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Convective basics and ESTOFEX
Speaker: Helge Tuschy
http://www.estofex.org/
http://www.dwd.de/
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Short vita
studied Meteorology / Geophysics at the Leopold-Franzens
University of Innsbruck, Austria
2002, 2007 internship National Weather Service Amarillo, Texas
2004, internship Storm Prediction Center ( SPC )
talks: ECSS, ICAM, media …
forecaster at ESTOFEX / member of ESSL
Since 2010 working at the DWD (RZ Leipzig, E-Germany)
favorite sport: baseball and soccer
favorite food: Italian style
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The outline
Basics about organized convection
• Overview about ESTOFEX• Case study (15th August 2008)• Future of ESTOFEX
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Convective forecast parametersand signatures
9-11 km
0-6 km
0-3 km
0-1 km0-3 km
SBCAPEMLCAPEMUCAPE
Low-level CAPE
Speed shear
Storm relative helicity
Lifted Condensation Level (LCL)
- mixing ratio (0-1 km) - 0-1 km mean wind streamlines- real time T/Td data 4
@ EUMETSAT
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Convective available potential energy
Surface based (SB) CAPE Mean / Mixed layer (ML) CAPE
Surface dewpoints / temperatures
realistic layer depth for thunderstorm inflow ?
Magnitude highly! variable in space and time
Pro: e.g. winter with thin low-level moisture
Contra: - in summer often way too high - decays too fast
Mean/Mixed temperatures / dewpoints within lowest 50 – 100 hPa
realistic layer depth for low topped supercells ?
Pro: often most reliable parameter
Contra: in winter often underestimates true magntiude
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Speed shear
@ Eye on the Twister
Cyclonic rotation
Anticyclonic rotation
@ LakeErieWX
a)
b1)
c)
d)
b2)
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Directional shear (helicity)
@ A REVIEW FOR FORECASTERS ON THE APPLICATION OF HODOGRAPHS TO FORECASTING SEVERE THUNDERSTORMS by Charles A. Doswell III
@ Dynamics of tornadic thunderstorms by Joseph B. Klemp
a)
b)
c)
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15 kt30 kt
Storm relative winds
Thunderstorm motion
e.g. 320° 12 kn
Storm relative winds (arrow) and storm relative helicity (colored area); here: 1-3 km SRH
Storm relative helicity
Sfc. To 1 km (tornadogenesis)
Sfc. To 3 km (mesocyclones)
dzzVk
kmCVH )ˆ3
0()(
Horiz. Vort. vector
90 °
270 °
180 °
0 °
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Be careful of composed parameters
Supercell composite parameter (SCP)Significant Tornado Parameter (STP)Energy Helicity Index (EHI)Derecho Composite Parameter (DCP)
Each parameter has its positive and negative side
Composed parameters mix those aspects; negative ones can multiply 9
11221 150
200
20
6
100
1
1500
2000
1500 Jkg
sbCIN
ms
BWD
sm
SRH
m
sbLCL
Jkg
sbCAPESTP )(
e.g. highly fluctuating
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European Storm Forecast Experiment (ESTOFEX) www.estofex.org
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Forecasters of ESTOFEX
Dr. Pieter Groenemeijer
Dr. Johannes Dahl
Dr. Oscar van der Velde
Christoph Gatzen
Oliver Schlenczek
Marko Korosec
Tomas Pucik
Helge Tuschy
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1st outlook of ESTOFEX
VALID 06Z THU 10/10 - 00Z FRI 11/10 2002ISSUED: TUE 08/10 23:10ZFORECASTER: HAVEN
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European Storm Forecast Experiment (ESTOFEX)
What is ESTOFEX?
An initiative of a team of European meteorologists and students in meteorology and serves as a platform for exchange of knowledge about severe convective storms in Europe and elsewhere.
ESTOFEX offers a GUIDANCE where organized convection is forecast. This guidance can be used by local forecast offices for daily warning preparation. ! !
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Which risk of (extremely) severe convective weather phenomena does ESTOFEX forecast ?
Severe convective weather phenomena:
• tornado (waterspouts)
• hail with a diameter of at least 2.0 cm
• wind gusts with a speed of at least 25 m/s (92 km/h or about 49 knots)
• excessive rainfall of at least 60 mm
Extremely severe convective weather phenomena:
• tornado; (E)F 2 or stronger
• hail with a diameter of at least 5.0 cm
• wind gusts with a speed of at least 33 m/s (119 km/h or about 65 knots)
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The meaning of the level areas• 41 km radius of a chosen point
• verification by EUCLID/ESWD
R = 25 miles
= 41 km
A ~ 5085 km2
Large hail report
Heavy rain report
Tornado report
Severe wind gust report
Evaluation of ESTOFEX forecasts: Severe thunderstorm forecasts
H.E. Brooks et al.
