22 Juni 2007 - Slowakije
21 Oktober 2007 - Griekenland
7 Juli 2008 - Slovenie
13 Juli 2008 - Italie/Slovenie
15 Augustus 2008 - Polen/Slowakije
23 Januari 2009 - ZW-Frankrijk
12 Juli 2010 - NO-Nederland,NW-Duitsland,Denemarken
14 Juli 2010 - Nederland/Belgie
30 Juni 2012 - ZO-Duitsland
15 Juli 2012 - Roemenie/Oekraine
15 Oktober 2012 - Italie (Sicilie)
27 Juli 2013 - N-Frankrijk, Nederland, Belgie
29 Juli 2013 - Italie, Tsjechie/Z-Polen
5 Dec 2013 - NO-Nederland,NW-Duitsland
(Bron) | Gewijzigd: 5 december 2013, 13:01 uur, door Takenu
Valid: Sun 05 Jul 2015 06:00 to Mon 06 Jul 2015 06:00 UTC
Issued: Sat 04 Jul 2015 23:36
A level 3 was issued for N Germany mainly for the damaging wind gusts, large and very large hail, tornadoes and excessive precipitation.
A level 2 was issued for parts of Benelux, NE France, S Denmark, NW Poland and parts of Germany mainly for the damaging wind gusts, large and very large hail, tornadoes and excessive precipitation.
A level 1 was issued for France, Denmark, S Germany, W Poland, W Czech Republic, W Austria, parts of Italy and Switzerland mainly for the large hail, severe wind gusts and excessive precipitation.
Valid: Sun 19 Jul 2015 06:00 to Mon 20 Jul 2015 06:00 UTC
Issued: Sun 19 Jul 2015 00:01
A level 3 was issued for parts of Poland and W Belarus mainly for the damaging wind gusts, large and very hail, excessive precipitation and significant tornado event.
A level 2 was issued for parts of Germany, Poland, Belarus, NW Ukraine and N Czech Republic mainly for the severe wind gusts, large hail, tornadoes and excessive precipitation.
A level 1 was issued for parts of S Finland and parts of Russia mainly for the large hail and severe wind gusts.
A level 1 was issued for parts of UK, Netherlands, S Denmark, Germany, Switzerland, N Italy, Austria, Czech Republic, Slovakia, W Hungary, Belarus and NW Ukraine mainly for the large hail, severe wind gusts and excessive precipitation.
A level 1 was issued for NE Spain mainly for the large hail and excessive precipitation.
Valid: Sat 05 Sep 2015 06:00 to Sun 06 Sep 2015 06:00 UTC
Issued: Fri 04 Sep 2015 22:00
A level 3 was issued for parts of Italy, Croatia, Bosnia and Herzegovina mainly for excessive rain, large hail, severe wind gusts and tornadoes.
A level 2 surrounds the level 3 area for the same threats but with less spatial coverage.
A level 1 surrounds level 2 mainly for excessive rain, large hail and severe wind gusts.
A level 1 was issued for E Spain and North Africa mainly for excessive rain and large hail.
Valid: Mon 31 Aug 2015 06:00 to Tue 01 Sep 2015 06:00 UTC
Issued: Mon 31 Aug 2015 06:15
Forecaster: VAN DER VELDE
A level 3 was issued for parts of Spain and France mainly for chances of very large hail and severe wind gusts.
A level 2 was issued for France, Benelux, N Germany and S Scandinavia mainly for chances of large hail, tornadoes and excessive convective precipitation.
Valid: Fri 17 Jun 2016 06:00 to Sat 18 Jun 2016 06:00 UTC
Issued: Thu 16 Jun 2016 20:12
A level 3 was issued for E-Hungary, W-Romania to SW-Ukraine mainly for damaging hail and severe wind gusts.
A level 2 surrounds that level 3 for a lesser risk of extreme events. Still large/very large hail, severe wind gusts, excessive rain and an isolated tornado event are possible.
A level 3 was issued for W-Belarus, NE Poland and Lithuania mainly for an augmented tornado risk (a significant event is possible), damaging wind gusts, large or very large hail and excessive rain.
A level 2 surrounds that level 3 for a lesser risk of extreme events. Still large/very large hail, severe wind gusts, excessive rain and an isolated tornado event are possible.
