<![CDATA[NBC 10 Philadelphia - Philadelphia Weather News and Coverage]]>Copyright 2017http://www.nbcphiladelphia.com/weather/stories http://media.nbcnewyork.com/designimages/NBC10_40x125.png NBC 10 Philadelphia http://www.nbcphiladelphia.comen-usThu, 19 Oct 2017 12:37:09 -0400Thu, 19 Oct 2017 12:37:09 -0400NBC Owned Television Stations <![CDATA[Latest Weather Forecast]]> Wed, 18 Oct 2017 20:54:51 -0400 http://media.nbcphiladelphia.com/images/213*120/WCAU_SocialDriver.jpg

A ridge of high pressure over the region will continue to deliver pleasant weather through the weekend. Temperatures remain in the 70s with mostly sunny skies. Humidity will be low creating dry conditions.

A weak cold front trails across the Delaware Valley Friday night producing a few high clouds, but no rain. The weekend will be dry with high clouds on Sunday.

By Monday a cold front to the west approaches with clouds. Showers and storms are possible late Monday night through Wednesday. Temperatures eventually return to average in the 60s on Wednesday.

Thu: Sunny. High 73

Fri: Sunny. High 73

Sat: Mostly sunny and warm. High near 75

Sun: Partly sunny and warm. High near 77

Mon: Mostly cloudy with a chance of rain and t-storms at night. High 78

Tue: Cloudy with rain and a thunderstorm. High 71

Wed: Cloudy with rain showers. High 66

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<![CDATA[NBC10 First Alert: Warming Up and Staying Dry Through Week]]> Mon, 16 Oct 2017 12:16:44 -0400 http://media.nbcphiladelphia.com/images/213*120/Pic7+-+Copy.jpg ]]> <![CDATA[DOWNLOAD the NBC10 App for Latest Weather]]> Mon, 08 Feb 2016 22:30:50 -0400 http://media.nbcphiladelphia.com/images/215*120/Follow+Storm+on+NBC10+App.JPG
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<![CDATA[Sign Up for School Closing Alerts]]> Wed, 09 Nov 2016 16:18:10 -0400 http://media.nbcphiladelphia.com/images/219*120/schoolbussnow.jpg Be alerted as soon as you or your child's school closes.
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<![CDATA[Glenn's Blog: Another Non-October-Like Weekend]]> Fri, 13 Oct 2017 14:03:39 -0400 http://media.nbcphiladelphia.com/images/213*120/Pumpkin+Patch+Sun+Pumpkin.jpg

Only Temporary Cooling

Even though the average high temperature in Philadelphia in October is 68 degrees, we’ve had more days in the 80s than in the 60s. Actually, it’s THREE TIMES as many 80s as 60s! So far, temperatures are running close to 9 degrees above average for the month. In Allentown, it’s more than 10 degrees above average.

A couple of days in the 60s Thursday and Friday are not putting much of a dent in the abnormally warm month. And even some more 60s early next week won’t have much impact. The overall pattern has been warm, not only around here, but for the entire eastern half of the country.

Here are the maps for the past 2 weeks:

The bottom map clearly shows colder than normal air in the west along with the warmer air in the east. That is obviously a sign of a particular weather pattern. And, here it is-at about 18,000 feet up, which is the main level meteorologists use to analyze weather patterns: 

The red areas represent above normal pressures, and the blues, the opposite. This is a warm pattern, no matter what time of year. In summer, it’s the pattern of heat waves. In winter, it’s a pattern where no snow is possible.

Of course, these weather maps change from day to day. But if a pattern is "locked in", after each time it changes significantly, it changes right back to the prevailing pattern. That’s how we can get a couple of chilly days, but then warm right back.

Is This 'Indian Summer'?

You may have already heard this pattern described as "Indian Summer." But in our part of the country, meteorologists consider it: "a spell of warm weather after the first frost." That term supposedly goes back to 1778. It’s hard to describe our current weather that way, since our temperatures haven’t even gone below 49 degrees yet! A frost? Not even close.

Will the Pattern Change Soon?

Not in the next week, at least. Even though we’ll cool off Monday and Tuesday, the rest of next week should feature above normal temperatures. Here’s that upper-air pattern for next Saturday:

Look familiar? That’s a lot like the current pattern. As long as all those blues are near Alaska, the reds will continue in the Eastern U.S.

Here is another model showing surface temperatures compared to normal next Saturday:

Warm in the east; cold in the west. Again.

