When is april 16 2011

The track of several hail producing supercells that moved across central and eastern North Carolina is clearly visible. The color scale on the image indicates the maximum expected hail size during the period with the light blue area indicating hail estimated at around a half inch in diameter, the darker blue area indicating hail greater than an inch in diameter, and the lighter green area indicating hail potentially larger than an inch and a half.

In the RAH CWA, the hail swath product highlighted eastern Harnett and Johnston Counties as locations with potentially the largest hail and there were numerous reports of golf ball size hail 1. The hail swath product also highlighted small portions of Sampson County where 2 inch diameter hail was reported and Wake County where 1.

The image above and to the right is a zoomed in view of the hail swath product across central and eastern portions of the RAH CWA with the tracks of the tornadoes that occurred in central North Carolina shown in black click on it to enlarge. In general, the radar estimated hail swaths were located to the north and west of tornado track which is consistent with a conceptual model of a tornado producing supercell thunderstorm.

Ortega, Travis M. Smith, and Gregory J. Regional Radar Loop A regional radar loop of the southeastern United States shows the evolution of the 16 April tornado event. A fairly large area of showers moved through western portions of central North Carolina just prior to and around the time of daybreak. The widely scattered showers and a few thunderstorms that developed and moved across central and eastern North Carolina between and UTC generally weakened as they moved northeast.

During the same period, a narrow line of thunderstorms developed in western Carolinas and reached the I corridor in North Carolina by around UTC. The thunderstorms continued to intensify between and UTC and grew into a fairly continuous convective line. Note that the isolated thunderstorms ahead of the line in northeastern South Carolina and south-central North Carolina developed quickly and then rapidly weakened leaving little in the way of discrete convection ahead of the line. Between and UTC the line fractured and several discrete supercells emerged.

These discrete thunderstorms would be responsible for the majority of the tornadoes on 16 April. The regional reflectivity image to the right click to on this link to enlarge is from UTC on 16 April and shows several supercells moving across central and eastern North Carolina.

The 3 different images to the right correspond to the 3 different types of imagery available in the various loops below. Note the clear hook signature on the thunderstorms near Clinton and northwest of Goldsboro. Another supercell which produced the Fayetteville-Smithfield tornado would produce a second tornado near Micro about 10 minutes after this radar image was generated.

The supercell that had produced the Sanford-Raleigh tornado was located over northeastern Franklin and southern Warren Counties at the time of this radar image. This same supercell would produce the Roanoke Rapids tornado about 25 minutes after this radar image was produced. Note - this loop includes 37 frames. During this event, the SPC meso-analysis products were consulted frequently to monitor the evolving environment, and locate the region of the greatest tornado threat.

The images and discussion below highlight several of the SPC meso-analysis products that provide insight into the evolution of the severe weather event. It should be noted that the SPC meso-analysis products are based on a combination of observed fields and RUC forecasts which are used for the background field and upper-air data for the analysis. While these analysis products provide a great tool, it is important to note that the analysis can include errors, especially when evaluating fields in the storm scale.

Analyzed MSLP black surface temperatures red , dew points blue and shaded, and wind barbs from SPC at UTC 16 April The surface analysis showed a low pressure system over the northern Great Lakes with a strong cold front extending southward into the western Piedmont of the Carolinas. The cold front marked the leading edge of a cooler and much drier air mass with dew points falling into the 40s across the Foothills of North Carolina. A warm front extended from the cold front eastward along the Virginia-North Carolina border marking the leading edge of a more unstable air mass.

The axis of greatest theta-e extended northward along and just ahead of the intensifying convection as shown in the UTC regional radar image. Given sufficient instability, thunderstorms tend to become more organized and persistent as vertical shear increases. Supercells are commonly associated with vertical shear values of 35 to 40 kts in this depth and the analysis at UTC supports the potential of supercells. It is interesting to note that when the convection developed a few hours earlier at UTC , it was more linear despite being in a region of similar bulk shear.

The SRH is a measure of the potential for cyclonic updraft rotation in right-moving supercells. Some studies suggest that the km SRH is a better indicator of storm rotation, which is related to tornadoes, but not directly the potential for tornadoes themselves. The LCL height is the height at which a parcel becomes saturated when lifted dry adiabatically. The importance of the LCL height is thought to relate to sub-cloud evaporation and the potential for outflow dominance.

Low LCL heights imply less evaporational cooling from precipitation and less potential for a strong outflow that would likely inhibit low-level mesocyclone development.

