Sterling, Virginia Lightning Climatologies

1
Sterling, Virginia Lightning Climatologies

• Pete Saunders
• Henry Fuelberg
• Florida State University

2
Time Series

• The following graphs depict the total flash
  counts versus the time they occur. The times
  have been converted from UTC to Eastern Standard
  Time (EST). The first graph, entitled Warm
  Season Hourly Counts gives a seasonal
  representation of the time in which most
  lightning flashes occur in the Sterling NWS area
  of interest. The subsequent graphs are a month by
  month illustration.
• The warm season indicates the months of
  April through September over an 11 year period.
  Finally, the area represented in the plots is
  between
• Latitude 36.5 N through 42.1 N
• Longitude -74.0 W through -80.5 W
• Please note The ordinate axes of the
  following graphs are not to scale

3
(No Transcript)
4
(No Transcript)
5
(No Transcript)
6
(No Transcript)
7
(No Transcript)
8
(No Transcript)
9
(No Transcript)
10
(No Transcript)
11
Remarks

• Examining lightning counts temporally
  illustrates the convective nature of the
  atmosphere climatologically throughout the warm
  season.
• As might be expected, the total flash counts
  for April are similar to those for September.
  The large jumps from April to May to June are
  interesting to note as well.
• July stands out as the month with the highest
  flash counts followed by a rather sharp decrease
  of about 10 000 flashes in August.

12
Spatial Density Maps

• The following maps depict the spatial
  densities of CG lightning flashes for the
  Sterling, Virginia research region. The first
  map, entitled Warm Season Flash Density, gives
  a seasonal representation of the areas with the
  highest density of CG lightning strikes for the
  entire warm season. The subsequent maps are a
  month by month representation of lightning
  density.
• Please Note
• The coordinates for the density maps are the
  same as previously mentioned with regards to the
  time series.
• Lightning densities do not follow the same
  scale on each map.

13
Low relative densities throughout the Delmarva
Peninsula
Interesting region of relatively high densities
in western P.G. County
Low densities in the mountain/valley regions of
VA and WVA
Region of highest lightning densities
14
Interesting pocket of relatively high density in
Baltimores southern suburbs (Anne Arundel County)
15
(No Transcript)
16
Highest June densities occur in eastern and
northwestern suburbs of Washington, D.C. (P.G.
County and Loudoun County respectively)
17
Very high densities in Norfolk, VA region
18
(No Transcript)
19
(No Transcript)
20
Remarks

• Southeastern Virginia has, by far, the largest
  area of high CG lightning flash densities.
• -We believe this is due to topographical
  effects which include but are not limited to a
  sea-breeze effect from the mouth of the
  Chesapeake Bay and the Atlantic Ocean along with
  the blocking of moisture by the Appalachian
  Mountains generally resulting in convergence. I
  would appreciate any input to confirm or deny
  this speculation.
• There are some hot spots in the D.C. and
  Baltimore suburbs that would be interesting to
  examine further.
• Overall, there appear to many micro climes
  in this region. I am looking forward to hearing
  your opinions on the general convective nature in
  this region during the warm season months. Any
  input/suggestions/explanations for the location
  of the highest and lowest lightning densities
  would be greatly appreciated.
• Also, please share this document with your
  forecasters in order to facilitate feedback and
  understanding.