Archief - De onweerthread 2014

solidraven zei:

Het is blijkbaar aan het onweren aan de kust/boven zee.

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Remnants of nocturnal convection will likely affect Western and Northern France and especially England in the morning hours. Since these storms will mostly be elevated, the severe weather risk should temporarily be low, though some heavy rainfall may still extend into the current forecast period. Activity will move northward into Scotland and onto the North Sea while it gradually decays.
Forecast models largely agree on clearing in the wake of these storms. With mostly sunny late morning and noon hours, a quick recovery of the air mass can be expected with CAPE values on the order of 1000 to 2000 J/kg (even higher per GFS) under deep-layer shear around 20 m/s. From the early afternoon onwards, more and more storms are forecast to initiate in the vicinity of the main frontal zone or along the mess of old outflow boundaries laid out by overnight's convection. They can quickly turn into multi- and supercells with a threat of large hail and severe wind gusts. Backbuilding and training activity may also easily produce a few flash floods, as the moisture content is exceptionally high (precipitable water around 40 mm).
Of particular concern are areas of reduced vertical mixing, which allow a moisture accumulation and the maintenance of enhanced low-level shear and helicity. This can be expected along the sea breeze front in Northern France and Belgium, and in general in Eastern England, where warm air advection re-intensifies on the forward flank of a weak surface low which is forecast to track from Northwestern France (06 UTC) into Northern England (18 UTC). If diurnal heating and/or the lift impulse by outflow boundaries suffice to break the capping inversion in these regions, particularly well-organized supercells could spawn a few tornadoes, possibly even including a strong one. However, mesoscale developments need to be awaited before the degree of this threat can further be specified.
Despite remaining uncertainties due to downstream effects of overnight's vigorous storms, a level 2 seems to be warranted.

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sink zei:

Ik vind het er in het zuiden toch redelijk grijs uitzien in de verte..
weet niet of dat van onderstaande is, maar heb toch het gevoel dat er wat zit aan te komen

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Trekhond zei:

Hoe noemt da weer voor die bliksemdetectie?

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