Andrea Paparelli
RE: 3/5/2008 – Douglassville, PA
Introduction
As you requested, I have reviewed the weather conditions for Doulgassville, PA on March 5,
2008. In order to determine with a reasonable degree of meteorological and scientific certainty the
weather conditions in Douglassville, PA, I examined official surface weather observations from the
National Weather Service at the following locations: Pottstown-Limerick Airport, Pottstown, PA, and
Reading Regional Airport, Reading, PA. I have also examined radar data from Ft. Dix, NJ obtained from
the National Climatic Data Center, and surface analysis maps obtained from the National Weather
Service’s Weather Prediction Center.
Events/Analysis of Data/Assumptions
Surface observations located at Pottstown-Limerick Airport and Reading Regional Airport
revealed that precipitation occurred between midnight and 9:00 AM. Observations also show high wind
gusts greater than 30 mph between 7:00 and 7:50 AM with peak gusts reaching 39 mph.
Surface analysis at this time show a surface low positioned near the location with a cold front
passing through this area. Radar data between 7:00 and 8:00 AM show a line of high reflectivity moving
from west to east within the vicinity of Douglassville. Specifically at approximately 7:30 AM data shows
high reflectivity of 35 to 50 DBZ in the area of Douglassville which corresponds with the high wind
observations and heaviest precipitation observations. Due to the distance of the radar from the
observation locations, the lowest elevation scan was sampling areas approximately 6,500 feet above
ground level. Attachments of materials reviewed are attached.
It is assumed that because of the distance of Douglassville from the radar, higher DBZ levels
could be sampled below. It is also assumed that the wind speeds that occurred in Douglassville are
similar to those that occurred at the neighboring airports due to their proximity to Douglassville and
their orientation in relation to Douglassville. Despite lower temperatures, it is assumed that the
environment was unstable enough and the front provided enough lift in the atmosphere to support
thunderstorms. Lastly, it is assumed that a thunderstorm could occur without any official observations
as it was noted that the thunderstorm detection equipment at both locations was out of service.
Summary
In summary, based on radar data, surface observations and surface analysis, I believe a
thunderstorm occurred in Douglassville, PA on March 5, 2008 between 7:00 and 8:00 AM. This is evident
by the high reflectivity seen on the radar images at approximately 7:30 AM. Accompanying these radar
images, observations show the heaviest precipitation and highest wind speeds occurring between 7:00
AM and 8:00 AM at both airports, with the highest gusts of 39 mph reported between 7:30 and 8:00 AM
at the Pottstown-Limerick airport. According to the Beaufort Wind Scale, at these speeds, trees can sway
and twigs can break from trees.
Pottstown-Limerick Airport – Approximately 11 miles southeast of location
Time (LST) Temperature (°F) Wind Speed (mph) Wind Gust (mph) Peak Wind (mph)
05:54
52
6
N/A
N/A
06:54
54
9
N/A
N/A
07:28
54
7
16
N/A
07:38
50
32
39
39
07:42
46
22
39
39
07:50
46
13
31
39
07:54
46
16
29
39
08:12
46
12
N/A
N/A
08:41
45
18
25
N/A
08:54
45
14
25
N/A
Direction
VRB
SSE
S
WNW
WNW
WNW
WNW
NW
W
W
Weather
Lt. Rain
N/A
Lt. Rain
Lt. Rain
Lt. Rain
N/A
N/A
Lt. Rain
N/A
Lt. Rain
Reading Regional Airport – Approximately 21 miles northwest of location
Time (LST) Temperature (°F) Wind Speed (mph) Wind Gust (mph) Peak Wind (mph)
05:54
52
6
N/A
N/A
06:54
52
9
N/A
N/A
07:03
48
26
37
37
07:12
45
22
36
37
07:15
45
22
36
37
07:24
45
18
35
37
07:54
45
17
N/A
37
08:29
43
10
N/A
N/A
Direction
SE
S
WNW
WNW
WNW
WNW
WNW
WNW
Weather
N/A
Rain
Hvy. Rain
Hvy. Rain
Rain
Rain
Rain
Lt. Rain
Radar Data – KDIX
Surface Map