Event Summary
     National Weather Service, Raleigh NC

March 4, 2008 Severe Weather Event
Updated 2008/04/27





Event Headlines -
...Widespread severe weather and 2 tornadoes occurred during the afternoon and evening hours of March 4, 2008...
...An EF-0 tornado touched down near Union Ridge in Alamance County and an EF-0 tornado touched down near Enfield in Halifax County ...
...There were in essence three rounds of severe weather, one with mainly discrete storms during the afternoon and two broken lines of storms during the early and late evening hours...
...Forecasters effectively used sectorized operations while issuing over 35 warnings over a 9 hour period...


Event Overview -
Widespread severe weather in the form of damaging straight-line winds and 2 confirmed tornadoes occurred across central NC on the afternoon and evening of Tuesday, March 4, 2008. The severe weather was associated with a vigorous upper level low and deep surface low moving northeast through the Tennessee Valley into the Mid-Atlantic.


Synoptic Overview -
During the afternoon and evening of Tuesday, March 4, 2008, a strong upper level low was moving northeast from the deep south into the Mid-Atlantic. As the upper low approached the area Tuesday afternoon and evening, a strong jet was rounding the base of the upper level low and ejecting into central North Carolina. The location of the low and the upper level jet placed central NC in a region of strong divergence aloft which favored the development of severe thunderstorms. As the upper level low passed just to the northwest of North Carolina near the end of the severe weather event, the associated trough axis also obtained a negative tilt over central North Carolina and Virginia. An unusually strong low level jet was associated with this system, with 00Z 03/05 RAOB data showing a 55-65 mph jet as low as1500-2500 ft above ground level. This unusually strong low level jet was a significant contributing factor to the damaging winds observed with thunderstorms on Tuesday evening.

A deep surface low, around 995 mb, accompanied the upper level low as it tracked through the Tennessee valley and Mid-Atlantic on Tuesday evening. The location and proximity of the deep surface low was such that all of central North Carolina was in the warm sector, with temperatures in the 70s, dew points in the 60s, and southerly surface winds at 10 to 20 mph with gusts up to 35 mph. The unusually warm temperatures and dew points were contributing factors in allowing enough instability for thunderstorms to develop on Tuesday afternoon and evening.


Severe Weather Reports -
Text of severe weather reports across central North Carolina





The Union Ridge Tornado

Around 454 pm on March 4, 2008 a weak tornado with winds of 70 to 75 mph touched down in northern Alamance County just northeast of the Union Ridge community. The tornado was rated an EF0 on the Enhanced Fujita Scale rating scale based on the observed damage and wind rating. The tornado initially touched down about a half mile south of Willie Pace Road. On the north side of Willie Pace Road, the tornado blew the roof off of a tobacco barn, lifted a carport, destroyed one shed and caused roof and porch damage to a home. The front porch of the home was shifted about 6 inches and one eave was broken off the house and tossed about 50 feet. A woman living next door took shelter when the Tornado Warning was issued and reported hearing a “roaring sound” as the tornado passed just west of her home.

Further north the tornado destroyed a barn on Vinson Road and damaged a tractor and irrigation system. Numerous trees were also blown down in the area and the converging pattern of the downed trees was indicative of a tornado. Just to the northeast of this home on Blaney Road the tornado blew a large oak tree into a brick home resulting in substantial roof damage. A garage in the back yard was also destroyed. The walls from the garage were blown about 50 feet from and the entire garage was moved about 20 feet before it collapsed.

The last home to be damaged was on Baynes Road. A single wide mobile home on Baynes Road lost its roof from the high wind. The roof was tossed about 70 feet before becoming wrapped around a tree.

Tornado: EF-0
Peak Wind: 75 mph
Path Length: 2 miles
Time/Date: 454 pm Tuesday March 4, 2008
Injuries: None
Fatalities: None

Special thanks to the Alamance County Emergency Management and the North Central Alamance Fire Department for assisting with the tornado survey.

