12-07-2007 | Estofex | m.b.t. 13-07-2007 t/m 14-07-2007
Een level-1 area reikt nog net over uiterst ZW-NL i.v.m. kans op grote hagel en in mindere mate tornado's.
Storm Forecast
Valid: Fri 13 Jul 2007 06:00 to Sat 14 Jul 2007 06:00 UTC
Issued: Thu 12 Jul 2007 16:42
Forecaster: TUSCHY
SYNOPSIS
Finally a significant change of the European weather pattern is underway. A well defined upper-level trough just west of Europe digs further towards the south, enhancing intense WAA over parts of western Europe.
Another upper-level trough over eastern Europe shifts towards the east, while a broad high pressure area over the Mediterranen constantly gains influence, while expanding towards the north / northeast.
DISCUSSION
... Ireland and United Kingdom...
An intense LL depression is forecast to develop SW of Ireland, moving rapidly towards the NE. Attendant warm front will cross UK from the south and should reach Scotland during the night hours. A broad shield of stratiform rain will keep temperatures in the lower tens (western / central UK ) and no surface based convection expected during the day .
Chances for a few thunderstorms should increase after 00Z as cold front and dry slot enter SW UK / SE Ireland. DLS of 25-30m/s will be present and each convective segment could support an enhanced downward transport of stronger winds. No level area was issued because confidence is growing that no more than an isolated thunderstorm will occur.
... NE-France, Belgium, the Netherlands and extreme western Germany...
Aforementioned LL depression over UK supports not only an intense warm-up process over the area of interest but also a significant increase of surface dewpoints. Yesterday afternoon,dewpoints of 15-19°C were common over NW France while spreading eastwards.
Mid-levels will stay warm, but strong diabatic heating ( ~ 25°C ) and dewpoints in the upper tens should help to release some low-end instability. EL values also indicate that deep convection will be indeed a distinct possibility and DLS of 15m/s and up to 200 J/kg SRH3 values will be present, too.
Belgium should be the focus for a few severe thunderstorms with large hail as the main threat, if trends in latest model output won't change significantly.
Even an isolated tornado can't be ruled out as LL shear constantly increases during the late afternoon / early evening hours and LCLs stay low.
Hagel(-schade) | Onweer/blikseminslag | Tornado/hoosverschijnsel(en) | Verwachtingen/waarschuwingen