Storm Forecast
Valid: Fri 13 Oct 2006 06:00 to Sat 14 Oct 2006 06:00 UTC
Issued: Thu 12 Oct 2006 17:14
Forecaster: TUSCHY

SYNOPSIS

995hPa low SW of Iceland and 1035hPa high pressure area over CNTRL Europe will still stand vis - à - vis and will continue to influence the European weather.
A small upper-level low should finally drip off into the western Mediterranean while another weak upper-level trough should continue to influence the weather over parts of SE Europe....Some marginal instability release should be possible over S-Germany, Switzerland, W-Austria and extreme NW Italy, but any developing TSTM will stay weak and short-lived... Coverage should be too low for highlighting any specific area.

DISCUSSION

...Western Mediterranean...


Compact upper-level low will spin around the Balearic Islands and should support scattered TSTM development over the western Mediterranean.
Synop stations over S-France had a long period of weak offshore flow during the the morning and afternoon hours ( Thursday), which helped to confine TSTM development well offshore.... This weak northerly flow should slowly translate into a more NE-ly flow which should support a more humid and better mixed LL airmass to get incorporated into the weakly developed LL cyclonic flow over the Balearic Islands.... . This finally should help to realize a higher moisture content at LL, overspreading the Balearic Islands and combined with still cool mid-levels, the release of a few hundreds J/kg of instability looks reasonable.
An interesting note will be that this upper-level system should slowly acquire a more neutral-core nature ( supported by the UKMET cyclone phase evolution ) and therefore an increase in convective acitvity of the upper-level low ( also around the center ) can be expected.
Activity should peak out during the late morning / early afternoon hours over the Balearic Islands and should decrease due to warming at mid-levels and strengthening NVA, when core of upper-level trough will finally shift towards the SE during the evening hours....
Diminishing T-Td spread, steepening lapse rates and weak shear under the base of the upper-level low should be supportive for possible waterspout development, although threat should be confined to an isolated event due to warming low-levels ( decline at LL-instability maximum ).

Conditions will become favorable for one or two clusters to form during the later afternoon and early evening hours downstream of this trough // Sardinia - northern coastal areas of Tunisia - Sicily //.... Diffluent upper-level flow and increasing UL divergence values ( left exit region of arriving mid-/upper level jet ) should support widespread TSTM development with an isolated severe wind gust threat, but shear should be too low for a categorical level...although area will be monitored for a possible upgrade due to an enhanced severe wind gust risk, if indeed a cluster of storms can manage to form west of Sicily, where shear will be somewhat better.

...SE Mediterranean...

Convection will continue over the SE Mediterranean as upper-level trough slowly shifts towards the east...Storms should not reach severe TSTM criteria.