Storm Forecast
Valid: Tue 30 May 2006 06:00 to Wed 31 May 2006 06:00 UTC
Issued: Mon 29 May 2006 22:50
Forecaster: GROENEMEIJER

SYNOPSIS

Tuesday at 06:00 UTC... a broad, deep longwave trough is still located over Europe.
A WSWly mid-level flow stretches from Italy to the eastern Ukraine. A northnorthwesterly flow stretches from the Atlantic over the British Isles and France into the western Mediterranean region. One shortwave is expected to be initially along a line from Frankfurt a.M. to Marseille and reach SErn Poland on Wednesday morning. Another shortwave is expected east of Scotland and reach Switzerland 24 hours later. A frontal zone is expected to stretch initially from the northern Adriatic Sea over northern Romania into the southern Ukraine.
The approach of the first-mentioned trough induces pressure falls resulting in the formation of a baroclinic low that is expected over the western Ukraine at midnight. As the low develops, western parts of the front will accelerate southeastward as a cold front. Over Bulgaria, Romania, a SSWly low-level jet is expected to advect very warm air northward.

DISCUSSION

northern and eastern Romania, Moldova, Ukraine

The surface warm front initially over southern Moldova is should move northward at the same time. 500-1000 J/kg MLCAPE is expected to develop near the triple point of the depression over NErn Romania, Moldova and adjacent parts of the Ukraine. Models forecast around 300 m2/s2 0-3 km SREH to develop as 20-25 m/s SWly winds at 500 hPa overspread a 15-20 m/s low-level jet on top of SEly surface winds.
AFWA MM5 and GFS agree that convective development will occur over NErn Romania and Moldova. Given the strong shear and helical environment, the development of supercells appears likely. These should be capable of producing large hail, damaging gusts and tornadoes. The cahcne of tornadoes will be maximized near the warm front where lowest LCL and LFC heights and highest SREH values should be present. Cells may gradually cluster into a linear MCS with a threat of damaging winds as they move eastward into the Ukraine.

Croatia, Bosnia-Herzegovina, Serbia and Montenegro, western Romania

Ahead of the cold front, small amounts of CAPE may form in places. Model guidance suggests that about 300 m2/s2 SREH should be present for right-moving storms ahead of the front as well as 25-35 m/s of 0-6 km bulk shear. A few storms will likely develop scattered across the level 1 area. These will be capable to produce isolated large hail and strong to severe gusts. The largest chance of convective development currently appears to be near the Adriatic coast. A chance of tornadoes will exist there as well, as 10-15 m/s of low-level shear should be present.

Spain

Models agree on the development of widespread convective storms across the southern half of the peninsula. Steep lase rates suggest that some risk of downbursts will exist. However, the primary risk appears to be localized flooding as the overall flow should be quite weak and storms will likely be slow-moving.