Roosevelt Severe & Unusual Weather

Wednesday, December 12, 2018

Another vigorous storm to dump more rain, mountain snow on Pacific Northwest

By Kyle Elliott, AccuWeather meteorologist

December 11, 2018, 11:29:42 PM EST

Following Sunday’s rainy, damp and chilly weather in the Pacific Northwest, an even stronger storm system will bring heavy rain and copious mountain snow to the region through Tuesday night.

Although residents in Seattle and Portland, Oregon, experienced an abnormally dry first week of December, the monthly rainfall deficits will be effectively erased this week.

The storm system that arrived Tuesday morning will continue to push inland over the northern Rockies through Wednesday.

The worst conditions in the coastal areas of the Northwest will continue through Tuesday night.

Not only will rain soak the Interstate-5 corridor from Seattle to Portland and snow bury the Cascades, but winds may also be strong enough to cause localized tree damage and power outages.

“Wind gusts of 40 mph are likely in the entire I-5 corridor from Portland to Salem and Seattle, with gusts up to 45 mph at the coast,” AccuWeather Senior Meteorologist Dave Houk said.

Rainfall amounts of 1 to 2 inches will be likely in Seattle and Portland, with up to 3 or 4 inches possible near the Washington coast.

Because severe to extreme drought is gripping a large portion of Oregon, according to the latest United States Drought Monitor, the rain will come as a welcome sight and help to fill up reservoirs across the state.

However, stream and river flooding concerns will ramp up farther north across western parts of Washington, where rainfall amounts are forecast to be highest.

At the very least, motorists will face treacherous travel conditions and have to contend with standing water on interstates and secondary roadways.

While rain dampens coastal areas, a healthy dose of snow is expected to fall in the Cascades and northern Rockies through Wednesday.

The current snowpack in the Washington Cascades is well below normal for this time of year, according to the U.S. Department of Agriculture Natural Resources Conservation Service.

“While the snowfall will be good news for winter sports enthusiasts and ski resorts, it can create travel difficulties over the mountain passes,” AccuWeather Meteorologist Renee Duff said.

Around a foot of snow is forecast to bury I-90’s Snoqualmie Pass, and a slick covering of snow can even fall on I-5’s Siskiyou Summit in Oregon by Tuesday night.

Motorists should be sure to reduce speed when traveling in heavy snow or on snow-covered roadways in order to reduce the risk of spinouts and accidents. Motorists should check with state highway departments for vehicle restrictions when venturing over the passes.

Download the free AccuWeather app to find out how much rain or snow is expected this week in your location.

Farther inland, strong winds are forecast to occur along the eastern slopes of the northern and central Rockies, associated in part with this storm as a Chinook wind event unfolds.

"Gusts to 80 mph are possible from western and central Montana to north central Colorado, beginning Tuesday night and lasting to Wednesday night in some locations," according to AccuWeather Senior Meteorologist Alex Sosnowski.

"Gusts this high pose a danger to motorists and may cause property damage," Sosnowski said.

Residents of the Northwest will barely have time to catch their breaths behind this system before the next storm comes ashore Wednesday night into Thursday.

In fact, the stormy pattern is expected to persist through the weekend and into next week as additional storm systems target the Northwest on an every-other-day basis.

"There seems to be at least five or six storms lined up, like a train, set to slam into the Northwest through the middle of next week," Sosnowski said.

"While this many storms in that short of time are not unusual for the region, they can still pack a punch and have significant negative impact on travel, commerce and shipping in the region prior to Christmas."

As much as 12 inches of rain and over 4 feet of snow may fall in the hardiest-hit locations by the middle of next week with the stormy weather pattern showing no signs of ending in the near future.

That type of rain and snowfall can lead to flash flooding and mudslides, as well as raise the risk of avalanches over time.

https://www.accuweather.com/en/weather-news/another-vigorous-storm-to-dump-more-rain-mountain-snow-on-pacific-northwest/70006845

Flooding rain, severe storms to aim for southeastern US, including areas buried under snow

By Alex Sosnowski, AccuWeather senior meteorologist

December 12, 2018, 2:39:13 PM EST

While the next storm on the way for the eastern United States will be warmer when compared to last weekend's storm, it may create trouble in the South in the form of flooding as rain and thunderstorms begin late this week.

Wet stretch ahead for southeastern US

In areas where there is little or no snow on the ground, the saturated state of the soil and a general 1-3 inches of rain forecast can be enough to cause urban and small stream flooding and lead to rises on some of the major rivers in the region.