Tornado track map - click to enlarge



The Enfield Tornado and Straight Line Wind Damage

At approximately 850 PM on March 4, 2008 a weak tornado with 65 to 85 mph winds touched down in southern Halifax County, approximately 4 miles to the east-southeast of Enfield, NC. This tornado was rated an EF-0 on the Enhanced Fujita rating scale based on the observed damage and wind rating. The tornado produced tree damage and took shingles off a home near the intersection of Thirteen Bridges Road and Douglas Hill Farm Road. The tornado downed and damaged numerous trees, as it tracked to the northeast into a swampy area for approximately one mile before lifting back up.

Severe straight line winds caused extensive damage to property at the intersection of NC Highway 125 and Piney Woods Road, approximately 6 miles to the east-northeast of Enfield, NC. Three sheds were destroyed, a cotton trailer was overturned, a grain bin was damaged, and shingles were blown off a roof by the straight line winds, which were estimated at 70 to 80 mph. Estimated time of the damage was between 1215 AM to 1230 AM.

Severe straight line winds estimated at 70 to 80 mph produced damage to a tower atop the Eastern Petroleum building at 347 Ringwood Road in Enfield, NC. A 140 foot metal tower atop the building was snapped in half and fell into the roof of the building. The time of damage was estimated between midnight and 1230 AM on March 5, 2008.

Severe straight line winds also caused irrigation towers to overturn at the Caledonia Prison Farm, at 2787 Caledonia Drive near Tillery, NC. A barn was damage at the farm as well. Estimated time of the damage was between midnight and 1230 AM. Winds were estimated at 60 to 70 mph.

Tornado: EF-0
Peak Wind: 85 mph
Path Length: 1 mile
Time/Date: 850 PM Tuesday March 4, 2008
Injuries: None
Fatalities: None

Tornado track map - click to enlarge



4 Panel Radar Reflectivity Loop -

The 4 panel image below shows the radar reflectivity imagery at 0148 UTC which was just a few minutes before the tornado touched down. The 4 panel imagery includes the reflectivity data at 0.5 degrees (upper left), 0.9 degrees (upper right), 1.3 degrees (lower left), and 1.8 degrees (lower right). The "hook" signature can be seen in the lowest two reflectivity elevation angles (top row).

A Java Loop of radar reflectivity imagery from 0130 UTC to 0202 UTC shows the evolution of the event

4 Panel Radar Reflectivity Loop- click to enlarge



4 Panel Radar Storm Relative Velocity Loop -

The 4 panel image below shows the radar Storm Relative Velocity (SRM) imagery at 0148 UTC which was just a few minutes before the tornado touched down. The 4 panel imagery includes the SRM data at 0.5 degrees (upper left), 0.9 degrees (upper right), 1.3 degrees (lower left), and 1.8 degrees (lower right). The rotational couplet can clearly be seen in the all of the elevation angles with the most intense circulation shown in the 1.3 degrees elevation angle (lower left).

A Java Loop of radar storm relative velocity imagery from 0130 UTC to 0202 UTC shows the evolution of the event

4 Panel Radar Storm Relative Velocity Loop - click to enlarge



Satellite

A Java Loop of visible satellite imagery from 0015 UTC on March 4 through 1115 UTC on March 5, 2008 is available here. Note - this loop includes 30 frames.

The water vapor satellite image below is from 2115 UTC (415 PM EST) on March 4. The upper low across western Tennessee is clearly visible. A large area of showers and thunderstorms is visible across much of the Carolinas. Another area of developing convection is visible across northeast Georgia, eastern Tennessee, and eastern Kentucky .

Water vapor satellite imagery from 2115 UTC on March 4, 2008



Regional Radar Loop

A Java Loop of regional reflectivity imagery from 1458Z on March 4 through 0758 UTC on March 5, 2008 is available here. Note - this loop includes 76 frames.

The regional reflectivity image below is from 0318 UTC on March 5, 2008. At this time there were 9 severe thunderstorm warnings in effect across portions of 15 counties in central North Carolina. The convection across central North Carolina was in the form of multiple line segments with bowing signatures.


regional reflectivity image



KRAX Radar Loops

Overview of the entire event with images from every 15 minutes between 1902 UTC (202 PM EST) March 4, 2008 through 0556 UTC (1256 AM EST) March 5, 2008.
Java Loop of KRAX reflectivity imagery every 15 minutes from 1902 UTC March 4, 2008 through 0556 UTC March 5, 2008.
Note - this loop includes 49 frames

Overview of the entire event with images from every volume scan between 1902 UTC (202 PM EST) March 4, 2008 through 0556 UTC (1256 AM EST) March 5, 2008.
Java Loop of KRAX reflectivity imagery from 1902 UTC March 4, 2008 through 0556 UTC March 5, 2008.
Note - this loop includes 142 frames

The KRAX reflectivity image below is from 0243 UTC or 943 PM EST on Tuesday, March 4, 2008.





