Dual-polarized radar data from May 19, 2013 that identified debris in the air (inside white circle) confirming a tornado was on the ground.

May 19, 2013

The NWRT PAR, a retired Navy surveillance radar adapted for weather, scanned a storm from its first radar echoes through its production of a tornado.  When this storm moved out of range, the PAR was directed to scan the tornado that formed in Norman, Okla. through the time the tornado moved into Shawnee, Okla., killing two people.

May 20, 2013

The NWRT PAR scanned the Newcastle-Moore tornadic storm for almost an hour.  This storm produced an EF5 tornado that killed 24 people and injured more than 300.

Earlier on May 19, 2013 the NWRT PAR scanned this storm from the time it formed, through the formation of a tornado until it died. This radar can complete a full scan of the weather in less than one minute.

WSR-88D scan from May 19, 2013. It takes 4-5 minutes for this radar to complete one full scan of the weather.

The NWRT Phased Array Radar scanned the tornadic storm that formed later, hitting Shawnee, OK.

WSR-88D scan of the May 20, 2013 storms.

May 20, 2013 Terminal Doppler Weather Radar scanned the Newcastle-Moore tornado from 1930-2059 UTC.

The NWRT Phased Array Radar scanned the tornadic storm over Moore for almost an hour from 2003-2059 UTC.

NSSL’s rotation tracks product uses radar data to detect circulations. Bright red, yellow and white identify areas of rotation near Edmond and Shawnee, Okla. on May 19, 2013.

May 19

Supercells formed during the afternoon on Sunday, May 19 across central Oklahoma.  The storm that tracked through Shawnee, Okla. proved deadly.  NSSL researchers were operating the experimental Multifunction Phased Array Radar (MPAR), the research dual-pol Doppler radar, and the mobile NOAA X-POL dual-pol radar.  NSSL researchers with the Mesoscale Predictability EXperiment launched weather balloons to make measurements of the pre-storm and near-storm environment.  Researchers and students with NSSL’s Severe Hazards Analysis and Verification Experiment made follow-up phone calls regarding the impacts of the severe weather in the area.  All collected valuable datasets.

NSSL researchers also helped conduct damage surveys.

The rotation tracks product shows areas of strong rotation over Newcastle and Moore, Okla. on May 20, 2013

May 20

Oklahoma endured a second day of severe weather as storms formed southwest of Oklahoma City, Okla.  Several of the storms produced tornadoes.  The most devastating storm produced a tornado near Newcastle, Okla.  The tornado was on the ground for an estimated 40 minutes.  Damage surveys are currently being conducted by the National Weather Service and NSSL staff.

The most current information can be found at the NOAA National Weather Service Forecast Office Norman website.

A team of eight severe storms meteorologists re-analyzed the event using all relevant U.S. Weather Bureau data on the Tri-State Tornado.  The results, published in the Electronic Journal of Severe Storms Meteorology, revealed previous analyses of the surface weather conditions were inaccurate and led to misconceptions about where the tornado formed in reference to the existing weather system.  The authors include retired NSSL Director Bob Maddox, retired NSSL/CIMMS researchers Chuck Doswell, Don Burgess and Charlie Crisp, retired Storm Prediction Center (SPC) meteorologist Bob Johns and current SPC meteorologist John Hart, and Steve Piltz from the National Weather Service Forecast Office in Tulsa, Okla.

The researchers concluded there was no singular feature in the meteorological setting that would explain the extreme character of the Tri-State tornado.  The storms of 18 March were associated with a rapidly moving cyclone that was not unusually intense.  The new analyses show a long-lived supercell that developed very near the center of the cyclone produced the tornado, possibly where a warm front and a distinct dryline intersected.  The south-to-north temperature gradient was very pronounced due to cooling produced by early morning storms and precipitation.  The tornadic supercell tracked at an average speed of 59mph moving farther away from the cyclone center with time.  And, the storm remained very close to the surface warm front.

Researchers did find as the supercell and dryline moved rapidly eastward, the northward advance of the warm front kept the tornadic supercell within a very favorable storm environment for several hours.  It appears this consistent time and space connection of the supercell, warm front, and dryline was extremely unusual.