Photo Credit: Getty Images
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<![CDATA[Blog: Hurricane Nate Hits Gulf Coast, Rain Heads Our Way]]> Fri, 06 Oct 2017 22:58:40 -0400 http://media.nbcphiladelphia.com/images/213*120/Philly-Rain.jpg

Photo Credit: NBCPhiladelphia.com ]]>
<![CDATA[Glenn's Blog: Gulf Coast Hit, Rain For Us]]> Thu, 05 Oct 2017 23:28:02 -0400 http://media.nbcphiladelphia.com/images/213*120/GettyImages-124088755.jpg

Photo Credit: NOAA via Getty Images]]>
<![CDATA[Rare October Harvest Moon Will Illuminate Night Sky Thursday]]> Thu, 05 Oct 2017 09:59:43 -0400 http://media.nbcphiladelphia.com/images/213*120/Harvest+Moon.jpg

Talk about an October surprise.

This year's Harvest Moon, the full moon that falls closest to the Northern Hemisphere's autumn equinox, when the harvest traditionally takes place, will grace the night sky on Thursday, Space.com notes

"With everything ripening at once, there was too much work to to do to stop at sundown. A bright full moon — a 'Harvest Moon' — allowed work to continue into the night," Tony Phillips wrote in a 2006 NASA article around the time of another October Harvest Moon.

The moon will be fully visible when it appears on Oct. 5, barring any cloud cover. The Harvest Moon normally falls in September, closer to the start of autumn, but September already had a full moon, according to the Old Farmer's Almanac.

Since the full moon usually appears very bright, anyone wanting to see the celestial body's noticeable features should be able to without a telescope.

What to Know

  • The peak of this year's Harvest Moon comes at 2:40 p.m EDT Thursday, according to Space.com, though the full moon lasts for a couple of days before and after.
  • Oct. 5 is the only night of the month where the moon will be in the sky all night. It rises after sunset and sets around sunrise the next morning, NJ.com reported

Photo Credit: Santiago Vidal/CON/Getty Images, File]]>
<![CDATA[Fabulous Fall Week Ahead ]]> Wed, 04 Oct 2017 00:39:21 -0400 http://media.nbcphiladelphia.com/images/213*120/Fall-Warmup-Lead-Photo1.jpg Don't put the flip flops away yet. We are in for a big fall warmup this week. Here's what's in store for us. ]]> <![CDATA[Why Does This Cloud Have a Hole in it?]]> Fri, 29 Sep 2017 22:44:03 -0400 WHAT IS IT?
This rare atmospheric phenomenon has several different names, but is best known as a “Hole Punch Cloud” or a “Fallstreak Hole”. They are seen in altocumulus type clouds like the one above or in cirrocumulus clouds found at higher altitudes. ]]>
This rare atmospheric phenomenon has several different names, but is best known as a “Hole Punch Cloud” or a “Fallstreak Hole”. They are seen in altocumulus type clouds like the one above or in cirrocumulus clouds found at higher altitudes. ]]>

Photo Credit: Eric Grant]]>
<![CDATA[Blog: When Will It Start to Feel Like Fall?]]> Mon, 25 Sep 2017 14:00:43 -0400 http://media.nbcphiladelphia.com/images/213*120/Krystal+Blog+925+1.png Temps feel like summer as the first full week of fall begins in the Philadelphia region. NBC10 First Alert Weather meteorologist Krystal Klei tells us how long the heat will last and if Hurricane Maria could impact the coast.

Photo Credit: NBC10]]>
<![CDATA[The Wildwoods Warns Irish Festival Crowds of Dangerous Waters]]> Fri, 22 Sep 2017 20:36:59 -0400 http://media.nbcphiladelphia.com/images/213*120/Wildwood_Warns_Crowds_of_Dangerous_Waters_Amid_Popular_Holid.jpg

Large crowds are in The Wildwoods this weekend for the annual Irish Fall Festival, but authorities are urging beach goers to stay out of the water. Shores are experiencing dangerous rip currents due to storms Jose and Maria. NBC10's Jersey Shore Bureau reporter Ted Greenberg is in North Wildwood.

<![CDATA[Science Behind Busy 2017 Hurricane Season]]> Wed, 20 Sep 2017 18:40:56 -0400 http://media.nbcphiladelphia.com/images/213*120/Maria1.png

Not since 2005 has the United States been affected by so many hurricanes and tropical storms. As of Sept. 2, we are at the peak or mid-way point of Atlantic hurricane season and there have been 13 named storms.

Only 4 other seasons in the past 22 years have produced that many named storms by mid-September.


For this 2017 to make the top 15 list of busiest Atlantic hurricane years we would need two more named storms by the end of the season on Nov. 30 and it is very likely we will surpass that mark.

There have been busier Atlantic hurricane seasons since 2005, but not for the United States.

