Tag Archives: Hermine

The Changing Climate of Atlantic Storms and How The Are Reported

Hurricanes are well defined systems with characteristics that quite literally set them apart from other storms. Large storms such as Nor’Easters are sometimes less well defined and interact more with major troughs, the jet streams, etc. We have come to understand Hurricanes as the worst case scenario, while other storms are less dangerous.

But sometimes, and I suspect more recently lately, these non-tropical storms become quite dangerous. The Great Storm of ’78 killed hundreds in New England and made us suddenly realize that coastal property was a temporary thing. But we sense the danger of recent storms less acutely because for all storms we have better warning systems, and most storms don’t kill that many people these days, like they used to. So worse storms seem less bad.

And sometimes, it turns out that these large powerful and dangerous extratropical systems and the tropical hurricanes or their remnants merge and interact, creating what sometimes emerges as aย “superstorm” or at least, a “really inconvenient storm.”

Sandy is an example of the former. Perhaps Hermine is an example of the latter. Hopefully not the former as well!

The focus on hurricanes as the dangerous big brother of temperate storms (including Nor’Easters) has unintentionally shaped our storm warning system to downplay by default non-hurricane storms, including the hurricanes themselves when they become extratropical. But the “remnants” of hurricanes over land are usually very dangerous because of the flooding they cause, and late in life former hurricanes are capable of ganging up with temperate systems to become very dangerous.

In the case of Superstorm Sandy, owing to global warming driven warm waters, the storm remained as a hurricane at the time it started to interact with temperate storm systems, and the result was one of the worst storms to hit the US East Coast. Yet, it was technically not a hurricane at landfall. Rather, it was a hurricane that ate another storm on its way to Ohio, and got too big, too powerful, too messy, and too dangerous to maintain use of the term (hurricane) normally reserved for better organized, more predictable, and better behaved dangerous storms.

Maybe we are seeing a shift in where the danger lies in Atlantic storms. There will never be a storm as dangerous as a Major Hurricane moving just the right way at just the right time against just the right piece of coastline. Ivan, Andrew, Katrina, like that. But the typical Category I hurricanes and the seemingly new phenomenon of more frequent post-tropical hybrids, and more frequent certain supercharged Nor’Easters seem all in about the same category of overall badness.

We are certainly seeing some self reflection on the part of meteorologists, who are always faced with the very difficult task of properly informing and educating the public, properly modulating alarm over a given storm system, always trying to not cause problems for the next storm by overstating or understating expectations. Some of this self reflection, as well as the gory details of how these different kinds of storms (Nor’Easter or Hurricane-Extratropical hybrid) develop is demonstrated in the following passages taken from various Hurricane Center discussions or Wikipedia, pertaining to the storms as indicated. I put them here for your enjoyment and/or horror.

1991 Perfect Storm

The 1991 Perfect Storm, also known as the The No-Name Storm (especially in the years immediately after it took place) and the Halloween Gale, was a nor’easter that absorbed Hurricane Grace and ultimately evolved back into a small unnamed hurricane late in its life cycle. The initial area of low pressure developed off Atlantic Canada on October 29. Forced southward by a ridge to its north, it reached its peak intensity as a large and powerful cyclone. The storm lashed the east coast of the United States with high waves and coastal flooding before turning to the southwest and weakening. Moving over warmer waters, the system transitioned into a subtropical cyclone before becoming a tropical storm. It executed a loop off the Mid-Atlantic states and turned toward the northeast. On November 1 the system evolved into a full-fledged hurricane with peak winds of 75 miles per hour (120 km/h), although the National Hurricane Center left it unnamed to avoid confusion amid media interest in the predecessor extratropical storm. It later received the name “the Perfect Storm” (playing off the common expression) after a conversation between Boston National Weather Service forecaster Robert Case and author Sebastian Junger. The system was the fourth hurricane and final tropical cyclone in the 1991 Atlantic hurricane season.

Hurricane and Superstorm Sandy

FIRST A NOTE ON THE NWS WARNING STRATEGY FOR SANDY. IN ORDER TO
AVOID THE RISK OF A HIGHLY DISRUPTIVE CHANGE FROM TROPICAL TO
NON-TROPICAL WARNINGS WHEN SANDY BECOMES POST-TROPICAL…THE WIND
HAZARD NORTH OF THE TROPICAL STORM WARNING AREA WILL CONTINUE TO BE
CONVEYED THROUGH HIGH WIND WATCHES AND WARNINGS WARNINGS ISSUED BY
LOCAL NATIONAL WEATHER SERVICE OFFICES.

