BACKGROUND OF THE SEVERE WEATHER SITE

PURPOSE OF THIS WEBSITE:

These website provides an outlook to the risks on severe weather over the Benelux region.

 

Technicaly, we use color codes to indicate the possible treath of the weather on the society. The collor indicates the RISK (which is in fact a combination of the PROBABILITY and the strength of the IMPACT) on inconvenience fo the society, with:

 

green = NIL (no problems expected)

yellow = SLGT (slight risk on inconveniences)
orange = MDT (moderate risk on inconveniences)

red = HIGH (high risk on inconveniences or moderate risk on very high inconveniences)

purple = EXTR (very dangerous situation expected)

 

We also provide some comments on the blog, which particularly is reserved for people who have some knowledge about meteorology. For the moment, the texts are provivided in Duth only.

 

WIND

 

Warnings for wind gusts (non-convective) are made using a matrix based on probability and the height of the expected gust value. The resulting color gives you an estimation of the risk and impact strength of this parameter. For the period October-April:

 

gust / prob.	< 10 %	10 - 30 %	30 - 60 %	60 - 80 %	> 80 %
< 90 km/h
90 - 110 km/h
110 - 130 km/h
130 - 150 km/h
> 150 km/h

 

For the period May-September:

 

gust / prob.	< 10 %	10 - 30 %	30 - 60 %	60 - 80 %	> 80 %
< 80 km/h
80 - 100 km/h
100 - 110 km/h
110 - 130 km/h
> 130 km/h

 

SNOW / ICE

 

Snow warnings are made for snowfall rates (cm/24h), under the conditions that all the fallen snow accumulates on the ground. If there is already a snow cover on the ground, this depth is not taken into account!

 

For the snow cover in the lower regions (<400 m), a matrix is used based on probability and expected snow rate. The resulting color gives you an estimation of the risk and impact strength of this parameter

 

snow rate / prob.	< 20 %	20 - 50 %	50 - 65 %	65 - 80 %	> 80 %
< 3 cm
3 - 8 cm
8 - 15 cm
15 - 30 cm
> 30 cm

 

For the snow cover in the higher regions (mainly the Ardennes region >400 m), an other matrix is used based on probability and expected snow rate. The resulting color gives you an estimation of the risk and impact strength of this parameter

 

snow rate / prob.	< 20 %	20 - 50 %	50 - 65 %	65 - 80 %	> 80 %
< 8 cm
8 - 15 cm
15 - 30 cm
30 - 60 cm
> 60 cm

 

Beside this snow, also clear ice due to precipitation on the roads plays a role in the warning system (ice layer in mm/24h)

 

ice / prob.	< 10 %	10 - 30 %	30 - 60 %	60 - 80 %	> 80 %
ice layer <1 mm
ice layer 1 - 5 mm
ice layer > 5 mm

 

SEVERE CONVECTIVE STORMS

 

For the warnings of severe* convective storms,  a matrix is used, based on the probability of severe convection and the foreseen strength of the convection. The resulting color gives you an estimation of the risk and impact strength of this parameter.

 

severe* convection / prob.	< 10 %	10 - 30 %	30 - 60 %	60 - 80 %	> 80 %
severe* convection
very severe* convection (with hail>3 cm and/or gusts >120 km/h)

 

(* hail > 1.9 cm and/or convective wind gusts >90 km/h and/or a tornado and/or flash floods of > 60 mm/3h)

 

On the map, the type of severe weather is mentioned as follow :

 

WIND : wind gusts (all types)

T-STORM : thunderstorms 

SNOW : snowcover or ice

SPOUTS : waterspouts

 

EARLY WARNINGS

 

  

 

Early warning: An "early warning" will be issued when there is a risk of at least 30% of a MDT RISK on severe weather for the period D+1 until D+2. The type of severe weather risk, as well as the foreseen period is mentioned on the early warning logo and some comments could be given in the text blog. As with the other forecasts, the continuity isn't guaranteed since this initiative is on a voluntary base! 

 

Short overview of the owner of this site:

My name is Karim Hamid and I'm an operational weather forecaster on the Royal Meteorological Institute of Belgium (RMI). Beside the tasks of weather forecasting, I'm also occupied with the research on severe thunderstorms, especially in my own country. Already in 2002, this website was online, but only with forecasts of severe storms. Since a few years, also forecasts of snow en non-convective storms are published. Some publication of me and other persons are available on http://users.fulladsl.be/spb4195/cursus.htm.

 

Because I manage this site in my spare time, I can't  guarantee daily updates.

GEBRUIKSVOORWAARDEN:

Geen enkele informatie mag, zonder toestemming van de website-beheerder, worden gekopieerd of verspreid onder welke vorm dan ook op het internet of via elk ander medium.

 

Het is evenwel toegelaten om de kaartjes:

http://users.fulladsl.be/spb4195/kc.png & http://users.fulladsl.be/spb4195/kc.png

te gebruiken op een website, mits duidelijke toevoeging van de bron, en wel onder volgende vorm:

 

“Bron: Karim Hamid, http://severeweatheroutlook.blogspot.com/”

 

Voorafgaande toestemming is evenwel vereist en kan bekomen worden via onderstaand email adres:

 

severeweatheroutlook@hotmail.com

 

De beheerder van de website is onder geen enkele voorwaarde verantwoordelijk voor eventuele gevolgen welke veroorzaakt kunnen zijn door een verkeerde weersverwachting op deze website. De inhoud welke op de website verschijnt is losgekoppeld van elke officiële weerinstantie en wordt op vrijwillige basis verzorgd. De continuïteit kan bijgevolg niet worden verzekerd.

 

Vragen en opmerkingen zijn welkom op: severeweatheroutlook@hotmail.com

 

De websitebeheerder

Karim Hamid