More rain is on the way

The past 30 days throughout New Jersey has seen a drastic change in the precipitation deficits throughout the state and especially along the New Jersey coast.  On August 1st, while the northern portions of New Jersey were running slightly above normal by 5% to 25% above normal, much of central and southern New Jersey were near to below normal.  In fact, the Monmouth County coast line ranged from a deficit of 15% to 25% below normal.  However, after a major rain storm in the middle of August and the heavy rain from Hurricane Irene, the precipitation departures are far different now.

Over much of New Jersey, rainfall departures run 100% to over 500% above normal over the past 30 days with portions of coastal Ocean County averaging 25% to 75% above normal.  The rainfall departure of over 8 inches of rain above normal this month has pretty much brought all of Monmouth County near to slightly above normal for the year in precipitation.  But will this pattern last?

The answer is yes.  The current weather pattern we are in features a trough axis that sets up over the Tennessee and Ohio River Valley and a ridge over the western Atlantic.  This pattern leads to numerous disturbances from the Polar jet stream to interact with tropical moisture from the Gulf of Mexico and Tropical Atlantic.  This tropical moisture can come from either organized tropical low pressure systems like depressions, tropical storms, or hurricanes or from the remnant moisture of these systems over the Southeastern United States.  

The staying power of this pattern is based on two factors.  One, the current Pacific pattern that is evolving will continue to promote a ridge in the Western United States lead to a trough in the East.  This pattern is not expected to change any time soon.  Two, the interaction of tropical low pressure systems in the northern Atlantic is keeping the North Atlantic Oscillation very volatile.  When the North Atlantic Oscillation constantly moves from positive to negative and back again, the entire weather pattern slows down over the Eastern United States.  These tropical low pressure systems, like the remnants of Irene over eastern Canada earlier this week, enhances this pattern and thus creates a feed back process.

The continuation of this pattern will mean trouble for Monmouth County as the water table is close to if not at saturation right now.  Additional rainfall will not be taken into the water table very easily and that will lead to the development of flash flooding of the smaller rivers and streams throughout the region and also will lead to more basements having to deal with high levels of ground water.  Based on current data, this pattern with the potential for heavy rainfall events will continue on through this month and into October.