VFR conditions expected next 24 hours except areas of MVFR
with local IFR conditions over the northern Sierra Nevada vicinity
showers. Isolated thunderstorms over the mountains 20Z-02Z. Chance
for MVFR ceilings in the Delta through about 17Z. Local westerly
wind gusts 20-25 kts after 20Z in the Delta and northern San
Joaquin Valley.

&&

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

$$








000
FXUS66 KSTO 221023
AFDSTO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
323 AM PDT Fri May 22 2015

.Synopsis...
Mild weather with mainly mountain showers and thunderstorms will
continue today. Warmer temperatures with fewer mountain showers
expected this weekend into next week.

&&

.Discussion...
Upper low center just off the coast of point Concepcion this
morning and moving to the southeast. Upper level deformation zone
over the Great Basin contained numerous showers during the day on
Thursday but most of these showers had dissipated by the early
morning hours this morning. As for our CWA this morning...a few
dissipating showers have drifted southwestward into the Northern
Sierra with remnant clouds and partly cloudy skies elsewhere. Main
upper low center is forecast to track through southern California
today. Stability proggs show slightly unstable conditions over the
mountain areas today under broad upper trough and cyclonic flow.
Scattered mountain thunderstorms are a likely occurrence again
today. Steering current today will be out of the northeast so not
out of the question that some of these showers will make it into
the valley at least in the form of dissipating showers or
thunderstorms. Cool airmass and variable cloud cover will keep
temperatures down a little below normal today. Upper trough axis
shifts to the eastern Great Basin on Saturday with Eastern Pacific
ridging starting to push inland over the area for a slight
warming. Still a threat of showers or thunderstorms over the
Sierra however as wrap around moisture pushes over the Sierra
crest. Still a bit more warming on Sunday with daytime highs
most areas pushing above normal for the first time in a few
weeks. With only slight movement of Great Basin trough...wrap
around moisture and Sierra crest showers or Thunderstorms remain a
possibility Sunday afternoon. Mid range models now in better
agreement in placing a weak low center over Washington state by
Monday afternoon with a trough sagging down over Northwest
California. This system showing enough instability and upward
motion for a threat of showers over the northern mountains and
Sierra. Otherwise...mainly fair skies and slightly above normal
temperatures continue.
&&

.Extended Discussion (Tuesday through Friday)

Trough pattern forecast to linger, albeit weaker, through the
extended period continuing a chance of daily diurnal deep
convection over the mountains while temperatures return to near
normal.

&&

.Aviation...

General VFR conditions expected next 24 hours except areas of MVFR
with local IFR conditions over the northern Sierra Nevada vicinity
showers. Isolated thunderstorms over the mountains 20Z-02Z. Chance
for MVFR ceilings in the Delta through about 17Z. Local westerly
wind gusts 20-25 kts after 20Z in the Delta and northern San
Joaquin Valley.

&&

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

$$









000
FXUS66 KSTO 221023
AFDSTO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
323 AM PDT Fri May 22 2015

.Synopsis...
Mild weather with mainly mountain showers and thunderstorms will
continue today. Warmer temperatures with fewer mountain showers
expected this weekend into next week.

&&

.Discussion...
Upper low center just off the coast of point Concepcion this
morning and moving to the southeast. Upper level deformation zone
over the Great Basin contained numerous showers during the day on
Thursday but most of these showers had dissipated by the early
morning hours this morning. As for our CWA this morning...a few
dissipating showers have drifted southwestward into the Northern
Sierra with remnant clouds and partly cloudy skies elsewhere. Main
upper low center is forecast to track through southern California
today. Stability proggs show slightly unstable conditions over the
mountain areas today under broad upper trough and cyclonic flow.
Scattered mountain thunderstorms are a likely occurrence again
today. Steering current today will be out of the northeast so not
out of the question that some of these showers will make it into
the valley at least in the form of dissipating showers or
thunderstorms. Cool airmass and variable cloud cover will keep
temperatures down a little below normal today. Upper trough axis
shifts to the eastern Great Basin on Saturday with Eastern Pacific
ridging starting to push inland over the area for a slight
warming. Still a threat of showers or thunderstorms over the
Sierra however as wrap around moisture pushes over the Sierra
crest. Still a bit more warming on Sunday with daytime highs
most areas pushing above normal for the first time in a few
weeks. With only slight movement of Great Basin trough...wrap
around moisture and Sierra crest showers or Thunderstorms remain a
possibility Sunday afternoon. Mid range models now in better
agreement in placing a weak low center over Washington state by
Monday afternoon with a trough sagging down over Northwest
California. This system showing enough instability and upward
motion for a threat of showers over the northern mountains and
Sierra. Otherwise...mainly fair skies and slightly above normal
temperatures continue.
&&

.Extended Discussion (Tuesday through Friday)

Trough pattern forecast to linger, albeit weaker, through the
extended period continuing a chance of daily diurnal deep
convection over the mountains while temperatures return to near
normal.

&&

.Aviation...

General VFR conditions expected next 24 hours except areas of MVFR
with local IFR conditions over the northern Sierra Nevada vicinity
showers. Isolated thunderstorms over the mountains 20Z-02Z. Chance
for MVFR ceilings in the Delta through about 17Z. Local westerly
wind gusts 20-25 kts after 20Z in the Delta and northern San
Joaquin Valley.

&&

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

$$









000
FXUS66 KSTO 221023
AFDSTO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
323 AM PDT Fri May 22 2015

.Synopsis...
Mild weather with mainly mountain showers and thunderstorms will
continue today. Warmer temperatures with fewer mountain showers
expected this weekend into next week.

&&

.Discussion...
Upper low center just off the coast of point Concepcion this
morning and moving to the southeast. Upper level deformation zone
over the Great Basin contained numerous showers during the day on
Thursday but most of these showers had dissipated by the early
morning hours this morning. As for our CWA this morning...a few
dissipating showers have drifted southwestward into the Northern
Sierra with remnant clouds and partly cloudy skies elsewhere. Main
upper low center is forecast to track through southern California
today. Stability proggs show slightly unstable conditions over the
mountain areas today under broad upper trough and cyclonic flow.
Scattered mountain thunderstorms are a likely occurrence again
today. Steering current today will be out of the northeast so not
out of the question that some of these showers will make it into
the valley at least in the form of dissipating showers or
thunderstorms. Cool airmass and variable cloud cover will keep
temperatures down a little below normal today. Upper trough axis
shifts to the eastern Great Basin on Saturday with Eastern Pacific
ridging starting to push inland over the area for a slight
warming. Still a threat of showers or thunderstorms over the
Sierra however as wrap around moisture pushes over the Sierra
crest. Still a bit more warming on Sunday with daytime highs
most areas pushing above normal for the first time in a few
weeks. With only slight movement of Great Basin trough...wrap
around moisture and Sierra crest showers or Thunderstorms remain a
possibility Sunday afternoon. Mid range models now in better
agreement in placing a weak low center over Washington state by
Monday afternoon with a trough sagging down over Northwest
California. This system showing enough instability and upward
motion for a threat of showers over the northern mountains and
Sierra. Otherwise...mainly fair skies and slightly above normal
temperatures continue.
&&

.Extended Discussion (Tuesday through Friday)

Trough pattern forecast to linger, albeit weaker, through the
extended period continuing a chance of daily diurnal deep
convection over the mountains while temperatures return to near
normal.

&&

.Aviation...

General VFR conditions expected next 24 hours except areas of MVFR
with local IFR conditions over the northern Sierra Nevada vicinity
showers. Isolated thunderstorms over the mountains 20Z-02Z. Chance
for MVFR ceilings in the Delta through about 17Z. Local westerly
wind gusts 20-25 kts after 20Z in the Delta and northern San
Joaquin Valley.

&&

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

$$








000
FXUS66 KSTO 220513
AFDSTO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
1013 PM PDT Thu May 21 2015

.Synopsis...
Mild weather with mountain showers and thunderstorms will continue
through Friday. Warmer temperatures with fewer mountain showers
expected this weekend into next week.

&&

.Discussion...

