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THE OPERATIONAL
APPLICATION OF THE
LIGHTNING JUMP ALGORITHM
FOR HAIL NOWCASTING IN
CATALONIA.
Farnell C., Rigo T., Puig O.
Servei Meteorològic de Catalunya (SMC).
Universitat de Barcelona (UB). Grup de Climatologia.
www.meteo.cat
Where is Catalonia?
2
Introduction
The LJ is a sudden increase of the total number of lightning rate (Williams
et al. 1999).
It is a consequence of strong updraft which favours the crash between ice
particles and a higher separation of the charge (Williams, 2001).
This tool is used for forecasting SEVERE WEATHER
Hail > 2 cm
Tornados / Waterspout
Downburst
Strong wind gust
Definition
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Font:
Introduction
Examples of Severe Weather recorded in Catalonia
Font: Jesús Coines
Font: Farnell C
Font: O. Rodríguez
Font: F.F: Teixidó
Font: F,F.Teixidó
Before the algorithm …
The LLS of the SMC
operates in both
frequencies, LF and
VHF, allowing the
detection of IC and
CG flashes.
Lightning Location System (LLS)
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Few networks in
Europe have this
capability (full IC
detection)
The LLS is composed
of 4 detectors, with an
efficiency of > 90%
over the territory
Before the algorithm …
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Detecting two types of flashes: intra-cloud and cloud-to-cloud
VHF
LF
Before the algorithm …
Multiplicity
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CG
IC
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5’
Convection starts
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15’
Separation of electrical charge
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45’
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The phenomena related to ordinary thunderstorms are strong rain and wind and small hail.
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35’
Warning is triggered
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Conceptual Outline
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65’
Severe phenomena
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Increase updraft. Increase electrical charge.
Lightning Jump - Algorithm
The tool is an adaptation of research algorithms developed in the USA
(Schultz, Gatlin…) with some different requirements .
We have not considered the threshold to distinguish between severe or
ordinary thunderstorms.
The original algorithm takes into account Radar + Lightning Data.
We only consider Lightning Data. Why?
The Lightning Data allow us to execute the algorithm every minute.
In contrast, we obtain Radar Data every 6 minutes.
Adjustment
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Lightning Jump - Algorithm
How to detect LJ warning?
For each minute, we analyze each thunderstorms
We transform the flashes to points on the map
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Algorithm
How to detect LJ warning?
The points are joined between them
Its center point characterizes the thunderstorm through :
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Coordinates Hour Flashes number Size
El Lightning Jump: una eina de predicció de temps sever
How to detect a severe storm?
12
Once we have the point which represents the thunderstorms
t
We see the thunderstorm's track during the last 12 minutes
REQUIRIMENTS
And its evolution of electrical activity
To make the algorithm work, it is necessary to accomplish: - Continuity in space - Continuity in time during the 12 minutes
Algorithm
This period of 12 minutes is divided into periods of 2 minutes. Then, we
calculate the average of Total Lightning (TL) of each period.
How to detect LJ warning?
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Algorithm
The averages are subtracted sequentially between them
How to detect LJ warning?
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The standard deviation of all DFRDT is calculated
Characteristics
This tool needs the TL (intra-cloud (IC) + cloud-to-ground (CG)) to work well.
Total Lightning (TL)
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CLOUD TO GROUND TOTAL LIGHTNING
More information in
Rigo et al presentation
Lightning Only CG
CG+IC (TL)
Nº alerts (2006 – 2015)
69
5,262
Characteristics
The number of LJ taking into
account multiplicity is higher
than not considering the
multiplicity (only the first node
of IC).
Multiplicity
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426 LJ
Type Of LJ
Without Multiplicity
With Multiplicity
Nº alerts (2016 )
104
426
Nº alerts (2017)
101 326
With Multiplicity Without Multiplicity
More information in
Rigo et al presentation
2016
2017
426
326
104
101
How it works operationally
Application to operative work
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Results – Experimental study 2006-2013
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PC 73% FAR 10%
SKILLS
SCORES
LEAD TIME
PC: Percentage of correct predictions FAR: False Alarms
1 hour of anticipation
Average of Lead Time 30 min
Moment of the record in surface
Results – Experimental study 2006-2013
2012/07/05
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Lead Time 90 min
Results – Operative 2016
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PC: Percentage of correct predictions FAR: False Alarms
SKILLS
SCORES
PC 93% FAR 7%
Average of Lead Time 56 min
Results – Operative 2016
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Anticipació
40 min
2016/08/16
Lead Time 40 min
Results – Operative 2017
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PC 81% FAR 22%
SKILLS
SCORES
The MULTIPLICITY allows to increase the Lead Time More than 2 hours of anticipation
Average of Lead Time 49 min
PC: Percentage of correct predictions FAR: False Alarms
Anticipació
5 - 90 min
Results – Operative 2017
Lead Time 5 - 90 min
Campaing “Picking Up The Stone” 2017 & 2018
Agreement with County Councils of Lleida and Girona
Agreement with l’ADV Terres de Ponent
Agreement with Leon Universtity (ULE).
Preparation to external level
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Exemple de granímetre
Part de l’anàlisi d’un granímetre.
Campaing “Picking Up The Stone” 2017 & 2018
Preparation of the web meteo.cat
Radio and social media advertising.
Preparation on:
whatsapp, 667051592
Manager of photos,
Social media:
– twitter #meteocatpedra
– Email: [email protected]
Preparation to internal level
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The hail observations collected during 2017 have been dobled thanks to #meteocatpedra
Campaing “Picking Up The Stone” 2017
179 observacions
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Campaing “Picking Up The Stone” 2017
Observations
Spatial Distribution of the Observations
LJ Warning
LJ wM
LJ woM
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Campaing “Picking Up The Stone” 2017
Observations LJ Warning
Monthly Distribution
LJ wM
LJ woM
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Campaing “Picking Up The Stone” 2017
Observations
Hourly Distribution
LJ Warning LJ wM
LJ woM
Thank you for your attention
see you in 2020 ;)
HAIL TEAM SMC