SANDY CONTINUES TO MAINTAIN AN AREA OF DEEP CONVECTION NEAR THE
CENTER…WITH AN EYE OCCASIONALLY VISIBLE ON SATELLITE IMAGERY.
ALTHOUGH THE SATELLITE PRESENTATION OF THE SYSTEM IS NOT VERY
IMPRESSIVE…SFMR MEASUREMENTS…FLIGHT-LEVEL WINDS…AND DROPSONDE
DATA FROM THE AIR FORCE HURRICANE HUNTERS INDICATE THAT THE WINDS
HAVE INCREASED TO NEAR 75 KT. SINCE THE HURRICANE WILL TRAVERSE
THE GULF STREAM THIS MORNING…AND THE SHEAR IS NOT TOO STRONG AT
THIS TIME…SOME MORE STRENGTHENING AS A TROPICAL CYCLONE IS
POSSIBLE IN THE NEXT FEW HOURS. HOWEVER…THE MAIN MECHANISM
FOR INTENSIFICATION LATER TODAY SHOULD BE BAROCLINIC FORCING. THE
OFFICIAL WIND SPEED FORECAST IS CLOSE TO THE LATEST GFS PREDICTION
AS THAT MODEL SHOULD BE ABLE TO HANDLE THE EVOLUTION OF THIS TYPE
OF SYSTEM FAIRLY WELL.

THE CONVECTIVE STRUCTURE OF SANDY HAS DETERIORATED TODAY…EVEN AS
THE CENTRAL PRESSURE HAS CONTINUED TO SLOWLY FALL…SUGGESTING THAT
THE CONVECTION IS NO LONGER DRIVING THE BUS. THE INTENSIFICATION
OBSERVED THIS MORNING WAS ASSOCIATED WITH STRONG WINDS OCCURRING TO
THE SOUTHWEST OF THE CENTER…OUTSIDE OF THE CENTRAL CORE…AND WAS
ALMOST CERTAINLY DUE TO BAROCLINIC FORCING.

SATELLITE…RADAR…SURFACE…AND RECONNAISSANCE AIRCRAFT DATA
INDICATE THAT SANDY MADE LANDFALL NEAR ATLANTIC CITY NEW JERSEY
AROUND 0000 UTC. THE INTENSITY OF THE POST-TROPICAL CYCLONE WAS
ESTIMATED TO BE NEAR 80 KT AT LANDFALL WITH A MINIMUM PRESSURE OF
946 MB. AT LANDFALL…THE STRONGEST WINDS WERE OCCURRING OVER
WATER TO THE EAST AND SOUTHEAST OF THE CENTER. HURRICANE-FORCE
WINDS GUSTS HAVE BEEN REPORTED ACROSS LONG ISLAND AND THE NEW YORK
METROPOLITAN AREA THIS EVENING. IN ADDITION…A SIGNIFICANT STORM
SURGE HAS OCCURRED ALONG A LONG STRETCH OF THE MID-ATLANTIC AND
SOUTHERN NEW ENGLAND COAST.

2016 Hermine

Satellite imagery indicates that Hermine has become a post-tropical
cyclone, with the coldest convective tops now located more than 200
n mi northeast of the exposed center. Despite this change in
structure, surface data from the Outer Banks indicate that some
strong winds persist near the center, and the initial intensity is
set to 55 kt for this advisory. During the next 48 to 72 hours,
Hermine will interact with a strong mid-latitude shortwave trough
and all of the global models show the system re-intensifying during
that time and a redevelopment of a stronger inner core, albeit one
situated underneath an upper-level low. Regardless of its final
structure, Hermine is expected to remain a dangerous cyclone through
the 5 day period.

Hermine more serene?

Update (Sunday PM):

Hermine is still a big storm and will affect eastern regions to some degree, but the storm never reformed as a hurricane, and is not not expected to do so. Also, the storm has jinked out to the east more than expected and will likely move farther east. So, there will be some coastal effects, but not much out of the ordinary.