Below is a list of the top 15 busiest Atlantic hurricane seasons (1851-present). Ten of the busiest seasons have been in the past 17 years.

1) 2005 - 28 storms

2) 1933 – 20 storms

3) 2012 – 19 storms

4) 2011 – 19 storms

5) 2010 – 19 storms

6) 1995 – 19 storms

7) 1987 – 19 storms

8) 1969 – 18 storms

9) 2008 – 16 storms

10) 2003 -16 storms,

11) 1936 – 16 storms

12) 2007 – 15 storms

13) 2004 – 15 storms

14) 2001 – 15 storms

15) 2000 – 15 storms

So, what is causing this busy season?

1. Warm Water in the Atlantic and Less Wind Sheer

The main reason for so much activity this year can in part be attributed to the Atlantic Multi-Decadal Oscillation (AMO). The warm phase of the AMO leads to a lack of vertical wind shear in the atmosphere combined with very warm sea surface temperatures and a more active West African monsoon season, all resulting in frequent storm development and rapid intensification over the Atlantic basin.

We have been in the warm phase since 1995. A prolonged cold phase with lower activity was in place between 1971-1994.


2. Possible La Nina

Increased activity this season may be also be due to the recent cooling in the central and eastern equatorial Pacific Ocean waters indicating a possible La Nina weather pattern is building for the winter ahead.

La Nina years favor more hurricanes and tropical storms in the tropical Atlantic basin with less activity in the tropical Pacific basin. La Nina is the positive phase of the El Niño Southern Oscillation (ENSO).

During this phase the equatorial waters in the central and eastern tropical pacific are much cooler than average, leading to more stable atmospheric conditions and less tropical activity over the Pacific basin and less stable conditions over the Atlantic basin with higher tropical activity.

The opposite is true in El Nino years with warmer water piling up along the central and eastern side of the Pacific basin leading to unstable conditions over the Pacific with higher tropical activity and more stable conditions over the Atlantic basin.

3. Steering Winds

Finally, the atmospheric steering mechanisms have also played a part in storm tracks. There is an area of dominant sub-tropical high pressure known as the “Bermuda High” located over the Atlantic Ocean. Winds turn clockwise around this high and steer the tropical systems west toward the Caribbean, Gulf of Mexico and the east coast of the United States.

In the case of Irma the western edge of this high pressure was closer to the U.S. east coast forcing a northern turn over Florida.

In Maria’s case the sub-tropical high is father east over the Atlantic and Maria’s northward turn should be farther east than Irma’s was.

Hurricane Harvey was blocked from moving with no dominant steering mechanism for more than a week. The result was constant rain that resulted in historic flooding.

Jose has twice been stuck circling in place with no strong steering mechanism. However, in Jose’s case the constant heavy rain has remained offshore and not over the east coast.

What’s Unusual About 2017?

Double Landfall on Northern Leeward Islands

Another distinction this year revolves around the northern Leeward Islands, which received a catastrophic hit from two major hurricanes, Irma and Maria. These islands had not experienced two major hurricanes in the same season since 1899 (118 years ago).

Rare April Hurricane

Also unusual was the first storm of 2017. Arlene was a rare off-season tropical storm in mid-April.

Record-Breaking Hurricane Irma

This season has also produced the strongest hurricane on record for the Atlantic Basin, Irma (Excluding the Caribbean and Gulf of Mexico) and two of the top 20 most intense storms in recorded history, Irma and Maria.

Intensity is correlated with the lowest central pressure of a hurricane. The lower the pressure, the stronger the storm with higher wind speeds and 9 of the most intense storms have been in the past 20 years.


Most intense Atlantic Hurricanes on record

1) Wilma (2005) 882mb – 185 mph

2) Gilbert (1988) 888mb – 185 mph

3) Labor Day (1935) 892mb – 185 mph

4) Rita (2005) 895mb – 180 mph

5) Allen (1980) 899mb – 190 mph

6) Camille (1969) 900mb – 175 mph

7) Katrina (2005) 902mb – 175 mph

8) Mitch (1998) 905mb – 180 mph

9) Dean (2007) 905mb – 175 mph

10) Maria (2017) 906mb – 175 mph *

11) Hurricane #10 (1924) 910mb – 165 mph

12) Ivan (2004) 910mb – 165 mph

13) Irma (2017) 914mb – 185 mph *

14) Janet (1955) 914mb – 175 mph

15) Isabel (2003) 915mb – 165 mph

16) Cuba (1932) 915mb – 175 mph

17) Opal (1995) 916mb – 150 mph

18) Hugo (1989) 918mb – 160 mph

19) Gloria (1985) 919mb – 145 mph

20) Hattie (1961) 920mb - 160 mph

Photo Credit: NOAA
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<![CDATA[Jose & High Tide Cause Beach Erosion at Jersey Shore]]> Wed, 20 Sep 2017 14:23:38 -0400 http://media.nbcphiladelphia.com/images/213*120/Jose_and_High_Tide_Causes_Beach_Erosion_at_Jersey_Shore.jpg

NBC10's Randy Gyllenhaal is live in North Wildwood, New Jersey where the rough waters caused by Hurricane Jose have put the beach underwater.

