Storm Forecast
Valid: Mon 19 Jul 2010 06:00 to Tue 20 Jul 2010 06:00 UTC
Issued: Sun 18 Jul 2010 19:31
Forecaster: DAHL

A level 1 was issued across extreme northwestern Russia ... the western Ukraine ... eastern Slovakia ... and northern Hungary mainly for excessive convective rainfall and marginally severe wind gusts.

A level 1 was issued across the southern Balkans mainly for
excessive convective fainfall.

SYNOPSIS

The upper-air analysis shows a deep longwave trough over the northwestern parts of Europe and the northeastern Atlantic.
This feature is in the process of slowly closing off into a cut-off low, reaching the British Isles by Tuesday 06 Z.
A very weak southern branch of the upper frontal zone extends across the Mediterranean regions, with a weak imbedded vorticiy maximum
crossing Ionian/Aegean regions on Monday. The SFC charts reveal a weakening high-pressure area over the central parts
of Europe and weak low-pressure systems over the eastern Atlantic associated with the upper long-wave trough.
The main low-level baroclinic zone extends roughly from Iberia across the Alps into NE Europe and overall will remain rather stationary
through the period.

DISCUSSION

... Extreme NW Russia ... Belarus ... W Ukraine into N Hungary ...

It seems that MLCAPEs east of the cold-frontal boundary will range from 1000 to 2000 J/kg on Monday, though a lack of
radiosonde data from critical parts of eastern Europe on Sunday makes it difficult as assess the instability over this region.
Extensive convection on Monday probably has a stabilizing effect, so that CAPEs should generally be on a weakening trend.
This is also supported by the ICAPE fields of GFS.

The large-scale kinematic environment is seasonably weak, and the organization of storms will be tied to cold-pool formation,
which may at least briefly support organized line segments. Also numerous outflow boundaries are likely to modify the
local low-level wind profile and it is not out of question that cells favorably interacting with these, may briefly
attain low-level rotation.

Overall however, the main severe threat is excessive convective precip with the slow-moving storms and also marginally severe
wind gusts. An isolated marginally severe hail event cannot be ruled out, but the lack of shear should generally
limit the potential for organized/severe thunderstorms. The storm coverage should be rather low over White Russia, and
it is thus not included in the LVL1 risk area.

... Balkan States ... southern Italy ...

Scattered diurnally driven thunderstorms are anticipated over the Balkan States as well as over southern Italy. Despite
partly impressive SFC dewpoints, the available sounding data and model predictions suggest that the thermodynamic profiles will
generally be only weakly unstable and rather dry. The stronger cells may be capable of gusty outflow winds and some hail approaching
severe limits, but the overall severe threat is rather low. The southern Balkans will be affected by a short-wave trough on Monday.
Given the favorable synptic-scale background lift as well as the
complex orography, storm coverage may be rather large, and a threat for local flooding exists in addition to the marginal
wind/hail threat.