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August 24, 2011

Biggest worry from Irene? Big rain, flooding

As forecast, Irene has strengthened today, with top sustained winds now blowing at 120 mph. The National Hurricane center says conditions are favorable for some further strengthening, and Irene could become a Cat. 4 storm in the next day or so.

But for Maryland, wind may not be our biggest worry as Irene approaches. Forecast models are predicting a potential for tremendous rain as the storm moves up the coast - as much as 11 or 12 inches of rain is predicted to fall this weekend just off the coast. It would take only a slight shift in the storm track to bring that kind of rain onshore.

And even if the computer's prediction proves accurate, the rain totals forecast for the Delmarva Peninsula still come in at 8 or 9 inches. And for the Western Shore, totals come to 4 to 5 inches.

The forecast map was sent to me by Prof Jeff Halverson, out at UMBC. "This is a very potent dynamical set-up for huge rainfall."

"It looks like areas to our north and east are in for a monster soaking this weekend," he said. "The morning models have Irene merging with a trough in the jet stream (crossing the Great Lakes on Saturday), and I suspect a potent coastal front will develop. This is looking more and more like a Floyd-type extra-tropical transition, but shifted further north than in 1999. Things are looking very wet from NJ north through Maine. The models have us right on the edge of this heavy rain shield, but I would not be surprised to see it back-build further west."


Hurricane Floyd (track map) swept up the coast in September 1999. Its storm track looks almost identical to Irene's, but a tad farther west, running right up the coastline from the Outer Banks to New York City, then charging inland over New England.Floyd flooding 1999

Floyd's wind and rain cut off electric power to almost half a million Marylanders, and many waited days for service to be restored. That triggered an order from then-Gov. Parris Glendening for regulators to investigate the utilities' emergency response plans. (BGE officials said Wednesday they are already monitoring Irene, and "taking proactive action to ensure it is prepared to aggressively respond to widespread and extended power outages should they occur.")

Some 750 trees fell in Baltimore alone during Floyd. Severe flooding struck in Crisfield, Elkton and North East. The governor later applied for federal disaster assistance for 11 counties. The largest damage estimate was $1.3 million in Harford County.

There were sewage spills, 255 roads were closed by flooding or downed trees. One death in Maryland was attributed to the storm.

Are you ready? Here's a preparedness guide from the Maryland Emergency Management Agency.

(SUN PHOTO: Bottom: Floyd flooding, Karl Merton Ferron, September 1999)

Posted by Frank Roylance at 3:00 PM | | Comments (4)
Categories: Hurricanes


The models have us right on the edge of this heavy rain shield, but I would not be surprised to see it back-build further west.

The worst-case scenario that has been discussed amongst the cognoscenti has been a back-build as it passes Cape Hateras, and pushes the storm right up the coast into NY City. That would push a significant surge directly onto Manhattan Island. The concern over this scenario was rising last night, especially on the Weather Channel. It seems to have gone from speculative entertainment to "uh, oh, the models are starting to align for this disaster."

Is that still in the works, or is the above quote from Professor Halverson indicating that we're going to see a regression back west with landfall occurring more directly into North Carolina and a movement of the storm into VA and MD? Are we now looking at the possibility of the surge moving up the Chesapeake? You seemed to be dismissing that as a likely possibility earlier today.

I know--so many questions. Hurricanes fascinate me (yeah, like that's a surprise!), and the dynamics involved are endless.

Hurricane Irene would cost NYC $40 billion if it hit to day. BIG DEAL we are wasting $10 billion each month in IRAQ . A war we started over 8 years ago. I hope this hurricane does not hit NYC , but if it does , Watch out for all the political rats to come out of their Washington holes, and start spewing their trash talk to the media. And the saucer shallow media will saturated the airways with 7/24 worthless stories. Using their favorite words HEROES, BRAVE, etc. Have we fixed up New Orleans from Hurricane Katrina ..YET. ???.. Don't think so , that's where the poor people live.

galacticcannibal, you have forfeited your rights to the internet. this is a weather blog, no place for your liberal political crusades.

I believe that 'Sam' should go read the First Amendment, and then court decisions about the First Amendment. I believe 'Sam' will find that the courts have been pretty uniform in stating that the owner of a private site can determine who can, and who cannot, post on that private site.

And then tell us how he/she/it has become owner of this site, thus can tell people who can, and who cannot, post on the Baltimore Sun weather pages.

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About Frank Roylance
This site is the Maryland Weather archive. The current Maryland Weather blog can be found here.
Frank Roylance is a reporter for The Baltimore Sun. He came to Baltimore from New Bedford, Mass. in 1980 to join the old Evening Sun. He moved to the morning Sun when the papers merged in 1992, and has spent most of his time since covering science, including astronomy and the weather. One of The Baltimore Sun's first online Web logs, the Weather Blog debuted in October 2004. In June 2006 Frank also began writing comments on local weather and stargazing for The Baltimore Sun's print Weather Page. Frank also answers readers’ weather queries for the newspaper and the blog. Frank Roylance retired in October 2011. Maryland Weather is now being updated by members of The Baltimore Sun staff

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