A level 1 surrounds all other level areas. All kind of severe is possible, but no extreme events are forecast.
A level 1 was issued for S-Germany mainly for isolated large hail and an isolated tornado event.
A level 1 was issued for N/W-Germany, Benelux, parts of France and S-UK mainly for excessive rain and an isolated tornado event.
A level 1 was issued for the Balearic Islands and NE Spain mainly for large hail and excessive rain. An isolated tornado event is possible.
A level 1 was issued for far W-Russia mainly for large hail and excessive rainfall amounts.
... SYNOPSIS ...
Positive tilted upper trough remains anchored over W-/CNTRL- and N-Europe. A significant impulse evolves along its eastern fringe over the Czech Republic/far E-Germany and Poland. This vortex deepens rapidly along a pronounced baroclinic zone while moving to the N/NE. On the one hand, northeastbound surging tongue of high IPV values indicates the substantial dynamics, which accompany that process, on the other hand they highlight a pronounced dry slot, which works its way from the Czech Republich over Poland to the NE.
Accompanied LL-vortex features a strong deepening rate for this time of year with surface pressure falling to 995 - 990 hPa. Phase diagrams feature transformation towards a shallow warm-core vortex, which reflects an healthy looking wrap-around occlusion. This occlusion advects a warm/moist and rather unstable air mass to the depression's center. A blend of different models places the depression over N/NW Poland at 12 UTC and over the CNTRL Baltic Sea during peak strength around 00 UTC. There, models diverge regarding further timing and track during its approach towards Finland. Reasoning probably is growing uncertainty how fast this vortex becomes vertically stacked. Until then, models in general show a unique picture with EZMW a tad slower compared to the German model suite.
Regarding fronts, the aforementioned depression pushes a sharpening warm front from Belarus to Estonia with a pronounced cold front surging over NE Poland to the E/NE. Betimes, the warm sector shrinks and the occlusion becomes the main boundary, which affects Finland.
Trailing cold front opens out into a wavy boundary, which runs from the W-Ukraine all the way to S-CNTRL Italy. An older front (already occluded for most parts) extends from N-Finland to the White Sea to W-Russia and features no substantial eastbound motion during the forecast. Regions like CNTRL/W-Europe continue to be affected by weak pressure gradients, where numerous mesoscale boundaries once again act as foci for CI.
A dangerous outbreak of severe thunderstorms is forecast over parts of E-CNTRL Europe which includes large and damaging hail, severe wind gusts, flash-flood producing rain and tornadoes!
... Parts of Poland, parts of Belaurs, Lithuania, Latvia and Estonia all the way to S-Finland ...
NNE-ward moving and deepening cyclone over the Baltic Sea results in a responding low-/mid-tropospheric wind field over the warm sector, which covers the area of interest. Backed LL flow causes enlarged hodographs with SRH-1/3km of more than 250/200 m^2/s^2 respectively. Maximized backing occurs along and just to the south of northbound moving warm front. The warm sector features 1-2 kJ/kg MLCAPE with decreasing values towards Latvia and Estonia. Cap weakens during the day as diabatic heating sets in, although impressive deep-layer forcing most likely erodes existing cap quite early. LCLs drop to 1 km or less, especially along the warm front, where moisture pooling offers abundant BL moisture (BL mixing ratios in excess of 12 g/kg). This moisture also offsets only modest mid-level lapse rates. Those weak lapse rates could lessen the overall hail risk a bit.
Two foci exist. The first one is the warm sector convection over Lithuania, NE Poland and W-Belarus. Cap probably suppresses initiation until noon. Between 12-18 UTC however, arriving deep-layer lift and ongoing diabatic heating should result in scattered supercells with all kind of hazards, including large hail (isolated very large hail possible with mature supercells despite modest mid-level lapse rates), severe wind gusts and excessive rain. The tornado risk is enhanced in the warm sector and a significant tornado event is possible for storms near the warm front.
