"Flash Drought" The Cause Of Northeast Fires, Water Shortages

Today started with yet more crystal clear skies over
Vermont, super odd for normally damp November.
It was another moment of a flash drought taking
over the Northeast, including here in Vermont. 

 You've definitely heard of flash floods.

Lord knows we've had enough of them around the nation  - and here in Vermont - this year. 

As we know flash floods are extremely rapid onset inundations. Everything could be fine at one moment, five minutes later cars and even houses are washing away.  

The Northeast is now having the opposite problem: A flash drought.

Flash droughts obviously don't come nearly as quickly as flash floods. But they do hit with pretty shocking speed. Just a few months ago, the Northeast was sopping wet. Now, the region is parches and on fire.

Regular droughts develop over many months and even years. A drought takes hold as month after month, rain and snow fall short. It does rain some but not nearly enough. After many months of such weather, the water has run out.

 Flash droughts usually hit in a matter of several weeks.  Several factors usually gang up on a region to cause a flash drought. 

First, it's the lack of rain - duh!  In flash droughts, the lack of rain is often extreme - the faucets from the sky basically get entirely shut off

Hotter, sunnier than normal weather turbocharges evaporation, so things dry out faster. Add a lot of wind to disperse the evaporated ground water and you go from rain forest to practically the Gobi desert in no time. 

As the Washington Post outlines:

"DC, Philadelphia and Newark each just experience record-long dry streaks. In fact, Philadelphia has only seen 0.69 inches of rain in two months. Most major Northeast cities are running five to seven inches behind average for the past 60 days. 

Temperatures have been running above average, resulting in increased evaporation. For November to date, Boston has been 4.6 degrees warmer than normal. New York has been 4.9 degrees above average, and DC has stood some 7.4 degrees above typical values. Coupled with minimal rainfall, it's no surprise the landscape is rapidly drying out."

Here's another  for example:

New Jersey is so far arguably the hardest hit state with this drought so far. On September 3, absolutely none of the Garden State was in drought. Eight weeks later, the entire state was. The severe version of the drought came in faster. Exactly 0 percent of New Jersey was in severe drought on October 1. Just six weeks later, this past Tuesday, 100 percent of New Jersey was in severe category of drought.

That's an awfully fast onset. 

You've probably heard me say that warmer air holds more moisture than cooler air. And that since climate change has made the world warmer, and the atmosphere can hold more moisture, flash floods are tending to become more frequent and worse than they used to be.

That's all true - if there's a convenient storm nearby to grab that moisture and organize it into those torrential downpours.  

But, the weather patterns sometimes get stuck in such a way to divert storms away from a certain region. A big ridge of high pressure in the atmosphere has held more or less firm and strong all autumn in the Northeast.

That's been diverting storms off to our west, south and east this autumn.  

This type of weather whiplash is becoming more common with climate change. Periods of too wet and too dry conditions are getting more extreme, and come at us faster than they used to in this warmer world. The trend will only worsen

In this autumn's case, one result is all those wildfires in the Northeast.

And increasingly worrisome water shortages. For instance, reservoirs serving New York City are draining fast. Schoharie Reservoir, north of New York, was down to 63 percent capacity this past week. Streams flowing into the reservoir were at record low flows, so the reservoir will continue to empty until the region gets a ton of rain. 

In New Jersey, officials are begging residents to conserve water and avoid wasteful behavior like watering lawns. It would take a good ten inches of rain at this point to put a meaningful dent in the drought conditions in New Jersey.

VERMONT AND FORECAST 

Here in Vermont, it hasn't been quite as extreme, but still, the dry conditions have come on with lightning speed.   Less than 1 percent of Vermont's land area was abnormally dry on September 17, and that had increased to 77 percent last week, according to the U.S. Drought Monitor.

Burlington crossed a threshold Saturday. Pretty much all year, precipitation had been running heavier than normal. Then the dry autumn hit, whittling away at that wet lead. On Saturday, year to date rainfall in Burlington went into the below normal column for the first time this year.

The Northeast- including Vermont - has their best shot in many weeks of seeing a decent rainfall later this week. Unless things fall apart once again, the region could 0.75 to 1.5 inches of rain if an expected storm behaves as expected.

That amount of rain would do very little to get rid of the actual drought, but it would go a long way toward tamping down all those wildfires in the region. 

Unfortunately, the storm could turn out just to be a temporary blip in the drought. Some long range forecasts suggest a return to drier than normal conditions in the Northeast starting in the final days of this month.