<![CDATA[Hurricane Maria Tears Through Puerto Rico]]> Wed, 20 Sep 2017 14:16:04 -0400 http://media.nbcphiladelphia.com/images/214*120/maria-en-puerto-rico-3.jpg

NBC10's Pamela Osborne reports on the deteriorating conditions in Puerto Rico as Hurricane Maria continues to tear through the island Wednesday.

Photo Credit: RTV/NBC News]]>
<![CDATA[The Impact Tropical Storm Jose Is Having at the Shore]]> Wed, 20 Sep 2017 08:44:37 -0400 http://media.nbcphiladelphia.com/images/213*120/The_Impact_Tropical_Storm_Jose_Has_At_The_Shore.jpg

Tropical Storm Jose brings another day of danger along the Jersey shore and Delaware beaches. The big concern Wednesday morning will be the high tide along the oceanfront. NBC10's Matt DeLucia has the latest conditions and more on the threat that still remains.

<![CDATA[How Hurricanes Get Their Names]]> Wed, 20 Sep 2017 11:20:24 -0400 http://media.nbcphiladelphia.com/images/213*120/names+get+their+hurricanes.jpg

Ever wonder how hurricanes are named? The tradition can be traced back to the 1800s, when storms were named to honor Catholic saints, and evolved over the years.

<![CDATA[Jersey Shore Feels Effects of Hurricane Jose]]> Tue, 19 Sep 2017 12:21:55 -0400 http://media.nbcphiladelphia.com/images/201*120/Ventnor+Street+Flooding.JPG

NBC10's Ted Greenberg is live in Margate, New Jersey where they are experiencing some flooding due to Hurricane Jose and high tides.

Photo Credit: NBC10]]>
<![CDATA[Hurricane Maria Batters Guadeloupe]]> Tue, 19 Sep 2017 11:59:18 -0400 http://media.nbcphiladelphia.com/images/215*120/Screen+Shot+2017-09-19+at+9.10.57+AM.png

Hurricane Maria swept over Guadeloupe and other parts of the Caribbean early Tuesday as it approached the U.S. Virgin Islands and Puerto Rico. Guadeloupe's Pointe-a-Pitre airport, as well as its capital, Basse-Terre, were battered with heavy wind and rain as Maria moved over the French territory. 

<![CDATA[Tropical Storm Jose Impacts Our Coast; Maria Strikes Land]]> Wed, 20 Sep 2017 19:52:14 -0400 http://media.nbcphiladelphia.com/images/205*120/Jose+Wave+Woman+Jersey+Shore.JPG

A Tropical Storm is impacting our area while a hurricane continues to batter the Caribbean.

The NBC10 First Alert Weather Team issued a First Alert starting through Thursday morning for the Jersey Shore and Delaware beaches due to the effects of Tropical Storm Jose. as of Wednesday most of the strong wind and rain is gone but flooding concerns remains, NBC10 First Alert Weather meteorologist Bill Henley said.

Here is what you can expect from Jose, which was a tropical storm with 70 mph sustained winds as of Wednesday afternoon:

  • Potentially life-threatening rip current risk due to rough seas. 
  • Minor coastal flooding with some moderate tidal flooding Wednesday morning and beach erosion.

Wednesday night, residents in Wildwood, New Jersey watched the crashing waves during high tide. Flooding from the bay also shut down access on roads for cars and trucks. Flooding was also reported in Atlantic City. 

As Jose impacts parts of our area, Hurricane Maria with 150 mph winds made landfall in Puerto Rico Wednesday. Here’s what to expect from Maria:

  • The storm hit Puerto Rico more directly than Irma leading to the potential for massive power outages on the island.
  • Officials call the storm "extremely dangerous" and urged people to seek shelter.
  • Maria is expected to remain a major hurricane into the weekend.

Click here for the latest information in Spanish from Telemundo 62 in Philadelphia.

The ultimate path of Maria could depend on what Jose does as it continues to move through the ocean, so stick with the First Alert Weather Team for the latest.