Thunderstorms that produce significant tornadoes generally have a lower LCL height with LCL heights less than 1, meters typically favoring the development of significant tornadoes. Analyzed STP values across the eastern Piedmont, Coastal Plain, and Sandhills region ranged between 2 and 5 units with a max of more than 4 across the southern Coastal Plain and the eastern Sandhills.

A majority of significant tornadoes EF-2 or greater damage have been associated with STP values greater than 1, while most non-tornadic supercells have been associated with values less than 1 in a large sample of RUC analysis proximity soundings. Click on the image below to enlarge NWS composite radar reflectivity imagery from UTC 16 April The regional composite reflectivity imagery is from the approximate time in which the analysis imagery above is valid.

Product ID information for the most frequently used products The threat of severe weather on Saturday was well advertised for several days in advance. Staffing was planned out well in advance, and a preliminary discussion of likely operational roles the day prior to the event, helped with a rapid spin-up on Saturday morning.

Of these three, one staff member assisted with the forecast databases and radar interrogation while another staff member monitored hydrologic conditions - Two SKYWARN radio operators helped out with storm reports This event provided some interesting examples of the recent advances in meteorology while illustrating some new opportunities for additional research.

First, high resolution NWP provided excellent forecasts indicating the timing and location of the squall line, the absence of discrete cells ahead of the squall line, and then the evolution of the squall line into discrete cells. Forecasters made very good use of pattern recognition ahead of the event along with storm scale conceptual models and warning polygon strategies.

Future work can further examine the uniqueness of the event noting the importance of low level moisture and shear in the processes which allowed a squall line to fragment in to multiple discrete supercells and examine total lightning trends with the long track tornadoes. This event will also be included in a comprehensive climatology of modern day tornadoes in central North Carolina. The Blacksburg NWS office provided quick-response backup for the Raleigh office for around 6 or 7 minutes as Raleigh staff members took shelter in the stairwell tornado shelter.

Blacksburg provided excellent service. In situations with long lived supercells, a strategy of each radar operator following a particular supercell for the duration of its life cycle in central North Carolina once again proved to be effective. This strategy has also been employed successfully in previous tornadic events.

Relaying information to customers, particularly the media through the use of NWSChat was highly effective in this event. We were able to communicate reasons for issuing or continuing warnings and share preliminary damage reports before all of the details were resolved and an LSR was sent. We also received numerous reports from the media and emergency management.

Monitoring local television stations from both Greensboro and Raleigh during the event revealed that in numerous instances, our information sent via chat was being delivered in some form by the media on-air.

Numerous staff members were needed to conduct storm surveys or cover shifts for those conducting the surveys during the days following the event. Staffing was already stretched thin to support operations during the day of the severe weather and fatigue was a concern for the days following the event. This team worked well together to provide good post-event information out to our customers.

Recent advances in Numerical Weather Prediction NWP and in computational efficiency have resulted in an improvement in and the availability of high resolution model forecasts on the convective scale.

These products did a good job in this event noting that the linear convective structure would evolve into discrete cells and that there would be very few discrete cells developing ahead of the line. All of the fatalities in central North Carolina occurred in mobile homes or in a vehicle.

There were no fatalities in permanent homes or structures despite the significant damage produced by the storm. References Barnes, and C. Newton, Thunderstorms in the synoptic setting. Another rotational couplet on the east side of Jacksonville around pm April 16, which led to a EF-3 tornado which produced extensive damage in the Piney Green area and again near Riverdale in Craven County. Please Contact Us. Please try another search. Multiple locations were found.

Please select one of the following:. Location Help. News Headlines. Customize Your Weather. Privacy Policy. April 16, Major Tornado Outbreak Weather. Current Hazards. Local Regional National. Rivers and Lakes. Climate and Past Weather.

Above is perhaps one of the most well known videos from the event. That guy was pretty lucky. He got some footage of the aftermath of one of the tornadoes that was eventually rated EF3.

While April 16, may not top the charts for tornado outbreaks on a national scale, it was the worst tornado outbreak in North Carolina history in terms of total number of tornadoes 31 and the number of strong tornadoes with 16 rated as EF2 and EF3. It surpassed a the previous daily total record for the state, the 20 tornadoes which occurred on May 7, Note: The March Outbreak had more violent tornadoes, but only 14 total in North Carolina itself.

Casey Letkewicz, a PhD student studying atmospheric science at North Carolina State University and photographer of the opening picture, offers this first-hand account of her experience that day:. There were a few other grad students my officemates , and my adviser. Seeing that made me think that something big was going to happen.

Once we identified a storm that had a track towards Raleigh, we all kept a close eye on it. Get a free love reading with the most frank answers. Start to seize love opportunities in your life!

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