Storm Forecast
Valid: Wed 23 Mar 2011 06:00 to Thu 24 Mar 2011 06:00 UTC
Issued: Tue 22 Mar 2011 22:07
Forecaster: PUCIK

No threat levels have been issued.

SYNOPSIS

A high pressure complex is forecast to be centered over British Isles and elongated in the southeast/nortwest direction. To its north a well defined baroclinic zone lies in a very strong northwesterly flow, reaching 90 m/s at 300 hPa and 60 m/s at 500 hPa level in the jet-streak embedded in the flow. As the series of disturbances move across the Norwegian Sea and Scandinavia, low-topped convection is anticipated especially over the coastal areas and Central Norway. Some of the convection might be weakly electrified but the overall conditions do not seem to be supportive of an organised, severe threat posing deep moist convection. Over Eastern Europe, flow diverts around the high with easterly flow over the Mediterranean regions and Southwestern Europe. Two disturbances are forecast here - one in the form of a short-wave trough with zonal orientation stretching from Turkey to the Ionian Sea and moving southwards. The other disturbance will be a cut-off low centered partly over Western Iberia, slowly progressing northwestwards.

DISCUSSION

... Northwestern Morocco ...

With easterly flow at lower levels of troposphere, shifting to southwesterly at mid and strong westerly at upper levels, sufficient wind shear will exist for the well organised convection, including supercells. Thanks to the easterly flow, an elevated mixed layer will be advected off the elevated regions, resulting in CAPE values reaching roughly hundreds of J/kg. Thermodynamic condtions would probably be conducive to low-topped supercellular convection posing threat of isolated large hail and/or severe wind gusts. GFS simulates high CIN values, reaching locally over -200 J/kg, which strongly decreases the likelyhood of storm initiation. Even though there seems to be some contribution from the synoptic-scale forcing on the forward flank of the cut-off low and low-level convergence over the unstable regions, models simulate only very spotty, if any precipitation over the region. Due to the uncertainities regarding the initiation and the degree to which cap will be eroded by forcing, Level 1 is not warranted at the moment.