Tag Archives: Global Warming Enhanced Storm

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.