Concerning the Elevated Water Issue and Calls to Dredge the Bay

There has been a lot of hearsay and conjecture regarding the elevated waters in the bay, and a call-to-action demanding the bay be dredged to alleviate the issue. It is unlikely debris (including sand and soil) are the cause of this as Archimedes Principle does not apply due to the fact that the bay is not a closed system. If you drop a bowling ball into a tub, the water level will indeed rise. The problem is, the bay is not a closed-system like a tub; it has open drains (inlets) at each end.  That is the first problem with the dredge-the-bay argument.

Secondly, while it is true that water levels in the bay have been running much higher than usual, so have water levels in the ocean and the inlets (there are plenty of tide gauge stations online, including one in Barnegat Inlet itself), demonstrating that the source of the flooding (the ocean) is high, and water, via gravity, wants to equilibrate and find a common level; it just so happens the location of that equilibrium point involves Barnegat Bay.

In fact, I am looking out my office window, which is right in the mouth of the an inlet (where the bays have unrestricted passage to drain back into the ocean), at a flooded marsh surface, and am keeping an eye on the tide via an array of USGS depth sensors to time my egress so as to not get trapped here by a flooded-out road until the next ebb late tonight. It is the ocean that is flooding the area here, NOT a bay allegedly swelled by debris.

USGS tide sensor at Little Egg Inlet

Great Bay Blvd just starting to flood

So, why is the ocean higher than usual? This can be explained by the fact that we are in a strong –NAO pattern, which sets up a high-pressure block over Greenland, which traps storms against the NE coast, causing extended periods of surge, thus increasing the duration and severity of coastal flooding events. In fact, this phenomenon is what caused Sandy to make that bizarre left-turn into the coast and is what has been causing storms to park near the coast and flood our shores since then.

Add to that that we are also in a +PNA pattern, which sets the stage for coastal storm development. Then note that we have a –AO dip in the jet stream feeding developing coastal storms with an ample supply of cold air. All this nurtures Nor’easters and supercharges them once they form.

If you need more explanation of all of this, please refer to the featured article I posted on March 5th titled “Some science behind the upcoming storm (and why people in the know are making a big deal of it)

This issue is much bigger than what happened/is going on in the tiny lagoonal estuary we call Barnegat Bay; it is a hemisphere-affecting phenomenon. I only hope the decision-makers listen to scientists who know better and not bow to the dredge-the-bay-from-shore-to-shore advocates pushing for well-intended but misguided gutting of the bay. Don’t get me wrong, I’d like to see a solution devised, but not based on mis-information and hysteria, and not at the expense of destroying the bay itself.

Current NAO, PNA, and AO

 

Some useful links:

http://waterdata.usgs.gov/nwis/uv/?site_no=01409335

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/pna/new.nao_index_ensm.html

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/pna/new.pna_index_ensm.html

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/daily_ao_index/ao.shtml

 

Winter Storm Saturn sort-of-post-mortem comments

Well, post-mortem may be an erroneous descriptor as the storm is still quite active offshore of our coast and will continue to affect us for days to come, but since the dramatic wind and rain has backed off for now, it’s worth paying the subject a visit.

If you tuned in to the news or kept your eye on social media over the last 24 hours, you know that Winter Storm Saturn did indeed cause quite a bit of storm-surge flooding in certain areas, and considerably less in others; it seemed like the further south you looked, the greater the surge.  A few factors were at play in this phenomenon:

The storm ejected a bit south than originally predicted; entry into the Atlantic off the DelMarVa region was modeled, but it appears the center of circulation over open waters wound up being over the Carolinas.  That put Delaware Bay and Chesapeake Bay right in that trouble zone (just north of the “eye”) during the height of the storm; water entered the mouths of the bays but had no way out and stacked up.  I’ve seen some footage of cars up to their side-view mirrors down in Ocean City, Maryland and at least one floating in a wash-out in North Carolina.

In some localized cases, the strong sustained NE-NNE winds through the height of the storm appear to have pushed water towards the mainland side, relieving flooding pressure on the bay-side of the barrier islands but causing trouble at some low-lying communities situated in/near embayments on the mainland.  And while that eventual shift to N-NNW was good for some areas, assisting tidal drainage in North-South oriented bays like Barnegat, it cause trouble for communities on north-facing shorelines within bays like Tuckerton Beach and the north shore of Long Island, pushing water towards them.

Also, once the storm ejected off the coast, it initially took more of an eastward track instead of the anticipated NE path.  That resulted in an easing of the surge in the northern half of the state as time went by rather than increased surging from an obliquely-approaching storm; while northern and central NJ did indeed receive quite a bit of swell and surge (including some overwashing of seawalls, breaching of dunes weakened by Sandy, and some minor to moderate street and property flooding), the fetch of the winds (illustrated below) was maximized for southern NJ and the aforementioned DelMarVa region, resulting in feet, rather than inches, of surge in roadways and low-lying communities.

