What is a Northeaster? Why is it pronounced Na’hreastah like we’re in Amoskeag? Why are they the worst storms ever? Why aren’t they called ice hurricanes? Checking the index in my handy Audubon Society Field Guide to North American Weather it explains, laymanly:
“As a cold front enters the trough along the South Atlantic Coast and cold polar air passes over the warm waters of the Gulf of Mexico or Gulf Stream off Georgia and the Carolinas, storms can develop quickly. They move nahtheest along the coast, delivering driving stow in winter and cold rain in summer–the famous na’hreasteah of the Atlantic seaboard.”
Having to be on the Delaware today, I thought I’d check out the prevailing conditions at Penn’s Treaty and along the Schuylkill (see below). The Delaware frothed angrily, swollen by thousands of Pennsylvania creeks and rivers while the Schuylkill had crested its banks at points–though not as severe as the June 2006 flood. The USGS station at Trenton shows the mighty Delaware at 17.5′ by 6:30 pm at the time of this post on Monday evening. The Schuylkill is officially at floodstage and appears to have stabilized and is falling below floodstage. We’re pulling for official Weather Service 20′ Floodstage Status on the Delaware here at Ruins: maybe even ruin a bridge or two near Phillipsburg/Easton. Seemingly all the Philadelphia bridges are holding up well, but this wasn’t always the case during spring storms and freshets.
By the mid-19th century, bridge building had substantially improved with the introduction of iron and steel trusses, stronger connectors, and more components which made catastrophic failure more improbable; but during floods, debris buffetted their masonry stone piers and hydraulic forces caused large hollows to form under their piers’ foundations. [cf. Tom Peters’ Building the 19th Century] In the spring flood season of 1850 a destroyed Conshohocken bridge slammed into the Flat Rock Bridge taking it down as well. Small bridges on the Delaware were swept away more commonly. [For the best single source on Delaware bridges, both extant and demolished, check out Frank T. Dale’s Bridges over the Delaware River: A History of Crossings (New Brunswick: Rutgers University Press, 2003] Yet physics remains indominable and bridge washouts still periodically occur. Tropical Storm Allison destroyed a SEPTA bridge near Rt. 309 and Fort Washington and in a heroic effort SEPTA rebuilt a 114′ span in a little over a month.
If you’re following at home, the USGS has real time flow graphs — see rivers like you’ve never seen them before: by height, flow velocity (fps), and temperature! BAM: [USGS]
For more pictures of the Schuylkill/Delaware at Penn Treaty [Flood Stage]