Lightning inside hurricane could predict intensity

[HurricaneJoe22]

http://www.palmbeachpost.com/state/cont ... ength.html

Lightning inside hurricane could predict intensity

By SUE MAJOR HOLMES
Associated Press Writer

LOS ALAMOS, N.M. — They're deceptively simple-looking detectors: one an antenna with built-in GPS, the other electronic sensors inside a large, upside-down metal salad bowl.

The sensors are the basis of a Los Alamos National Laboratory project studying lightning inside a hurricane to improve the accuracy and timeliness of forecasts for people in a storm's path.

The effort is in the second of three years of research. The team is gearing up for the Atlantic hurricane season that peaks in August and September.

Hurricane watchers use satellite images and computer simulations to forecast a storm's trajectory, but it's a challenge to predict how a hurricane will strengthen or weaken as it approaches land, lightning and radio scientist Xuan-Min Shao said.

Predictions of where a hurricane will hit have improved by 50 percent in the past two decades, said Robert Atlas, director of the National Oceanic and Atmospheric Administration's Atlantic Oceanographic and Meteorological Laboratory near Miami.

But, he said, NOAA and its partners have not made the same leap in forecasting storm strength, "largely because you're dealing with ... what's going on within the hurricane itself."

After research, the next step would be an operational system. Los Alamos, as a federal research laboratory, is not in the business of producing forecasts.

"The National Weather Service does that," said Chris Jeffery, one of the project's scientists. "This is a research and development project to demonstrate new technology, understand new fundamental relationships."

Their project spun off from the lab's work in nuclear nonproliferation.

Scientists trying to ensure that countries are not secretly detonating nuclear weapons must know the difference between radio signals produced by a nuclear bomb and anything else — lightning, for example.

Lightning and nuclear bombs both release radio waves at different frequencies.

The team, which has not published its research, found a close correlation between lightning and hurricane intensification in a study of nonproliferation sensor data gathered in 2005 during Hurricanes Katrina and Rita.

"If your hurricane people see the lightning all of a sudden become very active, you are probably expecting in the next couple hours that this hurricane will be intensified," Shao said.

Finding lightning associated with a hurricane eyewall — the wall surrounding the eye of the storm — is not new. But the Los Alamos scientists said their data was gathered from greater distances and tracked not only lightning bolts hitting the ground, but also flashes within clouds.

The intensity of intercloud flashes can help determine such things as the height of the storm, which researchers said can help determine whether the eyewall is symmetrical and tight.

The structure is important because a towering eyewall puts a lot of energy into the storm, Jeffery said.

"Eventually that energy works its way up and if your conditions are right, it forms a symmetric tight eyewall. It will spin up the storm," he said.

Jeffery is the principal investigator in the Hurricane Lightning Project, which involves densely packing sensors around the New Orleans area to observe hurricanes at a far higher resolution than possible in the past.

Scientist Cheng Ho heads a related project, the Los Alamos Sferic Array, which has stations in Florida and along the Texas coast operating at a low-frequency band that can detect storms thousands of miles away. The two complementary arrays cover the entire U.S. Gulf Coast.

"So if we're lucky we'll get a reasonable size, but not very damaging, hurricane hitting the New Orleans area, so we get the data but not much damage," Ho said. "If somehow the hurricane goes the other direction, then this wider arm will catch it."

Shao said the dual-band observations will not only pinpoint the location of lightning for researchers but also the physics involved by producing a three-dimensional picture.

The project needs multiple sensors to get a reading on the electromagnetic pulse produced by lightning.

"We can compare all the signals from the different stations and triangulate where the signal comes from," Shao said.

All the data gathered during a hurricane is sent over the Internet to Los Alamos for the team to analyze. The GPS provides accurate time information from the electromagnetic signals.

Pointing to a shelf with a line of retired sensors in inverted salad bowls from the local supermarket, Shao joked, "These are Mach zero salad bowls and we are going to Mach 4 salad bowls."

Atlas said new insights eventually could translate into improved forecasts up to one week before a hurricane hits land — crucial because of the time needed to evacuate a growing population along the coast.

"We believe if we do this, public confidence in the forecasts and public adherence to warnings will be dramatically increased so lives will be saved," he said.

[JonathanBelles]

This was a very interesting read. I've heard it said before on this forum that lightning in a hurricane signifies intensification, which is where I first learned that. I think there is a correlation between lightning and strengthening. I would love to do more research on this aspect of storms, and I will be watching over the next few years. I hope to bridge the gap between the track forecasts improvements and the intensity forecast improvements, which I think this project, in part, may be able to do. Maybe we can use this project to see if the same thing happens when a normal thunderstorm intensifies. Please keep all of us abreast of the findings of this and other projects dealing with lightning.

