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Delaware: The State of Severe Weather

Delaware weather is a paradox. Literally, in three parts of the state, we can have three different types of weather in a single day.  Yet, living in Delaware is becoming increasingly clearer as we approach the Spring and Summer months.  Delaware is a state with very severe weather risk.

 

Unlike say Tornado Alley between the MId-West and the plains like Texas, Oklahoma, Kansas, etc.. Delaware is starting to see more and more of its a fair share of severe weather. In the last two years, we have had at least three recorded tornadoes. One an EF-2 last May on Memorial Day weekend down near Laurel. And it happened at night which is more terrifying and rare. The most common severe weather that Delaware’s faces are thunderstorms, straight-line storms, and Derechos.  I want to discuss Derechos.

 

DERECHOS

In late June of 2012 Delaware and much of the lower half of the Mason-Dixon states experienced what is called a Derecho severe weather event. It started early in the morning out of thunderstorms in eastern Iowa. Derechos form because of elevated thunderstorms. They are, in a sense, strong thunderstorms that last hours and are damaging by the intensity of the size of the storm.  They also spread over hundreds of miles.

The picture below shows how air billows upon a high-pressure system over the East Coast. This building of airflow above the front can lead to the formation of abnormally higher than the normal mixed layer that leads to intense Derechos.

Add in unbreathable heat and humidity and there is always the possibility of a Derecho of any kind in the Spring and Summer months.

The radar echo shows a progressive derecho forming as a bow that drops from NW to SE. Straight lines just move in one “straight” direction via the winds and upper-level jet.

 

The Derecho event in June of 2012 moved over 700 miles in 10 hours and killed 22 people and left hundreds of thousands without power.

 

We are sure to see something like this as storms are growing more powerful overheated Gulf moisture and heated ocean waters.

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The Fall Line: The Difference Between All rain and mostly snow for the I-95 Big Cities

Above is a picture of the major cities of the East Coast. The very fine white area is called the “Fall Line”.   Can weather really straddle a line? Does one or two degrees west or east of the line make a difference? The two answers are: Yes, Yes. If you look to the west of the “Fall Line” you will see that the land rises-elevation. Temperatures are impacted by that small difference. In Philadelphia, it could be 34 degrees as a storm approaches. Fifteen miles west of Philadelphia in Montgomery County it could be 32 degrees and falling as a storm approaches.  You could have snow in Lower Merion, and rain in Center City-cold rain at that. In that case, if it’s 34 degrees in Philadelphia you can rest assured it’s 35 in Wilmington, DE almost a certain rain event as you can see Wilmington, DE almost is sinking in the sediment of the Delaware River.  Yet, at the same time, it could be 35 in Wilmington, DE and further north and west of Wilmington, DE in Chadds Ford just a mere 6-8 miles from Wilmington to its south could be startling the freezing line and could either bet wet snow or even just snow.

So, the weather follows I-95 because of I-95 changes in elevation. It’s the strangest, but the most fascinating piece of geography that no other part of the country has.

 

Snowstorm along the I-95. Arctic cold air is the solution if you want big snows in the megalopolis cities of Washington, D.C. to New York City.

 

 

Avoidable Tragedy In Tennessee? No, just a Tragedy of Judgement

This week’s big weather news was in Tennessee.  Early Tuesday morning a line of streaming showers due to an elongated trough of showers and thunderstorms entered the Tennessee Valley. All day  Nashville and the surrounding counties had been under heavy rain and some thunderstorms.  Little did anyone know what was coming later that evening.

Yet, the one agency that is supposed to inform and give the proper time protections misjudged the storms and this led to at least 25 fatalities, a spawn of several tornadoes of greater than EF-1 strength and one confirmed EF-4 which led to millions in damage, destruction, and all, in the middle of the night.

“It slipped through the cracks at NOAA, so, therefore, when there’s no activation warning from their end, the community outdoor sirens do not activate,” said Ronnie Pearson, director of Warren County Emergency Management.