Mountain showers and thunderstorms have all dissipated this
evening. Skies are partly cloudy over the area with a moderate
onshore flow and winds gusting to 20 mph delta to srn sac/nrn sj
valleys. Short term models indicate showers to rotate back over
the Sierra from Nevada after midnight will keep shower chances
going. Likely to see another layer of status cloudiness towards
morning srn/sac valley. Current forecast is on track no update
needed.

.Previous Discussion...
A broad upper level trough remains quasi-stationary along the
West Coast, with blocking ridge situated over the Rockies. Several
shortwaves have been rotating through this upper trough, and the
current one is moving toward the California coast today.
Widespread showers and thunderstorms have once again developed
this afternoon across the interior mountains of Northern
California once again. Lightning networks haven`t detected quite as
much lightning as yesterday, but today`s showers do seem to be
producing more in the way of precipitation. We`ve also seen a few
reports of snow above 8000 ft or so along the high Sierra. With
southeast to easterly flow aloft, some showers may try to work
their way down the hill toward the Valley this evening into Friday
morning. The ARW, NMM, and HRRR all hint at this possibility.

The aforementioned shortwave pushes south toward Southern
California on Friday, with steering flow becoming more northerly.
While we should still expect some mountain showers and
thunderstorms Friday afternoon, they shouldn`t be as widespread.

Northerly flow aloft will continue over Northern California
through the weekend. This should promote warmer weather, with
temperatures closer to normal. Isolated showers will still be
possible over the mountains, but confined to primarily Lake Tahoe
and southward.

Dang

&&

.Extended Discussion (Monday through Thursday)

For the extended period, the ability of the general upper trough
pattern over the region to persist through the rest of May is
impressive. with no significant heat-ups in sight. Upper low
pressure systems with weak short waves will pass through at times.
Unlike the current system, most of the lows will be centered to the
north and east of the forecast area. Most of the instability will
linger over the mountains, with afternoon heating bringing some
thunderstorms. The Valley should remain generally dry.

Temperatures will gradually warm to near to slightly above normal
levels by mid week on. Daytime highs in the valley will generally
be in the low to mid 80s with 70s in Delta Breeze influenced areas
(upper 60s for the Vallejo/Benicia area). Mountain highs will
range in the 50s/60s while Foothills warm into the 70s. EK

&&

.Aviation...

General VFR conditions expected for tonight. Could see some
bkn020-025 cigs for the Delta and into the southern Sacramento
Valley 12-18z Friday morning. The Delta could see gusts to 30kt
tonight.

&&

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

$$








000
FXUS66 KSTO 220513
AFDSTO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
1013 PM PDT Thu May 21 2015

.Synopsis...
Mild weather with mountain showers and thunderstorms will continue
through Friday. Warmer temperatures with fewer mountain showers
expected this weekend into next week.

&&

.Discussion...

Mountain showers and thunderstorms have all dissipated this
evening. Skies are partly cloudy over the area with a moderate
onshore flow and winds gusting to 20 mph delta to srn sac/nrn sj
valleys. Short term models indicate showers to rotate back over
the Sierra from Nevada after midnight will keep shower chances
going. Likely to see another layer of status cloudiness towards
morning srn/sac valley. Current forecast is on track no update
needed.

.Previous Discussion...
A broad upper level trough remains quasi-stationary along the
West Coast, with blocking ridge situated over the Rockies. Several
shortwaves have been rotating through this upper trough, and the
current one is moving toward the California coast today.
Widespread showers and thunderstorms have once again developed
this afternoon across the interior mountains of Northern
California once again. Lightning networks haven`t detected quite as
much lightning as yesterday, but today`s showers do seem to be
producing more in the way of precipitation. We`ve also seen a few
reports of snow above 8000 ft or so along the high Sierra. With
southeast to easterly flow aloft, some showers may try to work
their way down the hill toward the Valley this evening into Friday
morning. The ARW, NMM, and HRRR all hint at this possibility.

The aforementioned shortwave pushes south toward Southern
California on Friday, with steering flow becoming more northerly.
While we should still expect some mountain showers and
thunderstorms Friday afternoon, they shouldn`t be as widespread.

Northerly flow aloft will continue over Northern California
through the weekend. This should promote warmer weather, with
temperatures closer to normal. Isolated showers will still be
possible over the mountains, but confined to primarily Lake Tahoe
and southward.

Dang

&&

.Extended Discussion (Monday through Thursday)

For the extended period, the ability of the general upper trough
pattern over the region to persist through the rest of May is
impressive. with no significant heat-ups in sight. Upper low
pressure systems with weak short waves will pass through at times.
Unlike the current system, most of the lows will be centered to the
north and east of the forecast area. Most of the instability will
linger over the mountains, with afternoon heating bringing some
thunderstorms. The Valley should remain generally dry.

Temperatures will gradually warm to near to slightly above normal
levels by mid week on. Daytime highs in the valley will generally
be in the low to mid 80s with 70s in Delta Breeze influenced areas
(upper 60s for the Vallejo/Benicia area). Mountain highs will
range in the 50s/60s while Foothills warm into the 70s. EK

&&

.Aviation...

General VFR conditions expected for tonight. Could see some
bkn020-025 cigs for the Delta and into the southern Sacramento
Valley 12-18z Friday morning. The Delta could see gusts to 30kt
tonight.

&&

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

$$









000
FXUS66 KSTO 220513
AFDSTO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
1013 PM PDT Thu May 21 2015

.Synopsis...
Mild weather with mountain showers and thunderstorms will continue
through Friday. Warmer temperatures with fewer mountain showers
expected this weekend into next week.

&&

.Discussion...

Mountain showers and thunderstorms have all dissipated this
evening. Skies are partly cloudy over the area with a moderate
onshore flow and winds gusting to 20 mph delta to srn sac/nrn sj
valleys. Short term models indicate showers to rotate back over
the Sierra from Nevada after midnight will keep shower chances
going. Likely to see another layer of status cloudiness towards
morning srn/sac valley. Current forecast is on track no update
needed.

.Previous Discussion...
A broad upper level trough remains quasi-stationary along the
West Coast, with blocking ridge situated over the Rockies. Several
shortwaves have been rotating through this upper trough, and the
current one is moving toward the California coast today.
Widespread showers and thunderstorms have once again developed
this afternoon across the interior mountains of Northern
California once again. Lightning networks haven`t detected quite as
much lightning as yesterday, but today`s showers do seem to be
producing more in the way of precipitation. We`ve also seen a few
reports of snow above 8000 ft or so along the high Sierra. With
southeast to easterly flow aloft, some showers may try to work
their way down the hill toward the Valley this evening into Friday
morning. The ARW, NMM, and HRRR all hint at this possibility.

The aforementioned shortwave pushes south toward Southern
California on Friday, with steering flow becoming more northerly.
While we should still expect some mountain showers and
thunderstorms Friday afternoon, they shouldn`t be as widespread.

Northerly flow aloft will continue over Northern California
through the weekend. This should promote warmer weather, with
temperatures closer to normal. Isolated showers will still be
possible over the mountains, but confined to primarily Lake Tahoe
and southward.

Dang

&&

.Extended Discussion (Monday through Thursday)

For the extended period, the ability of the general upper trough
pattern over the region to persist through the rest of May is
impressive. with no significant heat-ups in sight. Upper low
pressure systems with weak short waves will pass through at times.
Unlike the current system, most of the lows will be centered to the
north and east of the forecast area. Most of the instability will
linger over the mountains, with afternoon heating bringing some
thunderstorms. The Valley should remain generally dry.

Temperatures will gradually warm to near to slightly above normal
levels by mid week on. Daytime highs in the valley will generally
be in the low to mid 80s with 70s in Delta Breeze influenced areas
(upper 60s for the Vallejo/Benicia area). Mountain highs will
range in the 50s/60s while Foothills warm into the 70s. EK

&&

.Aviation...

General VFR conditions expected for tonight. Could see some
bkn020-025 cigs for the Delta and into the southern Sacramento
Valley 12-18z Friday morning. The Delta could see gusts to 30kt
tonight.