[wxman57]

From the presentations on this subject that I've attended at the various hurricane conferences, a sudden increase in lightning can signal an intensification phase. However, the lead time isn't very long, just a few hours. So the researchers are talking about very short-term intensity forecast improvement (a few hours ahead of an intensification phase), not out to 5 days.

[srainhoutx]

From the presentations on this subject that I've attended at the various hurricane conferences, a sudden increase in lightning can signal an intensification phase. However, the lead time isn't very long, just a few hours. So the researchers are talking about very short-term intensity forecast improvement (a few hours ahead of an intensification phase), not out to 5 days.

This caught my attention while living in the Lower FL Keys as Katrina was passing just to our N. As Katrina was heading W exiting FL Bay, we began to hear thunder and we all know what happened in the hours that followed on it's journey into the GOM.

[Frank2]

Yes, it's been an observation made by many recon flights - the obs that had "frequent lightning inside eyewall" in remarks were often the systems that did go through intensification, so it does seem there is a real connection...

[Extremeweatherguy]

When I was chasing Edouard in Texas last August, I experienced quite a bit of cloud-to-ground lightning as the storm was coming ashore near High Island. A couple of the bolts could even be described as "stunning". Given a little more time over water, I believe Edouard might have been able to come ashore as a much stronger storm.

[Dave C]

when jim leonard taped omar in Guam I believe the same year we had Andrew there was a couple flashes in the first eyewall then when he taped the 2nd half there was frequnt strikes and he noted much stronger winds 2nd half. It was 120 mph just before landfall and 145 as the storm pulled away.

[Stormsfury]

Surprising that no one mentioned Hurricane Opal back in 1995. Opal had a tremendous amount of lightning during its sudden and frightening intensification phase.

From the AMS (this is also provided with a link below...
On the Rapid Intensification of Hurricane Opal (1995) over the Gulf of Mexico

V. Mohan Karyampudi, Univ. of Maryland, College Park, MD; and E. B. Rodgers, H. F. Pierce, and J. Weinman

Hurricane Opal, which occurred on 3-5 October 1995 over the Gulf of Mexico, intensified rapidly (from category 1 to Category 4) within a short period of 24 hours (i.e., between 1200 UTC on 3 October and 1200 UTC 4 October). Much rapid deepening was confined, however, within a short period of 2 hours (0900-1100 UTC 4 October) as the central pressure dropped from 933 to 916 hPa as the eye contracted from a radius of 30 km to 15 km (Marks et al. 1998). It is well known that tropical cyclone intensification largely depends on three physical processes: 1) internal storm dynamics, 2) large-scale upper-tropospheric influences, and 3) air-sea interactions. In the case of Opal, previous studies have shown that its rapid intensification can be explained by influences of upper-tropospheric-trough interactions (e.g., Rodgers et al. 1998; Bosart et al. 1999) and air-sea interactions (Shay et al. 1998; Hong et al. 1999). Although a greater understanding of Opal's rapid intensification has been achieved from these observational and numerical modeling studies, the role of internal storm-scale dynamics during Opal's short but strong rapid intensification phase (0900-1100 UTC) is not well understood. Furthermore, it is not clear what environmental factors were responsible for the abrupt weakening of Opal after 1200 UTC 4 October prior to landfall. Therefore, the purpose of this study is to investigate not only the role of eyewall convective processes in the rapid intensification of phase of Opal but also the effect of dry air intrusion on the rapid weakening of Opal using both observational and numerical simulation results. Preliminary results from both the NLDN lightning and ECMWF gridded data analysis revealed the occurrence of increased frequency of cloud-to-ground lightning strokes associated with vigorous cumulonimbus convection close to the eye center between 0800 and 1400 UTC on 4 October, which coincided well with the inner eyewall convective burst episode indicated by large convective latent heat release derived from the SSM/I data. It is hypothesized that Opal's rapid intensification can be explained by the sudden increase in convective latent heat release (LHR), which must have contributed to strong updraft velocities as evident from an increase in lightning flashes, and hence induced compensating subsidence within the eye to cause a rapid decrease in hydrostatic pressure through adiabatic warming. This short-term convective burst appears to have been caused by an increase in CAPE resulting from enhanced surface moisture fluxes during Opal's passage over the WOE as well as by the convective destabilization caused by the upper-tropospheric trough. These results including the MM5 model simulations in capturing the intensification and weakening phases of Opal will be presented at the conference.
http://ams.confex.com/ams/last2000/tech ... _12859.htm



Also found this with searching for Opal information about the lightning strikes during the rapid intensification process. Apparently, the same occurred with Cyclone Nargis in 2006.

http://dsc.discovery.com/news/2009/01/1 ... tning.html