There it is. An admission of failure on the part of the NOAA.  Folks in Warren County, Tennessee knew nothing of what was coming their way.  Little did anyone in the counties hit hard to know to prepare properly. There were strong thunderstorms or severe thunderstorms warnings but no tornado watches the entire day even though the severity indices showed the high potential. Nobody can know for sure. There was a 2 percent chance according to the SPC (Storm Prediction Center) in Norman, Oklahoma of tornado development all day, but that wasn’t enough according to the standards of the NOAA in Nashville to issue anything but a severe weather statement all day. There were tornado warnings issued for the western part of the state but were canceled by 12:15am Tuesday morning.

Warning Coordination Meteorologist Joe Sullivan issued a statement saying conditions over south-central Kentucky were less favorable for tornadoes, but storm projections did support large hail and possibly a few strong to severe wind gusts. Sullivan did note that  ” The storm that produced the tornado was not of the same type (supercell) that produced the tornadoes that night in Tennessee or near Crofton in northern Christian County, KY,” explained Sullivan. “This tornado was the result of the intersection of storms moving in two different – nearly perpendicular – directions.  While the intersection of storm boundaries is not entirely uncommon, only rarely do they produce tornadoes.”

Nashville Weather Service forecasters sniffed this out in their Monday morning update, writing “the primary risk appears to be hail, but locally damaging winds and even a couple of tornadoes would be possible should capping erode.” It was a very low-probability but high-impact potential. Granted, you can’t issue a tornado warning until one hits the ground somewhere, but even as the day wore on not even the slightest indication of a tornado watch was issued. Those can last up to 12 hours at a time.


Doppler radar resolves a “debris ball” at 12:36 a.m. on Tuesday as the tornado moved into Nashville, barely a minute after the warning was issued and several minutes or more after the tornado touched down. (Matthew Cappucci/GR2 Analyst)

A rapidly-evolving environment

As late as 10:35pm news outlets were still clamoring at the severity levels of the storm:

“Storm mode looks to become increasingly messy, with multi-cell clusters eventually forming into a broken line,” the Nashville Weather Service had written in their meteorological forecast discussion at 10:14 p.m. “Damaging winds and hail continue to be the main concern, though an isolated tornado cannot be ruled out.”

Thus, there it is. As late as 10:35pm the NWS still had more than two hours to give some people still up warning.

A  warning was finally issued for the Nashville metro area at 12:36am Tuesday morning.  The tornado hit at 12:41am. And a lot of people were asleep. And a lot of people didn’t have an NOAA radio available.  Yet, what good is any of this if you are asleep.

This image shows the radar at the time the tornado entered Nashville which had NO warnings even though this debris ball (area in pink and purple with the white dots) of tornado induced debris traveled for 275 miles for 4 hours towards Nashville that started in the western part of the state.

 

Image

This was the TWEET earlier in the day on Monday which was put out. You can clearly see the areas in yellow had a “slight” risk of severe weather and those were the areas impacted. However, all other risk factors were higher except tornado development which stayed at a “low” threat.

 

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At 11:45om a tornadic supercell was detected on radar heading towards Nashville. STILL, no warning issued by NOAA at this point for the Nashville metro area.

 

Sources and Pictures from The Washington Post.   Matthew Cappucci Matthew Cappucci is a meteorologist for Capital Weather Gang. He earned a B.A. in atmospheric sciences from Harvard University in 2019  and has contributed to The Washington Post since he was 18. He is an avid storm chaser and adventurer and covers all types of weather, climate science, and astronomy.

TELECONNECTIONS: THE WHY ANSWER FOR THE NON-WINTER OF 2019-20

The Winter of 2019-2020 was never going to be one.  And, in the future, when I look at the teleconnections in November and they look almost the same as they do as we enter March then that’s probably telling us all something. I’ve learned my lesson.

The teleconnections are one small piece of the puzzle of forecasting in meteorology. They provide us with a snapshot of what the atmosphere is doing.

The PNA is the Pacific-North American index. This tells us what kind of ridging is taking place. A (+) PNA tells us there is high ridging out west allowing storms to come in, up and over the Rockies, and down the shute towards the middle of the country and East Coast.  A (-) PNA tells us the opposite. There is no ridging. Meaning there are flat waves coming in from the Pacific. It’s most progressive.

The NAO is the North American Oscillation index. It gives us a view of high latitude blocking over Greenland. A (-) NAO tells us there is blocking. A (+) NAO tells us there is hardly any block. This is key in that if a storm is coming up the East Coast it doesn’t allow it to cut towards the Great Lakes or through the Appalachians. Both cases provide us with mostly rain.

