Thursday, July 21, 2016

Severe Drought Expands in Southern New England

Dry conditions continue across Southern New England.  The area of moderate and severe drought continues to expand.  The dryness started in 2014.  Hurricane Arthur helped dent the conditions in July of 2014.  The heavy snow of January-March 2015 was rather dry and fluffy so that did not do much to alleviate the problem.  After some relief in June of 2015 (Tropical Storm Bill) we went right back to dry.  I decided to do some research and I've found a lot of information.

1) The meteorological cause of the current drought

2) Impacts on the region

3) Historical Droughts in Southern New England  

Here is the Northeast Regional Drought Monitor,
US Drought Monitor Northeast Region 7-19-2016
Percent of Normal Precipitation 1/1/16 to 6/30/16 (CPC)
The first chart shows the latest drought monitor.  Severe and moderate drought has conquered more area with this update.  The second chart shows the percent of normal precipitation for the first half of 2016.  We are running around 75% in Southern New England.  We ran about 80-90% in 2015.   So why exactly has this happened?  

There are two main reasons.  The current reason is the general jet stream set up.  It features a trough off the Pacific Northwest Coast and a trough off the East Coast.  Normally that means cooler and wet but we are on the dry western side of the trough.  Also we are close enough to the ridge every few days we are getting close to 90.  That ridge however takes most of the storms and pushes them to our south.  So West Virginia has had bad flooding and plenty of rain.  Virginia and Maryland have as well.  Last night's upper air chart shows this pattern well. 
00z NAM 500 mb vort, heights Wednesday 8 PM (image NCEP)
The ridge in the Atlantic subsequently weakens cold fronts as they head towards New England.  So the patterns allows for disturbances to ride above the ridge but by the time they get to the Northeast they are rather weak.  That means scattered thunderstorms which don't really help the drought.  It rains hard for a half hour and we might pick up a half inch of rain but it runs off into the storm drains without being able to soak into the ground.  

As for the Atlantic it seems like it is in a period of transition.  From 1995 until 2012 or so the basin was hyper active with tropical cyclone activity.  All oceans do through phases where a warm or cold state is favored.  They also transition to these phases.  One Atlantic transition from warm to cold occurred in the 1960's.  The Atlantic was active from 1925-1965 (give or take) but it began to transition in the later part of the 1950's.  Interestingly enough a rather severe drought began in 1961 that continued through 1969 (Harkness et al, 1986 pg 30).  The drought peaked in 1965-66 (Copeland 1966).  This period of dryness really began in 2014 so history tells us this could (but likely will not) last awhile.  

The Quabbin reservoir fell to 45% capacity in 1967.  Communities faced water restrictions and watering bans.  The Quabbin was built after the 1929-1932 drought.  In fact several towns were moved in order to create the the water supply.  Eastern MA communities were hit hard in the early 30's and they needed to create more water supply.  The Quabbin can hold 416 billion gallons of water and it services over 18 communities.  So how is the Quabbin doing today?

The Quabbin is 90% full as of July 1.  So despite a severe drought the water supply is fine.   Here is the summary off the Massachusetts Water Resources Authority website.
MWRA Quabbin summary
 We have a long way to go to worry about drought warnings and emergencies.   But remember this is on the Whitinsville Water Company web page

State Of Massachusetts Mandatory Annual Water Restrictions

Until Further Notice, There Will Be Mandatory Restrictions On All Non-Essential Outdoor Water Use From 9am To 5pm Every Day Be Between May 1st And September 30th.  This Will Be In Effect Every Year.  Further Information Is Can Be Found At Water Restriction Notice

I reached out to WWC to find out how filled our reservoirs are and I am waiting to hear back.   My guess is we are doing okay .  Uxbridge water (despite the E. Coli issue and the contaminated soil near the water supply) looks to be nearly full (UPDATE 7/22/16 Uxbridge has a water ban more on this Sunday).  So our lawns are turning brown, its dusty and fire danger is elevated but our water supply is in good shape,  This is obviously something to pay attention to going forward because I don't see the pattern changing anytime soon.  We could use a tropical system but we don't want to go from drought to flood and then right back to drought.  All in all this nothing compared to the issues in California but we don't live in California.  

Another note I found interesting was that there was a drought from 1980-1983.  It was before my time but I was told the gypsie moths were horrible in 1981 and 1983.  That makes sense because the fungus that keeps the caterpillar population in check grows best in moist conditions,  Unless we turn things around next winter get ready for more caterpillars and moths in 2017.   This is a topic that has really got my attention so be on the look out for more posts on this topic if you've found it educational/interesting.

-Zack Green

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