'Atmospheric rivers' threaten U.S. coasts

Fire hose weather systems are whipping rain and snow at
both coasts with mighty gusts. The one in the Northeast
will begin letting up this week, but the one on the Pacific
Coast is just getting cranked.
Will the latter deliver a wind-whipped torrent to
remember or more drought relief?
Californians will get to decide by Thursday, as a storm
front piles in behind an "atmospheric river" that is driving
tropical moisture ashore, the National Weather Service
says.
Atmospheric rivers are 250-400 miles wide and split off
like a tributary from a much larger band of moisture from
the tropics.
They only come occasionally but are necessary to fill up
water reservoirs, the NWS says.
"Up to 50% of annual precipitation on the West Coast
occurs in just a few AR events."
Pineapple Express
Some are called "Pineapple Expresses," because they drag
moisture over from right around Hawaii. The current one
has hosed the West Coast since late November.
On the weather map, it looks like a cloud river in the sky
flowing straight at the coast, and in combination with the
storm system chasing it ashore, it is expected to dump 2-5
inches of rain in many places this week.
The highest elevations of northern California might get 10
inches of rain, forecasters said.
San Francisco could see 2 to 4 inches in the city with up
to 8 inches in the hills. Southern California might get 1 to 2
inches with twice as much in the hilly areas.
That much rain may be more common, if you live along the
Gulf or Atlantic Coasts, but for parched California, which
researchers at the University of Nebraska say is the most
drought stricken in the country, it's a lot to handle at once.
And in many areas, it comes on top of high rains last
week. The weather service warned there could be
moderate river flooding in California and Washington.
Flooding possible
In the Bay Area on Tuesday, public works crews got
ready for a downpour. A road crew vacuumed mud and
trash out of a storm drain, CNN affiliate KTVU
reported.
"This is not the most glamorous work that there is, even
with equipment like this. This is still really hard work.
Hard and dirty work but something that has to be done to
make sure the system functions properly when we do have
a big storm," Caltrans spokesman Bob Haus told KTVU.
The Sheriff's department in Solano County, which has a
lot of waterfront land, is handing out sandbags to residents.
Bay Area power crews cut pine tree limbs hanging over
power lines ahead of winds of 30 to 40 mph with gusts up
to 70 mph.
Those howling winds will also drive in high surf up and
down the West Coast, with some breakers rising 20 feet
high.
They are expected to push up water levels in Washington's
Puget Sound, which could have residents of Seattle and
Tacoma wading through shoreline puddles.
The area will live up to its reputation for sogginess, as
about half a foot of rain is expected to fall between early
Wednesday and late Thursday, the weather service
predicts.
Nor'easter
The wet maker on in the Northeast looks more like a
circular water sprinkler, spinning in moisture from the
Atlantic, where it is clashing with cold air.
The nor'easter's wet, cold misery -- from chilly rain to
snow and ice -- have slushed the Northeast and will
continue to as the gyrator drifts north through northern
New England.
Syracuse, New York, should expect to see 2 inches of
snow accumulate overnight Tuesday, another 8 on
Wednesday and 3 more on Thursday.
The 6-10 inches of snow in Greenville Junction, Maine, on
Wednesday will get a glazing of freezing rain more than
once this week, the NWS predicts.
Winds will be high there, too, with gusts of 40 to 60 mph.
They could cause coastal flooding in Maine.
Real rainmaker
There were reports of record rain on Tuesday from the
New York metropolitan area with nearly 3 inches falling.
At John F. Kennedy International Airport, 2.95 inches
fell, the most on this date.
At LaGuardia Airport, where 2.65 inches fell, the delays
at one point reached four hours.
According to the flight tracking website FlightAware.com,
more than 2,600 flights departing from and/or landing in
the United States were delayed Tuesday and 1,200 were
canceled.
Heavy rain tapered off Tuesday evening, but some areas
were still flooded, the New York office of the National
Weather Service said. Flood warnings for three counties
just north of Manhattan were issued.
Earlier, the pooling water kept motorists off the streets.