&&

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

$$









000
FXUS66 KSTO 220513
AFDSTO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
1013 PM PDT Thu May 21 2015

.Synopsis...
Mild weather with mountain showers and thunderstorms will continue
through Friday. Warmer temperatures with fewer mountain showers
expected this weekend into next week.

&&

.Discussion...

Mountain showers and thunderstorms have all dissipated this
evening. Skies are partly cloudy over the area with a moderate
onshore flow and winds gusting to 20 mph delta to srn sac/nrn sj
valleys. Short term models indicate showers to rotate back over
the Sierra from Nevada after midnight will keep shower chances
going. Likely to see another layer of status cloudiness towards
morning srn/sac valley. Current forecast is on track no update
needed.

.Previous Discussion...
A broad upper level trough remains quasi-stationary along the
West Coast, with blocking ridge situated over the Rockies. Several
shortwaves have been rotating through this upper trough, and the
current one is moving toward the California coast today.
Widespread showers and thunderstorms have once again developed
this afternoon across the interior mountains of Northern
California once again. Lightning networks haven`t detected quite as
much lightning as yesterday, but today`s showers do seem to be
producing more in the way of precipitation. We`ve also seen a few
reports of snow above 8000 ft or so along the high Sierra. With
southeast to easterly flow aloft, some showers may try to work
their way down the hill toward the Valley this evening into Friday
morning. The ARW, NMM, and HRRR all hint at this possibility.

The aforementioned shortwave pushes south toward Southern
California on Friday, with steering flow becoming more northerly.
While we should still expect some mountain showers and
thunderstorms Friday afternoon, they shouldn`t be as widespread.

Northerly flow aloft will continue over Northern California
through the weekend. This should promote warmer weather, with
temperatures closer to normal. Isolated showers will still be
possible over the mountains, but confined to primarily Lake Tahoe
and southward.

Dang

&&

.Extended Discussion (Monday through Thursday)

For the extended period, the ability of the general upper trough
pattern over the region to persist through the rest of May is
impressive. with no significant heat-ups in sight. Upper low
pressure systems with weak short waves will pass through at times.
Unlike the current system, most of the lows will be centered to the
north and east of the forecast area. Most of the instability will
linger over the mountains, with afternoon heating bringing some
thunderstorms. The Valley should remain generally dry.

Temperatures will gradually warm to near to slightly above normal
levels by mid week on. Daytime highs in the valley will generally
be in the low to mid 80s with 70s in Delta Breeze influenced areas
(upper 60s for the Vallejo/Benicia area). Mountain highs will
range in the 50s/60s while Foothills warm into the 70s. EK

&&

.Aviation...

General VFR conditions expected for tonight. Could see some
bkn020-025 cigs for the Delta and into the southern Sacramento
Valley 12-18z Friday morning. The Delta could see gusts to 30kt
tonight.

&&

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

$$








000
FXUS66 KSTO 212216
AFDSTO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
316 PM PDT Thu May 21 2015

.Synopsis...
Mild weather with mountain showers and thunderstorms will continue
through Friday. Warmer temperatures with fewer mountain showers
expected this weekend into next week.

&&

.Discussion...
A broad upper level trough remains quasi-stationary along the West
Coast, with blocking ridge situated over the Rockies. Several
shortwaves have been rotating through this upper trough, and the
current one is moving toward the California coast today.
Widespread showers and thunderstorms have once again developed
this afternoon across the interior mountains of Northern
California once again. Lightning networks havent detected quite as
much lightning as yesterday, but today`s showers do seem to be
producing more in the way of precipitation. We`ve also seen a few
reports of snow above 8000 ft or so along the high Sierra. With
southeast to easterly flow aloft, some showers may try to work
their way down the hill toward the Valley this evening into Friday
morning. The ARW, NMM, and HRRR all hint at this possibility.

The aforementioned shortwave pushes south toward Southern
California on Friday, with steering flow becoming more northerly.
While we should still expect some mountain showers and
thunderstorms Friday afternoon, they shouldn`t be as widespread.

Northerly flow aloft will continue over Northern California
through the weekend. This should promote warmer weather, with
temperatures closer to normal. Isolated showers will still be
possible over the mountains, but confined to primarily Lake Tahoe
and southward.

Dang

&&

.Extended Discussion (Monday through Thursday)

For the extended period, the ability of the general upper trough
pattern over the region to persist through the rest of May is
impressive. with no significant heat-ups in sight. Upper low
pressure systems with weak short waves will pass through at times.
Unlike the current system, most of the lows will be centered to the
north and east of the forecast area. Most of the instability will
linger over the mountains, with afternoon heating bringing some
thunderstorms. The Valley should remain generally dry.

Temperatures will gradually warm to near to slightly above normal
levels by mid week on. Daytime highs in the valley will generally
be in the low to mid 80s with 70s in Delta Breeze influenced areas
(upper 60s for the Vallejo/Benicia area). Mountain highs will
range in the 50s/60s while Foothills warm into the 70s. EK

&&

.Aviation...

General VFR conditions expected for tonight, except in
SCT showers and ISO evening thunderstorms in the mountains and
foothills, possibly passing through the northern Sacramento Valley
. Could see some bkn020-025 cigs for the Delta and into the
southern Sacramento Valley 12-18z Friday morning. The Delta could
see gusts to 30kt tonight, with southwest gusts to around 20kt for
the Sacramento metro area through 05z. EK

&&

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

$$








000
FXUS66 KSTO 211618
AFDSTO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
918 AM PDT Thu May 21 2015

.Synopsis...
Mild weather with mountain showers and thunderstorms will continue
through Friday. Warmer temperatures with fewer mountain showers
expected this weekend into next week.

&&

.Discussion...
A broad upper level trough remains quasi-stationary along the West
Coast, with blocking ridge situated over the Rockies. Several
shortwaves have been rotating around this upper trough, and the
next one is moving toward the California coast today. Doppler
radar is detecting a few showers over the mountains. The marine
layer remains at very deep levels along the coast, and a
considerable amount of marine stratus is pushing through the Delta
into the Valley this morning.

Another round of showers and thunderstorms will be developing
today across interior Northern California mountains today.
Steering flow will be a SE to easterly direction today, which is a
more favorable direction for convection on the west slopes of the
Sierra. Elevated instability doesnt look as good as yesterday,
though we still cant rule out a few stray showers reaching the
Valley floor this evening into Friday morning. Hi-Res models show
a considerable amount of precipitation falling along the Sierra
today. It wouldnt be surprising to see some snow accumulations
along the high Sierra passes south of Tahoe.

The aforementioned shortwave pushes south toward Southern
California on Friday, with steering flow becoming more northerly.
While we should still expect some mountain showers and
thunderstorms Friday afternoon, they shouldn`t be as widespread.

Northerly flow aloft will continue over Northern California
through the weekend. This should promote warmer weather, with
temperatures closer to normal. Isolated showers will still be
possible over the mountains, but confined to primarily Lake Tahoe
and southward.

Dang

&&

.Extended Discussion (Monday through Thursday)

Starting to sound like a broken record, but models continue to
illustrate a slightly unsettled environment for the extended forecast.
Valley should remain dry while instability persists over
mountains which could trigger showers and afternoon/evening
thunderstorms. Daytime highs in the valley will generally be in
the low to mid 80s with 70s in Delta Breeze influenced areas.
Mountain highs will range in the 50s/60s while Foothills warm into
the 70s. JBB

&&

.Aviation...

Onshore flow this morning has allowed low clouds to move through
the Delta region into Sacramento area and are banking up against
the Sierra Foothills. MVFR conditions this morning for that
vicinity through 16-18z, otherwise, the rest of our CWA will be VFR. Delta
breeze will continue to range 15-25 kts with gusts up to 30 kts
today. TAF sites will be fairly light (around 10 kts or less)
except for KSMF, KSAC, KMHR, KSCK between 17-04z when the delta
breeze enhances and increases winds at these sites with speeds
between 10-20 kts.  JBB


&&

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

$$










000
FXUS66 KSTO 211618
AFDSTO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
918 AM PDT Thu May 21 2015

.Synopsis...
Mild weather with mountain showers and thunderstorms will continue
through Friday. Warmer temperatures with fewer mountain showers
expected this weekend into next week.

