The 2015 NWS Spring and Summer Weather Update

Transcription

1 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

2 Western North Carolina Severe Weather Climatology Tony Sturey

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4 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.

5 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.

6 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

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8 Topography of Forecast Area 6,684 FT 350 FT

9 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

10 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

11 Average number of days during a 10-year period with a tornado within ~25 mi of any point. Based upon a 58-year climatology. <

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14 Average number of days per year with a damaging convective wind gust within ~25 mi of any point. Based upon a 25-year climatology

15 Average number of May days per decade with a damaging convective wind gust within ~25 mi of any point

16 Average number of July days per decade with a damaging convective wind gust within ~25 mi of any point

17 Total Number of Days of Damaging Thunderstorm Winds Within a 15 Mile Radius

18 Total Number of Days of Damaging Thunderstorm Winds Within a 15 Mile Radius

19 Average days per year with large hail within ~25 mi of any point. Based upon a 25-year climatology

20 Myth Number 1 No Tornadoes in the Cold Season

21 Burke County January 2012

22 Myth Number 2 No Tornadoes in the Mountains

23 Great Smoky National Park, 2013 Late Spring, Early Summer

24 Myth Number 3 No Tornadoes in Urban Areas Overnight

25 Charlotte NC, March 3, 2012 Wee Hours

26 Myth Number 4 No Tornadoes: Except When All Personnel are in Their Place of Establishment

27 Vale Area, October 2010

28 The End NOAA NWS Greenville-Spartanburg, SC Tony Sturey Warning and Coordination Meteorologist

29 North Carolina Spring and Summer Outlooks Nick Petro

30 Climate.gov Outlook for the Nation

31 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.

32 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.

33 Past 90 day rain and latest drought monitor

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35 What about severe thunderstorms and tornadoes?

36 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

37 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

38 April 16, 2011

39 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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45 Will the pattern change?

46 Looking farther down the road using climatology

47 Recent changes to the Storm Prediction Center Convective Outlooks Phil Hysell

48 SPC Outlook Changes October 2014

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50 SPC Outlooks Before 10/ Tiers - SLGT, MDT and HIGH See Text Used for Marginal Situations

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54 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

55 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

56 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

57 Example of Change

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60 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

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62 Thank You! Tony Sturey, WCM NWS Greenville/Spartanburg, SC Nick Petro, WCM NWS Raleigh, NC Phil Hysell, WCM NWS Blacksburg, VA