POST-TROPICAL CYCLONE HERMINE FORECAST/ADVISORY NUMBER 30
NWS NATIONAL HURRICANE CENTER MIAMI FL AL092016
2100 UTC SUN SEP 04 2016

CHANGES IN WATCHES AND WARNINGS WITH THIS ADVISORY…

A TROPICAL STORM WARNING HAS BEEN ISSUED FROM WATCH HILL…RHODE
ISLAND EASTWARD TO SAGAMORE BEACH…MASSACHUSETTS INCLUDING BLOCK
ISLAND…MARTHA’S VINEYARD…AND NANTUCKET.

THE TROPICAL STORM WARNING HAS BEEN DISCONTINUED FROM FENWICK
ISLAND…DELAWARE SOUTHWARD…AND ALSO DISCONTINUED FOR DELAWARE
BAY NORTH OF SLAUGHTER BEACH.

SUMMARY OF WATCHES AND WARNINGS IN EFFECT…

A TROPICAL STORM WARNING IS IN EFFECT FOR…
* NORTH OF FENWICK ISLAND TO SAGAMORE BEACH
* DELAWARE BAY SOUTH OF SLAUGHTER BEACH
* BLOCK ISLAND
* MARTHA’S VINEYARD
* NANTUCKET

Original Post:

Hermine was bad enough for florida, though of course, nothing like a Major Hurricane. But, the downgraded storm may not be done with us yet. There is a very good chance that Hermine will reform into a hurricane, or at least something that we’ll call a hurricane because it will look like a hurricane, blow like a hurricane, and hurt like a hurricane, over the next several hours. This will happen after the land-damaged storm passes over global warming heated ocean waters. Sometime between mid day and early evening on Saturday, Hermine could gain hurricane strength and directly affect New Jersey and nearby places.

Barrier islands from the Carolinas to New Jersey, but especially around Delmarva, New Jersey, and New York, are at risk for storm surges, with a major risk in southern Delmarva and Virginia Beach, and the lower Tidewater. Outer New Jersey may experience something like a 6 foot storm surge Sunday night or early Monday AM.

This is Labor Day Weekend. A very large number of people go to these areas over this Final Weekend before the perceived end of summer. Causeway roads that connect these barrier islands to the mainland may be washed out, and the barrier islands themselves are not great places to be.

The big question at hand is this: Will the state authorities in these areas have the will and the wiles to warn their citizens and visitors off these dangerous areas, or will they avoid damaging business by sitting on their hands. Then, either way — whether a particular area is damaged by the storm or damaged by safety in light of the storm — will there be some help for those businesses? Oh, and lets not forget to include these considerations in the costs of this storm.

So be careful, watch the weather, and pay attention, if you live anywhere on the US East Coast.

Atlantic’s Hermine Is A Big Deal (UPDATED)

For the latest post on Hermine GO HERE.

Update Thursday PM

Hermine has grown in strength, and may even make landfall as a Category 2 storm. At least a strong Category 1.

The right front quadrant of the storm is where the main “punch” (of winds) is located. If the storm winds come into an embayment, they can really build up the storm surge. Look at this image:

rbtop_lalo-animated

You can see the right front quadrant of the storm heading right into Apalachee Bay. Barrier islands to the west of the bay’s head, and the communities right in the bay, are very much at risk for severe flooding.

Here is a blowup of part of the NWS’s experimental storm surge product for the area:

Screen Shot 2016-09-01 at 7.51.24 PM

You can see the increase in storm surge intensity/risk in the bay.

Also, there is a small possibility that the storm, which will turn “extratropical” as it passes over Florida and joins an existing storm system, will later move out to sea in an area conducive to re-formation. Not too likely but the idea is being bandied about.

Update (Noon Thursday):

It is very likely that Hermine will become an actual hurricane by the end of business day today, or during the early evening. It is really starting to look like one now, as of this writing.

The storm is likely to make landfall (as a hurricane?) before mid day tomorrow (Friday). There is a very serious storm surge threat from some point east of Apalachicola, all the way over to about Spring Hill, or even a bit farther south (heading towards Tampa). Especially at risk are areas around Big Bend Wildlife Management area and Suwanee River, where embayments may focus the storm surge.

Some of these places may have storm surges over over 9 feet above the ground.

After that, the National Weather Service is trying to be vague, because Hermine will interact with a large existing low pressure system. How much rain, where, how much wind, where, all that, is not clear. By the time the storm gets to near Norfolk, it might not even be near Norfolk. This could become a land threatening Nor’Easter affecting New York or Boston, or it could to out to sea and rain mainly on boats. Stay tunes.