&&

.Discussion...
A broad upper level trough remains quasi-stationary along the West
Coast, with blocking ridge situated over the Rockies. Several
shortwaves have been rotating around this upper trough, and the
next one is moving toward the California coast today. Doppler
radar is detecting a few showers over the mountains. The marine
layer remains at very deep levels along the coast, and a
considerable amount of marine stratus is pushing through the Delta
into the Valley this morning.

Another round of showers and thunderstorms will be developing
today across interior Northern California mountains today.
Steering flow will be a SE to easterly direction today, which is a
more favorable direction for convection on the west slopes of the
Sierra. Elevated instability doesnt look as good as yesterday,
though we still cant rule out a few stray showers reaching the
Valley floor this evening into Friday morning. Hi-Res models show
a considerable amount of precipitation falling along the Sierra
today. It wouldnt be surprising to see some snow accumulations
along the high Sierra passes south of Tahoe.

The aforementioned shortwave pushes south toward Southern
California on Friday, with steering flow becoming more northerly.
While we should still expect some mountain showers and
thunderstorms Friday afternoon, they shouldn`t be as widespread.

Northerly flow aloft will continue over Northern California
through the weekend. This should promote warmer weather, with
temperatures closer to normal. Isolated showers will still be
possible over the mountains, but confined to primarily Lake Tahoe
and southward.

Dang

&&

.Extended Discussion (Monday through Thursday)

Starting to sound like a broken record, but models continue to
illustrate a slightly unsettled environment for the extended forecast.
Valley should remain dry while instability persists over
mountains which could trigger showers and afternoon/evening
thunderstorms. Daytime highs in the valley will generally be in
the low to mid 80s with 70s in Delta Breeze influenced areas.
Mountain highs will range in the 50s/60s while Foothills warm into
the 70s. JBB

&&

.Aviation...

Onshore flow this morning has allowed low clouds to move through
the Delta region into Sacramento area and are banking up against
the Sierra Foothills. MVFR conditions this morning for that
vicinity through 16-18z, otherwise, the rest of our CWA will be VFR. Delta
breeze will continue to range 15-25 kts with gusts up to 30 kts
today. TAF sites will be fairly light (around 10 kts or less)
except for KSMF, KSAC, KMHR, KSCK between 17-04z when the delta
breeze enhances and increases winds at these sites with speeds
between 10-20 kts.  JBB


&&

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

$$









000
FXUS66 KSTO 211100
AFDSTO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
400 AM PDT Thu May 21 2015

.Synopsis...
Scattered showers and mainly mountain thunderstorms through the
end of the week with slightly below normal daytime temperatures.
Drier over the weekend and early next week except for a continued
shower threat over the Sierra. Temperatures warming to slightly
above normal.

&&

.Discussion...
Large upper low continues to develop off the central coast with
shortwaves pivoting around the low bringing just scattered clouds
at this time mainly south and north ends of the forecast area.
Delta breeze has been fairly strong throughout the night and
morning hours with sustained winds at Travis AFB in the teens and
gusts in the lower 20s. As a result..coastal stratus has worked
its way inland through the delta and southern Sacramento valley
banking up against foothills south of Auburn. The main upper low
center is forecast to shift to the southeast today towards the
Socal coast. Stability proggs indicate the most unstable
conditions over the mountains surrounding the Sacramento valley so
have a chance of showers and thunderstorms here. Could see a few
showers over the valley locations as well as some Sierra storms
could get pulled into the valley in upper southeast flow around
the low. Variable cloud cover and cool airmass in the low will
bring in high temperatures today a little below normal. The upper
low center is forecast to swing through southern California on
Friday with a similar stability pattern expected to today.
Therefore...expect mountain thunderstorms again with a threat of
showers in the valley under variable cloud cover.

Most of California will be under upper level northwest to north
flow on Saturday under the back edge of the upper low forecast to
be over the eastern Great Basin by Saturday afternoon. Much of the
CWA will see some clearing by Saturday afternoon but the Sierra
could still some showers or thunderstorms remaining under cyclonic
flow and moisture feed from the main upper low. With clearing
skies and warmer airmass...should see daytime highs Saturday climb
to near normal. Only minor changes expected on Sunday with upper
low only moving slightly. Should see enough clearing and airmass
warming Sunday however to bring the first significantly above normal
temperatures since early May.

&&

.Extended Discussion (Monday through Thursday)

Starting to sound like a broken record, but models continue to
illustrate a slightly unsettled environment for the extended forecast.
Valley should remain dry while instability persists over
mountains which could trigger showers and afternoon/evening
thunderstorms. Daytime highs in the valley will generally be in
the low to mid 80s with 70s in Delta Breeze influenced areas.
Mountain highs will range in the 50s/60s while Foothills warm into
the 70s. JBB

&&

.Aviation...

Onshore flow this morning has allowed low clouds to move through
the Delta region into Sacramento area and are banking up against
the Sierra Foothills. MVFR conditions this morning for that
vicinity through 16-18z, otherwise, the rest of our CWA will be VFR. Delta
breeze will continue to range 15-25 kts with gusts up to 30 kts
today. TAF sites will be fairly light (around 10 kts or less)
except for KSMF, KSAC, KMHR, KSCK between 17-04z when the delta
breeze enhances and increases winds at these sites with speeds
between 10-20 kts.  JBB


&&

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

$$








000
FXUS66 KSTO 211100
AFDSTO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
400 AM PDT Thu May 21 2015

.Synopsis...
Scattered showers and mainly mountain thunderstorms through the
end of the week with slightly below normal daytime temperatures.
Drier over the weekend and early next week except for a continued
shower threat over the Sierra. Temperatures warming to slightly
above normal.

&&

.Discussion...
Large upper low continues to develop off the central coast with
shortwaves pivoting around the low bringing just scattered clouds
at this time mainly south and north ends of the forecast area.
Delta breeze has been fairly strong throughout the night and
morning hours with sustained winds at Travis AFB in the teens and
gusts in the lower 20s. As a result..coastal stratus has worked
its way inland through the delta and southern Sacramento valley
banking up against foothills south of Auburn. The main upper low
center is forecast to shift to the southeast today towards the
Socal coast. Stability proggs indicate the most unstable
conditions over the mountains surrounding the Sacramento valley so
have a chance of showers and thunderstorms here. Could see a few
showers over the valley locations as well as some Sierra storms
could get pulled into the valley in upper southeast flow around
the low. Variable cloud cover and cool airmass in the low will
bring in high temperatures today a little below normal. The upper
low center is forecast to swing through southern California on
Friday with a similar stability pattern expected to today.
Therefore...expect mountain thunderstorms again with a threat of
showers in the valley under variable cloud cover.

Most of California will be under upper level northwest to north
flow on Saturday under the back edge of the upper low forecast to
be over the eastern Great Basin by Saturday afternoon. Much of the
CWA will see some clearing by Saturday afternoon but the Sierra
could still some showers or thunderstorms remaining under cyclonic
flow and moisture feed from the main upper low. With clearing
skies and warmer airmass...should see daytime highs Saturday climb
to near normal. Only minor changes expected on Sunday with upper
low only moving slightly. Should see enough clearing and airmass
warming Sunday however to bring the first significantly above normal
temperatures since early May.

&&

.Extended Discussion (Monday through Thursday)

Starting to sound like a broken record, but models continue to
illustrate a slightly unsettled environment for the extended forecast.
Valley should remain dry while instability persists over
mountains which could trigger showers and afternoon/evening
thunderstorms. Daytime highs in the valley will generally be in
the low to mid 80s with 70s in Delta Breeze influenced areas.
Mountain highs will range in the 50s/60s while Foothills warm into
the 70s. JBB

&&

.Aviation...