Photo Credit: NBC10]]>
<![CDATA[The Fujiwara Dance: What If Jose and Maria Interact? ]]> Tue, 19 Sep 2017 16:51:12 -0400 http://media.nbcphiladelphia.com/images/213*120/huracan+maria+18+sept.jpg


In this historic, horrific hurricane season, one monster Category 4 hurricane has hit in the Gulf of Mexico (Harvey), and the latest one in Florida (Irma). Each caused tens of billions in damage-and lives. Now the newest monster is causing another Caribbean catastrophe in islands just south of the ones crushed by Irma. It strengthened to a Category 5 Monday night. The first to be hit: Dominica is getting a direct, “Barbuda-like” blast. Close by will be Guadeloupe and Martinique.

That small island just to the left of Maria’s eye is Dominica. Guadeloupe is the island just north of that; Martinique is the island just to the south. The only good thing about Maria is how small it is. The “donut of destruction” is only about 40 miles across, and the eye is barely 10 miles wide. But it is continuing to strengthen rapidly in the warm waters of the Atlantic.

The next target, unfortunately, appears to be Puerto Rico. Although there were more than a million without power after the storm, the core of Irma’s strength passed north of the island. What is going to happen if a Category 4 or 5 hurricane makes a direct hit? No one knows how bad it could be, since the last Category 4 strike was in 1932. And there has been only one recorded Category 5 direct hit was in 1928. Maria is now predicted by the National Hurricane Center to take a direct hit as a Category 5. That is truly a worse-case scenario.

You’d have to be in your 90s to remember a storm as strong as the one that may be about to hit. I say “may” because the computer models vary between a direct hit and a “graze” just to the north.

The 48-hour position is very close to the island. And yes, the Virgin Islands are in the path-again. After Puerto Rico, the forecast tracks are a bit east of the Bahamas.


It might sound like we’re making this up, but there really is a Fujiwara Effect, named after the person who discovered it. When two tropical systems get too close to each other (about 800 miles or less), they start to influence each other. And, ideally, they actually start rotating counter-clockwise around each other. If one of the storms is much bigger than the other, the smaller one can get absorbed into the bigger one.

Above is an example of the Fujiwara Effect from 2009 in the Western Pacific (the area with the most tropical storms on earth). Here is the write-up on what happened with these storms:


Here is the track of one of those “Super-typhoons”:

(Courtesy Unisys)

You might not be familiar with the map, since it’s the other end of the world. China is in the upper left, and the track of the storm came from the east into the Philippines. What you should notice is the consistent track to the northwest, and then the storm suddenly stops and GOES RIGHT BACK WHERE IT CAME FROM, before resuming the westward track. What made that happen? That was when the other Super-typhoon approached from the west, and the two storms rotated a bit.

This is just one of a few Fujiwara examples I found, and some strange tracks happened as a result. Here is Hurricane Emmy from 1976, which was influenced by Francis:

This is another example of a fairly typical track changed quickly, and then resumed when the two storms get farther apart.


There is obviously very little history of these strange movements. That makes it even harder to predict. I doubt our computer models will be able to handle it. Exactly when will Storm #1 start changing course? Will it strengthen or weaken? And what will happen to Storm #2?

Here is the forecast map for the European model (the world’s best overall):

This is a 132 hour forecast, so this is more than 5 day’s away (valid Saturday evening). Jose is on the right side of the picture, and Maria at the lower right. The storms are about 800 miles apart and seem to be similar size (the intensity may be quite higher for Maria, but it’s a small storm). If this pattern verifies, it would possibly lead to a Fujiwara. One thing that could happen is that Maria getting closer could force Jose to move toward the East Coast, while Maria turns more to the right. This would save the U.S. from the monster Maria, but increase the threat from Jose.

This unusual pattern leads to even more uncertainty than tropical forecasts beyond 5 days (which are often iffy anyway). My advice is to be extra wary of any forecasts more than 5 days out with this pattern.

Photo Credit: EFE
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<![CDATA[Hurricane Jose's Impact on NJ, Del.]]> Mon, 18 Sep 2017 07:56:24 -0400 http://media.nbcphiladelphia.com/images/213*120/Tracking_Hurricane_Jose_In_Our_Area.jpg

Hurricane Jose is churning up dangerous rip currents along the Delaware beaches and at the Jersey shore. Swimmers are urged not to go in the water. NBC10's Katy Zachry explains the risks of Hurricane Jose.

<![CDATA[Jersey Shore, Delaware Beaches Feel Jose's Impact]]> Mon, 18 Sep 2017 10:32:47 -0400 http://media.nbcphiladelphia.com/images/213*120/20170917+BlogThumb.jpg Dangerous rip currents, rough surf and beach erosion hit the Jersey shore and Delaware beaches as Hurricane Jose brushes by the East Coast.]]> <![CDATA[Glenn's Blog: Irma, Harvey & Climate Change]]> Thu, 14 Sep 2017 15:28:30 -0400 http://media.nbcphiladelphia.com/images/203*120/nhc-irma-harvey-jose-thursday.JPG

'Too Soon'. No.

