Tropical Storm Bertha Floods
Summer 1996, The Set Up:
Typically jet stream patterns will break down after a period of time with PNA patterns shifting from positive to negative. This happened to some extent by the summer of 1996 with the mean low pressure trough generally weaker than it was during the winter and and a bit more transitory, migrating from the Midwest, Ohio Valley region back into the Northeast. The overall phase of the PNA pattern, however, remained mainly positive through the summer. This meant a southwest flow of rich moisture was almost continuously transported into the Northeast keeping it cloudy, humid, occasionally wet with torrential downpours, and cooler than normal. In fact no 90° days occurred at Albany in July 1996 and the month ended as the eleventh coolest on record. Wet and in some cases saturated ground conditions as a result existed across portions of eastern New York and western New England in July due to the prevailing conditions. It would not take that big of a storm to initiate significant flooding across the region. And that storm, the former Hurricane Bertha, found itself steered by the upper air flow created by the positive PNA jet stream pattern, right into the Northeast on Saturday, July 13, resulting in torrential rains and localized severe flooding in parts of the area.
Hurricane Bertha moved into North Carolina, around the Wilmington area, on Friday, July 12. The storm packed category two class sustained winds of 105 mph with gusts to 125 mph and drenched the Mid Atlantic region with four to six inches of rain in about twelve hours. The system weakened to a tropical storm during the night as it raced up the coastal plane. By Saturday morning tropical storm Bertha was producing 50mph sustained winds with gusts to 65mph along the southern New England coasts of Connecticut. Rhode Island and Massachusetts. The interaction of Bertha and a stalled weather front over New York and interior New England caused torrential rain to fall throughout the day. Between four and six inches of rain swamped the Capital region and western New England in less than a twelve hour period. Officially at Albany 4.17" of rain fell on the 13th setting a new twenty-four hour rainfall record for the date. The twenty-four hour period was also the 4th all time wettest twenty-four hour period on record to date at Albany. Widespread flooding of small streams and creeks occurred throughout the area, especially in Greene county, along the western slopes of the hills and mountains there where approximately six inches of rain fell in less than twelve hours. Widespread urban and poor drainage flooding also occurred during the height of the storm throughout the region. Fortunately, most of the flooding was of short duration with no major damage reported, with the exception of some areas in hard hit Greene County. By Sunday, the 14th, the storm had moved away and temperatures soared into the mid 80's in its wake allowing a brief drying process to begin.
Bertha's rains combined with rains from locally torrential thunderstorms vaulted July, 1996 into sixth place of all time wettest on record at Albany with the final monthly rainfall total of 7.14".
The chart below depicts the track of Hurricane Bertha and the zones of heaviest rainfall and estimated winds and wind gusts at certain times and places along the storm's path as it moved from the Mid Atlantic through southeast New England.