Onshore flow this morning has allowed low clouds to move through
the Delta region into Sacramento area and are banking up against
the Sierra Foothills. MVFR conditions this morning for that
vicinity through 16-18z, otherwise, the rest of our CWA will be VFR. Delta
breeze will continue to range 15-25 kts with gusts up to 30 kts
today. TAF sites will be fairly light (around 10 kts or less)
except for KSMF, KSAC, KMHR, KSCK between 17-04z when the delta
breeze enhances and increases winds at these sites with speeds
between 10-20 kts.  JBB


&&

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

$$









000
FXUS66 KSTO 211100
AFDSTO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
400 AM PDT Thu May 21 2015

.Synopsis...
Scattered showers and mainly mountain thunderstorms through the
end of the week with slightly below normal daytime temperatures.
Drier over the weekend and early next week except for a continued
shower threat over the Sierra. Temperatures warming to slightly
above normal.

&&

.Discussion...
Large upper low continues to develop off the central coast with
shortwaves pivoting around the low bringing just scattered clouds
at this time mainly south and north ends of the forecast area.
Delta breeze has been fairly strong throughout the night and
morning hours with sustained winds at Travis AFB in the teens and
gusts in the lower 20s. As a result..coastal stratus has worked
its way inland through the delta and southern Sacramento valley
banking up against foothills south of Auburn. The main upper low
center is forecast to shift to the southeast today towards the
Socal coast. Stability proggs indicate the most unstable
conditions over the mountains surrounding the Sacramento valley so
have a chance of showers and thunderstorms here. Could see a few
showers over the valley locations as well as some Sierra storms
could get pulled into the valley in upper southeast flow around
the low. Variable cloud cover and cool airmass in the low will
bring in high temperatures today a little below normal. The upper
low center is forecast to swing through southern California on
Friday with a similar stability pattern expected to today.
Therefore...expect mountain thunderstorms again with a threat of
showers in the valley under variable cloud cover.

Most of California will be under upper level northwest to north
flow on Saturday under the back edge of the upper low forecast to
be over the eastern Great Basin by Saturday afternoon. Much of the
CWA will see some clearing by Saturday afternoon but the Sierra
could still some showers or thunderstorms remaining under cyclonic
flow and moisture feed from the main upper low. With clearing
skies and warmer airmass...should see daytime highs Saturday climb
to near normal. Only minor changes expected on Sunday with upper
low only moving slightly. Should see enough clearing and airmass
warming Sunday however to bring the first significantly above normal
temperatures since early May.

&&

.Extended Discussion (Monday through Thursday)

Starting to sound like a broken record, but models continue to
illustrate a slightly unsettled environment for the extended forecast.
Valley should remain dry while instability persists over
mountains which could trigger showers and afternoon/evening
thunderstorms. Daytime highs in the valley will generally be in
the low to mid 80s with 70s in Delta Breeze influenced areas.
Mountain highs will range in the 50s/60s while Foothills warm into
the 70s. JBB

&&

.Aviation...

Onshore flow this morning has allowed low clouds to move through
the Delta region into Sacramento area and are banking up against
the Sierra Foothills. MVFR conditions this morning for that
vicinity through 16-18z, otherwise, the rest of our CWA will be VFR. Delta
breeze will continue to range 15-25 kts with gusts up to 30 kts
today. TAF sites will be fairly light (around 10 kts or less)
except for KSMF, KSAC, KMHR, KSCK between 17-04z when the delta
breeze enhances and increases winds at these sites with speeds
between 10-20 kts.  JBB


&&

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

$$








000
FXUS66 KSTO 211100
AFDSTO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
400 AM PDT Thu May 21 2015

.Synopsis...
Scattered showers and mainly mountain thunderstorms through the
end of the week with slightly below normal daytime temperatures.
Drier over the weekend and early next week except for a continued
shower threat over the Sierra. Temperatures warming to slightly
above normal.

&&

.Discussion...
Large upper low continues to develop off the central coast with
shortwaves pivoting around the low bringing just scattered clouds
at this time mainly south and north ends of the forecast area.
Delta breeze has been fairly strong throughout the night and
morning hours with sustained winds at Travis AFB in the teens and
gusts in the lower 20s. As a result..coastal stratus has worked
its way inland through the delta and southern Sacramento valley
banking up against foothills south of Auburn. The main upper low
center is forecast to shift to the southeast today towards the
Socal coast. Stability proggs indicate the most unstable
conditions over the mountains surrounding the Sacramento valley so
have a chance of showers and thunderstorms here. Could see a few
showers over the valley locations as well as some Sierra storms
could get pulled into the valley in upper southeast flow around
the low. Variable cloud cover and cool airmass in the low will
bring in high temperatures today a little below normal. The upper
low center is forecast to swing through southern California on
Friday with a similar stability pattern expected to today.
Therefore...expect mountain thunderstorms again with a threat of
showers in the valley under variable cloud cover.

Most of California will be under upper level northwest to north
flow on Saturday under the back edge of the upper low forecast to
be over the eastern Great Basin by Saturday afternoon. Much of the
CWA will see some clearing by Saturday afternoon but the Sierra
could still some showers or thunderstorms remaining under cyclonic
flow and moisture feed from the main upper low. With clearing
skies and warmer airmass...should see daytime highs Saturday climb
to near normal. Only minor changes expected on Sunday with upper
low only moving slightly. Should see enough clearing and airmass
warming Sunday however to bring the first significantly above normal
temperatures since early May.

&&

.Extended Discussion (Monday through Thursday)

Starting to sound like a broken record, but models continue to
illustrate a slightly unsettled environment for the extended forecast.
Valley should remain dry while instability persists over
mountains which could trigger showers and afternoon/evening
thunderstorms. Daytime highs in the valley will generally be in
the low to mid 80s with 70s in Delta Breeze influenced areas.
Mountain highs will range in the 50s/60s while Foothills warm into
the 70s. JBB

&&

.Aviation...

Onshore flow this morning has allowed low clouds to move through
the Delta region into Sacramento area and are banking up against
the Sierra Foothills. MVFR conditions this morning for that
vicinity through 16-18z, otherwise, the rest of our CWA will be VFR. Delta
breeze will continue to range 15-25 kts with gusts up to 30 kts
today. TAF sites will be fairly light (around 10 kts or less)
except for KSMF, KSAC, KMHR, KSCK between 17-04z when the delta
breeze enhances and increases winds at these sites with speeds
between 10-20 kts.  JBB


&&

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

$$









000
FXUS66 KSTO 210409
AFDSTO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
909 PM PDT Wed May 20 2015

.Synopsis...
Cool weather with mountain showers and thunderstorms will continue
through the end of the week. A chance of showers and isolated
thunderstorms in the valley for Thursday and Friday. Mostly dry
with warmer weather returns next week except for slight chances of
precipitation over the mountains.

&&

.Discussion...
Low pressure area continue over the west coast this evening. We
are still seeing some showers along the coastal range and in the
central valley north of Willows. The showers will continue to
decrease through the evening with a few isolated showers possible
in the overnight hours...mainly over higher terrain.

The low will begin to move south to off the central coast for
Thursday and then move into Southern California for Friday. In
general most of the activity will stay over the mountains but a
few showers or isolated thunderstorms may be able to work its way
into the valley as the low transitions into Southern California.
No major changes in temperatures with below normal highs
continuing through Friday. Decent flow through the delta will
continue as well.

On Saturday a low pressure system will drop down from the north
into Oregon but may be able to bring enough daytime instability
over the mountains to trigger a few showers and thunderstorms.
The low will then move south into Northern California Saturday
night to increase the chances of showers and isolated
thunderstorms. The Sacramento valley may be able to get a few
showers during this time frame.

&&

.Extended Discussion (Sunday through Wednesday)

No major changes made to the extended forecast. Low and associated
trough will be pulling away to the east on Sunday as weak ridging
briefly builds in. Shower and thunderstorm chances will be
limited to along the Sierra crest into the mountains of Shasta
County for Sunday into Monday. Models in somewhat of an agreement
with next system dropping SE from Gulf of Alaska into Pacific
Northwest on Monday into Tuesday. General consensus on track is
that bulk of system would skirt NorCal to the northeast and into
Idaho/Montana, but still some uncertainty at this point. This
would generally continue the pattern of convective chances into
Tues/Weds, mainly across the Sierra and northern mountains. Valley
and most of foothills look to remain dry into mid-week at this
point. Regardless, temperatures should warm a bit by Sunday and
remain rather consistent into mid-week. Highs will range from the
the 80s in the valley to 50s/60s in the mountains. CEO


&&

.Aviation...