The second focus is the NEward surging cold front with dry slot approaching from the SW. Main uncertainty is ongoing DMC from the previous night over SW/CNTRL Poland. Despite some temporal weakening during the forenoon hours (still capable of producing severe events!), this convection re-intensifies rapidly when crossing E/NE Poland. Intense 30 m/s speed max at 700 hPa approaches this convection from the SW and a potential scenario will be a developing severe MCS, which races to the N/NE. Widespread severe/damaging wind gusts will be the main hazards, although expected shear will probably support a few tornado events as well. Large hail is also possible and combined with severe wind gusts, damaging wind-driven hail could be a life-threatening risk!
Due to the high coverage of severe thunderstorms, a confined level 3 was issued.
Over N-Estonia and S-Finland, convection becomes increasingly elevated with the main hazard being heavy rain. However in case of local near surface based convection, an ongoing isolated tornado risk still exists.
... W-Ukraine to E-Croatia ...
Very warm 850/700 hPa temperatures overspread most of SE-Europe and cause robust capping. This cap gradually erodes along its western fringe due to marginal cooling and faint forcing by passing short-waves. Main focus for CI will be a SE-ward trailing frontal boundary, which interacts with the rough orography like the Carpathians and the Dinaric mountains. Isolated to scattered thunderstorms erupt in an environment with 1-2 kJ/kg MLCAPE and MUCAPE peaks of more than 3000 J/kg! Very fat mid-level CAPE profiles overlap with 30 m/s 0-6 km shear. 25 m/s 0-3 km shear support well organized and long-lived supercells with a damaging hail threat (hail diameter in excess of 5 cm is likely). A deep and well mixed subcloud layer also assists in very intense downdrafts, which probably cause a few hurricane-force wind gust events - combined with the hail, life-threatening storms with high-end impact are possible. Another confined level 3 area was issued despite ongoing uncertainties of final thunderstorm coverage.
During the night, supercells grow upscale into one or two severe MCSs (mainly driven by intense cold pools) and hence the level 2 was expanded far to the E/SE. Severe/damaging wind gusts, large or very large hail and an excessive rainfall risk exist. With a cooling/moistening BL, the tornado risk also increases.
... Extreme NE Germany, NW Poland, covering most of the Baltic Sea and E-Sweden ...
Impressive wrap-around occlusion advects a very moist/unstable air mass to the depression's center and therefore beneath the left exit region of an astonishing (for June) 60 m/s upper-level jet. Deepening vortex supports influx of that air mass to the CNTRL/S-Baltic Sea before weakening during the overnight hours in response of a weakening trend of that vortex. Forecast soundings inside that occlusion show 700-1000 J/kg MUCAPE and PWATs of 30-40 mm. Unidirectional shear within this pronounced deformation band probably results in embedded enhanced/banded convection, which causes excessive rainfall amounts. 12 hourly rainfall amounts beneath that deformation zone will probably be in the range of 40-80 mm with locally higher amounts. Therefore an high-end level 1 and a level 2 were issued for the S-CNTRL Baltic Sea (level 2 where maximized thunderstorm activity exists). Due to ongoing track uncertainties of that depression, also SE/E-Sweden was included into the enhanced rainfall risk.
... Balearic Islands to E-Spain ...
First chance for isolated severe storms already exists with ongoing convection from the previous night. A SW-NE aligned low-pressure channel weakens during the day, which results in a breakdown of the BL flow and in the evolution of numerous more or less pronounced convergence zones. Those will be a focus for isolated CI, as cap should be overcome at least on an isolated scale. Temporal drying of the low/mid-troposphere however limits overall coverage.
Main focus for CI resides on the final approach of the mid/upper trough during the night, where steepening mid-level lapse rates and cooling low-/mid tropospheric air atop warm SSTs result in weakly capped 1-1.5 kJ/kg SBCAPE.
DLS oscillates aoa 20 m/s during the day with enhanced LL shear along the convergence zones during the day and in general during the night. Hence, well organized multicells/isolated supercells with large hail, excessive rain and strong to isolated severe wind gusts are forecast. The tornado threat is enhanced along the convergence zones, but also exists with any supercell during the overnight hours.
... Pyrenées and NE Spain ...
Diurnal heating and a sharpening mid-level trough over the S-Bay of Biscay result in backed winds over NE Spain, which support the onshore advection of a modified maritime air mass. As BL spreads to the Pyrenées, steep mid-level lapse rates atop cause MLCAPE of 1 kJ/kg along the coast with decreasing values to the N/NW. Forecast soundings show thickening mid-level CAPE profiles with moderate shear of 15 m/s in the hail growth layer and hence the main risk will be large hail. In addition, an isolated severe downburst event is possible next to the Pyrenées with a deep/dry subcloud layer and an isolated tornado event is possible along the coast with a more humid BL air mass and stronger LL shear.
