# Presentation: 124149

## SEVERE WEATHER CLIMATOLOGY FOR THE BLACKSBURG, VA WFO COUNTY WARNING AREA

- Robert Stonefield and James Hudgins
- Update through 2007 by Kathryn Prociv
- National Weather Service Forecast Office
- Blacksburg, Virginia

## Informational Tidbits

- 4527 Severe Weather Events (Tornado, Hail and Wind) from 1950 to 2007.
- Data collected from NCDC and SPC.
- Demographics: 1.7 million people across 20,000 square miles.
- 1.1 million people reside east of the Blue Ridge.

## Population Density by County

**Population Density by County**

## All Severe Weather Events by Month

- All Severe Weather Events by Month

** ****22% **
**[979]**

** ****22%**
**[988]**

** ****22%**
**[992]**

**May-July 65% [2959]**

** ****10%**
**[433]**

** ****12%**
**[545]**

**4527 Total Events**

## All Severe Weather Events by Time

- All Severe Weather Events by Time

**27%[1228]**

**16% [713]**

**<4% [199]  (2a-8a)**

**4527 Total Events**

**14%[618]**

**53% [2383] (2p-6p)**

**26%[1155]**

## Tornados by Month

**3% [135] of all **
**severe weather **
**events [4527] **
**are Tornados. **
**  ****95 East**
**  ****40 West**

**16% [22] were **
**tropical cyclone**
**induced tornados**

**56% [76] Apr-July**

**Average 2 per year**

## Tornados by Time

**135 reported tornados (1950-2007)**

**64% [87] (12p-6p)**

**28%**
**[38]**

**22%**
**[29]**

**15%**
**[20]**

## Tornados by Magnitude

**76% [103]**

**24%[32]**

**0%[0]**

**19 tornados in April, ****9 were (F2-F3)!**

**135 reported tornados (1950-2007)**

## Tropical Tornados by County

**Of the 135 tornados, 16% [22] were tropical cyclone-induced tornados**

**90% [20] were F0-F1**

**Ivan spawned Two F2 **
**Tornados (Bedford **
**and Henry County)**

## Severe Hail by Month

**85% [1559] April-July**

**1% [18] Oct.-Feb.**

**0% **
**[0]**

** ****33%**
**[608]**

**41% [1845] of all severe weather events [4527] is Severe Hail.**

** ****16%**
**[291]**

** ****24%**
**[435]**

**12%[225]**

## Severe Hail by Time

**88% [1628] (12p-8p)**

**59% [1095] (2p-6p)**

**1845 Severe Hail Events**

** ****13%**
**[250]**

** ****30%**
**[558]**

** ****29%**
**[537]**

** ****15%**
**[283]**

## Severe Hail by Magnitude

**81%[1500]**

**17%[311]**

**2%[34]**

**1845 Severe Hail Events**

## Severe Winds by Month

**56% [2547] of all severe weather events [4527] is Severe Winds.**

**77% [1959] May-Aug.**

** ****14% **
**[355]**

** ****21% **
**[534]**

** ****27% **
**[679]**

** ****15% **
**[391]**

## Severe Winds by Time

**78% [1989] (12p-8p)**

**48% [1221] (2p-6p)**

**2547 Severe Wind Events**

**14% **
**[348]**

**25% **
**[632]**

**23% **
**[589]**

**17% **
**[420]**

## Highlights

**If a storm does become severe, 56% of the events are from convective winds, 41% are from hail, and 3% are tornados, of which, 16% are from tropical systems.**
**Tornados that touch down in the WFO Blacksburg CWA are generally east of the Blue Ridge and near the North Carolina and Virginia border. **
**Tornados developing within the WFO Blacksburg CWA usually occur between the months of April and July. **
**On average, two tornados touch down within the WFO Blacksburg CWA per year.**
**The majority (72%) of the tornados occur between 12:00 pm and 8:00 pm with a diurnal peak between 2:00 pm and 6:00 pm.**
**Weak tornados account for 76% of all the tornado events. **
**Of the strong tornados (24%), most occur during the month of April. **
**No violent tornados have been reported within the CWA.**
**90% of the tropical cyclone-induced tornados are weak tornados. Ivan spawned two F2 tornados (Bedford and Henry County on September 17, 2004).**

## Highlights Continued

**Severe hail occurs most often between the months of April and July (85%), with a seasonal peak in May. **
**The majority (88%) of severe hail occurs between 12:00 pm and 8:00 pm with a diurnal peak between 2:00 pm and 6:00 pm.**
**Severe hail of 0.75 to 1.00 inch constitutes 81% of all severe hail reports.**
**Severe thunderstorm wind events are most likely to occur between the months of May and August (77%), with a seasonal peak in July.**
**The majority (78%) of severe thunderstorm damaging winds occur between 12:00 pm and 8:00 pm, with a diurnal peak between 2:00 pm and 6:00 pm.**

**THE END**

**SEVERE WEATHER CLIMATOLOGY PAPER FOR THE RNK (1950-2005:**
- _[http://www.erh.noaa.gov/rnk/Research/Svr_Wx_Climo.pdf](http://www.erh.noaa.gov/rnk/Research/Svr_Wx_Climo.pdf)_
**OTHER LOCAL CLIMATE STUDIES:**
- _[http://www.weather.gov/climate/local_data.php?wfo=rnk](http://www.weather.gov/climate/local_data.php?wfo=rnk)_