This is not a major hurricane, but it is likely to be a significant flooding and rain event for a lot of people over a large area. This is also going to mess up Labor Day weekend, which will have a significant economic impact on many areas where people usually visit and recreate.

Original Post:
For a while there it looked like the Atlantic might develop up to four simultaneous named storms, but that has not worked out. One of the storms will never get a name, one of the disturbances now looks like it may never be a storm. Gaston continues to chug away towards the Azores.

But one of these four weather events is now a named storm that will matter.

Tropical Storm Hermine is a global warming enhanced storm that will produce record rainfall events, catastrophic inland flooding, and likely, coastal storm flooding, in many locations in the US east.

Paul Douglas of Aeris Weather notes that this storm reminds him, somewhat of Sandy, because of its bigness and wetness and potential to reach far inland. It will not be as bad as Sandy, but, he notes, “there is a growing potential for disruptive weather all up and down the East Coast from Friday into Sunday; coastal Georgia and the Carolinas right up I-95 into Washington D.C. and New York City may be impacted by 40-60 mph winds, flash flooding and coastal flooding and beach erosion as Hermine churns north.”

Also like Sandy, a blocking pattern in the Atlantic will cause Hermine to stay longer off the coast than otherwise.

Places that normally flood are likely to flood. The storm will come over land at the base of the Florida Peninsula and the Florida Panhandle. It is possible that the storm will be a weak Category One hurricane just before landfall, but not likely. It will then cross florida and run up the coast, either just on land or just off shore. One model h as the storm curving back from the Atlantic into southern Newe England, another model has it staying on land until New York City, then curving back out over Long Island. That gives you the range of uncertainty for the storm’s activity in several days from now.

But the track for the first several days is pretty well understood. Across the base of florida, then across Georgia, South Carolina, and into or near the Tidewater area, staying near the coast the whole time, more or less straddling the strandline.

It will be windy and wet with a lot of rainfall. The loss of Labor Day business will be bad for tourism regardless of any damage to such facilities that may occur as well.

Is Hermine enhanced by global warming?

Hermine is a weather event. Global warming caused by the human release of greenhouse gasses (and other human effects) is a climate phenomenon. So how can we possibly connect them?

Well, we have moved well past the days when one could pose such a lame brained question. Climate is weather, long term, and weather is climate, here and now. So, if climate is fundamentally changed, then the wether is fundamentally changed. The question is not whether weather that drenches or withers and climate wither are bound! The question is, what ways are a particular untoward weather event and the recent changes in the climate bound?

Here’s how.

Warmer seas and warmer air, causing generally more moisture in the air; and changes in air currents due to Arctic warming and other effects, causing a more uneven distribution of moisture in the air causing big dry areas and big wetter areas, and large wet blobs to form up and then move more slowly than usual across the landscape, make something like this storm (which at the base of it could have happened anyway) be bigger, wetter, slower-moving and thus rainier.

Climate Signals has a nice summary here.

Atlantic Storm Update: Prospects of Gaston, Hermine, Ian and Julia

Original Post:

The Atlantic storms are getting interesting.

Two different systems are poised to become named storms, but it is not clear which one will be awarded the name Hermine, and which one Ian. If the storm recently near Cuba develops as expected, it could become a weak hurricane before making landfall along Florida’s Gulf coast. This will not likely be a very impressive hurricane, but it will be big and wet, and the area is already experiencing too much water. Flooding will ensue.

A third system is moving off of Africa, with 40% chance of forming into a storm over the next several days. This system looks really promising for a hurricane.

Hurricane Gaston is still hanging out in the middle of nowhere, but it will likely menace the Azores.

Update (Wednesday AM):

Gaston is at present a Major Hurricane, and will continue heading east, weakening to a tropical storm before arriving in the Azores.

There are three other systems of interest. The Cuban storminess that has been on everyone’s mind for a while refuses to get organized into a namable storm. Another, in the Atlantic, is also developing slowly. Both disturbances are likely to become sufficiently organized and strong to become named tropical storms, and that is likely to happen before sunset today. Which one will get organized first to claim the name of Hermine? Which one will become Ian? Neither is likely to spin up to hurricane strength.

The more southerly of the two storms, in the area of Cuba, is likely to sweep across the base of the Florida Peninsula and cause a mess (but as a tropical storm, not a hurricane). the other is likely to stay out to sea, in the Atlantic.