Expect travel delays to expand as the rain wets the roads, areas of fog develop and the cloud ceiling lowers around the airports, including Atlanta, Charlotte, North Carolina, and Orlando, Florida.

Flash flooding and severe thunderstorms may occur

Heavy to locally severe thunderstorms are likely over Florida and may extend northward along the southern Atlantic coast from Friday to early Saturday.

"The greatest threats from the storms are expected to be flooding downpours and strong wind gusts," according to AccuWeather Lead Storm Warning Meteorologist Eddie Walker.

"However, a few isolated tornadoes cannot be ruled out," Walker said.

Some of the heaviest rainfall from the storm may fall from Florida to the Carolina coast.

"It is in the southeastern corner of the U.S., especially in parts of Florida, where downpours may train and lead to flooding on a more regional basis," according to AccuWeather Meteorologist Maggie Samuhel.

Lingering snow to be a problem

Snow has been melting and will continue to disappear in some areas in the wake of last weekend's heavy snowfall. However, enough will remain on the ground over the southern Appalachians and in many Piedmont areas as rain from the next storm arrives on Friday.

At the very least, where snow is piled up and is blocking storm drains, urban flooding is likely.

The time to clear the snow from storm drains along streets and in parking lots is prior to the next storm's arrival.

A man sits on a mountain of snow at a shopping center parking lot as he waits for his boss to pick him up after plowing in Greensboro, N.C., Monday, Dec. 10, 2018. (AP Photo/Chuck Burton)

In some cases where the snow partially melted and turned to ice, it may take a long time for this wintry concoction to go away. Ice ruts on driveways and back roads may remain through the storm over the countryside in the mountains.

Where heavy snow remains on roofs, especially flat or shallow pitched roofs, there is the risk of collapse. Enough rain may fall at first to add a great deal of weight to the roof, since the snow may act like a sponge.

For example, one gallon of water weighs about 10 pounds. So, in some cases, there may be parts of the roof that have imaginary gallon jugs stacked 2 to 4 layers deep where snow has drifted. Often, it is the uneven snow load on a shallow roof that leads to failure as rain pours down.

Only remove snow from a roof if you can do so safely, such as using a roof brush or contact a professional that is properly insured.

In terms of wintry precipitation with the storm on the way, there is likely to be a period of wet snow and/or sleet over the highest elevations as the storm begins on Friday.

The storm may end as a bit of snow or snow showers in some of these same areas and others spanning Sunday and Sunday night.

What will impacts be in northeastern US?

Like the storm from last weekend, this storm will have a northern edge.

This time, precipitation is forecast to reach farther north when compared to last weekend. The northern edge may set up somewhere from northern Pennsylvania and southern New York state to southern or central New England.

Even with this more northern edge, much of the affected area in the mid-Atlantic and New England can expect rain to be the main form of precipitation.

Areas of fog and a low cloud ceiling may lead to airline delays in Washington, D.C., to Philadelphia to New York City from Saturday to Sunday.

The same wet conditions are forecast to spread over Cincinnati, Pittsburgh, Indianapolis and Cleveland for a time this weekend.

A few pockets of snow and ice may occur over the central Appalachians and the storm may begin as snow and/or ice along the northern edge.

AccuWeather will continue to provide updates on the precipitation and risks expected from the storm. Download the free AccuWeather app to see your pinpointed forecast and any weather-related warnings.

Cyclone and storms: two extreme weather systems to lash eastern Australia

A tropical cyclone is predicted to hit Queensland, Australia this weekend (Dec. 14, 2018 weekend) that will affect New South Wales, South Australia, Victoria and Tasmania as extreme weather sweeps over most of eastern Australia.

The cyclone picked up its strength in the Gulf of Carpentaria and is expected to upgrade to a category 2 storm by Wednesday afternoon, and is expected to reach a Cat. 3 by Thursday morning. It will move east into Queensland by Friday, bringing heavy rains and strong winds.

An extreme low-pressure system is forming in the area of Victoria that will bring storms and floods to the southern part of Australia, and it is forecasted that rain might ease in intensity by Thursday, but could spread in the area, reaching the northern tip of Tasmania.

Some north-western parts of the state could experience their wettest day of the year.

Source: The Guardian https://www.theguardian.com/australia-news/2018/dec/12/cyclone-and-storms-two-extreme-weather-systems-to-lash-eastern-australia