Forecast Update
Valid: Fri 28 Sep 2012 15:00 to Sat 29 Sep 2012 06:00 UTC
Issued: Fri 28 Sep 2012 14:47
Forecaster: TUSCHY

A level 2 was issued for parts of E/NE Spain, the Balearic Islands and parts of the W-Mediterranean mainly due to excessive rainfall, large to very large hail, strong to severe wind gusts and a few tornado events.

A level 1 surrounds the level 1 with similar risks but with minor intensity.

SYNOPSIS

Please refer to the main outlook issued at Thu 27 Sep 2012 22:11 Z

DISCUSSION

... Level 2 ...

An east/northeastward moving convergence zone/cold front remains progressive with a long-lived and mature V-shaped MCS present. Initiation of that MCS occurred a bit more offshore than yesterday anticipated, which may temporarily lower the heavy rainfall risk along the SE coast of Spain. Nevertheless, the first 100 mm/h and more rainfall amounts already arrived, which is enough for flash flooding.

Of interest is the strong inflow towards the evolving MCS with stations to the NE reporting sustained winds of 15-30 kt (local gusts up to 45kt) from SE Spain all the way to the Balearic Islands. This may be also the result of the gradually consolidating/strengthening lower tropospheric vortex over E-central Spain. This increases confidence in a potential slow-down of that MCS during the next few hours and a re-orientation more into a W-E direction, given increasing moisture influx from the E/NE. If this verifies, the flash flood risk may increase significantly over E-Spain, given back-building activity and slower forward motion. The Balearic Islands will also see an increase in severe thunderstorm activity during the following hours, despite ongoing uncertainties, how far east storms build into the capped air mass (refering to Palma de Mallorca, 12Z).

To emphasize the hazard once again: The risk of excessive and potential life-threatening rainfall amounts with locally serious flash flooding remains valid!

Beside the excessive rainfall risk, 12Z sounding/hodogrpah of Murcia confirms the risk of well organized thunderstorms with that MCS as not much extra heating is needed for more robust CAPE within an highly sheared environment (especially robust directional shear). An isolated tornado event is possible next to strong to severe wind gusts and isolated large hail.

The level areas were adjusted, but overall distribution remains the same.