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Science and History
The Science and History of Hurricane Interception
How it Used to Be . . .before 2003...
So, I will tell you how it "used to be" when chasing. One must do this in the frame of reference that there are no computers in the car to determine exactly where the eye of the hurricane is at all times. And this was the most difficult thing to do as each hurricane has come ashore. This is where science and intuition came into large play; as the information available to the public was limited to the latest 3 or 6 hour advisory position from the NHC. Knowing where that wobbling eye was at all times was not a simple task; but is the most critical of determinations.
Since the mid-1960s, each time a hurricane came ashore, 40-80 news crews (local, network, cable) have set out to intercept the storm. (Until the mid-1990s, the number of actual (non-news-crew) hurricane chasers was less than 6. Three or so from 1965 - 1987, then a few more in the late 1980's,, then a small handful more from 1996 to 2004, and now over 60.
The news crews chasing knew, when they departed, that the center would come ashore somewhere in a 100-150 mile stretch of coastline; as that was the average margin of error for hurricane motion in a 24 hr. forecast.
As the hurricane approaches shore the weather conditions gradually deteriorate; eventually bringing gusts in the spiral bands to 50-60 miles an hour. At this point, when blinding rain, debris, and gusts make travel quite dangerous, the eventual landfall of the core is still quite uncertain; and could be anywhere in a 50-75 mile stretch—sometimes more. At this pt. 99% of the news crews have hunkered down in a specific city each; usually cities with a nice hotel.
This core area (the goal of the chaser to intercept AS it comes ashore) ranges from 5-15 miles across. Areas of coastline that are accessible, in many areas of the Gulf and Atlantic coasts, are not continuous for sure, so it's not just a matter of just "driving the coastline" until you get to the right place. Usually one has to drive an inland road, then find a causeway to the right barrier island. If you get to a barrier island too soon and the eye shifts just a little bit east or west, north or south, you get stuck on that island as the surge builds up ahead of the hurricane, and blocks the escape route back to the mainland.
Knowing the potential tidal surge of THIS hurricane, the elevation of the causeways to the barrier islands, and the elevation of the islands are all critical. Some margin for error in these forecasts is also a calculation needed. This keeps one from drowning (again, 90% of hurricane deaths are from drowning in the surge), and minimizes the likelihood of getting stranded by rising waters on the causeways and the barrier islands themselves.
One usually has to make a final adjustment in position just several hours before the central core comes in, and this means driving from 30 minutes to over an hour in torrential blinding rain, with winds gusting over hurricane force in quick squalls. You just don't know the final landfall point until these conditions are occurring along a 100+ area of coastline.
Again, knowing exactly where the eye was, was not that simple. You had the official position, period. It was often hours old; hence the eye could be 10-30 miles further along, and possibly right or left, of the previous or forecast track. Local radio and TV stations often omit the exact position in their excitement, or present their own less-informed forecasts.
This is where one's knowledge base, and application of that knowledge base (intuition) determined whether the intercept would be successful. Just being 10 miles from that central core can make a difference on whether you experience 80 mph winds, or 130 mph winds.
Below is a conglomeration of some of that knowledge base:
1. No two hurricanes have taken the exact same path.
2. The area of maximum winds, although most often in the NE quadrant, is NOT in the NE quadrant about 35% of the time. Examples: Andrew: NW quadrant; Katrina as it crossed S. Florida, SE quadrant; Isabel, NC, NW quadrant.
3. Direction of motion of the hurricane is mostly caused by the flow at mid levels (around 500 mbs.). In weaker storms, maybe the 700-500 mb level. In the strongest hurricanes, maybe between 550-400 mb level. If the storm is changing strength as it comes ashore one must know what the flow is at various levels, and determine which levels are most affecting motion. Since these mid and upper level maps are updated by data only every twelve hours, the chaser has to make his own forecasts as to how these mid and upper level winds are changing over time.
4. Intensity is most affected by upper level winds (200 mb. outflow); but can also be affected by the orientation of the land relative to the angle of approach of the eye, dry air coming off land, and water temp. If another hurricane has come over the area lately, water will be cooler due to upwelling. If passing over warmer water (like Gulf Stream) as it approaches land, this can enhance intensification; as has happened often (Andrew, and the Labor Day Hurricane of 1935 are examples) when hurricanes approach S. Florida.
5. The eye is often changing shape; causing the max wind area to shift markedly. The shape changes from oblong ne-sw, to circular, to oblong nw-se. The eye also is often expanding or contracting as it approaches; this also shifting the area and expanse of the central core.
5a. The timing in the cycle of an eyewall replacement phase is extremely difficult to pin down.
6. In banded-eyed hurricanes, there is a blob of convection or vorticity max. (like a mouse in a snakes belly), accompanied by the area of maximum winds, rotating around and around the center. As this blob rotates around the eye the direction of the whole hurricane's motion wobbles, with a constant shift to the left just behind that rotating ball.
