New England flooding, air pollution, and the season's first typhoon

By: Dr. Jeff Masters , 2:05 PM GMT on May 15, 2006

Major flooding has hit southern New Hampshire, southwest Maine, and northeast Massachussetts today, where more than 10 inches of rain has fallen in the past four days. The culprit is a "cut off low", a large low pressure system over the Great Lakes that got separated from the jet stream on Thursday, and has stayed almost stationary since since then, with no upper level winds to push it along. The counter-clockwise flow of air around the low has drawn copious amounts of moist oceanic air over New England. The rains from this moisture have brought the Warner river at Davisville and the Smith River at Bristol to flood stage this morning. With another 1-2 inches of rain expected across the region today, these rivers should crest several feet above flood stage, with moderate to major flooding. The cut-off low is expected to drift slowly northeastward today and get re-absorbed by the jet stream on Tuesday, which will finally bring an end to the worst of the rains. Howver, the weather pattern over the next week is expected to remain wet over the eastern half of the U.S., and more rain is expected in the Northeast later this week as the jet stream continues to remain in a typical Springtime active pattern.

Figure 1. Rainfall amounts for New England estimated by radar, ending at 8:30am EDT Monday May 15.

Air pollution season is here
May marks the beginning of air pollution season in the U.S., when summertime brings the hot temperatures, high amounts of UV radiation, and stagnant air that can trigger air pollution "Action Days". This week marks the annual observance of Air Pollution Awareness week, and at EPA's request, I will be writing several blogs highlighting air pollution. In particular, I'll discuss why one of NOAA's P-3 hurricane hunter airplanes will be in Texas for air pollution research this hurricane season, instead of flying hurricanes.

Quick intro on air pollution
Today, I'll present a quick summary of what pollutants we're concerned about. The Environmental Protection Agency (EPA) calculates the Air Quality Index (AQI) for five major air pollutants regulated by the Clean Air Act: ground-level ozone, particle pollution, carbon monoxide, sulfur dioxide, and nitrogen dioxide. Ozone and particle pollution are the two most serious pollutants in the U.S. Particle pollution alone has been estimated to cause over 20,000 premature deaths the U.S. each year, and 800,000 worldwide (although the exact mortality numbers and definition of "premature deaths" is controversial).

Ozone is a colorless gas composed of three atoms of oxygen. Ozone forms both in the Earth's upper atmosphere and at the surface. Where ozone forms determines whether it is helpful or harmful to your health.

Good ozone naturally forms in the stratosphere, a layer of air about 10 - 30 miles (16 - 48 km) above Earth's
surface. This protective layer shields us from the sun's harmful ultraviolet rays. Without this layer, we would all be blinded and sunburned. Unfortunately, human-created chemicals are destroying this beneficial layer of ozone. Over the South Pole in springtime, the ozone loss is so severe that an "Ozone Hole" forms, letting significant amounts of harmful ultraviolet light reach the surface.

Ozone from the stratosphere sometimes gets transported to the surface, particularly in high mountainous regions. Hikers on Mt. Everest who don't use bottled oxygen can be at risk of death from breathing poisonous levels of ozone near the mountain's summit in some weather conditions.

Bad ozone forms near Earth's surface when the ultraviolet light in sunlight triggers a chemical reaction with "precursor pollutants" emitted by cars, power plants, and industrial sources. These precursor pollutants consist of nitrogen oxides (NOx) and volatile organic hydrocarbons (VOC). Ozone near ground level is a harmful pollutant. Ozone pollution isn't limited to big cities like Los Angeles, Houston and New York. It's also found in smaller cities like Raleigh, NC and Cincinnati, OH. It can be a problem in rural areas, including some national parks. Ozone and the pollutants that react to form it (NOx and VOCs) can also be carried on the wind to affect air quality in urban and rural areas hundreds of miles away.

Particle pollution is a mixture of microscopic solids and liquid droplets suspended in air. This pollution, also known as particulate matter, is made up of a number of components, including acids (such as nitrates and sulfates), organic chemicals, metals, soil or dust particles, and allergens (such as fragments of pollen or mold spores). Unlike summertime ozone, particle pollution can occur year-round. It is worst in summer, though, when winds are lighter and the air becomes more stagnant.

Particles come in a wide range of sizes. Fine particles are less than 2.5 micrometers in diameter. How small is that? About 1/30th the diameter of the average human hair--so small, you'd need an electron microscope to see them.

Some fine particles can be emitted directly (think of smoke from a woodstove). But most are formed secondarily from complex atmospheric reactions of gases such as NOx and sulfur dioxide (SO2), that are emitted from power plants, industries, cars, buses and trucks. These fine particles are the worst for your health, since their small size allows then to penetrate deep into your lungs.

Inhalable coarse particles are larger than 2.5 and up to 10 micrometers in diameter. Sources of coarse particles include crushing or grinding operations and dust stirred up by vehicles traveling on roads. These particles are not as injurious to your health, as their large size allows them to be filtered out more readily by your nose before they reach your lungs.

