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The Continuing Evolution Of Severe Weather Forecasting In The United States: Observations And Forecasts, Watches and Warnings. John T. Snow Dean, College of Geosciences and Professor of Meteorology The University of Oklahoma Norman, Oklahoma U.S.A. Presented: 17 November 2004
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John T. SnowDean, College of Geosciences and Professor of MeteorologyThe University of OklahomaNorman, Oklahoma U.S.A.
Presented: 17 November 2004
Revised: 24 November 2003
This talk was prepared using materials from the websites maintained by the following organizations of the National Oceanic and Atmospheric Administration:
The use of these materials is gratefully acknowledged. These folk are the experts on severe weather monitoring and prediction, and on the communication of watches and warnings to the public. Any misinterpretation of their materials is my personal responsibility.
Moore, Oklahoma, 3 May 1999
Lakeview, Texas, 19 April 1977
Severe thunderstorms with large hail and damaging winds are expected in your area between 2 pm and 9 pm today
SEVERE THUNDERSTORM WATCH NUMBER 229
NWS STORM PREDICTION CENTER NORMAN OK
1210 AM CDT SUN MAY 4 2003
THE NWS STORM PREDICTION CENTER HAS ISSUED A SEVERE THUNDERSTORM WATCH FOR
EFFECTIVE THIS SUNDAY MORNING FROM 1210 AM UNTIL 600 AM CDT.
HAIL TO 2 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS TO 55 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.
THE SEVERE THUNDERSTORM WATCH AREA IS ALONG AND 105 STATUTE MILES EAST AND WEST OF A LINE FROM 65 MILES NORTH OF OMAHA NEBRASKA TO 40 MILES EAST SOUTHEAST OF EMPORIA KANSAS.
REMEMBER...A SEVERE THUNDERSTORM WATCH MEANS CONDITIONS ARE FAVORABLE FOR SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH AREA. PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR THREATENING WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS AND POSSIBLE WARNINGS. SEVERE THUNDERSTORMS CAN AND OCCASIONALLY DO PRODUCE TORNADOES.
The SPC is the element of the National Weather Service/National Centers for Environmental Prediction charged with providing timely and accurate forecasts and watches for severe weather over the contiguous United States, including thunderstorms/tornadoes, heavy rain, heavy snow, and fire weather events.
The SPC produces a suite of products to relay forecasts of organized severe weather as much as three days ahead of time, and continually refines the forecast up until the event has concluded. All products issued by the Storm Prediction Center are available on the World Wide Web. Its products are commonly used by National Weather Service offices, emergency managers, TV and radio meteorologists, private weather forecasting companies, the aviation industry, storm spotters, agriculture, educational institutions and many other groups.
WWUS8 KMKC 030013
MKC WW-A 030013
STATUS REPORT ON WW NUMBER 361 AND 362
IN WW 361 THE THREAT OF SEVERE WEATHER CONTINUES TO THE EAST OF A
LINE FROM 50 SW WINK TO 30 NE CNM TO 40 E ROW TO 65 W CVS.
IN WW 362...CONTINUE WW.
TORNADO WATCH WILL LIKELY BE REQUIRED FARTHER EAST INTO THE ERN TX
PANHANDLE AND WRN TX AND OK BY 02Z.
NUMEROUS SUPERCELLS CONTINUE DEVELOPING OVER THE SRN HIGH PLAINS
EAST OF THE DRYLINE IN AN AXIS THAT EXTENDS FROM NEAR WINK TX TO
NEAR CLAYTON NM. NUMEROUS REPORTS OF BASEBALL HAIL HAVE BEEN
RECEIVED. WV IMAGERY SHOWS SHORTWAVE LIFTING NEWD THROUGH UT AND
WRN CO. DEEP LAYER SHEAR PROFILES HAVE INCREASED TO 60 KT AS MID
LEVEL SPEED MAX ON THE SRN PERIPHERY OF SHORTWAVE LIFTS NEWD TOWARD
THE SRN PLAINS. INDIVIDUAL CELLS WERE MOVING NEWD AT AROUND 35 KT.