Mainly VFR conditions next 24 hours in the valley. Areas of
MVFR/locally IFR in showers with isold thunderstorms through this
evening with another round possible after 18z Thurs. Delta breeze
will continue with winds 15-20 kts with gusts to 30 kts before
relaxing to around 15G25 kts tonight. Marine stratus will spread
into the Delta region tonight with brief period of MVFR possible
in the Sacramento region Thursday morning.


&&

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

$$








000
FXUS66 KSTO 210409
AFDSTO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
909 PM PDT Wed May 20 2015

.Synopsis...
Cool weather with mountain showers and thunderstorms will continue
through the end of the week. A chance of showers and isolated
thunderstorms in the valley for Thursday and Friday. Mostly dry
with warmer weather returns next week except for slight chances of
precipitation over the mountains.

&&

.Discussion...
Low pressure area continue over the west coast this evening. We
are still seeing some showers along the coastal range and in the
central valley north of Willows. The showers will continue to
decrease through the evening with a few isolated showers possible
in the overnight hours...mainly over higher terrain.

The low will begin to move south to off the central coast for
Thursday and then move into Southern California for Friday. In
general most of the activity will stay over the mountains but a
few showers or isolated thunderstorms may be able to work its way
into the valley as the low transitions into Southern California.
No major changes in temperatures with below normal highs
continuing through Friday. Decent flow through the delta will
continue as well.

On Saturday a low pressure system will drop down from the north
into Oregon but may be able to bring enough daytime instability
over the mountains to trigger a few showers and thunderstorms.
The low will then move south into Northern California Saturday
night to increase the chances of showers and isolated
thunderstorms. The Sacramento valley may be able to get a few
showers during this time frame.

&&

.Extended Discussion (Sunday through Wednesday)

No major changes made to the extended forecast. Low and associated
trough will be pulling away to the east on Sunday as weak ridging
briefly builds in. Shower and thunderstorm chances will be
limited to along the Sierra crest into the mountains of Shasta
County for Sunday into Monday. Models in somewhat of an agreement
with next system dropping SE from Gulf of Alaska into Pacific
Northwest on Monday into Tuesday. General consensus on track is
that bulk of system would skirt NorCal to the northeast and into
Idaho/Montana, but still some uncertainty at this point. This
would generally continue the pattern of convective chances into
Tues/Weds, mainly across the Sierra and northern mountains. Valley
and most of foothills look to remain dry into mid-week at this
point. Regardless, temperatures should warm a bit by Sunday and
remain rather consistent into mid-week. Highs will range from the
the 80s in the valley to 50s/60s in the mountains. CEO


&&

.Aviation...

Mainly VFR conditions next 24 hours in the valley. Areas of
MVFR/locally IFR in showers with isold thunderstorms through this
evening with another round possible after 18z Thurs. Delta breeze
will continue with winds 15-20 kts with gusts to 30 kts before
relaxing to around 15G25 kts tonight. Marine stratus will spread
into the Delta region tonight with brief period of MVFR possible
in the Sacramento region Thursday morning.


&&

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

$$









000
FXUS66 KSTO 210409
AFDSTO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
909 PM PDT Wed May 20 2015

.Synopsis...
Cool weather with mountain showers and thunderstorms will continue
through the end of the week. A chance of showers and isolated
thunderstorms in the valley for Thursday and Friday. Mostly dry
with warmer weather returns next week except for slight chances of
precipitation over the mountains.

&&

.Discussion...
Low pressure area continue over the west coast this evening. We
are still seeing some showers along the coastal range and in the
central valley north of Willows. The showers will continue to
decrease through the evening with a few isolated showers possible
in the overnight hours...mainly over higher terrain.

The low will begin to move south to off the central coast for
Thursday and then move into Southern California for Friday. In
general most of the activity will stay over the mountains but a
few showers or isolated thunderstorms may be able to work its way
into the valley as the low transitions into Southern California.
No major changes in temperatures with below normal highs
continuing through Friday. Decent flow through the delta will
continue as well.

On Saturday a low pressure system will drop down from the north
into Oregon but may be able to bring enough daytime instability
over the mountains to trigger a few showers and thunderstorms.
The low will then move south into Northern California Saturday
night to increase the chances of showers and isolated
thunderstorms. The Sacramento valley may be able to get a few
showers during this time frame.

&&

.Extended Discussion (Sunday through Wednesday)

No major changes made to the extended forecast. Low and associated
trough will be pulling away to the east on Sunday as weak ridging
briefly builds in. Shower and thunderstorm chances will be
limited to along the Sierra crest into the mountains of Shasta
County for Sunday into Monday. Models in somewhat of an agreement
with next system dropping SE from Gulf of Alaska into Pacific
Northwest on Monday into Tuesday. General consensus on track is
that bulk of system would skirt NorCal to the northeast and into
Idaho/Montana, but still some uncertainty at this point. This
would generally continue the pattern of convective chances into
Tues/Weds, mainly across the Sierra and northern mountains. Valley
and most of foothills look to remain dry into mid-week at this
point. Regardless, temperatures should warm a bit by Sunday and
remain rather consistent into mid-week. Highs will range from the
the 80s in the valley to 50s/60s in the mountains. CEO


&&

.Aviation...

Mainly VFR conditions next 24 hours in the valley. Areas of
MVFR/locally IFR in showers with isold thunderstorms through this
evening with another round possible after 18z Thurs. Delta breeze
will continue with winds 15-20 kts with gusts to 30 kts before
relaxing to around 15G25 kts tonight. Marine stratus will spread
into the Delta region tonight with brief period of MVFR possible
in the Sacramento region Thursday morning.


&&

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

$$









000
FXUS66 KSTO 210409
AFDSTO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
909 PM PDT Wed May 20 2015

.Synopsis...
Cool weather with mountain showers and thunderstorms will continue
through the end of the week. A chance of showers and isolated
thunderstorms in the valley for Thursday and Friday. Mostly dry
with warmer weather returns next week except for slight chances of
precipitation over the mountains.

&&

.Discussion...
Low pressure area continue over the west coast this evening. We
are still seeing some showers along the coastal range and in the
central valley north of Willows. The showers will continue to
decrease through the evening with a few isolated showers possible
in the overnight hours...mainly over higher terrain.

The low will begin to move south to off the central coast for
Thursday and then move into Southern California for Friday. In
general most of the activity will stay over the mountains but a
few showers or isolated thunderstorms may be able to work its way
into the valley as the low transitions into Southern California.
No major changes in temperatures with below normal highs
continuing through Friday. Decent flow through the delta will
continue as well.

On Saturday a low pressure system will drop down from the north
into Oregon but may be able to bring enough daytime instability
over the mountains to trigger a few showers and thunderstorms.
The low will then move south into Northern California Saturday
night to increase the chances of showers and isolated
thunderstorms. The Sacramento valley may be able to get a few
showers during this time frame.

&&

.Extended Discussion (Sunday through Wednesday)

No major changes made to the extended forecast. Low and associated
trough will be pulling away to the east on Sunday as weak ridging
briefly builds in. Shower and thunderstorm chances will be
limited to along the Sierra crest into the mountains of Shasta
County for Sunday into Monday. Models in somewhat of an agreement
with next system dropping SE from Gulf of Alaska into Pacific
Northwest on Monday into Tuesday. General consensus on track is
that bulk of system would skirt NorCal to the northeast and into
Idaho/Montana, but still some uncertainty at this point. This
would generally continue the pattern of convective chances into
Tues/Weds, mainly across the Sierra and northern mountains. Valley
and most of foothills look to remain dry into mid-week at this
point. Regardless, temperatures should warm a bit by Sunday and
remain rather consistent into mid-week. Highs will range from the
the 80s in the valley to 50s/60s in the mountains. CEO


&&

.Aviation...