And the last the EPO is our cold air source. (+)EPO tells us there is no cold air source. A (-)EPO says there is a cold air source and it has staying power depending on how negative it is.

These are two indices from the last two weeks. And, as you can see, none of them are good for East Coast storms/snow in the winter months. If there is no cold air, if storms are just coming in and coming out, and if there is very little blocking then you can almost book it there won’t be any snow coming our way anytime soon.

And this has been the story the entire winter. It’s officially over in a couple of weeks, but meteorology winter is over tomorrow- March 1st.

Folks, it’s over okay. That’s it.

It is what it was. The DEAD winter of 2019-2020 with an official grand total of 0.9 inches of snow in the state of Delaware.

 

Possible Severe System Coming On Wednesday Evening

A fairly strong upper-level low with some vertical wind shear threatens the MId-Atlantic with some high winds and rain for Wednesday afternoon/early evening.  A strong 998mb low is forecast to develop somewhere along the PA/WV border and produce cold, heavy snow to areas like Ohio, Indiana, western PA, and upstate New York. Yet, on the other side of that front is warmer air pushing from the Gulf and Atlantic waters.  And whenever you get warm air and colder air in the same area together it could produce a KABOOM! with severe thunderstorms, or high winds.  More on this tomorrow.

 

500mb chart showing the upper level low colliding with the eastern branch of the southern jet later Wednesday night. It could produce some severe storms Wednesday evening.

 

Storm Prediction Center depiction showing the area of marginal severe storm risk on Wednesday.

OFFICIAL: Winter 2019-20 Dead

screenshot (5)

The Madden-Julian Oscillation which determines the eastward propagation of storms from Asia to the Pacific will be entering into the “Circle of Death” after spending some time in Phase 7 which is a neutral zone indicating probable transition into either a colder phase like 8-9-1-2. Yet, all ensembles are pointing inward towards the circle which means it has NO influence on weather patterns.

 

screenshot (6)

 

Likewise, our teleconnections which have been horrible ALL winter are indicating that winter is just simply dead in the Eastern 2/3 of the country. There is no ridging (-PNA), there is no high block in Greenland  (+NAO) and no cold air (+EPO).  And this goes through the 5th of March. And if you add in all of the other factors not favoring anything significant in the East like a coastal storm as we are going into March, then it’s all over folks.

Winter 2019-20 is dead. Adios!

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The Lack Of Winter: Warming or Just Normal?

Winter 2019-2020 in the Mid-Atlantic from Washington D.C. to Boston, Mass has been, simply, strange or has it?

According to early winter predictions the NOAA stated in October 2019 very clearly:

“neutral conditions are in place this year and expected to persist into the spring. In the absence of El Nino or La Nina, long-term trends become a key predictor for the outlook, while other climate patterns, such as the Madden-Julian Oscillation and Arctic Oscillation (AO), will likely play a larger role in determining winter weather”

In other words, instead of La Nina or El Nino we’ve had “La Nada”. Nothing. The Pacific waters have had no impact on our winter. The jet streams have been let loose and are so divergent north and south they can’t see each other. Judah Cohen from the Atmospheric Environmental Research is an expert in the area of the AO index. He stated in his most recent blog:

“I know I sound like a broken record when I start every blog by how surprised I am by the stratospheric PV remains on the strong side of normal and even at times near or at record strong for the date. Today there has been some chatter/news about a record daily high for the AO today. But the incessant stretch of positive to strongly positive AO since late December, based on the polar cap geopotential height anomalies (PCHs) plot originated in the polar stratosphere with cold/negative PCHs/strong PV back in mid-December that propagated to the surface over a course of two weeks.”

500mb_HGT_2020021000_Days11_15.png

The graphic above shows the GEFS ensemble for temperature variation over the globe. (Courtesy of https://www.aer.com/science-research/climate-weather/arctic-oscillation/)

In other words, there has been a pool of cold air sitting on top of the North Pole just swirling around the Arctic Ocean and there has been nothing to push it south enough to allow any major, long sustaining cold weather to give the East wintry precipitation. The extent of the cold has been kept out West and it just seems to be that way this winter 2019-2020.

