Archief - Overstromingen West Vlaanderen

Storm Forecast
Valid: Sun 25 Jun 2006 06:00 to Mon 26 Jun 2006 06:00 UTC
Issued: Sat 24 Jun 2006 23:45
Forecaster: GROENEMEIJER

SYNOPSIS

Sunday at 06:00 UTC... a ridge stretches from Tunisia to Poland and a longwave trough is located over the eastern Atlantic. A moderate southwesterly flow is present over western continental Europe in between. A shortwave trough extends from the Bay of Biscay over northeastern Spain.

DISCUSSION

northwestern and north-central France, Benelux...

A deepening surface low is expected ahead of the aforementioned shortwave centered over centrl France. An area of elevated storms and stratiform precipitation should be ongoing over Wrn France. As the surface low deepens, the low-level wind field is expected to intensify, leading to strong low-level shear around its centre.

Heating of the boundary layer should allow for surface-based convective development on the Nrn and Ern flanks of the low as 500-1000 J/kg MLCAPE50 should be able to develop.
High storm-relative helicity values are expected to develop on the low's Nrn flank, partially within the zone that should allow for surface-based storms. Especially in this area, supercells should be able to develop quite easily and an enhanced threat of large hail and -given the strong low-level shear- tornadoes should be present. A negative for supercell development, however, is the rather limited deep-layer shear with 500 hPa winds on the order of only 15-20 m/s, that will decrease further into the evening. The fact that the shear will be present mostly in a shallow layer and the strength of the forcing suggest that many storms will be organized linearly into one or more small bow echoes. These should be able to bring winds in excess of the severe limit of 25 m/s in places. Additionally, a few tornadoes may occur with the bowing system as well.

Severe weather will likely develop with the first surface-based convection over north-central France in the early afternoon and shift into Belgium and the Rheinland and later the SErn Netherlands as it get increasingly linearly organized.

Large areas of stratiform and elevated convective precipitation are expected on the low's Wrn flank. It is here that flash flooding will probably be a primary threat. Mind that the issued threat levels do not incorporate flash flood threat.

eastern France, Switzerland, extreme northwestern Italy...

Ahead of the cold front of the low pressure system, MLCAPE of 500-1000 J/kg will likely develop in an environment of 15-20 m/s deep-layer (0-6 km bulk) shear and somewhat higher towards the SE. Scattered storms are expected to initiate primarily during the afternoon. These are likely to organize into multicells and later a few linear, bowing systems. Isolated large hail is expected with the storms and some severe wind gust threat is likely to develop with maturing linear systems.

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Woverke zei:

Hmm aan weerstation Aalst te zien gaat er een ferm onweer met wolkbreuk binnen een uurke in Vlaanderen zijn (precies wel enkel Limburg vooral)

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An AM radio makes an excellent lightning detector. During a thunderstorm you can listen in on individual lightning bolts on your AM radio. Tune the radio to a station and each crackling sound that you hear is from the radio waves emitted by a lightning bolt. You will notice that you hear the static crackle at the same moment you see a flash of lightning. This is because radio waves and visible light both travel at the speed of light. The sound of thunder travels at the speed of sound (about 1,000 feet per second) and thus lags behind the flash of light (or AM crackle)*. You will notice that there will be some lightning bolts that you detect that are not seen. These are lightning bolts that are high up in the thunderstorm cloud or even in another thunderstorm cell.



You can make your own lightning strikes (on a much smaller scale) and detect them on your AM radio. Tune your AM radio to a station with its antenna extended. Take an inflated balloon and rub it back and forth for awhile on your own clean, dry, oil-free hair (fur works well also). Slowly bring the balloon close to the antenna. You may need a quite classroom to hear the effect, but the static crackle becomes audible as you bring the balloon slowly near the antenna.



* You can use the time lag between lightning and thunder as an excellent way to judge the distance to the lightning. Count the seconds after you see the flash of lightning. Each second equals about 1,000 feet or five second equals about a mile. If you see the flash of lightning and then hear the thunder by the time you count to ten (or sooner) you are within two miles of the lightning and could be at some risk of getting a lightning strike!

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GaMe® zei:

Mijne AM radio begint te kraken Dus het komt eraan!
Moet ge zeker is doen.. Da is heel efficient.. As ge't hoort donderen ofzo, zet u radio op ne AM zender.. Bij iedere bliksem zal de radio kraken gaan.. Neemt het kraken toe, word het heviger, neemt het af, dwaalt het weg..
Is echt leuk Als het onweer dichtbij is, kunt ge zien dat da ook werkelijk just bij iedere bliksem kraakt!



Wist je trouwens dat als je een bliksem ziet gaat gij gemiddeld 30 keer op en neer aan een snelheid van 300 000km/s (national geographic)

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Woverke zei:

http://www.blitzortung.de/index.php?mode=0&map=0&lang=e

komt weer een leuk onweertje af precies

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Woverke zei:

http://www.blitzortung.de/index.php?mode=0&map=0&lang=e

komt weer een leuk onweertje af precies

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Woverke zei:

http://www.blitzortung.de/index.php?mode=0&map=0&lang=e

komt weer een leuk onweertje af precies

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DJ_CUBEE1 zei:

ksnappet ni, dien website refresht elke tien seconden en toch komen er maar af en toe bliksems bij normaal gezien zijn er toch veel meer bliksems per minuut eigenlijk ...

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