Meanwhile, the disturbance off the African Coast (to the right of the map) retains a certain amount of ambiguity as dry air reduces its chances of formation. But, it will reveal its will over the next several days as it moves west. We will see.

It is possible that we could see four names storms churning away simultaneously in the Atlantic. That is probably not a record, but it could be. My impression is that this happens now and then. Do you know? There have been as many as 8 storms formed in a given month (but not necessarily extant at the same time) a few times. So, four at the same time may be highly unusual.

ADDED:

OK, I found this about simultaneous storms:

Four hurricanes have existed simultaneously twice: August 22, 1893 and September 25-27, 1998 with Georges, Ivan, Jeanne and Karl as hurricanes. In 1971 there were 5 tropical cyclones simultaneously, but only 2 were hurricanes. [source]

Note, that refers to hurricanes, not named storms. So it is not an answer to the question.

Update (Wed PM):

Hermine exists and is expected to strengthen over the next two days or so, but not to full hurricane strength, before hitting florida near the base of the peninsula. After that, it will come out the other side, and hug the coast until at least North Carolina. Then it will go off to sea.

The second disturbance in the Atlantic will turn into a named storm, perhaps within a day or two, and Gaston will still be a named storm, so there will be three named storms at the same time. Gaston will be on or near the Azores by the end of the day Friday. The fourth stormy event, off the coast of Africa, is looking less likely to turn into a named storm any time soon.

The 2016 Atlantic Hurricane Season So Far. Keep an eye on Hermine.

A quick note about the current Atlantic hurricane season. With resect to just the US, we’ve had a fairly low level season, and it is easy to become complacent about this time, but in fact, the risks from Atlantic hurricanes rise about this time of year, so pay attention. Watch for Hermine. More on that below.

We are approximately in the middle of the 2016 Atlantic Hurricane Season, by calendar time. The number of named storms (tropical storms plus hurricanes) predicted for this year is about 14, taking the average of all the predictions made so far, and there have been 7 storms including one currently brewing in the middle of the Atlantic. So, perhaps we are right on track.

But, the first of those seven storms actually happened last year, but after the Hurricane Prediction Center had closed the book on the 2015 season, so Hurricane Alex got dumped into the 2016 season. (It happened in Janurary.) So, we are a bit behind in the total number of named storms.

But, we are not really half way through the hurricane season. It starts on June 1 and ends on November 30th, though as was the case with Alex, individual storms sometimes fail to get the memo. But, more importantly, the peak of the season tends to be around September 10th, and the distribution of Atlantic hurricanes over they year tends to be a bit skewed, with the latter half of the season being more active.

During the period 1851 to 2015 there were 1619 Atlantic tropical storms or hurricanes recorded. 609 of them happened prior to the end of August. The remaining 1010 happened in September, or later, with September and October having most of them.

So, roughly speaking, if we are half way to the predicted 14 named storms now and still in late august, one could guess that we’ll slightly exceed average expectations, but likely fall within the range of those expectations. We’d have to have over 20 or so named storms to raise the eyebrows of most of the predictors.

I get the impression that the percentage of named Atlantic storms that made landfall this year has been on the high side, though there has been no catastrophic landfall to date.

Katrina made landfall in about four days from now (in 2005). Among the deadliest, Sandy (which was a Hurricane that ate another storm and became too big and powerful to maintain its status as a hurricane by landfall, thus dubbed a “super storm” and enigmatically left off most hurricane lists) was later in the year, as were Stan, Jeanne, Mitch, Gordon, Fifi-Oriene, Flora, Jeremie, several other storms. Of recent deadly storms, Katrina was relatively early, and only 1979’s David came close (formed August 25th, fizzled out on September 8th).

So, speaking just of the more powerful storms, that is generally a phenomenon of September or October and now and then November.

Gaston is the currently active named storm. It is likely to form into a hurricane over the weekend, veer right before coming too close to Bermuda, and remain pretty far out in the Atlantic. There are no clear predictions of what it will do by mid week, but it is likely to weaken a bit on Wednesday. Gaston will be in hurricane-hostile territory at that time, so may be it will just go away.

Hermine is the name that would be given to what is now a tropical disturbance, should it form a tropical storm. The changes that it will do so are not small. If Hermine forms up into a reasonable storm, the chances that it would miss already-water-logged Florida are very small. I expect Hermine to be a significant weather event for the southern US.