One of the duties that I performed while with the National Weather Service was to conduct storm surveys, after the fact evaluation of reported storm damage. It is a very interesting undertaking that can often be very frustrating, is usually time consuming, and can frequently be very difficult. Distinguishing between damage caused by a tornado and damage caused by straight line wind is tough. The task is very easy when you are dealing with an F3 or F4 tornado because there is rarely any doubt as to the cause of the damage.
The difficulty comes into play when you are trying to determine if an event with some minimal amount of damage is a weak tornado or strong wind. This is where I've heard things like "it made a tremendous noise" or "the trees are twisted off" both of which convince some people that the event was a tornado. But neither of those factors is conclusive.
The bottom line is that the person doing the survey must use his or her best judgment from the evidence at hand and arrive at a conclusion. I've often found it very useful to try to examine small, light weight debris to see if it seemed to respond in a manner that would suggest rotation.
Well, so much for that. What I was leading to is that meteorologists with the NWS out of the Shelby County airport office conducted a storm survey of the report of a possible tornado in Autauga County on April 1. Here is their storm report.
...STORM SURVEY IN AUTAUGA COUNTY FROM APRIL 1ST STORMS...
NATIONAL WEATHER SERVICE PERSONNEL SURVEYED THE STORM DAMAGE IN BILLINGSLEY AND DETERMINED THE DAMAGE WAS THE RESULT OF STRAIGHT LINE WINDS.
A STRONG LINE OF THUNDERSTORMS MOVED ACROSS CENTRAL ALABAMA DURING THE AFTERNOON HOURS ON APRIL 1. THE ISOLATED DAMAGE WAS MAINLY CONFINED TO THE BILLINGSLEY SCHOOL PROPERTY NEAR THE INTERSECTION OF CR 77 AND TOM TURNER ROAD, ABOUT 1 MILE EAST OF BILLINGSLEY. A LARGE SECTION OF METAL ROOFING ON THE SCHOOL WAS PEELED BACK. CEILING INSULATION AND SMALL METAL DEBRIS LITTERED AREAS DOWNWIND. THE EXPOSED CLASSROOMS SUSTAINED ADDITIONAL WATER DAMAGE. SEVERAL WINDOWS WERE BROKEN OUT OR CRACKED BY AIRBORNE DEBRIS. ONE AIR CONDITIONER WAS THROWN ON ITS SIDE AND DAMAGED. A FEW TREES EAST OF THE SCHOOL WERE SNAPPED OFF. SEVERAL VEHICLES IN THE PARKING LOT SUFFERED DENTS AND BROKEN WINDOWS FROM FLYING DEBRIS. THE DAMAGING WINDS OCCURRED AT APPROXIMATELY 529 PM CST ON APRIL 1.
I think I'll also nominate today as one of the prettiest spring days you will ever see.
-Brian-
The difficulty comes into play when you are trying to determine if an event with some minimal amount of damage is a weak tornado or strong wind. This is where I've heard things like "it made a tremendous noise" or "the trees are twisted off" both of which convince some people that the event was a tornado. But neither of those factors is conclusive.
The bottom line is that the person doing the survey must use his or her best judgment from the evidence at hand and arrive at a conclusion. I've often found it very useful to try to examine small, light weight debris to see if it seemed to respond in a manner that would suggest rotation.
Well, so much for that. What I was leading to is that meteorologists with the NWS out of the Shelby County airport office conducted a storm survey of the report of a possible tornado in Autauga County on April 1. Here is their storm report.
...STORM SURVEY IN AUTAUGA COUNTY FROM APRIL 1ST STORMS...
NATIONAL WEATHER SERVICE PERSONNEL SURVEYED THE STORM DAMAGE IN BILLINGSLEY AND DETERMINED THE DAMAGE WAS THE RESULT OF STRAIGHT LINE WINDS.
A STRONG LINE OF THUNDERSTORMS MOVED ACROSS CENTRAL ALABAMA DURING THE AFTERNOON HOURS ON APRIL 1. THE ISOLATED DAMAGE WAS MAINLY CONFINED TO THE BILLINGSLEY SCHOOL PROPERTY NEAR THE INTERSECTION OF CR 77 AND TOM TURNER ROAD, ABOUT 1 MILE EAST OF BILLINGSLEY. A LARGE SECTION OF METAL ROOFING ON THE SCHOOL WAS PEELED BACK. CEILING INSULATION AND SMALL METAL DEBRIS LITTERED AREAS DOWNWIND. THE EXPOSED CLASSROOMS SUSTAINED ADDITIONAL WATER DAMAGE. SEVERAL WINDOWS WERE BROKEN OUT OR CRACKED BY AIRBORNE DEBRIS. ONE AIR CONDITIONER WAS THROWN ON ITS SIDE AND DAMAGED. A FEW TREES EAST OF THE SCHOOL WERE SNAPPED OFF. SEVERAL VEHICLES IN THE PARKING LOT SUFFERED DENTS AND BROKEN WINDOWS FROM FLYING DEBRIS. THE DAMAGING WINDS OCCURRED AT APPROXIMATELY 529 PM CST ON APRIL 1.
I think I'll also nominate today as one of the prettiest spring days you will ever see.
-Brian-