Dr. Masters co-founded wunderground in 1995. He flew with the NOAA Hurricane Hunters from 1986-1990. Co-blogging with him: Bob Henson, @bhensonweather
By: Dr. Jeff Masters , 4:58 PM GMT on March 31, 2010
Record rains from a slow-moving and extremely wet Nor'easter have triggered historic flooding in Rhode Island and Southeastern Massachusetts, with several rivers exceeding their 100-year flood levels. The 16.32" of rain that has fallen on Providence, Rhode Island, this month is the most rain recorded in any month, besting the previous record of 15.38" set in October 2005. Blue Hill Observatory in SE Massachusetts also set a record for wettest month ever, with 18.79" (previous record: 18.78", August 1955.) Records extend back to 1905 and 1885 at the two sites. The Rhode Island all-time state record for heaviest precipitation in a month was smashed as well, thanks to the 19.62" observed this March at North Kingstown. The old state record was 16.70", set at North Foster in October 2005. Many locations in the Northeast recorded their wettest March ever, including New York City and Boston.
Figure 1. Observed precipitation for the month of March. Image credit: NOAA.
From a historical perspective, river flooding in parts of Rhode Island and eastern Massachusetts is expected to rival or exceed the all-time record floods of August 1955, when Hurricanes Connie and Diane hit within one week of each other. Several rivers in the region that set their all-time flood heights just two weeks have set new records this week. It's pretty remarkable that we are having record rainfall and record flooding in the cold season month of March. It's much easier to set records in August, when there is much more moisture in the air available for record rains.
Here is a summary of the major flooding occurring, courtesy of the National Weather Service:
* Pawtuxet River in Rhode Island...flooding will exceed what occurred in middle March. Record-shattering flooding is forecast along the Pawtuxet River through Thursday. Records at the Cranston gauge date back to 1939.
* Blackstone River in Rhode Island...flooding at Woonsocket is forecast to be the worst flooding since the flooding associated with Connie and Diane in 1955. However...due to the heavier rains which have fallen below Woonsocket...flood impacts approaching the 1955 event may be realized.
* Charles River at Dover Massachusetts...near record flooding is forecast. This is expected to be the worst flooding since the flooding associated with Connie and Diane in 1955.
* Neponset River at Norwood Massachusetts...major flooding has already occurred...with a crest of 11.2 feet. This crest is well below the record crest of 14.65 feet which occurred in August 1955 with Connie and Diane.
* Sudbury at Saxonville Massachusetts...record flooding is forecast. This will be the worst flooding since the April 1987 flood.
While the storm responsible for the rains has moved out to sea, there will be a prolonged period of urban and small stream flooding...which should last for at least a couple of days. To keep track of the flood situation, use our wundermap with the USGS river layer turned on.
Severe weather season is here
Two tornadoes occurred near Charlotte, NC on Sunday, March 28, 2010. One of these twisters passed within a few miles of one of the FAA's high-resolution TDWR Doppler radars. Our tornado expert, Dr. Rob Carver, has written an excellent post showing high-resolution images and animations of this tornado.
I'll have a new post on April Fool's Day.
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