Warning Strategies

Forecasters used surface and meso-analysis throughout the warning process. The SPC meso-analysis page was invaluable and it was used frequently to find the locations that had the greatest tornado and severe thunderstorms threat.

SPC mesocale discussion graphic Forecasters used sectorized warning strategies during the event. The CWA was divided into three sectors for most of the event with regions and orientation of the sectors changing as the event evolved.

This event was one of the first events in the new storm-based warning era. There were over 35 warnings issued during the event with over 70 percent of the warnings covering multiple counties. An overview of the entire event with radar imagery and warning polygons from every volume scan between 1902 UTC (202 PM EST) March 4, 2008 through 0556 UTC (1256 AM EST) March 5, 2008 can be viewed in this loop.

The event initially began with scattered thunderstorms during the afternoon in an environment supportive of sustained supercells. As the event evolved, the wind profile became more favorable for line segments and two squall lines swept through North Carolina with significant severe weather during the early and late evening hours.





Mesoscale Data

Analyzed mean sea level pressure (black) and surface wind barbs from SPC at 21 UTC on Tuesday, March 4, 2008
A surface low can be seen across eastern Tennessee with an associated cold front extending southward across far western North Carolina and central Georgia. A south to southeast wind at 10 to 15 knots is analyzed over central North Carolina. The backing wind from the southeast provided enhanced shear as noted in the 21 UTC 0-1 km Storm Relative Helicity (SRH) data. SRH is a measure of the potential for cyclonic updraft rotation in right-moving supercells.

SPC Analysis at 21 UTC on Tuesday, March 4, 2008.



500 MB heights, temperatures (red), dew points (green), and wind barbs (black) from SPC at 21 UTC on Tuesday, March 4, 2008
A negatively tilted, 5400 meter 500 MB closed low was located over far western Kentucky and Tennessee. A 95 knot jet is analyzed across northern Georgia and northeastward across far western South Carolina and extreme southwestern North Carolina. The temperatures at 500 MB were relatively mild in the -12 to -15 degree C range.

SPC Analysis at 21 UTC on Tuesday, March 4, 2008.



850 MB heights, temperatures (red/blue), dew points (green), and wind barbs (black) from SPC at 21 UTC on Tuesday, March 4, 2008
A broader but negatively tilted trough of low pressure can be seen in the 850 mb pattern across the Ohio and Tennessee valleys. An intense southwesterly flow at around 50 to 60 knots is present across Georgia and South Carolina. The 850 mb jet with wind speeds of 65 mph extends from northeast Georgia, across western South Carolina, and into western portions of the North Carolina Piedmont. Slightly warmer air with 850 MB temperatures in the 9 to 12 degree range was analyzed across the central North Carolina and upstream over South Carolina.

SPC Analysis at 21 UTC on Tuesday, March 4, 2008.



Analyzed low level lapse rates in the 0-3 km layer (blue, green, orange, and red) from SPC at 21 UTC on Tuesday, March 4, 2008
A lapse rate is the rate of temperature change with height and the image below is for the layer from the surface to around 9,000 feet. Note the surface based, low level lapse rates shown below range in the 5.5 to 6.5 deg C/km across include much of central North Carolina. Values less than 6 degrees C/km represent "stable" conditions, while values near 9 degrees C/km are considered "absolutely unstable." In between these two values, lapse rates are considered "conditionally unstable" meaning that if enough moisture is present, lifted air parcels could have a negative LI (lifted index) or positive CAPE.

SPC Analysis at 21 UTC on Tuesday, March 4, 2008.



