Wednesday, October 28, 2020

Pre-Halloween soaker, fueled by Zeta, to bring dose of wintry weather to Northeast

 By Alex Sosnowski, AccuWeather senior meteorologist

Published Oct. 28, 2020 12:43 PM







Hurricane Zeta will bring the biggest blow to the storm-weary Gulf Coast this week, but forecasters expect its effects to be far-reaching across the United States. The storm's quick movement is predicted to continue after it makes landfall and moves inland -- even when it loses wind intensity over land and weakens into a tropical rainstorm. The system may not fully merge with a winterlike storm that snarled travel and cut power with heavy icing in the southern Plains; however, the two storms will blend together enough to unleash rains that could cause a risk of flooding in the Northeast -- and a helping of wintry weather across parts of the region.

The shield of rain from Zeta will reach well to the north of the center of the storm as tropical moisture will rise up and over a wedge of cool air in place over the Northeast.

"Rain from Zeta will spread over portions of West Virginia, Virginia, western Maryland and southwestern Pennsylvania prior to daybreak on Thursday," AccuWeather Senior Meteorologist Brett Anderson said.

"The rain will continue to advance northeastward at a swift pace and extend to the southern tier of New York state and southern New England during the afternoon hours on Thursday," Anderson added.

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Both the morning and afternoon commutes on Thursday in Baltimore, Washington, D.C., Richmond, Virginia, and Pittsburgh could be slowed and hazardous at times due to drenching rain, poor visibility and slippery conditions. The rain should hold off until the midday hours in Philadelphia, and it will be the evening drive in New York City and Boston that could be riddled with delays.

"The combination of fallen leaves and drenching rain will lead to clogged storm drains that can cause street and secondary road flooding," said AccuWeather Senior Meteorologist Bill Deger. Fallen leaves could make roads even more slick in the region.

Adding to the miserable weather, there will be enough of a circulation from Zeta remaining to spawn gusty winds from Virginia to the Maryland, Delaware and New Jersey coasts on Thursday. Gusts between 40 and 50 mph can occur in this swath, which can be enough, when combined with drenching rain and wet soil conditions to cause some poorly rooted trees to topple over. And with that risk will come the threat of sporadic power outages.

Zeta will continue to race off to the North Atlantic Thursday night, but after that, the situation will become even more complicated. The storm sweeping eastward from the Plains and colder air plunging from the Midwest and southern Canada will come into play in the pattern.

The southern Plains storm will lose a lot of its frigid weather characteristics by the time it heads east, but the fresh injection of cold air from the Midwest and southern Canada will make up for it somewhat. The result will be a change from rain to snow over portions of northern and western Pennsylvania to portions of upstate New York and central and northern New England.

"This change to wintry precipitation is likely to be a mere show of wet snowflakes in the valleys of central and northeastern Pennsylvania to the Hudson Valley of New York state and the Boston area of Massachusetts from Thursday night to Friday morning," AccuWeather Senior Storm Warning Meteorologist Brian Wimer said.

However, the higher elevations of northern Pennsylvania, the southern tier of New York state, the Berkshires of western Massachusetts and the southern portions of the Green and White mountains of Vermont and New Hampshire will pick up a few inches of wet, clinging snow, Wimer added.

An AccuWeather Local StormMax™ of 10 inches of snow is forecast to fall over the ridges and peaks in the Catskills and Green and White mountains.

Motorists venturing through secondary roads in the higher elevations in the mountains should be prepared for slushy conditions and poor visibility.

It is possible that a small slushy amount of snow will fall on the hills of northwestern New Jersey and in western Connecticut. There is a chance that the rainstorm will end with wet snowflakes in part of the New York City metro area, the south coast of New England and perhaps even Long Island, New York, during Friday morning.

The cold blast will also usher in a significant amount of dry air. This setup could result in a sharp northern edge to the snow and rain area across the northern parts of New York state and New England. Should the dry air race southward at a fast pace it could greatly tone down the amount and duration of the snow, which may only last a few hours to begin with.

Although Zeta will not be solely responsible for snow in the Northeast, because of its speedy exit Thursday evening and the Plains storm on its heels and aiding in the wintry conditions, there have been cases where tropical systems have brought snow to the U.S. October is the most likely the time of the year for tropical systems to behave in a two-faced manner with downpours and snow.

Superstorm Sandy tapped into cold air on its western flank and produced up to a couple of feet of snow on the central and southern Appalachians during late October 2012.

After moving off the east coast of Florida in October 2005, Hurricane Wilma's moisture fed into a coastal storm, which caused high waves and beach erosion along the northeastern U.S. coast, along with high winds and snow from Pennsylvania up to New England, where more than 20 inches of snow fell.

There is still the remote chance of a last-minute, total phase of Zeta and the Plains storm or rapid strengthening of the Plains storm as it nears the coast. This remote scenario could unload heavy snow over much of central and southern New England, even at some low elevation and coastal locations.

Regardless, much of the Northeast can expect a dry and chilly Halloween weekend in the wake of the storm duo. Since a southward dip in the jet stream will persist in the Northeast into next week, an outbreak of cold air is forecast to sweep from the Great Lakes on Sunday to the central and northern Appalachians and coastal Northeast during Sunday night and Monday.

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The leading edge of that cold air push could lead to rain showers at the tail end of the weekend into early Monday near the Atlantic coast. Lake-effect snow can set up off lakes Erie and Ontario early next week with some accumulation possible in the traditional snowbelts downwind of the lakes along with snow showers in the central and northern Appalachians.

Temperatures in the throes of the cold outbreak could drop to 20 degrees Fahrenheit below normal early next week, which will put highs in the lower to middle 30s over the higher elevations to the middle to upper 40s around the Chesapeake Bay. Heating demands and fuel expenditures will likely surge, and many Americans may reach for warmer clothing.

Keep checking back on AccuWeather.com and stay tuned to the AccuWeather Network on DirecTV, Frontier and Verizon Fios.

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