7. In determining where the exact offshore center is located, while one is on the shore ahead of landfall, one has to know whether the storm is intensifying or weakening. If it is in steady state, the wind will be almost parallel to the isobars. If it is intensifying the inflow will be cutting across the isobars, up to 30 degrees, heading more towards the center. If weakening, the wind motion will be cutting a little across the isobars, but angling away from the center---as the storm is "filling." Knowing which state the hurricane is in, makes one’s estimate of location of the exact center much more accurate. You are making your determination by observing the direction of motion of the surface winds and the lower cloud elements.
8. Despite the official forecast and progs that might be predicting a NE turn as a landfalling storm is approaching a trough in the westerlies, the hurricane's outflow itself can slightly erode the trough, causing the westward trajectory to last a few hours longer--bringing the core and eye inland further south or west of most forecasts.
9. Motion can also be affected by the orientation of the land relative to the angle of approach; or by the orientation of a mountain range near the coastline.
10. Knowing if the hurricane is approaching an area that will cut off moisture and wind inflow. Typically, but not always, hurricanes hitting the north Gulf draw dry air into their NW quadrant as they get close to landfall. This weakens the west and south sides of the hurricane; and shifts the max wind area eastward.
11. Getting a feeling for the spacing of the spiral bands in each storm, lets one know when he can change positions, or work their way up the coastline to intercept a curving hurricane, or one that approaches the coast at a steep angle. The general sequence of events over many hours is like this:
Winds gradually increase to a steady 40 mph between spiral bands, then gust to 55 or so as a band comes ashore. Then the sustained winds drop back to around 45 mph, until the next band passes over, when the winds gust to 60-65 mph. Band passes, but winds are now a steady 50-55 mph; until the next band, when the gusts reach hurricane force (75 mph.). And so the intensity of the winds stair-steps up to their maximum just before the eye. The spacing and timing of the relatively weaker sustained winds lets one know and for how long a period he can move a few miles up the road to better his interception position; or just find a more secure place to place his vehicle as the wind gradually shifts direction.
*And, of course, just having a data bank in one’s head how “similar” hurricanes reacted in a general area is quite helpful. Also, knowing the road system of each specific area and potential low areas subject to early flooding is critical as well.
HISTORY OF HURRICANE CHASING
Keep in mind several news photographers chased hurricanes in the 1950s; most well known is Clarence G. of CBS. I met him during Hurricane Diana in 1984, as a stringer for CBS, and he told me of his 3 decades of filming hurricanes, and lectured me on proven methods of filming hurricanes.
They say Thomas Edison was the first chaser: he filmed the aftermath of the Great Galveston Hurricane of 1900, that killed 6000-9000 people, depending on the historian.
Others say Moses was the first storm chaser, in general, as he knew to be at the shore of the Red Sea as a giant tornado formed over his people and moved out over the sea, the giant eye and wall cloud parting the sea around the Hebrews. As the tornado moved across the Sea his people walked inside the eye, the sea being held back by the outer ring of the large "tornado eye." The sea returned behind the eye and drowned Yul Brenner's army, as Charlton Heston led his people onto the far shore of the Red Sea. (Much later on he became president of the National Rifle Association, I have heard).
Arthur P, long time researcher at the NHC, chased Hurricane Donna to the Florida Keys in 1960. He woke up in his motel bed, floating near the ceiling, as the surge crashed ashore. Winds gusted near 185 mph in that hurricane, and Lake Surprise in Key Largo was blown dry for over an hour. I don't believe he chased after that. Donna went on to extremely affect all of Florida and most of the whole east coast of the USA.
In 1965, several Florida State University seniors headed out from Tallahassee to intercept Hurricane Betsy near New Orleans. They made it to Mississippi, when a huge tree collapsed across US 90. No interstates back then, and the only way to continue west was to drive 60+ miles inland. Timing of landfall ahead made that impossible. Two of these guys, Joe G and David W soon after went to work for the NWS, eventually becoming "high" administrators, and never chased again.
Terry Nixon, myself, and Dane C (son of "famous" NHC forecaster Gil C, and later a NWS employee and then administrator) chased Hurricane Inez from Tallahassee, back to Miami in 1966. Terry and myself chased together until 1989-1990: Hurricane Hugo to Puerto Rico and S. Carolina in 1989, and finally Trudy to Baja California in 1990. Terry chased one more hurricane, Andrew to Miami, from N. Florida by himself.
Jim L started chasing in 1972, and we also chased a few storms together; like Frederick to Mobile, Alabama and Alicia to Texas. Jim passed away in 2014. I continue to chase today.
In the late 1980s two more chasers from Miami got into the act.
In the mid 1990s another 4 or 5 people began to chase.
Since 2004 the number has increased to over 60.
There are a few others who have chased here and there; but the above list pretty much covers the "dedicated" hurricane chasers from 1966-2003.
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I possess extensive footage from all of these chases since 1984: which will certainly enhance the production of a TV documentary centered on the Science and History of Hurricane Chasing. The costs of production would also be held down considerably by encorporating much of this footage.
Many clips captured over the years can be viewed here:
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The above outline could be the complete subject matter of one TV production. OR, it could be combined with my more detailed script / outline detailing my long history of intercepting 70+ tropical cyclones and the pioneering of the storm-video business, as one complete production. That other outline can be read at the following URL:
http://www.hurricanevideo.citymax.com/articles.html
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