Analyzed mid level lapse rates in the 700-500 MB layer (blue, green, orange, and red) from SPC at 21 UTC on Tuesday, March 4, 2008
A lapse rate is the rate of temperature change with height and the image below is for the layer from the surface to around 9,000 feet. Note the surface based, low level lapse rates shown below range in the 5.5 to 6.5 deg C/km across include much of central North Carolina. Values less than 6 degrees C/km represent "stable" conditions, while values near 9 degrees C/km are considered "absolutely unstable." In between these two values, lapse rates are considered "conditionally unstable" meaning that if enough moisture is present, lifted air parcels could have a negative LI (lifted index) or positive CAPE.

SPC Analysis at 21 UTC on Tuesday, March 4, 2008.



Analyzed mixed layer convective available potential energy (MLCAPE) (red) and mixed layer based convective inhibition (MLCIN) (blue lines - shaded) from SPC at 21 UTC on Tuesday, March 4, 2008
MLCAPE values were less than 500 J/kg across central Georgia with the greatest instability across the southern Coastal Plain and Sandhills where MLCAPE values were around or a little greater than 250 J/kg.

SPC Analysis at 21 UTC on Tuesday, March 4, 2008.



Analyzed most unstable convective available potential energy (MUCAPE) (red) and lifted parcel level (dashed black lines and shaded in yellow and green) from SPC at 21 UTC on Tuesday, March 4, 2008
MUCAPE values were small, generally around 500 J/kg are across central North Carolina with the greatest instability across the southern Piedmont, Sandhills, and southern Coastal Plain. The instability in this area is largely surface based with the instability across the northeast Piedmont and the northern Coastal Plain originating just above the surface.

SPC Analysis at 21 UTC on Tuesday, March 4, 2008.



NWS Composite Reflectivity Imagery from 2121 UTC on Tuesday, March 4, 2008 (421 PMM EST).
The composite reflectivity imagery is from the approximate time in which the analysis imagery above is valid.

Composite Reflectivity Imagery from 2121 UTC on Tuesday, March 4, 2008.



Archived Text Data from the Severe Weather Event

Select the desired product along with the date and click "Get Archive Data."
Date and time should be selected based on issuance time in GMT (Greenwich Mean Time which equals EDT time + 4 hours).


Product ID information for the most frequently used products...

RDUAFDRAH - Area Forecast Discussion
RDUZFPRAH - Zone Forecast Products
RDUAFMRAH - Area Forecast Matrices
RDUPFMRAH - Point Forecast Matrices
RDUHWORAH - Hazardous Weather Outlook
RDUNOWRAH - Short Term Forecast
RDUSPSRAH - Special Weather Statement
RDULSRRAH - Local Storm Reports (reports of severe weather)
RDUSVRRAH - Severe Thunderstorm Warning
RDUSVSRAH - Severe Weather Statement
RDUTORRAH - Tornado Warning


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Selected Photographs of the Severe Weather Event

Photos courtesy of Jeff Orrock, Jason Beaman, and Brandon Dunstan.
(click on the image to enlarge.)



Three sheds destroyed and trees damage from straight line winds on NC Highway 125 - Click to enlarge           Damage to a barn at the Caledonia Prison Farm from straight line wind damage - Click to enlarge           Irrigation towers overturned at the Caledonia Prison Farm from straight line wind damage - Click to enlarge

Damage to trees by an EF-0 Tornado on Thirteen Bridges Road and Douglas Hill Farm Road - Click to enlarge           Trees damaged by the EF-0 tornado Luke Road - Click to enlarge           Several large trees downed - Click to enlarge

Barn destroyed on Vinson Road - Click to enlarge           Garage destroyed on Blaney Road - Click to enlarge           Roof, porch and eave damage on Willie Pace Road - Click to enlarge

Large area of trees felled - Click to enlarge           Barn destroyed on Vinson Road - Click to enlarge                 Downed trees and debris - Click to enlarge


Acknowledgements

Many of the images and graphics used in this review were provided by parties outside of WFO RAH. The surface analysis graphic was obtained from the Hydrometeorological Prediction Center. The upper air analysis images were obtained from the University of Wyoming. GOES satellite data was obtained from National Environmental Satellite, Data, and Information Service. SPC meso-analysis graphics provided by the Storm Prediction Center.


Case study team -
Jeff Orrock
Jason Beaman
Brandon Dunstan
Barrett Smith
Michael Strickler
Gail Hartfield
Phil Badgett
Jonathan Blaes

For questions regarding the web site, please contact Jonathan Blaes.


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