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ProbabilitiesVerification of severe and significant severe events (1266 forecasts)
Level areas % coverage of severe events
% coverage of significant severe
events
(svr.[%])(sig.svr.[%])
Level 0 0.40 % 0.01 % < 5
Level 1 4.90 % 0.80 % 5 – 15
Level 2 14.50 % 2.80 % >15 3 – 5
Level 3 22.20 % 11.10 % > 5
Lightning probabilities
Marginal lightning probabilities 15.0 %
Enhanced lightning probabilities 50.0 %
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The meaning of the level areas
1) E.g. probability of 15 % means a 15 % chance for that event to happen within a radius of 41 km around each point. May seem low, but compared to climatology, it is significant
2) Level 0 expected probability of severe convection appears insignificant
3) Level 1 most common threat level; low threat of severe weather
4) Level 2 large confidence of severe storm occurrence and slight risk for
extreme severe
5) Level 3 major severe thunderstorm outbreak (e.g. 15th August 2008 )
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How do we prepare our outlooks?
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ESTOFEX outlook
Surface data
AVHRR SST (spout forecast)
European radar data
(Meteox and local data)
Wind profiler
Soundings:
Real time/model
Lightning data
(EUCLID)
Ensemble prediction system (EPS) data from global models
Model data:
- global models
- local / regional models
- self-produced outputs for convective forecasts
EUMETSAT
Satellite data [HVIS !]
Climatology
(e.g. thunderstorm days)
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Synopsis
Short overview
- upper level streamline pattern (e.g. trough, ridge, jets)
- low levels (e.g. sig. boundaries, characteristics of the planetary boundary layer quality regarding moisture, temperature)
- possible: short outline of model credibility (e.g. ensembles, EFIs etc.)
- if necessary: short side notes for significant weather events like a depression with a potential (sub) tropical character
Discussion
Header
Severe Weather Outlook Day 2 (SWODY 2):
General discussion
Severe Weather Outlook Day 1 (SWODY 1):
Discussions of each area of interest within different paragraphs. The following points are discussed:
- kinematic environment (shear)
- instability
- forcing
- storm mode
- time frame/duration
Structure of a Severe Weather Outlook
Day 1 or 2 (SWODY 1 or SWODY 2)
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Tornado outbreak 15th August 2008 (Poland)
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Pattern recognition !
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T
H
h
Upper levels
White:
isohypse
Green:
isohumid
Yellow:
lapse rates (2-4 km AGL)
Pink arrow:
300 hPa jet wind
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T
t
Low levels
White:
isobare
Green:
isohumid
Arrows:
850 hPa jet wind and temperature advection (colorized)
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SYNOPSIS
Active weather pattern continues as a strong upper-level trough shifts to the east over central Europe. […]. At the surface, a quasi-stationary frontal boundary is still in place, running from the Alpes over CNTRL Poland to W-Russia, […].
DISCUSSION
** A major severe-weather event is forecast for parts of central Europe and an outbreak of severe thunderstorms with tornadoes, damaging wind gusts and significant hail can be expected. **
[…]35-40 m/s 0-6km bulk shear values over the northern central Mediterranean. During the afternoon and evening hours, shear also increases
significantly E/NE of the Alpes, with 0-6km DLS values of 25-35m/s all the way to N-Poland. […] LL shear of locally up to 20m/s and also very high SRH values, maximized over Poland, but also augmented all the way down to the N-Adriatic Sea.
Very rich BL moisture and steep mid-level lapse rates along the front result in near 1000 J/kg MLCAPE, with locally higher MUCAPE values. […] Another interesting point is abundant LL CAPE release along the boundary, which could be a backing mechanism for tornado development, which has to be monitored in the upcoming model runs.
Forecast soundings from central Italy to Poland indicate that the environment is prime for tornadoes/a few strong ones/large hail/a few damaging events included and severe to damaging wind gusts. […]
Severe Weather Outlook Day 2: 13th August 2008
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Severe weather outlook day 2 (SWODY 2) Issued: Wed 13 Aug 2008 21:18 Z
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Level areas:
13th Aug 2008
Lightning data:
15th Aug 2008
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Severe weather outlook day 1 Issued: Thu 14 Aug 2008 21:16 Z Issued: Fri 15 Aug 2008 18:09 Z
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Future of ESTOFEX
- More forecasters participating in this experiment, e.g. from the Mediterranean or E/SE Europe
- Platform for forecasters to discuss realtime / past events
- To bring more meteorological students on board
- Creation of a detailed climatology about European convection (also push verification of outlooks)
- In the long term future: maybe an institution for European convective forecasts ?
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