There have been quotes after the storms: “It’s too early to talk about climate change and these hurricanes.” Or, “It’s very insensitive to the people in ____” (add disaster location here). Ask the storm victims in Texas or Florida if it’s too soon, or insensitive. Maybe we really should ask the victims that question. Chance are, they’d say “no”. It’s natural for people to want to know WHY and HOW their life just changed.

Is it too soon, or insensitive for police to ask victims of a car crash what just happened? Yes, they may be in shock. Yes, it may be uncomfortable. But it is my experience that people who say “It’s too soon….” really mean: “I don’t want this subject to be talked about. Ever!” Increasingly, it’s getting too uncomfortable to try to defend the idea that climate change had no impact on these recent disasters (Oh yes, let’s add the record wildfires out west).

The Non-Alarming Part

* Hurricanes are a part of nature, and probably have been around longer than humans.

* Even “monster” hurricanes (Category 4 and 5) have happened in the past, long before any human influence on climate.

* Previous hurricanes (and typhoons or cyclones, they are all the same thing) have stalled, leading to record flooding.

* Human activities, aside from adding greenhouse gases to the atmosphere, have clearly led to more flooding and more deaths than before humans existed. Destroying wetlands, farms and trees, and replacing them with concrete has made flooding worse.

* The number of hurricanes in recorded history is too small, and the natural variability of them is so large that it’s hard to prove climate/hurricane connections.

So We Throw Our Hands Up And Can’t Say Anything. Right?

Of course not. Just because we don’t know everything doesn’t mean we know nothing. Not everyone who smokes ends up getting lung cancer. But if you do get lung cancer, chances are high that you are or were a smoker. Science is not always about absolutes and 100 percent certainty. We knew enough back in the 1950s to SUSPECT that smoking led to increased cancer risk. Additional evidence in the 60s led to warnings on cigarette packs.

In this case, no respectable scientist is going to say that climate change CAUSED Harvey and Irma. That’s not the proper question anyway. Climate scientists don’t talk about hurricanes that way. It’s called a “straw man argument.” That means “misrepresenting an opponent’s position to make it easier to refute.”

The analogy of a baseball player using steroids has been used by many climate scientists. A player like Giancarlo Stanton does not need any steroid help to hit home runs. They go so far that the question is absurd. But what about a player who happens to use steroids and hits the ball just over the fence. We can’t prove that he wouldn’t have hit the homer without the use of steroids, but we’re pretty darn suspicious. On the other hand, no amount of steroids would enable me to hit a homer off a major league pitcher (maybe a little leaguer).

So, if it only takes 5 inches of rain to flood your house, getting 20 inches from Harvey probably wouldn’t make you suspect that climate change had any significant impact. But if it takes 18 inches to flood, you might reasonably be suspicious that the extra couple of inches wasn’t all “nature”.

The Climate Change/Hurricane Connection

The world is governed by laws of physics. At least this world is. There are equations to describe those laws. Some are simple, while others are complex. But they have been accepted by the scientific world for centuries. One of them is the Clausius-Clapeyron equation. It shows that there is about a 3-percent increase in average moisture in the atmosphere for every 1 degree (Fahrenheit) of warming. So:

Warmer ocean = more moisture

More moisture = more rain (or snow)

More rain = higher chance of flooding, or more area is flooded

The waters in the Gulf of Mexico, the Caribbean and Tropical Atlantic have all warmed in recent decades. The amounts have varied, and daily weather patterns change those numbers, too. But that 3 percent moisture increase per degree is an AVERAGE over the earth. Storms tend to have the moisture gather in small areas. So we don’t know exactly how much more moisture was around for Harvey or Irma due to climate change. But we’re pretty sure it had some effect on increasing rainfall.

There are complicating factors that could add even more to the "moisture effect."

Warmer ocean = more intense storm

More intense storm = more wind

More wind = more “convergence” (winds coming together)

More convergence = more rain

So, this is a “multiplier”, also known as a “positive feedback.” So, what seems to be just a slight increase could be leading to larger ones than even current climate scientists agree on.

[[287977901, C]]

Another factor that can actually be measured is sea level rise. We know how much it has risen over the decades. That amount is added to any storm surge, and increases the number of homes affected. This was calculated for Sandy, for example by the Institute for Environmental Studies in the Netherlands. The extra foot of sea level rise in the past century added about $2 billion extra damage. That didn’t mean anything if you were near the coast and flooded badly, but if you were in the area that flooded by a foot or less, it meant everything.

