Area Forecast Discussion
Issued by NWS Sacramento, CA

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FXUS66 KSTO 230455
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
855 PM PST Wed Feb 22 2017

.Synopsis...
Significant flooding concerns continue as runoff from the recent
rain continues to work its way downstream adding stress to
waterways. A couple of weak but cold storms move through
Friday/Saturday then Sunday/Monday. An extended period of dry
weather starts after the storm next week.

&&

.Discussion...
Lingering showers mainly over the mountains at this time will
continue to decrease overnight. Low pressure area is over Nevada
at this time but some wrap around moisture will continue to
produce some showers over the mountains through Thursday.

Much colder air has been filtering in behind this system and
valley temperatures will dip into the mid 30s tonight. Light
northerly flow will help to dry out the airmass and help setup
what looks like a lot of freezing temperatures Friday morning. The
temperatures look to range between 29 and 34 degrees in the valley
for the lows. Peaches, plums, apricots and almonds will be at
risk of damage as they should be in bloom now.

A weak system will move into the region late Friday/Friday night
mainly over the northern end of the forecast area before spreading
southward on Saturday. The airmass will remain cold with continued
cold air moving into the region. A mix of rain/snow may occur over
the northern end of the Sacramento valley late Friday night and
Saturday morning. Precipitation amounts are light so only a
dusting of snow looks possible for most of those areas at this
time. Amounts look very light even for the mountains with this
system at around a quarter of an inch or less and some areas in
the valley may not even receive some precipitation.

.Previous Discussion...
Disturbance passing southeast through northern California will
keep showers and a few thunderstorms going into the evening. Some
of the stronger storms will have small hail. A brief period of
heavy snow may pass over the Sierra including interstate 80 and
highway 50 between 5 pm and 9 pm with up to 3 inches of snow
...locally heavier in a few spots.

Northwest flow behind broad upper trough over Rockies will prevail
over NorCal with a couple of weak disturbances dropping southeast.
This will keep a few showers over the mountains...but generally
dry for the valleys Thursday/Friday. Patchy frost with valley
temps low to mid 30`s Friday...especially north Sac valley.

Next system dropping south Saturday continues to trend
weaker...with precip forecast greatly reduced from earlier
forecast. The system is now forecasted to produce less than 0.50
inches mountains and a few inches of Snow. Better potential is
possible later in the weekend.

&&
.EXTENDED DISCUSSION (Sunday THROUGH Wednesday)


Forecast remains on track for the extended period. Long term
models continue to show a cold upper trough dropping
southeastward. This system could bring some light precipitation
Sunday into Monday. Model guidance indicates that this system will
be out of phase with the moisture to its south and won`t have much
moisture to work with. Best chances of precipitation will be
across higher terrain. Cold air associated with this system should
keep snow levels relatively low. Dry conditions will prevail
generally Tuesday through at least the rest of next week as upper
ridging builds in. Temperatures will be near or slightly below
normal on Wednesday, with Valley highs in the low 60s.


&&

.AVIATION...


Scattered showers ovr the mtns tonight. VFR vly with occasional
MVFR CIGS/VSBYS in showers for mtns. Gusty NW winds G30 kts in
wake of storms. Snow levels around 3000 feet lowering to 2000 to
2500 feet by Thursday morning. VFR conditions on THU as drier NW
flow develops over rtes as upper low moves E of the region.


&&

.STO WATCHES/WARNINGS/ADVISORIES...
Flash Flood Watch through Saturday morning for Carquinez Strait
and Delta.

&&

$$



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