Mainly VFR conditions next 24 hours in the valley. Areas of
MVFR/locally IFR in showers with isold thunderstorms through this
evening with another round possible after 18z Thurs. Delta breeze
will continue with winds 15-20 kts with gusts to 30 kts before
relaxing to around 15G25 kts tonight. Marine stratus will spread
into the Delta region tonight with brief period of MVFR possible
in the Sacramento region Thursday morning.


&&

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

$$








000
FXUS66 KSTO 202209
AFDSTO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
309 PM PDT Wed May 20 2015

.Synopsis...
Cool weather with mountain showers and thunderstorms will continue
through the end of the week. Warmer and drier weather returns next
week.

&&

.Discussion...
A broad upper level trough remains situated across the West, with
embedded shortwave sitting along the northern coast. Numerous
showers and thunderstorms have developed across the mountains of
Northern California, with several hundred lightning strikes
detected. These thunderstorms are producing a fair amount of
rainfall, even as they are exhibiting a south-to-north storm
motion. Temperatures across the forecast area are generally a few
degrees warmer than 24 hours ago.

Expect precipitation to begin tapering off early in the evening as
storms continue to progress northward. The short-range, hi-res
models suggest that the northern Sacramento Valley may see a
shower or thunderstorm this afternoon or evening as well.

Another reinforcing shortwave will approach the coast Thursday
into Friday, with perhaps a Fujiwhara interaction at play.
Forecast precipitable water ratches up according to the NAM, with
decent instability over the mountains. Upper level steering flow
should back to more of an easterly direction. Considering these
factors, we could see some locally heavy precipitation along the
Northern Sierra Thursday afternoon, and a few showers may make it
down to the Valley floor Thursday night into Friday.

The upper low will move inland over Southern California on Friday,
with northerly flow aloft over NorCal. We should see less in the
way of convective activity that day. Another upper low will
approach the Pacific Northwest coast on Saturday.

Dang

&&

.Extended Discussion (Sunday through Wednesday)

No major changes made to the extended forecast. Low and associated
trough will be pulling away to the east on Sunday as weak ridging
briefly builds in. Shower and thunderstorm chances will be
limited to along the Sierra crest into the mountains of Shasta
County for Sunday into Monday. Models in somewhat of an agreement
with next system dropping SE from Gulf of Alaska into Pacific
Northwest on Monday into Tuesday. General consensus on track is
that bulk of system would skirt NorCal to the northeast and into
Idaho/Montana, but still some uncertainty at this point. This
would generally continue the pattern of convective chances into
Tues/Weds, mainly across the Sierra and northern mountains. Valley
and most of foothills look to remain dry into mid-week at this
point. Regardless, temperatures should warm a bit by Sunday and
remain rather consistent into mid-week. Highs will range from the
the 80s in the valley to 50s/60s in the mountains. CEO


&&

.Aviation...

Mainly VFR conditions for the period for valley sites. Periods of
MVFR/locally IFR in showers and thunderstorms across higher
terrain through this evening with another round possible after 18z
Thurs. Delta breeze will continue in onshore flow with gusts of
15-25 kts possible before relaxing to around 10 kts tonight.
Elsewhere, winds will remain fairly light. Marine stratus may
again impinge into the Delta region Thursday morning with brief
period of MVFR possible.


&&

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

$$









000
FXUS66 KSTO 201607
AFDSTO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
907 AM PDT Wed May 20 2015

.Synopsis...
Cool weather with mountain showers and thunderstorms will continue
through the end of the week. Warmer and drier weather returns next
week.

&&

.Discussion...
A broad upper level trough remains situated across the West, with
embedded shortwave sitting just off the Bay Area coast. A few
showers continue, mainly across far Northern California, while
most of our forecast area remains dry. A deep marine layer coupled
with modest onshore flow allowed for narrow band of marine stratus
to again reach the Sacramento metro area this morning.
Otherwise...quite a bit of cloud cover is prevalent across NorCal,
the remnants of yesterday`s convective activity.

More of the same is expected today, with showers and thunderstorms
likely to develop over the higher elevations. With southeasterly
flow aloft today, a shower or thunderstorm may reach the northern
Sacramento Valley this afternoon/evening.

Another reinforcing shortwave will approach the coast on Thursday
into Friday. Forecast precipitable water ratches up significantly
according to the NAM, with decent instability over the mountains. Upper
level steering flow should back to more of an easterly direction.
Considering these factors, we could see some locally heavy
precipitation along the Northern Sierra Thursday afternoon, and a
few showers may make it down to the Valley floor Thursday night
into Friday.

The upper low will move inland over Southern California on Friday,
with northerly flow aloft over NorCal. We should see less in the
way of convective activity that day. Another upper low will
approach the Pacific Northwest coast on Saturday.

Dang

&&

.Extended Discussion (Sunday through Wednesday)

No significant changes to the extended forecast. From Sunday into
Wednesday, much of interior NorCal will be dry except for the
possibility of showers/thunderstorms over the Sierra Crest
including the Lassen Park area into the mountains of Shasta
County. Instability indices continue to indicate that best chances
for convection would be limited to those regions. The GFS and
ECMWF models are consistent on Sunday with the following synoptic
pattern: a trough over the Great Basin to our east, offshore
ridging to our west, and a weak cut-off low over the Pacific NW to
our north. The cut-off low will track southward towards NorCal by
Monday, though the models differ on its track for Monday into mid-
week. In addition, there could be some zonal flow or weak
troughing aloft for CA in that time-frame. Temperatures will hover
within a few degrees of normal with valley highs generally in the
80s and foothills/mountains in the 50s to 60s. JBB/CEO


&&

.Aviation...

VFR conditions next 24 hours for TAF sites. Periods of MVFR
possible in the Delta region this morning due to marine stratus.
Local MVFR also expected during showers and afternoon/evening
thunderstorms later today. Best chance for showers/thunderstorms is
across higher terrain and in the Sacramento valley north of
Interstate 80. Delta breeze will be 10-20 kts with gusts up to 25
kts. This onshore flow will enhance winds (10-18 kts) between 21z -
3z for the KSMF, KSAC, KMHR, and KSCK sites. Otherwise, winds in
NorCal should be fairly light. JBB


&&

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

$$









000
FXUS66 KSTO 201607
AFDSTO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
907 AM PDT Wed May 20 2015

.Synopsis...
Cool weather with mountain showers and thunderstorms will continue
through the end of the week. Warmer and drier weather returns next
week.

&&

.Discussion...
A broad upper level trough remains situated across the West, with
embedded shortwave sitting just off the Bay Area coast. A few
showers continue, mainly across far Northern California, while
most of our forecast area remains dry. A deep marine layer coupled
with modest onshore flow allowed for narrow band of marine stratus
to again reach the Sacramento metro area this morning.
Otherwise...quite a bit of cloud cover is prevalent across NorCal,
the remnants of yesterday`s convective activity.

More of the same is expected today, with showers and thunderstorms
likely to develop over the higher elevations. With southeasterly
flow aloft today, a shower or thunderstorm may reach the northern
Sacramento Valley this afternoon/evening.

Another reinforcing shortwave will approach the coast on Thursday
into Friday. Forecast precipitable water ratches up significantly
according to the NAM, with decent instability over the mountains. Upper
level steering flow should back to more of an easterly direction.
Considering these factors, we could see some locally heavy
precipitation along the Northern Sierra Thursday afternoon, and a
few showers may make it down to the Valley floor Thursday night
into Friday.

The upper low will move inland over Southern California on Friday,
with northerly flow aloft over NorCal. We should see less in the
way of convective activity that day. Another upper low will
approach the Pacific Northwest coast on Saturday.

Dang

&&

.Extended Discussion (Sunday through Wednesday)

No significant changes to the extended forecast. From Sunday into
Wednesday, much of interior NorCal will be dry except for the
possibility of showers/thunderstorms over the Sierra Crest
including the Lassen Park area into the mountains of Shasta
County. Instability indices continue to indicate that best chances
for convection would be limited to those regions. The GFS and
ECMWF models are consistent on Sunday with the following synoptic
pattern: a trough over the Great Basin to our east, offshore
ridging to our west, and a weak cut-off low over the Pacific NW to
our north. The cut-off low will track southward towards NorCal by
Monday, though the models differ on its track for Monday into mid-
week. In addition, there could be some zonal flow or weak
troughing aloft for CA in that time-frame. Temperatures will hover
within a few degrees of normal with valley highs generally in the
80s and foothills/mountains in the 50s to 60s. JBB/CEO


&&

.Aviation...

