http://weather.gov The 2015 NWS Spring and Summer Weather Update Western North Carolina severe weather climatology Tony Sturey, WCM Greenville/Spartanburg, SC North Carolina Spring and Summer Outlooks Nick Petro, WCM Raleigh, NC Recent changes to the Storm Prediction Center Convective Outlooks Phil Hysell, WCM Blacksburg, VA
http://weather.gov Western North Carolina Severe Weather Climatology Tony Sturey
KNOW YOUR RISK Of the estimated 100,000 thunderstorms that occur each year in the United States, about 10 percent are classified as severe. This map depicts the average number of days with thunderstorms each year. Florida has more days with thunderstorms than any other state. FACT: All thunderstorms are dangerous due to lightning and strong winds.
KNOW YOUR RISK Lightning kills an average of 30 to 50 people each year in the U.S. and injures several hundred more. FACT: More than 80% of lightning fatality victims are male, typically between the ages of 15 and 40. FACT: If you are outdoors and can hear thunder, you are in danger of being struck by lightning.
KNOW YOUR RISK A tornado is a violently rotating column of air extending from a cumuliform cloud, such as a thunderstorm, to the ground. Joshua Jans FACT: Tornadoes can move in any direction and can travel at speeds up to 70 mph. Roger Edwards This map shows the average number of tornadoes per year in each state. 6
Topography of Forecast Area 6,684 FT 350 FT
GSP County Warning Area Facts Highest = 6,684 feet - Mt. Mitchell, NC Lowest = 270 feet - Chester County, SC Difference = 6,414 feet High 8 COUNTIES WITH TOTAL OF 55 PEAKS > 6,000 FT. Low
GSP County Warning Area Facts Annual Station Rainfall (Highest East of the Rockies) 133 inches - Lake Toxaway, NC 130 inches - Rosman, NC (More than 10 feet of rain in one year!) Transylvania County French Broad River Upper Whitewater Falls Looking Glass Rock
Average number of days during a 10-year period with a tornado within ~25 mi of any point. Based upon a 58-year climatology. <1 4-5 2-3
Average number of days per year with a damaging convective wind gust within ~25 mi of any point. Based upon a 25-year climatology. 1-2 3-4 5-6 7-8
Average number of May days per decade with a damaging convective wind gust within ~25 mi of any point. 8-10 4-6
Average number of July days per decade with a damaging convective wind gust within ~25 mi of any point. 10-14 2-6 18-22
Total Number of Days of Damaging Thunderstorm Winds Within a 15 Mile Radius
Total Number of Days of Damaging Thunderstorm Winds Within a 15 Mile Radius
Average days per year with large hail within ~25 mi of any point. Based upon a 25-year climatology. 4-5 2-3
Myth Number 1 No Tornadoes in the Cold Season
Burke County January 2012
Myth Number 2 No Tornadoes in the Mountains
Great Smoky National Park, 2013 Late Spring, Early Summer
Myth Number 3 No Tornadoes in Urban Areas Overnight
Charlotte NC, March 3, 2012 Wee Hours
Myth Number 4 No Tornadoes: Except When All Personnel are in Their Place of Establishment
Vale Area, October 2010
The End NOAA NWS Greenville-Spartanburg, SC Tony Sturey Warning and Coordination Meteorologist Anthony.sturey@noaa.gov
http://weather.gov North Carolina Spring and Summer Outlooks Nick Petro
http://weather.gov Climate.gov Outlook for the Nation
http://weather.gov CPC Temp and Precip Outlooks for April, May, and June Equal changes for above, near, or below normal temperatures across North Carolina. Odds favor the chance for above normal precip across North Carolina.
http://weather.gov Spring flood and drought outlooks Minor river flooding is possible from the Gulf Coast through the Ohio River Valley and into the Southeast from Texas eastward and up the coast to Virginia. Though, heavy rainfall at any time can lead to flooding, even in areas where overall risk is considered low.
http://weather.gov Past 90 day rain and latest drought monitor
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http://weather.gov What about severe thunderstorms and tornadoes?
http://weather.gov Thunderstorm Ingredients All thunderstorms require 3 ingredients for their formation: 1. Moisture the foundation for clouds and precip. 2. Lifting mechanism initiates the upward movement. 3. Instability keeps the upward movement going. Page 36
http://weather.gov A 4 th Ingredient for strong to severe storms: Wind Shear Weak shear vs. Strong shear The longer the updraft lives, the stronger the storm can become, and the better the chance for severe t-storm impacts. Page 37
http://weather.gov April 16, 2011
http://weather.gov Average weather pattern from Feb 1 thru March 15, 2015 Cold air Dry stable air coming off the Rockies spread eastward Gulf moisture shunted eastward
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http://weather.gov Will the pattern change?
