Storm Hub Hudson Valley: NWS Predicts Overnight Accumulation

The National Weather Service downgraded its notice for Orange and Putnam counties to an advisory, as it had done earlier Wednesday for Dutchess County.

Here are the latest overnight predictions from the National Weather Service for the lower Hudson Valley overnight, as of 10 p.m.:

Rockland and Westchester: Additional snow accumulations of 2 to 4 inches are expected.

Orange and Putnam: Additional snow accumulations of up to 2 inches are expected.

Dutchess County: Additional snow accumulations of 2 to 5 inches are expected. The highest totals in extreme southern Dutchess County.

AccuWeather reported 5,000 flights were canceled Wednesday as the nor'easter coated the I-95 corridor with snow and ice.

The fourth snowstorm of March began dumping snow on the tri-state area Wednesday, including the southern end of the Hudson Valley. The National Weather Service reported 3.5 inches of snow in White Plains as of 2:30 p.m.

Airlines canceled all remaining flights for Wednesday at LaGuardia Airport. Westchester County is suspending its bus service as of 6 p.m.

New York Gov. Andrew M. Cuomo visited Rockland and Westchester counties Wednesday afternoon after checking out the storm on Long Island and in NYC.

"I've been in New York City, I've been in Long Island, I've been in Westchester, I'm here now — I can tell you the roads are bad," he said at a press conference in Suffern. "We've had fatal accidents on Long Island, we've had multiple car accidents on the Long Island Expressway, we were on the Thruway, it is not safe to be out there unless you must be there. Also, when someone is on the road, all it takes is one car to get stuck, one accident and then everything backs up and then the people who are out there to do their job, the plows, the salters, the spreaders - everything stops. And when you have the snow that comes down as fast as this snow is coming down, you block up a road and those plows get stuck, now we have a real problem and it becomes a cascading effect. So if you don't have to be on the road, don't be on the road."

SEE: One Dead, Five Injured In Wantagh Parkway Crash; Road Closed

Westchester County is suspending Bee-Line and Paratransit operations systemwide at 6 p.m. Wednesday due to poor road conditions and concern about the safety of passengers. County officials said, "We will evaluate conditions early tomorrow morning, and resume operations when the road conditions improve. For further information, access our website."

Radar maps may show snow across most of the region, but because there is so much dry air, in many places it's evaporating before it hits the ground, Hudson Valley Weather reports.

"So periods of snow are certainly possible late this afternoon and tonight… but the strength of this dry air is the wildcard," said Alex Marra and Bill Potter of Hudson Valley Weather.

If you want, you can help the National Weather Service by submitting a snow total report. Click here to learn how.

UPDATE: Dutchess County officials said the snow is still expected to affect the county, with snow anticipated to intensify after sunset.

SEE ALSO: Snow Expected To Intensify, Dutchess County Says

UPDATE: Gov. Cuomo declared a state of emergency for Putnam, Rockland and Westchester counties, along with Long Island and New York City. He is also activating 300 National Guard members who will be deployed to areas affected by the storm.

SEE ALSO: Cuomo Declares State Of Emergency For Downstate NY

UPDATE: More than 2,100 New York City flights were canceled by Wednesday morning as the region braced for its latest - and potentially snowiest - nor'easter yet.

READ MORE: Thousands Of NYC Flights Canceled

Tractor trailer ban in effect: Tractor Trailers Banned Wednesday On Major Roadways.

UPDATE: Metro-North is running reduced service on Wednesday, with some peak trains combined or cancelled.

SEE: Metro-North Limits Service During March 21 Storm

The National Weather Service issued a revised forecast for the March 21 snowstorm at 4 a.m. Wednesday. Here are its county-by-county predictions:

Rockland and Westchester counties: Total snow accumulations of 12 to 18 inches are expected, with locally higher amounts possible.

Orange and Putnam counties: Total snow accumulations of 7 to 12 inches, with locally higher amounts possible

Dutchess County: Total snow accumulations of 3 to 7 inches are expected across northern Dutchess and northern Litchfield Counties, with 6 to 10 inches across southern Dutchess and southern Litchfield Counties.

Ulster County: Total snow accumulations of 1 to 4 inches, with localized amounts up to 6 inches in southeastern Ulster

For everybody, the NWS says:

Travel will be very difficult to impossible, especially this afternoon. Snow will develop during the morning and become heavy by afternoon. Expect significant reductions in visibility at times. A combination of the heavy snow and wind gusts up to 30 mph could bring down tree limbs and power lines, creating power outages.

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In addition to the winter storm warnings, there are also coastal flood advisories in effect for the Long Island Sound.

• Coastal Flood Advisory in effect from March 22, 12:00 AM EDT until March 22, 04:00 AM EDT
• Coastal Flood Advisory in effect from March 21, 12:00 PM EDT until March 21, 06:00 PM EDT

Many municipalities have declared states of emergency.

• Nyack Declares State Of Emergency
• Ossining Declares Snow Emergency For Wednesday
• Yorktown Declares Snow Emergency Wednesday
• Sleepy Hollow Declares Snow Emergency Wednesday

Con Edison and O&R utilities issued storm statements.

• O&R: All Hands to Mobilize for 'Significant Weather Event'
• HV Snow: Con Edison Warns Of Downed Power Lines

Most lower Hudson Valley schools are closed. Other cancellations include:

• White Plains Lower Hudson Transit Open House To Be Rescheduled
• Hearing On Hudson Valley Storm Response Postponed Due To Storm

As the storm develops, check back with Patch for updates on conditions, travel and transportation.

PHOTO/ Lanning Taliaferro