Harvey: The Storm That Refused to Move. Why?

No, we don’t know the answer to that question. And this is actually where an active climate change debate is happening right now (not the basics of climate change. They moved on from that long ago).

There have been some studies in the past decade that suggest a connection between the rapid ice melt in the Arctic and “blocking patterns” in the atmosphere much farther south. HIGH pressure across Canada, the North Atlantic or Greenland becomes even higher. One possible example was Sandy’s rare, sharp left turn that allowed it to slam into North Jersey. Some climate scientists suspect a connection, and have written peer-reviewed papers showing the reasoning.

[[442054743, C]]

The most recent paper was published earlier this year by Dr. Michael Mann of Penn State, along with climate scientists from Minnesota, Germany and the Netherlands. It’s pretty complex stuff, but they did use real world data, and concluded:

“Both the models and observations suggest this signal has only recently emerged from the background noise of natural variability.”

Their 41 references include some of the biggest names in climate science. Some of their quotes:

Coumou et al.19 showed that the Northern Hemisphere summer jet and associated storm activity have weakened since 1979 and hypothesized that this could lead to more persistent, and therefore more extreme, summer weather.

This adds to the weight of evidence for a human influence on the occurrence of devastating events such as the 2003 European heat wave, the 2010 Pakistan flood and Russian heat wave, the 2011 Texas heat wave and recent floods in Europe.

Weather Channel meteorologist Stu Ostro has followed the Arctic weather pattern changes for more than a decade. No computer models, just weather maps of the actual weather. There are striking similarities in the strength of HIGH pressure well north in many record floods.

Irma: Most Intense

Irma was a borderline Category 4 hurricane when it hit the Florida Keys, with 130 mph maximum winds. But it was a Category 5 with 185 mph winds when it hit part of the Caribbean, including the Virgin Islands. At one point, it was the most intense hurricane ever recorded in the Atlantic Basin outside the Caribbean. Is it a coincidence that the most intense hurricane in the Atlantic occurred two years after the most intense hurricane in the Eastern Pacific (Patricia-215 mph), and only a few years after the most intense typhoon landfall in the Western Pacific (Haiyan-196 mph)? These “coincidences” are getting out of hand!

Did it really make that much difference that Irma went from 185 mph to 130 mph? It sure did. The chart below was the result of a study of hurricane damage back in 1998 (by Pielke and Lansea). The damage goes up exponentially, so there’s a huge difference!

[[444477983, C, 569, 205]]

So, every bit of wind increase would make the resulting damage a lot worse. A 140 mph storm would cause FIVE times the damage of a 120 mph storm. And it’s not just the wind. The storm surge of an average hurricane would be about FIVE feet higher in the 140 mph storm, and at least TEN feet higher in the 185 mph Irma.

What’s my point? The warmer ocean than “normal” approaching the Caribbean probably intensified Irma somewhat. How much, we don’t know at this time. Research in the coming years may be able to answer that. We also don’t know yet if the unusually large size of Irma was related to the warming ocean (remember Sandy was the largest ever recorded in the Atlantic). If Irma hadn’t hit Cuba first, those winds in the Keys, Marco Island and Naples would have been much higher.

Also, add in the increased rainfall due to the increased moisture in the atmosphere, as explained earlier. The heavy rain in some areas (like Jacksonville) combined with the storm surge to create record flooding.

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The Bottom Line

1. No, it’s not too soon to talk about the climate change/hurricane connection.

2. The warmer ocean probably increased both the strength and rainfall.

3. There is increasing evidence that warming in the Arctic could be helping to stall storms, or steer them in unusual ways. This is a more controversial part of the conversation, but “attribution science” is gradually getting more respect in the climate science community.

4. There is still plenty of push-back on the climate/hurricane connection. But scientists aren’t just making up this stuff. They are collecting evidence and learning more each year.

5. Scientists tend to hesitate on making big pronouncements until they are at least 90 percent sure they are right. With such variable weather normally, it takes a lot of evidence to reach that level of confidence.

Because of all of the above, I have a very long-range forecast:

Twenty years from now, a lot of people will be saying: “What were they thinking back then? It was SO obvious that climate change was affecting extreme weather!”

Photo Credit: National Hurricane Center
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<![CDATA[Al Roker Talks Weather, Climate Change and Extreme Events]]> Thu, 14 Sep 2017 07:55:51 -0400 http://media.nbcphiladelphia.com/images/213*120/Roker.gif

"Today" host Al Roker talks with NBC's Eric Hinton about writing a weather book for children, how journalists should report on extreme weather events and why there are more of them than ever.

