Flood walls hold on the Susquehanna

The Army Corps of Engineers is breathing a sigh of relief today. After the failure of New Orleans' levees during Hurricane Katrina revealed that the Army Corps had failed to properly construct those structures, they must have been very anxiously watching the flood walls restraining the rampaging Susquehanna River in Wilkes-Barre, PA yesterday. The new flood walls, built in response to the record flooding from Hurricane Agnes in 1972, were built 3-5 feet higher at a cost of $200 million. The new walls took 20 years to build, and were completed in 2003. Do to the uncertainty of how long the new walls could hold back such a large volume of water, over 100,000 people were evacuated yesterday from the Susquehanna's flood plain. The Susquehanna crested late Wednesday at 34.4 feet, just six feet below the tops of the new flood walls, and 16 feet above flood stage. The river is slowly declining, and was at 32 feet this morning at 4 am EDT.


Figure 1. Measured rainfall from the week's rains. Tropical moisture streaming north along a stationary trough of low pressure triggered rains as heavy as 3 inches per hour in the mountains of Pennsylvania.

Hurricane Agnes of June 1972 did $8.6 billion in damage to Pennsylvania and surrounding areas. Agnes at the time was the costliest hurricane in history, a distinction it held for 20 years--when Hurricane Andrew came along. Thanks to the recent spate of intense hurricanes hitting the U.S., Agnes has fallen to number nine on the list of costliest hurricanes of all time. Six of the nine costliest hurricanes of all time occurred in the past two years!

Tropical wave in the Caribbean
A strong tropical wave moved through the Windward Islands yesterday, bringing heavy rain and wind gusts up to 36 mph. Strong upper-level winds from the west severely disrupted the wave overnight. This wind shear of 20-30 knots is expected to continue, and no development is likely today. The wave is expected to bring thunderstorms and gusty winds to Puerto Rico and Hispanolia as it moves west-northwest at 20 mph. The wave could get more organized once it gets closer to the U.S., if it can find an area of lower wind shear to take advantage of. The prospects of this happening are low, as most of the ocean areas surrounding the U.S. are expected to have high wind shear over the coming week. None of the computer models develop this wave, and there is really nothing anywhere in the Atlantic that looks to be of concern over the next few days.


Figure 2.Latest satellite image of the tropical wave in the Caribbean.


Figure 3. Model forecast tracks of the tropical wave in the Caribbean.

Thanks to all of you who tuned into my "Tropical Round Table" interview last night on http://radio.nhcwx.com/. I'll be summarizing much of what I said in tomorrow's blog. In particular, I'll focus on how different the large-scale atmospheric patterns for this year's hurricane season are compared to last year's season. This year will not be a repeat of 2005!

Jeff Masters