Valid: Tue 27 Sep 2011 06:00 to Wed 28 Sep 2011 06:00 UTC
Issued: Mon 26 Sep 2011 16:38
A level 2 was issued for eastern Sicily, Malta and surrounding areas mainly for excessive convective rainfall.
A level 1 was issued for the rest of Sicily and surrounding areas mainly for excessive convective rainfall.
The dominating feature on Tuesday will be the gradually strenghtening ridge and developing omega block over W-CNTRL Europe. A weak mid/upper level disturbance remains almost stationary just offshore Sicily and will be the focus for another round of intense and excessive convective rainfall around Sicily. At surface, a weak cyclone deepens further just south of Sicily. Overnight on Wednesday, it gradually organizes into a rather intense small scale cyclone. WRF model simulates this developing tropical-like system additionally during Wednesday south of Sicily.
... eastern Sicily, Malta and surrounding areas ...
Still cool mid level temps will support another unstable environment around Sicily, as BL moisture remains very high, therefore resulting in around 500-1000 J/kg of MLCAPE. Very high PWAT values and persisting SE-erly LL flow will result in orographic precipitation over eastern Sicily, combined with pulsating/multicell storms. As wind shear is almost non-existent or very low, storm motions will be only few knots and almost stationary storms/clusters will additionally enhance flash floods threat. Expect daily accumulations in several tens of mm, while locally accumulations exceeding 100mm/24hrs are possible where clusters may persing for a longer period of time. A level 2 was issued for the areas where this threat will be maximized. A waterspout or two could form as well, given the enhanced LL lapse rates/instability and weak wind field.