Illustration of the fetch from Winter Storm Saturn.  Image credit: Magicseaweed.com

So, the assessment of this storm to date is that it was a bit underwhelming in some areas (particularly if you were anticipating and bracing for the worst or a bit inland and hoping for a snow-event), overwhelming in others (particularly in the coastal areas in the southern half of NJ and DelMarVa), and absolutely fascinating due to it’s complexity.  Also, despite improved weather today, Saturn has stalled a bit over the Atlantic thanks to that -NAO I addressed in my post on Monday, making a turn to the NE, and receiving energy and moisture from another system approaching from the west via the Great Lakes, so it will continue to throw precipitation, swell and sideshore winds at our coast through the remainder of the work-week, which means continued storm surge (particularly around high tides) and sustained swell, which means further erosion of our already-battered beaches and dunes.  Since it ain’t over, I may post a post-post-mortem down the line, but this should feed your brain a bit for now.

 

 

 

Some science behind the upcoming storm (and why people in the know are making a big deal of it)

So, why is everyone making a big deal about the upcoming storm? Besides the obvious vulnerabilities to our Sandy-damaged shorelines and communities (ocean and bayside areas will be vulnerable to coastal flooding, erosion, and wash-over events due to increased water levels and wave heights; low-lying areas inland may also be susceptible to flooding from nearby creeks and even storm drains), there are a number of variables that are coming together that may have cumulative (bad) effects.

First is the fact that it looks like the storm looks like it is going to have tight circulation, with an “eye” and the appearance of a tropical storm/hurricane, which means conditions may mimic the effects of one as well. Here is a screen-grab of the wind prediction posted over at magicseaweed.com:

Because it looks like this storm is going to eject somewhere off the Mid-Atlantic seaboard and be slow to move off, it is likely that the tri-state area is going to be on the “wrong side” (North) of the storm’s center, receiving strong NE-NNE-N winds for a good period of time, maximizing wind, waves, and storm-surge.  This means that nearshore waters and back-bays will likely have trouble draining as the tidal ebb out to sea will have to fight a continued surging of water towards land.  Again, I’ll post a screen-grab from magicseaweed.com illustrating this point:

The good news is that we are between the new and full moon states at the moment, which means the storm surge won’t have too much of an assist from the lunar tide.

 

Now, let me introduce a little equation punctuated with some humor:

(+PNA)+(-NAO)+(-AO)= OMG!

(I added the “OMG!” for comedic effect, but the three variables on the left side of the equation are legit)

 

PNA

The PNA (Pacific/North American Teleconnection Pattern) is a driving factor in storm formation in the northern hemisphere.  Associated with the strength and location of the East Asian Jet Stream, it encourages or suppresses storm formation.  A –PNA brings warm weather up from the South, which encourages tropical development (this is the mechanism by which Hurricane Sandy gained strength as she moved up the Eastern Seaboard), while a +PNA state brings cold weather down from the Arctic and fuels winter storm development.  We are currently in a strong +PNA.

 

AO

The AO (Arctic Oscillation) sets up either warm air over the eastern half of the United States during its positive phase or allows cold, dry arctic air to plunge southward during its negative phase.  This plunging of cold, dry arctic air can fuel developing winter coastal storms.  A shift from a positive to negative AO at precisely the “right time” set up conditions to spawn a Nor’easter that then fused with Sandy, resulting in her transformation from a warm-core hurricane to cold-core hybrid storm) as she approached the eastern seaboard.  This is what appears to be setting up for this mid-week storm (not a hybridization, but rather the development of a true cold-core Nor’easter).

 

NAO

The NAO (North American Oscillation) is part of the Arctic Oscillation and is another strong driving factor in storm movement in the Atlantic basin.  A +NAO leads to increased westerly winds around the arctic and keeps cold air constrained to higher latitudes.  Storms are allowed to move freely, and if a strong Bermuda High is at work, they latch onto it and ride it like an escalator into open water.  Conversely, a -NAO results in suppressed westerly winds, allows cold Arctic air to slip south, and allows a “blocking high” to setup over Greenland.  This blocking high, true to it’s moniker, hinders storms from moving off to the northeast; they get “stuck” against the coast, and if a cold-core storm and fed an ample supply of cold arctic air (see AO, above), continue to churn (throwing swell and surge against the coast).  This –NAO is what happened during Sandy, and what is happening now; this storm will likely get held against the coast for an extended period of time by this blocking action.

 

Hopefully that explains some of the science behind why this storm is the talk of the town.

On a final note, looking back to the coastal flooding we experienced on December 27th, which was a news-worthy event in itself as it flooded out a number of homes in low-lying areas that had never been flooded out until Sandy came along:  Unlike the upcoming event, it came during an extreme lunar tide, so its surge had a bit of additional help in that respect.  That said, it was under a +PNA, -AO, +NAO state, so while a broad, slow-moving storm, it had a clearer path out to sea (thanks to less blocking) than this one will likely have.  Regardless of these minor differences, the similarities between the two systems are enough to serve as a heads-up regarding what we may soon experience.