Typhoon Chanchu
The season's first typhoon, a Category 4 storm with 140 mph winds named Chanchu, has turned north, and is now threatening to strike Hong Hong on Wednesday. Chanchu briefly made it to supertyphoon status on Sunday, when it had 150 mph sustained winds and a 910 mb central pressure. This was good enough for a Category 4 rating on the U.S. Saffir-Simpson scale, but not Category 5--which starts at 156 mph. A supertyphoon is defined as any tropical cyclone in the Western Pacific that attains maximum sustained winds of 150 mph. It is not unusual to get a supertyphoon in May, and this last happened in 2004, when Supertyphoon Nida reached Category 5 status with sustained winds of 160 mph. I'll have more on Typhoon Chanchu tomorrow.

Figure 2. Typhoon Chanchu at peak intensity Sunday, with 150 mph sustained winds and a 910 mb pressure.

Jeff Masters

Spicket River Rises (sabre1100)
Prime water front property for a barbain price no doubt
Spicket River Rises
York Beach flooding (SkyLazaria)
Mothers Day flooding in York Beach, Maine.
York Beach flooding

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329. weatherguy03
10:49 PM EDT on May 15, 2006
Just alittle preview PP!..LOL Hopefully this will be the beginning of the rainy season..LOL
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328. ProgressivePulse
2:47 AM GMT on May 16, 2006
Yeah I know Weatherguy! Like I said, close!
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327. ProgressivePulse
2:43 AM GMT on May 16, 2006
Not quite but daym close
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326. weatherguy03
10:44 PM EDT on May 15, 2006
Hey PP. Nah, it has too much shear around it. And is forming along cold front. Also, doesnt have enough time to get going. But will give South Florida some much needed rain. Just what the rain doctor ordered!
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325. atmosweather
10:43 PM EDT on May 15, 2006
Posted By: atmosweather at 10:28 PM EDT on May 15, 2006.
It is forecast to stall for the next 72 hours and then move out over the mid-Atlantic.
Member Since: September 24, 2005 Posts: 33 Comments: 9265
324. weatherguy03
10:41 PM EDT on May 15, 2006
Well keep looking at those models then..LOL

Here is low tracking across Florida per GFS..Link

Like I said nothing tropical, just your run of the mill low pressure.
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323. ProgressivePulse
2:41 AM GMT on May 16, 2006
I was just going to comment Weatherguy! Looks to be popping like a bud of a depression.
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322. StormJunkie
2:40 AM GMT on May 16, 2006
I was talking about the big giant spin aroun ky/wv.

Member Since: August 17, 2005 Posts: 26 Comments: 17164
321. Levi32
6:40 PM AKDT on May 15, 2006
Well I am off for a short while everyone. Got to give the dog some play time. I also have to eat dinner. See you all later!

Rich I hope you got my mail.
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319. weatherguy03
10:34 PM EDT on May 15, 2006
Uh Michael yes it is. Its an area of developing low pressure. Not gonna form into anything tropical. From Tampa discussion tonite:


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9:32 PM CDT on May 15, 2006
yeah atmosweather if it survives its trek across into the caribbean especially the central or western caribbean it would be very interesting
Member Since: August 26, 2005 Posts: 0 Comments: 407
315. StormJunkie
2:32 AM GMT on May 16, 2006
Sat loop
Member Since: August 17, 2005 Posts: 26 Comments: 17164
314. StormJunkie
2:30 AM GMT on May 16, 2006
That thing might be able to hold together for 72hrs if it keeps pulling all that moisture from the Gulf.

Member Since: August 17, 2005 Posts: 26 Comments: 17164
312. louastu
2:24 AM GMT on May 16, 2006
Alright, I am back.

The system in the EPAC is not looking so good now.

The invest in the WPAC is looking pretty good.

Chanchu looks like it is going through an EWRC.

311. atmosweather
10:30 PM EDT on May 15, 2006
I don't mean right as it gets into the Atlantic I mean if it travels as a wave and survives into the Caribbean.
Member Since: September 24, 2005 Posts: 33 Comments: 9265
9:27 PM CDT on May 15, 2006
Cape Verde season doesn't begin until mid august nothing will come out of that cluster coming off Africa... but if it did that would be record breaking and this season would be scary
Member Since: August 26, 2005 Posts: 0 Comments: 407
309. atmosweather
10:28 PM EDT on May 15, 2006
It is forecast to stall for the next 72 hours and then move out over the mid-Atlantic.
Member Since: September 24, 2005 Posts: 33 Comments: 9265
308. StormJunkie
2:24 AM GMT on May 16, 2006
The Great Lakes low is really impressive. Is it ever going anywhere or ist it just gonna sit there?
Member Since: August 17, 2005 Posts: 26 Comments: 17164
307. atmosweather
10:25 PM EDT on May 15, 2006
Its worth watching if the subtropical jet breaks down like the models forecast.
Member Since: September 24, 2005 Posts: 33 Comments: 9265
306. Levi32
6:25 PM AKDT on May 15, 2006
Here is the GFS initial shear analysis. There is actually pretty low shear south of the Cape Verde Islands. This is the only analysis I can get that shows that far south.
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305. ProgressivePulse
2:21 AM GMT on May 16, 2006
Why, every time a good soaking approches West Palm, it falls apart! Storms moving in this evening, about a half an hour ago, they move into the metro area and goodbye, almost instantly. We have maybe a Half Inch of rain here.
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9:23 PM CDT on May 15, 2006
atmosweather it is way too soon for the waves to develop that comes off Africa! SST might be warm enough to sustain development but the shear will tear it apart
Member Since: August 26, 2005 Posts: 0 Comments: 407
301. Levi32
6:23 PM AKDT on May 15, 2006
Rich where do you get instability and low level convergence forecasts? I don't know of any.
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300. atmosweather
10:21 PM EDT on May 15, 2006
Now THAT is the one that I talked about yesterday which IS worth watching.
Member Since: September 24, 2005 Posts: 33 Comments: 9265
299. atmosweather
10:19 PM EDT on May 15, 2006
The wave still looks decent, and it is certainly not dissipating any time soon. I'm not sure if it can gain latitude fast enough to get into the favorable Caribbean though. If it does, we need to watch it. I'm gonna check the instability and the low level convergence forecasts for that area for 120 hours, then I'll be able to give a more accurate forecast on it.
Member Since: September 24, 2005 Posts: 33 Comments: 9265
298. Levi32
6:20 PM AKDT on May 15, 2006
There is a monster wave over Africa in the bottom right corner of this image:

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9:13 PM CDT on May 15, 2006
of the 28 named storms last year 15 made landfall thats over half!!

TS Arlene-AL-FL Border
TS Bret-Mexico
Hurricane Cindy-Louisiana
Hurricane Dennis- Florida Panhandle
Hurricane Emily- Mexico twice
TS Gert- Mexico
TS Jose- Mexico
Hurricane Katrina- S. Florida/LA-MISS
Hurricane Rita- LA-TX Border
Hurricane Stan- Mexico
TS Tammy- NE Florida
Hurricane Vince- Spain (as a weakening TS)
Hurricane Wilma- Mexico/Florida
TS Alpha- Dominican Republic
Hurricane Beta- Nicaragua
Member Since: August 26, 2005 Posts: 0 Comments: 407
296. rxse7en
10:00 PM EDT on May 15, 2006

Is it worth noting that this run shows the lows creeping north towards the Cape? Once (if) those highs start clearing out of the Atlantic, Africa's gonna start spewing tropical waves at us again. :D

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295. TheLuckyTacoBlizzard
2:15 AM GMT on May 16, 2006
: atmosweather where is are Bermuda High and how far is it for the hurricane to hit the usa?
294. franck
2:15 AM GMT on May 16, 2006
If you click on 'satellite' on the WU homepage map and animate it, it looks like the weather for nearly all the North American continent is setting up around the cutoff low over the Great Lakes. Super strange.
Member Since: August 30, 2005 Posts: 0 Comments: 1150
293. Levi32
6:17 PM AKDT on May 15, 2006
Rich what do you think of our little wave nearing the Caribbean? I am impressed the convection keeps firing in places. I wonder if it will survive until the shear weakens.
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292. atmosweather
10:12 PM EDT on May 15, 2006
Yes, the Bermuda High had a lot to do with it, but also, it was because a high proportion of storms formed in the western Atlantic or the Caribbean, which means that the storm has to hit land somewhere.
Member Since: September 24, 2005 Posts: 33 Comments: 9265
291. TheLuckyTacoBlizzard
2:09 AM GMT on May 16, 2006
Avarhirion hmm what link was that? how are you
290. Avarhirion
1:31 AM GMT on May 16, 2006
What continues to boggle my mind about last year is not so much the number of storms, but how many formed and decided to go straight for land. Porportionately, fewer storms "spun out" than normal. Why? Was it the western position position of the bermuda high? Or something else?

TheLuckyTacoBlizzard's link spurred this comment, in case you're all wondering.
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289. Levi32
6:03 PM AKDT on May 15, 2006
Rich did you get my e-mail from earlier?
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287. TheLuckyTacoBlizzard
1:19 AM GMT on May 16, 2006
: atmosweather come to my blog
286. atmosweather
9:15 PM EDT on May 15, 2006
Well its really more than 1600 deaths, there are still over 3500 missing as of last week, and I don't think many of them are still alive.
Member Since: September 24, 2005 Posts: 33 Comments: 9265
285. TheLuckyTacoBlizzard
1:10 AM GMT on May 16, 2006
MichaelSTL oh i see come see what the update maps color have today in my blog see you there
283. TheLuckyTacoBlizzard
1:07 AM GMT on May 16, 2006
MichaelSTL they did 895
280. turtlehurricane
1:02 AM GMT on May 16, 2006
i ahv updated my blog
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1:00 AM GMT on May 16, 2006
a hurricane doesnt deserve nothing as far as im concerned except maybe respect for the power they harness...thats it
Member Since: August 26, 2005 Posts: 0 Comments: 407

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Dr. Masters co-founded wunderground in 1995. He flew with the NOAA Hurricane Hunters 1986-1990. Co-blogging with him: Bob Henson, @bhensonweather

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