June 2006 Floods

(Click on thumbnails for larger images)


Across the Mid-Atlantic and Northeast, exceptionally heavy rainfall occurred during June 22-28. Rain amounts exceeded 254 mm (10 inches) in some areas, with numerous daily and monthly rainfall records set. Flooding was widespread throughout the greater Washington, DC area, northward through parts of Pennsylvania and New York. As the Susquehanna River rose above flood stage, up to 200,000 people in the Wilkes-Barre, PA area were forced to evacuate. Regionally, there were 16 deaths blamed on the flooding, along with preliminary damage estimates exceeding $100 million.


a)      b)  c)


Figure 1.  Public Information Statements and special web page descriptions of the event from a) NWS Baltimore-Washington, b) NWS Mount Holly, NJ and c) NWS State College, PA are above. 



d) e)f)


Figure 2.  Sequence of surface maps from 12Z a) 24 June, b) 25 June, c) 26 June, d) 27 June, e) 28 June and f) 29 June.  Note the waves of low pressure that track along the nearly stationary front in the eastern U.S. providing several rounds of low-level focus for several periods of heavy rain.  This is certainly an extended period of wet weather due to a long-term nearly stationary front.




Figure 3.  Wind barbs, anomalies and preciptable water (PWAT) for a) 06Z 27 June NAM initialized 850 hPa U and V winds, b) 06Z 27 June NAM initialized 1000 hPa PWAT  and V winds, and c) 09Z 26 June SREF 850 hPa U and V winds forecast valid 03Z 28 June.  Note the extreme 850 hPa V wind anomalies, in the deterministic NAM and the SREF, both at 4 to 5 SD above normal.  The PWAT was 2-4 SD above normal as well during the event.  These are 2 factors that supported unusually extreme rainfalls.


a) b) c)


Figure 4.  PWAT from a) 18Z MREF 22 June, b) 18Z MREF 24 June and c) 09Z SREF 26 June.  Note the 2 to 3 SD above normal PWAT coming in 2 surges, one around 22 June and the other around 26 June.  Note the one wave of higher PWAT on 22 June, and another wave on 26 June.  This is consistent with the multiple waves of low pressure on the stationary front in figure 2.




Figure 5.  Probabilities for 2 inches of rain in 84 hours from a) SREF initialized 09Z 24 June valid 21Z 27 June and b) SREF initialized 09Z 25 June valid 21Z 28 June.  Note the widespread probabilities above 50% implying a large area would likely see more than 2 inches of rain.  Also note the spread, suggesting virtually every member was suggesting an area of 2 or more inches, but due to the lack of overlap, the pure probability display did not resolve the potentially more widespread area where 2 or more inches of rain was possible.  Real-time probabilities do not exceed 36 hour forecasts, but differences in probabilities beyond 36 hours are often negligible.  The 2 probabilities for 84 hours were specially created for a formal study.



Figure 6.  Two perspectives of the observed rainfall during the June flood event.



Graphs of river stages from Cohoes, Utica and Troy.



Graphs of river stages from Mohawk River at Tribes Hill, Schenectady and stage at Sacandaga Reservoir.



Graphs of river stages from Rondout Creek at Rosendale, Esopus Creek at Cold Brook Mt. Tremper, and Esopus Creek at Mt. Marion.



Graphs of river stages from Moose River at McKeever, Mohawk River at Little Falls, and Sacandaga River at Hope.



Graphs of river stages from West Canada Creek at Hinckley and West Canada Creek at Kast Bridge.