<![CDATA[See How Hurricane Irma Dumped Rain as It Passed Over US]]> Tue, 12 Sep 2017 14:08:26 -0400 http://media.nbcphiladelphia.com/images/212*120/Screen+Shot+2017-09-12+at+9.20.08+AM.png

The map below shows hourly rainfall in the Southeastern United States as the powerful storm Irma pounded the region early Sunday morning through Monday afternoon.

The National Weather Service releases hourly data on rainfall across the U.S., as measured in inches. The circles on the map are proportional to the amount of rainfall at a given point in the grid in a particular hour.

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This story uses functionality that may not work in our app. Click here to open the story in your web browser.]]>
<![CDATA[NJ Oceanographer Can Forecast Tidal Flooding]]> Tue, 12 Sep 2017 07:59:34 -0400 http://media.nbcphiladelphia.com/images/213*120/NJ_Oceanographer_Can_Forecast_Tidal_Flooding.jpg

A New Jersey oceanographer has made it his life's work to study and predict storm surge flooding in storms such as Hurricane Irma. Brian Thompson reports.

<![CDATA[Irma's Weather Impact in our Area]]> Mon, 11 Sep 2017 10:58:17 -0400 http://media.nbcphiladelphia.com/images/213*120/rain-generic-GettyImages-456729820.jpg

Photo Credit: Getty Images]]>
<![CDATA[Local Families Worry About Loved Ones in Irma's Path]]> Sat, 09 Sep 2017 13:54:04 -0400 http://media.nbcphiladelphia.com/images/213*120/Local_Families_Worry_About_Loved_Ones_in_Irma_s_Path.jpg

While some seven million people are leaving their homes in Florida, some people can't make it out. And those with ties to our area are sharing fears with local loved ones. NBC10's Keith Jones reports.

<![CDATA[Irma's Latest Track: A Shift West]]> Fri, 08 Sep 2017 23:32:41 -0400 http://media.nbcphiladelphia.com/images/213*120/Irma_s_Latest_Track__A_Shift_West.jpg

New data released at 11 p.m. Friday shows Hurricane Irma making a slight shift to the west meaning Florida's West Coast will take the brunt of the storm. NBC10 First Alert Weather Chief Meteorologist Tammie Souza explains what it means.

<![CDATA[Florida Evacuees Head to Philly]]> Fri, 08 Sep 2017 17:00:34 -0400 http://media.nbcphiladelphia.com/images/213*120/Florida_Residents_Continue_to_Evacuate_Irma.jpg

As Hurricane Irma gets closer and closer to Florida, residents are paying hundreds of dollars to escape the storm. NBC10's Aaron Baskerville was at Philadelphia International Airport as the crowds rushed in.

<![CDATA[South Florida Prepares for Potential Hurricane Irma Landfall]]> Sat, 09 Sep 2017 21:43:48 -0400 http://media.nbcphiladelphia.com/images/213*120/GettyImages-845055800.jpg From getting gas for their vehicles to buying all the supplies they can, residents and visitors across the area are getting ready for a potential strike from Hurricane Irma.

Photo Credit: Carolyn Cole/LA Times via Getty Images]]>
<![CDATA[Stuck in the Path of Irma With Supplies Dwindling]]> Mon, 11 Sep 2017 07:34:28 -0400 http://media.nbcphiladelphia.com/images/213*120/Stuck_in_the_Path_of_Irma_With_Supplies_Dwindling.jpg

Some local residents are stuck in Florida as Irma approaches. NBC10s Keith Jones reports on how supplies are dwindling.

<![CDATA[Florida Prepares for Irma]]> Thu, 07 Sep 2017 12:42:02 -0400 http://media.nbcphiladelphia.com/images/213*120/Florida_Prepares_for_Irma.jpg

NBC10's Tim Furlong reports from Hollywood Beach, Florida, where it is calm before the storm.

<![CDATA[In Photos: Hurricane Irma Lashes Through the Caribbean]]> Sun, 10 Sep 2017 20:20:15 -0400 http://media.nbcphiladelphia.com/images/213*120/AP_172527248703821.jpg Record-breaking Hurricane Irma roared through the Caribbean, going from 185 mph to 150 mph winds by Friday morning. Irma made landfall in the Florida Keys Sunday morning.

Photo Credit: Desmond Boylan/AP]]>
<![CDATA[Flying to Philly to Escape Irma]]> Thu, 07 Sep 2017 09:15:39 -0400 http://media.nbcphiladelphia.com/images/213*120/Flying_to_Philly_To_Escape_Irma.jpg

NBC10's Matt DeLucia visited Philadelphia International Airport Thursday and spoke to travelers escaping Hurricane Irma's path.