VFR conditions next 24 hours for TAF sites. Periods of MVFR
possible in the Delta region this morning due to marine stratus.
Local MVFR also expected during showers and afternoon/evening
thunderstorms later today. Best chance for showers/thunderstorms is
across higher terrain and in the Sacramento valley north of
Interstate 80. Delta breeze will be 10-20 kts with gusts up to 25
kts. This onshore flow will enhance winds (10-18 kts) between 21z -
3z for the KSMF, KSAC, KMHR, and KSCK sites. Otherwise, winds in
NorCal should be fairly light. JBB


&&

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

$$










000
FXUS66 KSTO 201037
AFDSTO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
337 AM PDT Wed May 20 2015

.Synopsis...
Variable clouds with mainly mountain showers and afternoon
thunderstorms through the end of the week as the west coast
remains under the influence of a low pressure system. Daytime
highs forecast to remain near normal. Mainly Sierra showers next
week as another low drops southward out of the Pacific Northwest.
Daytime temperatures warming back above normal.

&&

.Discussion...
Showers have ended over the CWA this morning with temperatures
running similar to 24 hours ago. Large upper low over the eastern
Pacific and west coast not forecast to move a lot today so
should see weather fairly comparable to Tuesday. Not seeing any
shortwave disturbances that might directly impact the forecast
area so going with chance pops of mainly mountain showers again
today. Most instability and moderate orographics over the
mountains and northern Sacramento valley so have limited
thunderstorm threat to these areas. Overall airmass not expected to
change much so daytime highs today near normal and similar to
Tuesday. Upper trough and closed low forecast to start moving to
the southeast and inland on Thursday. This should cause afternoon
showers to become more widespread but main instability remains
over the mountains so kept thunderstorm threat limited to
mountains and northern Sacramento valley where orograpics or
terrain convergence are the greatest. By Friday...models all shift
main upper trough east of the CWA and into the Great Basin. Norcal
remains under cyclonic flow however so shower threat continues.
Limited the thunderstorm threat to mainly the Sierra mountains on
Friday closest to the trough axis with just a general shower
threat farther west. May see some clearer skies and slight warming some
areas on Saturday as the upper trough continues eastward and weak
ridging slides quickly over the area. Wrap around type moisture
may still influence the Sierra for a threat of showers there.
&&

.Extended Discussion (Sunday through Wednesday)

No significant changes to the extended forecast. From Sunday into
Wednesday, much of interior NorCal will be dry except for the
possibility of showers/thunderstorms over the Sierra Crest
including the Lassen Park area into the mountains of Shasta
County. Instability indices continue to indicate that best chances
for convection would be limited to those regions. The GFS and
ECMWF models are consistent on Sunday with the following synoptic
pattern: a trough over the Great Basin to our east, offshore
ridging to our west, and a weak cut-off low over the Pacific NW to
our north. The cut-off low will track southward towards NorCal by
Monday, though the models differ on its track for Monday into mid-
week. In addition, there could be some zonal flow or weak
troughing aloft for CA in that time-frame. Temperatures will hover
within a few degrees of normal with valley highs generally in the
80s and foothills/mountains in the 50s to 60s. JBB/CEO


&&

.Aviation...

VFR conditions next 24 hours for TAF sites. Periods of MVFR
possible in the Delta region this morning due to marine stratus.
Local MVFR also expected during showers and afternoon/evening
thunderstorms later today. Best chance for showers/thunderstorms is
across higher terrain and in the Sacramento valley north of
Interstate 80. Delta breeze will be 10-20 kts with gusts up to 25
kts. This onshore flow will enhance winds (10-18 kts) between 21z -
3z for the KSMF, KSAC, KMHR, and KSCK sites. Otherwise, winds in
NorCal should be fairly light. JBB


&&

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

$$









000
FXUS66 KSTO 200357
AFDSTO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
857 PM PDT Tue May 19 2015

.Synopsis...
Variable clouds with mainly mountain showers and afternoon
thunderstorms through the week as the west coast remains under
the influence of a low pressure system. Daytime highs forecast to
remain below normal.

&&

.Discussion...
Lingering showers over the mountains with most of the activity
over the far northern part of the state this evening.  Low
pressure system will stay off the coast through Wednesday so
expect little change in conditions for tomorrow.

The low will begin to move south to off the central coast for
Thursday and then move into Southern California for Friday. In
general most of the activity will stay over the mountains but a
few showers or isolated thunderstorms may be able to work its way
into the valley as the low transitions into Southern California.
No major changes in temperatures with below normal highs
continuing through Friday. Decent flow through the delta will
continue as well.

&&

.Extended Discussion (Saturday through Tuesday)

Area will be sandwiched between ridging building over eastern
Pacific and trough departing to the east for the start of the weekend.
Models continue to differ on the track and speed of the trough as
it departs. GFS moves the trough off faster to the east with
riding across the area for the weekend into Tuesday, which would
lead to a dry forecast. ECMWF/GEM are slower with the departure
and continue the chance for mountain showers and thunderstorms
through at least Sunday. Given uncertainty, have not made major
changes to going forecast. Feel that there may be enough
instability present to continue the chance for daily showers and
thunderstorms across higher terrain through Sunday for now. May
then see a break in convection for Monday and Tuesday. Regardless,
valley should remain dry in either scenario. Temperatures will
hover within a few degrees of normal with valley highs generally
in the 80s and foothills/mountains in the 50s to 60s. CEO


&&

.Aviation...

Mainly VFR conditions next 24 hours for interior NorCal except
during showers and afternoon/evening thunderstorms that bring
periods of MVFR. Best chance for showers/thunderstorms is across
higher terrain and far northern portions of Sacramento valley.
Delta breeze will be 10-20 kts with gusts up to 25 kts.


&&

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

$$








000
FXUS66 KSTO 200357
AFDSTO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
857 PM PDT Tue May 19 2015

.Synopsis...
Variable clouds with mainly mountain showers and afternoon
thunderstorms through the week as the west coast remains under
the influence of a low pressure system. Daytime highs forecast to
remain below normal.

&&

.Discussion...
Lingering showers over the mountains with most of the activity
over the far northern part of the state this evening.  Low
pressure system will stay off the coast through Wednesday so
expect little change in conditions for tomorrow.

The low will begin to move south to off the central coast for
Thursday and then move into Southern California for Friday. In
general most of the activity will stay over the mountains but a
few showers or isolated thunderstorms may be able to work its way
into the valley as the low transitions into Southern California.
No major changes in temperatures with below normal highs
continuing through Friday. Decent flow through the delta will
continue as well.

&&

.Extended Discussion (Saturday through Tuesday)

Area will be sandwiched between ridging building over eastern
Pacific and trough departing to the east for the start of the weekend.
Models continue to differ on the track and speed of the trough as
it departs. GFS moves the trough off faster to the east with
riding across the area for the weekend into Tuesday, which would
lead to a dry forecast. ECMWF/GEM are slower with the departure
and continue the chance for mountain showers and thunderstorms
through at least Sunday. Given uncertainty, have not made major
changes to going forecast. Feel that there may be enough
instability present to continue the chance for daily showers and
thunderstorms across higher terrain through Sunday for now. May
then see a break in convection for Monday and Tuesday. Regardless,
valley should remain dry in either scenario. Temperatures will
hover within a few degrees of normal with valley highs generally
in the 80s and foothills/mountains in the 50s to 60s. CEO


&&

.Aviation...

Mainly VFR conditions next 24 hours for interior NorCal except
during showers and afternoon/evening thunderstorms that bring
periods of MVFR. Best chance for showers/thunderstorms is across
higher terrain and far northern portions of Sacramento valley.
Delta breeze will be 10-20 kts with gusts up to 25 kts.


&&

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

$$









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