INCREASING LOW LEVEL INFLOW ASSOCIATED WITH DEVELOPING LOW LEVEL
JET WILL SUPPORT CONTINUED EWD DEVELOPMENT INTO THE EVENING.
INCREASING STORM RELATIVE FLOW AND SHEAR PROFILES SUGGEST THREAT
FOR SUPERCELLS WITH LARGE HAIL...DAMAGING WIND AND ISOLATED
TORNADOES WILL CONTINUE AS ACTIVITY DEVELOPS EWD INTO INSTABILITY
AXIS ACROSS THE TX AND OK PANHANDLES WHERE SBCAPES ARE AS HIGH AS
WWUS8 KMKC 032333
MKC WW-A 032333
STATUS REPORT ON WW NUMBER 195
CLUSTER OF INTENSE THUNDERSTORMS...INCLUDING STRONG TORNADIC
SUPERCELLS WEST/SOUTHWEST OF OKLAHOMA CITY AREA IS ONGOING. STRONG
AND INTENSIFYING DIVERGENT UPPER FLOW FIELD...ENHANCED BY MID/UPPER
JET DIGGING ACROSS THE SOUTHERN ROCKIES...WILL CONTINUE TO SUPPORT
EVOLUTION INTO LARGER SEVERE CONVECTIVE SYSTEM...AHEAD OF DRY LINE
...THROUGH THE EVENING HOURS. GIVEN ONGOING AND EXPECTED TRENDS...
WW MAY BE REPLACED WITH NEW WW INCLUDING NORTHERN OKLAHOMA AND
PARTS OF NORTH CENTRAL TEXAS WITHIN THE NEXT HOUR OR SO.
Spotters report a severe thunderstorm with large hail and damaging winds near your vicinity, moving to the NE at 50 km/hour. Take shelter immediately, and remain in shelter for next 30 minutes.
BULLETIN - EAS ACTIVATION REQUESTED TORNADO WARNING NATIONAL WEATHER SERVICE CLEVELAND OH 644 PM EST WED NOV 12 2003
THE NATIONAL WEATHER SERVICE IN CLEVELAND HAS ISSUED A
* TORNADO WARNING FOR... WAYNE COUNTY IN NORTHEAST OHIO...
* UNTIL 730 PM EST
* AT 644 PM EST NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A SEVERE THUNDERSTORM CAPABLE OF PRODUCING A TORNADO 10 MILES WEST OF WOOSTER...MOVING EAST AT 50 MPH.
* SOME LOCATIONS NEAR THE PATH OF THIS STORM INCLUDE... DALTON DOYLESTOWN ORRVILLE WOOSTER
LAT...LON 4092 8199 4095 8177 4098 8165 4075 8165 4072 8212 4089 8212
BULLETIN - EAS ACTIVATION REQUESTED TORNADO WARNING NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX 905 AM CST MON NOV 17 2003
THE NATIONAL WEATHER SERVICE IN LEAGUE CITY HAS ISSUED A
* TORNADO WARNING FOR... WHARTON COUNTY IN SOUTHEAST TEXAS MATAGORDA COUNTY IN SOUTHEAST TEXAS
* UNTIL 945 AM CST
* AT 900 AM CST...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A SEVERE THUNDERSTORM CAPABLE OF PRODUCING A TORNADO 8 MILES WEST OF MARKHAM...OR ABOUT 14 MILES WEST OF BAY CITY...MOVING NORTHEAST AT 20 MPH.
* LOCATIONS IN THE PATH OF THE SEVERE THUNDERSTORM INCLUDE... MARKHAM AND BOLING
THE SAFEST PLACE TO BE DURING A TORNADO IS IN THE INTERIOR HALLWAY OR ROOM SUCH AS A CLOSET ON THE LOWEST LEVEL OF A STURDY BUILDING. USE BLANKETS OR PILLOWS TO COVER YOUR BODY AND ALWAYS STAY AWAY FROM WINDOWS.
