Improving New York City Thunderstorm Forecasts

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Thunderstorm Forecasting in
NYC
Christina Speciale, Rutgers University
Dr. Steven Decker, Rutgers University
Brandon Hertell, Consolidated Edison
Agenda
•
•
•
•
•
•
Introduction
Hypothesis
Methodology
Results
Summary
Future Work
2
Introduction
3
Introduction
• Meteorologists use atmospheric variables to forecast
potential thunderstorm development & strength
• Atmosphere measured 2x daily via weather balloon
– 8am & 8pm (EDT) (12z & 00z)
4
Introduction
• Variables provide insight to the state of the atmosphere
• Standard ranges for these variables have been
developed to forecast severe thunderstorms
• Applied uniformly
Atmospheric Variables
Stability
Thunderstorm Type
CAPE
(Convective Available Potential Energy)
Shear
CIN
(Convective Inhibition)
TT
(Total Totals)
LI
(Lifted Index)
Helicity
SWEAT
(Severe Weather Threat Index)
5
Hypothesis
6
Hypothesis
Are standard t-storm variable ranges
relevant in the NYC area?
– Potential customization of variables?
– Where and when do NYC t-storms occur?
– Synoptic features present?
7
Methodology
8
Methodology
• Build severe thunderstorm database
– Events 2006-2009
– Within or near ConEdison service territory
– Must include one or more of the following conditions
 58mph or above wind gusts
 ¾”+ hail
 Spawn tornado
• Goal was 30 events, found 39
9
Methodology
• Collect atmospheric and surface weather data
– National Weather Service (NWS)
– Storm Prediction Center (SPC)
– Hydrometeorological Prediction Center (HPC)
Albany
Buffalo
Pittsburgh
Chatham
Upton
Sterling
Sounding Locations
Surface Analysis
10
Methodology
• Organized and sorted data by
–
–
–
–
Time and location
Atmospheric variables
Synoptic features
Significant weather observed
11
Results
12
Results
Stability
Standard Range
CAPE (J/kg)
CIN (J/kg)
Lifted Index
Relative
Frequency
0-999 Marginally unstable
81%
1000-2499 Moderately unstable
16%
2500-3499 Very unstable
2%
3500+ Extremely unstable
1%
0-199 Convection possible
80%
200+ Convection not likely (stable)
20%
0+ Stable
48%
-1 to -3 Marginally stable
28%
-4 to -6 Moderately unstable
19%
-7 Very unstable
5%
13
Results
Thunderstorm Type
Standard Ranges
SWEAT
Total Totals
Relative
Frequency
0-299 No activity expected
89%
300-399 isolated moderate to heavy thunderstorms
11%
400-500 severe thunderstorms and tornadoes possible
0%
500+ severe thunderstorms and tornados likely
0%
44-49 thunderstorms likely
76%
50-54 isolated to scattered severe thunderstorms
23%
55+ numerous severe thunderstorms
1%
14
Results
Thunderstorm Type Con’t
Standard Range
0-149 severe thunderstorm unlikely
89%
150-299 possible severe thunderstorm development
10%
Helicity (0-1km)
300-399 favorable severe thunderstorm development
(m2/s2)
Shear (0-6km)
(kts)
Relative
Frequency
0.5%
400+ likely severe thunderstorm with tornado possible
0.5%
0-19 severe thunderstorm unlikely
18%
20-44 possible severe thunderstorm development
64%
45+ likely severe thunderstorm development
18%
15
Results
16
Results
17
Results
18
Results-Synoptic Features
ge
Ri
d
Be
lo
w
Tr
o
ug
h
e
Be
lo
w
Ri
dg
RH
S
rJ
et
Un
de
Tr
o
ug
h
50
40
30
20
10
0
RH
S
Frequency (%)
County Position
Position
19
Summary
20
Summary
• Standard atmospheric variable ranges do not always
apply in NYC
– 2 of 7 variables
– Potential customization – CAPE, LI, Total Totals, Helicity,
SWEAT
• June, July, August most likely months for severe weather
• Westchester, Queens, & New York Counties had highest
number of severe weather reports
• Low pressure, cold fronts, & jet stream location are
contributing factors to severe weather
21
Future Work
22
Future Work
• Match event timing to closest sounding
• Narrow thunderstorm database further to the “most
severe” events
• Look for combinations or patterns between variables
• Expand thunderstorm database
• Find additional sounding information
23
Acknowledgement
• Dr. Steven Decker, Associate Professor,
Rutgers University
• Brandon Hertell, ConEdison
24
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