Reasons to be concerned...
Jim Cisco, NOAA’s Hydrometeorological Prediction Center:“It’s almost a weeklong, five-day, six-day event. It’s going to be a widespread serious storm.” (via the Associated Press)
National Weather Service (NWS), Philadelphia: “The storm will be slow moving. This worsens the impact for coastal flooding as it will affect multiple high tide cycles.”
2) Lack of precedent
Brad Panovich, broadcast meteorologist, Charlotte: “It’s very rare to see a strong tropical system merge with such a strong winter like trough of low pressure. Throw in a full moon and the potential is there for a significant storm. This system is 1 part Hurricane, 1 part Nor’easter and 1 part Blizzard potentially. Impacts of all 3 types of storms are possible depending on location.
“For those on the coast don’t let the Category of the storm or whether it’s “just” a Nor’easter dictate your response. Your personal memories of previous storms are no use in this unique situation.”
Jim Cisco, NOAA’s Hydrometeorological Prediction Center: “We don’t have many modern precedents for what the models are suggesting.” (via the Associated Press)
3) Potential for record flooding
NWS Philadelphia: “If the center of the storm makes landfall along the New Jersey or Delaware coast, record coastal flooding is possible [for DE and NJ beaches].”
4) Expanding area of strong winds
James Franklin, National Hurricane Center: “[Sandy] will get broader [when it makes landfall]. It won’t be as intense, but its effects will be spread over a very large area.” (via the Associated Press)
Dave Tolleris, Wxrisk.com: “In [the mid-Atlantic] winds could reach up to 75 miles per hour in gusts during the height of the storm which will be fairly prolonged.”
5) Inland snow potential
NOAA’s Hydrometeorological Prediction Center: “HEAVY SNOWS POSSIBLE ON THE SOUTHWEST EDGE WHERE THE ONTINENTAL POLAR AIR RUSHES ACROSS THE UPPER OHIO VALLEY AND CENTRAL APPALACHIANS AND ADJACENT LOWLANDS TO THE EAST”
Dave Tolleris, WxRisk.com: “The snowstorm potential here remains high especially in the elevation above 800 or 1000 feet. It is still too early to know which portion of the interior Middle Atlantic mountain areas are going to see the heavy snow but somebody is gonna get really crushed with an early season snowfall.”
6) Potentially worse than 1991 Perfect Storm, that struck 21 years ago
Background on Perfect Storm, Will Komaromi, researcher University of Miami: “Something similar [to Sandy] happened in late October through early November 1991. It was known as “the Perfect Storm”, resulting in 13 fatalities and caused > $200 million in damages to the northeastern U.S. and fishing and shipping interests. In the Perfect Storm, northward-moving Hurricane Grace phased with a mid-latitude trough, similar to the one over the Central U.S. today. . . .
“The Perfect Storm deepened to 972 mb...”
Why Sandy could be more powerful, Will Komaromi: “Most of the models now indicate even stronger jet dynamics will occur next week than occurred during for the Perfect Storm, and that today’s storm could potentially deepen to well below 960 mb or even below 950 mb. The fact that the Gulf Stream is anomalously warm for this time of year means that Sandy will weaken less as a tropical system...”
Sandy will be worse, Jeff Masters: “The Perfect Storm only did $200 million of damage and I’m thinking a billion.Yeah, it will be worse.”(via the Associated Press)
7) Some good advice
National Weather Service, Philadelphia: “Leaves! There a lot of leaves on the ground. Leaves are excellent material to clog/block storm drains, worsening local/neighborhood flooding. Get leaves and any other obstructing materials away from storm drains before this storm arrives.”