http://weather.gov Looking farther down the road using climatology
http://weather.gov Recent changes to the Storm Prediction Center Convective Outlooks Phil Hysell
SPC Outlook Changes October 2014
SPC Outlooks Before 10/2014 3 Tiers - SLGT, MDT and HIGH See Text Used for Marginal Situations
Day 1-3 Outlook Changes Increase risk categories to 5 levels for Day 1, Day 2, & Day 3 Outlooks Category 1 = MRGL Category 2 = SLGT Category 3 = ENH Category 4 = MDT Category 5 = HIGH SPC Severe Weather Outlook Probability-to-Categorical Description Tables (2014) Day1 0% 2% 5% 10% 10% sig 15% 15% sig 30% 30% sig 45% 45% sig 60% 60% sig Tor TSTMS MARGINAL SLGT ENHANCED MDT HIGH Wind TSTMS MARGINAL SLGT ENHANCED MDT HIGH Hail TSTMS MARGINAL SLGT ENHANCED MDT Day2 0% 5% 15% 15% sig 30% 30% sig 45% 45% sig 60% 60% sig All Svr TSTMS MARGINAL SLGT ENHANCED MDT HIGH Day3 0% 5% 15% 15% sig 30% 30% sig 45% 45% sig All Svr Day4-8 TSTMS 15% MARGINAL 30% SLGT ENHANCED MDT All Svr SLGT ENHANCED sig = Significant Severe Tstms = Hail 2+ and/or Wind 65KT/75 MPH Tor= EF2 or Stronger
Day 1-3 Outlook Changes Increase risk categories to 5 levels for Day 1, Day 2, & Day 3 Outlooks Replace See Text with Marginal for lowest risk probabilities (Day 1 - Day 3) SPC Severe Weather Outlook Probability-to-Categorical Description Tables (2014) Day1 0% 2% 5% 10% 10% sig 15% 15% sig 30% 30% sig 45% 45% sig 60% 60% sig Tor TSTMS MARGINAL SLGT ENHANCED MDT HIGH Wind TSTMS MARGINAL SLGT ENHANCED MDT HIGH Hail TSTMS MARGINAL SLGT ENHANCED MDT Day2 0% 5% 15% 15% sig 30% 30% sig 45% 45% sig 60% 60% sig All Svr TSTMS MARGINAL SLGT ENHANCED MDT HIGH Day3 0% 5% 15% 15% sig 30% 30% sig 45% 45% sig All Svr Day4-8 TSTMS 15% MARGINAL 30% SLGT ENHANCED MDT All Svr SLGT ENHANCED sig = Significant Severe Tstms = Hail 2+ and/or Wind 65KT/75 MPH Tor = EF2 or Stronger
Day 1-3 Outlook Changes Increase risk categories to 5 levels for Day 1, Day 2, & Day 3 Outlooks Replace See Text with Marginal for lowest risk probabilities (Day 1 - Day 3) Insert Enhanced between high-end SLGT & low-end MDT probabilities SPC Severe Weather Outlook Probability-to-Categorical Description Tables (2014) Day1 0% 2% 5% 10% 10% sig 15% 15% sig 30% 30% sig 45% 45% sig 60% 60% sig Tor TSTMS MARGINAL SLGT ENHANCED MDT HIGH Wind TSTMS MARGINAL SLGT ENHANCED MDT HIGH Hail TSTMS MARGINAL SLGT ENHANCED MDT Day2 0% 5% 15% 15% sig 30% 30% sig 45% 45% sig 60% 60% sig All Svr TSTMS MARGINAL SLGT ENHANCED MDT HIGH Day3 0% 5% 15% 15% sig 30% 30% sig 45% 45% sig All Svr Day4-8 TSTMS 15% MARGINAL 30% SLGT ENHANCED MDT All Svr SLGT ENHANCED sig = Significant Severe Tstms = Hail 2+ and/or Wind 65KT/75 MPH Tor = EF2 or stronger
Example of Change
Day 4-8 Outlook Changes Increase risk categories to 5 levels for Day 1, Day 2, & Day 3 Outlooks Replace See Text with Marginal for lowest risk probabilities (Day 1 - Day 3) Insert Enhanced between high-end Slight & low-end Moderate probabilities Add a 15 percent (Slight Risk) to Day 4-8 Outlooks SPC Severe Weather Outlook Probability-to-Categorical Description Tables (2014) Day1 0% 2% 5% 10% 10% sig 15% 15% sig 30% 30% sig 45% 45% sig 60% 60% sig Tor TSTMS MARGINAL SLGT ENHANCED MDT HIGH Wind TSTMS MARGINAL SLGT ENHANCED MDT HIGH Hail TSTMS MARGINAL SLGT ENHANCED MDT Day2 0% 5% 15% 15% sig 30% 30% sig 45% 45% sig 60% 60% sig All Svr TSTMS MARGINAL SLGT ENHANCED MDT HIGH Day3 0% 5% 15% 15% sig 30% 30% sig 45% 45% sig All Svr TSTMS MARGINAL SLGT ENHANCED MDT Day4-8 15% 30% All Svr SLGT ENHANCED Expected to result in better alignment with WFO forecasts and DSS
Thank You! Tony Sturey, WCM NWS Greenville/Spartanburg, SC Anthony.Sturey@noaa.gov Nick Petro, WCM NWS Raleigh, NC Nicholas.Petro@noaa.gov Phil Hysell, WCM NWS Blacksburg, VA Phil.Hysell@noaa.gov