Estofex: Level 1 voor België en Zuid(west) Nederland
Bericht van: Anthony [Tilburg] , 02-07-2009 14:07
DISCUSSION
... E-CNTRL UK, E/NE-France, extreme W-Germany, Luxembourg, Belgium and parts of the Netherlands ...
Words like 'forcing', 'front' and 'dynamic' can finally be involved again in the forecast. A constantly weakening cold front from W-France draws near during the afternoon hours and probably dissolves somewhere over the highlighted area. Shear at all levels remains weak although a marginal increase in speed shear is possible at mid-levels. The main advantage with such a feature is that moisture pooling along the convergence zone will assist in a concentrated swath of 800-1500J/kg MLCAPE as mid-level lapse rates steepen somewhat. Excessive rain due to slow storm movement will be the main hazard, but an isolated large hail report can't be ruled out, given better instability release and a slim increase in wind speeds throughout the troposphere. However the main effect of this set-up will be the longevity of thunderstorms mainly over Belgium, the Netherlands, Luxembourg and W-Germany, which will continue well into the night, probably until next morning. Isolated tornadoes are possible during the peak time heating with GFS showing LL CAPE of roughly 200J/kg.
In general the same for E-/CNTRL-UK, where stronger shear ought to offset weaker buoyancy, so multicell storms are possible. Isolated flash flooding and large hail are the main hazard. Prolonged period of divergence at high levels, weak surface 'trough' and the slow eastward progression of the surface front could locally yield a favorable environment for isolated spots to see repeated thunderstorm development both in the prefrontal airmass and during the passage of the front, which could locally increase flash flood risks.
... E-CNTRL UK, E/NE-France, extreme W-Germany, Luxembourg, Belgium and parts of the Netherlands ...
Words like 'forcing', 'front' and 'dynamic' can finally be involved again in the forecast. A constantly weakening cold front from W-France draws near during the afternoon hours and probably dissolves somewhere over the highlighted area. Shear at all levels remains weak although a marginal increase in speed shear is possible at mid-levels. The main advantage with such a feature is that moisture pooling along the convergence zone will assist in a concentrated swath of 800-1500J/kg MLCAPE as mid-level lapse rates steepen somewhat. Excessive rain due to slow storm movement will be the main hazard, but an isolated large hail report can't be ruled out, given better instability release and a slim increase in wind speeds throughout the troposphere. However the main effect of this set-up will be the longevity of thunderstorms mainly over Belgium, the Netherlands, Luxembourg and W-Germany, which will continue well into the night, probably until next morning. Isolated tornadoes are possible during the peak time heating with GFS showing LL CAPE of roughly 200J/kg.
In general the same for E-/CNTRL-UK, where stronger shear ought to offset weaker buoyancy, so multicell storms are possible. Isolated flash flooding and large hail are the main hazard. Prolonged period of divergence at high levels, weak surface 'trough' and the slow eastward progression of the surface front could locally yield a favorable environment for isolated spots to see repeated thunderstorm development both in the prefrontal airmass and during the passage of the front, which could locally increase flash flood risks.
Bericht laatst bijgewerkt: 02-07-2009 14:12