With reanalysis beginning 70 years after the tornado, it was impossible to confirm the complete continuity of the damage path along the reported path.  Even with extensive field work discovering 2,395 individual damage points, there were 32 gaps of at least one mile in length, but only 7 gaps longer than 2.5 miles in length.  All of the longer gaps were in the Missouri portion of the path; within the sparsely-populated Ozark mountain area.  Assuming that gaps shorter than 2.5 miles might still represent a continuous tornado, the continuous path was at least 174 miles long.  Additional, previously unreported tornadoes were also found before the beginning and after the end of the Tri-State Tornado.  The research also allowed for conclusion that the storm was a supercell; classic in its stages and high-precipitation in the later stages.  The supercell also produced accompanying hail up to baseball size and non-tornadic damaging winds.

http://www.ejssm.org/ojs/index.php/ejssm/issue/archive

NSSL researchers will team with Colorado State University and Purdue to launch weather balloons carrying instrument packages called radiosondes.  They hope to find out how thunderstorms interact with the atmosphere that surrounds and supports them, and how this affects formation of new thunderstorms.  They also hope to ingest the balloon data into computer models to see how the extra data collected during the afternoon can help predict the location and severity of evening storms better.

Researchers with the National Center for Atmospheric Research will use a Gulfstream V aircraft to sample pre-storm jet stream winds, upper–level temperatures and other features across Colorado and nearby states.  The aircraft will cruise at 40,000 feet for up to six hours so researchers can thoroughly canvass the region. The data they collect will also be ingested into computer models to show how well the extra data can help predict local and regional weather conditions into the next day.

Additional participants are from the University at Albany, State University of New York and the University of Wisconsin-Milwaukee.

http://www.eol.ucar.edu/projects/mpex/

Map of where visiting forecasters/researchers to the @NOAAHWT warning program have come from since 2007.

Researchers will target storms within 120nm of NWRT/PAR to examine the strengths and limitations of storm cluster identification and tracking algorithms, and their usefulness for enhanced rapid sampling of severe storms. They will also use the data to understand how a thunderstorm evolves into a supercell and as it begins to produce a downburst or possible tornado. Researchers will evaluate how useful this information could be for enhanced warning lead-time during severe weather warning operations.

In addition, NSSL will work with 12 National Weather Service forecasters during six weeks in May, June, and July. They will assess how the use of rapid-scan NWRT/PAR helps with situational awareness and warning decisions during simulated severe weather events.

New this year, NSSL’s dual-pol research radar will be used as a proxy for future dual-pol Multi-function Phased Array Radar (MPAR) observations. Researchers will observe rapid changes in dual-pol signatures that occur in cyclic supercells and downbursts.

http://www.nssl.noaa.gov/projects/parise/

Tornado in Wyoming

NSSL tornado climatology expert, Harold Brooks has written a blog post about the remarkable absence of tornado activity during the 12-month period from May 2012 to April 2013. The estimated number of EF-1 or stronger tornadoes for this period is 197, a record low.

Brooks compared the current 12-month period with previous (E)F1 or stronger tornado counts back through 1954. He found the previous low for (E)F1 and stronger tornadoes in a 12 consecutive calendar month period was 247, from June 1991-May 1992.

This apparent record was set less than two years after the record for most EF1+ tornadoes in a 12-month period was set, with 1050 from June 2010-May 2011.

Read the full post here:  U.S. Severe Weather Blog.

Slakey to speak at NWC

The National Weather Center will host renowned physicist Dr. Francis Slakey, Associate Director of Public Affairs at the American Physical Society, at 4 p.m. April 23 in Room 1313. Slakey ‘s topic is also the title of his book, “To the Last Breath – A Memoir of Going to Extremes.” The book is on Amazon’s “2012 Best Books of the Year” list.

In 2009, Slakey became the first person to summit the highest mountain on every continent and surf every ocean (including the Arctic) on Earth. He plans to share how he used the laws of physics to his advantage in his climbing expeditions and the knowledge of the geophysics of waves to surf. He will also talk about how his adventures led him on a path to address global challenges such as climate change. For years Slakey has inspired students and researchers across the nation to address societal challenges through science and motivated them to turn their ideas into legislation.

This seminar is part of a new “Science Policy and Its Significance to Weather, Water and Climate” class offered by the University of Oklahoma and taught by NSSL /CIMMS research meteorologist Subhashree Mishra. Speakers include:

- Harold Brooks, NSSL Research Meteorologist

- Mike Douglas, NSSL Research Meteorologist

- Pam Heinselman, NSSL Research Meteorologist

- Kevin Kelleher, NSSL deputy director

- Edwin Kessler, retired NSSL director

- Pete Lamb, CIMMS director

More information is available here: http://som.ou.edu/seminars/