There have been at least eleven winters in the Philadelphia/Wilmington, DE area of fewer than four inches of snow with 1997-98 being at the top with only 0.8 inches that year. It looks like we could beat that this winter.

Thus, the predominant notion that global warming has caused this snowless winter in the NE corridor from Washington, D.C. to Boston which has had snow but not their gigantic February numbers of recent years, is by far not the culprit.

It’s just this winter.

THE DEFEAT OF THE SPANISH ARMADA BY A HURRICANE 1588

Fifth in a series on how weather impacted and changed world history.

Queen Elizabeth was a wonderful leader and tremendously strong Queen of England. She had astounded others with her vision for England both domestically and in the world. However, she was going to be tested for the dominance of Europe by the Spanish in 1588.

The Spanish were bent on defeating the young Queen and invade England to create a Catholic Europe. And they had the strength of manpower and ships.  Phillip II was awkwardly related to Elizabeth in that he wasn’t Elizabeth’s real father.  Phillip was Catholic and Elizabeth was Protestant. Phillip was King of Spain. He wanted to test his step-daughter.

In early July the Spanish fleet set sail. The English fleet lay in wake of seeing the Spanish. By mid-July, the first ships had been seen.  Initially, the campaigns were back and forth. Yet, the Spanish made a long trip even further by sailing up and around Scotland. It prolonged their return to Spain. As they made this turn around Spain they made a navigational area that sailed their ships directly into westerly winds and to compound that they were the equivalent to a hurricane.

Ships were destroyed. Men were killed in the thousands. And the English took thousands of Spanish prisoners. The end was near for the Spanish.

And England remained Protestant. Elizabeth was now a touted world leader and someone to be feared.

CHALLENGER: IT WAS COLD IN FLORIDA

Fourth in a ten-part series on how weather events impacted U.S. History 

 

ChallengerMission Control: “Challenger, go to throttle up.”  

Challenger: “Roger” “Go to throttle up.” 

Then a massive cracking of the cold Florida air that morning of January 28, 1986. The Space Shuttle Challenger was on its 25th flight with seven astronauts including a civilian turned astronaut Sharon Crista McAuliffe. She was a teacher in a school in New Hampshire who had been chosen to be the first civilian space astronaut in the NASA program.

The launches at the Cape had become almost routine in those days, but this was to be a special morning for all of us. Now, in Florida in the winter it does get cold.

However, this January morning as unusually cold with temperatures in the mid 20’s near takeoff.  NASA cancels flights for all kinds of reasons. A clear, beautiful cold day wasn’t going to stop the mounting pressure to get Sharon Crista MaCullife into space that morning.

NASA knew that specific parts of the ship, as well as the boosters, could be impacted by the cold weather. Ice had built up on the shuttle the previous night with temperatures down near 20. Normally, all of these conditions would have been enough for NASA to cancel the flight and wait for warmer temperatures. Not this morning.

As the shuttle lifted off the space pad it zoomed into the atmosphere with breathtaking speed and a glow of the burning boosters powering away into the cold, brisk morning. Thousands watched on the ground and millions on live TV around the world and country cheered the nervous excitement of takeoff.  As the plane reached 4 nautical miles into the heavenly skies the last words came from the flight deck:

Mission Control: “Challenger, go to throttle up,” 

Challenger: ” Roger” “Go to throttle up.”  and unheard as they muttered these last words according to the flight recorder  and transcript, “Uh-Oh!” 

Challenger was gone. A burst of combustion and a massive, rocking explosion disintegrated the entire ship. The solid rocket boosters shot off into the ocean. Pieces of debris fell all over the Atlantic near Cape Canaveral. Seven beautiful lives were lost. A nation watching as a school teacher who was experiencing the time of her life evaporated in front of her students watching in New Hampshire. It was over in 73 seconds.

Later it was found that due to the cold temperatures the O-ring expanded on the solid booster had started to leak gases which ignited the external tank attached to the shuttle. The ship actually disintegrated not exploded, but the outcome of the crew was never in doubt. They were literally evaporated into thin air. They never felt a thing.

The investigation led to the faulty O-ring but there was a memo circulated around NASA recommending the flight not take place in temperatures below 53 degrees for fear of the O-ring issue. The decision makers never saw that memo.   It was 26 degrees in Cape Canaveral that morning.  It should of never happened.