IF IN MOBILE HOMES OR VEHICLES...EVACUATE THEM AND GET INSIDE A SUBSTANTIAL SHELTER. IF NO SHELTER IS AVAILABLE...LIE FLAT IN THE NEAREST DITCH OR OTHER LOW SPOT AND COVER YOUR HEAD WITH YOUR HANDS.
PLEASE REPORT SEVERE WEATHER TO THE COUNTY SHERIFF...LOCAL POLICE... OR DEPARTMENT OF PUBLIC SAFETY. THEY WILL RELAY YOUR REPORT TO THE NATIONAL WEATHER SERVICE.
A TORNADO WATCH REMAINS IN EFFECT UNTIL 100 PM CST MONDAY AFTERNOON FOR SOUTHEAST TEXAS.
LAT...LON 2901 9631 2888 9617 2912 9586 2925 9602
2002 Storm Spotter Talk ScheduleCalendarTable
National Weather Service Weather Forecast Office
8.5 meter antenna; ~1o beam
500 kW transmitter
Volume scanning strategy
Reflectively and Doppler field
138 installations across US
Hook Echoes and Vortex Doppler “Couplets” reliably indicate the presence of mesocyclones in the troposphere
Image/Text/Data from the University of Illinois WW2010 Project.
Flood / Flash Flood
High Wind/High Profile Vehicle
Storms on NEXRAD Radar
Center for Analysis and Prediction of Storms
Courtesy National Severe Storms Laboratory
The specialized storm prediction mission requires meteorologists with a high level of expertise in convective storm forecasting, as well as excessive precipitation, winter weather, and conditions leading to high fire dangers.
In the U.S., almost all severe weather forecasters have at least a BS degree in atmospheric science from a college or university; most have done graduate-level studies and/or hold a Master of Science degree.
At the Storm Prediction Center and in NWS FO, all lead forecasters have at least 5 years of specialized experience, with veteran forecasters having over 20 years of severe storm forecasting experience.
Motivation: Almost all severe storms forecasters are passionate about violent weather, with an intense desire to learn about and become better at predicting it. For many, this dates back into childhood -- a first-hand encounter with violent storms, images on TV or in books and magazines, or even a deep attraction to storms which goes back too far to recall. Others start out in other fields or college majors, then became fascinated with severe weather. In any case, this desire leads to...
Education: Consistently good severe storms forecasters have a solid educational background in atmospheric science which allows them to understand "textbook" concepts of thunderstorm formation. They don't stop with their college education, either. They constantly re-educate themselves in the latest discoveries about severe thunderstorms and tornadoes -- reading scientific journal articles on cutting-edge research, perhaps doing some research themselves. The understanding of storms which results lets the forecaster think of "conceptual models" -- visualizations of what the storms will do and how.
Flexibility: Because the atmosphere doesn't read textbooks or science journals, the forecaster must adapt those "classroom" ideas to an endless variety of day-to-day situations which may look a lot different. He or she also should be able to recognize when and why a forecast is not working out, and make the right adjustments. These skills come from...
Experience: In meteorology, history never repeats itself exactly. But certain types of situations do recur, allowing the forecaster to set a mental benchmark for what to expect. From there, he or she can better decide what data will be most important to examine, and what data will not be as relevant to the situation. Experienced forecasters are able to learn how bad forecasts went wrong and how good forecasts worked each time, building a more complete mental warehouse of severe storm forecast knowledge as time passes. When the experience is continually blended with motivation, flexibility and more education, he or she will keep improving as a forecaster.
Courtesy Oklahoma City Area National Weather Service Forecast Office
Point: Media are essential partners in both educating the public and communicating near-real time information regarding the onset of severe weather
At Laughlin AFB in Del Rio, Texas, downburst winds on 24 May 2003 did significant damage to the radome of the KDFX WSR-88D.
It is estimated the wind which did this damage was in the range of 80-85 knots.
Dean, College of Geosciences
The University of Oklahoma
Sarkeys Energy Center, Suite 710
100 E. Boyd Street
Norman, Oklahoma 73019