... N-Italy, far S-Austria and NW-Slovenia ...
As the main upper trough refuses to push east and keeps its positive tilt, deep SW-erly flow regime continues to affect N-Italy. Hence, BL moisture remains rather high with BL mixing ratios of 8-9 g/kg. Steepest mid-level lapse rates exist over NW Italy and along the S-Alps, where 500-1000 J/kg MLCAPE is forecast. Dependant on the exact shape of the trough and timing/track of short-waves, DLS oscillates aoa 15 m/s. Hence expect a few organized multicells/supercells with large hail and strong to isolated severe wind gusts. Betimes, thunderstorms cluster and the heavy rainfall risk increases. Southern most storms (which f.ex. approach the N Adriatic Sea) have to be monitored for and low-end tornado risk as depth of BL moisture increases with somewhat stronger backed BL flow. The risk gradually diminishes during the night.
... N-France, Belgium/parts of the Netherlands to N/NW-Germany and S-UK ...
Ageostrophic response to the deepening LL vortex to the east results in a pronounced confluent flow regime over the area of interest (mainly N-Germany). Complexity increases as a few models develop a second circulation over Benelux, which would result in another convergence zone from N-France to NW-Germany. Similar to the previous days, forecast soundings show very moist profiles with elongated/thin CAPE profiles and very low LCLs but also augmented LL lapse rates (mainly diabatically driven) with substantial LLCAPE build-up. Hence another round of slow moving and gradually clustering thunderstorms is forecast to evolve during the forenoon hours. Those clusters leisurely spread east and excessive rain is likely. Also, aforementioned favorable LL CAPE forecast and augmented 0-2 km convergence signals indicate enhanced probabilities for another round of a few funnel/isolated tornado reports.
... S-Germany ...
Just north of the Alps, a passing short-wave during the afternoon hours adds enough synoptic-scale lift for at least isolated CI. 15 m/s DLS with 200 m^2/s^2 SRH-3 support an isolated well organized multicell/supercell event. Large hail and strong/isolated severe wind gusts would be the main hazard, although dropping LCLs during the evening may offer a short time-frame for an isolated tornado event. This activity moves to N-Austria and weakens after sunset.
... W-Russia ...
A broad level 1 was issued for slow moving storms. 1-1.5 kJ/kg MLCAPE but weak DLS support pulsating thunderstorms with excessive rain and large hail. An high-end level 1 covers that risk. Activity diminishes after sunset.
Valid: Sat 18 Jun 2016 06:00 to Sun 19 Jun 2016 06:00 UTC
Issued: Sat 18 Jun 2016 06:09
A level 3 was issued for NE Romania, N Moldova and parts of Ukraine mainly for very large hail, damaging wind gusts and excessive precipitation.
Valid: Sun 19 Jun 2016 06:00 to Mon 20 Jun 2016 06:00 UTC
Issued: Sat 18 Jun 2016 23:17
Forecaster: PUCIK / GROENEMEIJER
A level 3 was issued for S Serbia, extreme NW Bulgaria and SW Romania mainly for large to very large hail, damaging wind gusts and to the lesser degree for tornadoes and excessive rainfall.
Valid: Mon 20 Jun 2016 06:00 to Tue 21 Jun 2016 06:00 UTC
Issued: Mon 20 Jun 2016 07:01
A level 3 was issued for W Romania, E Hungary, NE Serbia, mainly for large to very large hail, damaging wind gusts, excessive precipitation and tornadoes.
A level 2 was issued for Belarus, E Lithuania, W Ukraine, W Romania, E Hungary and Serbia mainly for large to very large hail, damaging wind gusts, excessive precipitation and tornadoes.
A level 1 was issued for area extending from W Russia up to W Balkan Peninsula mainly for large hail, severe wind gusts and excessive precipitation.
Cut-off over Italy weakens and geopotential heights are constantly rising over most of the S, E and SE Europe. A thermal boundary (a quasi-stationary wavy front) within northwardly moving tropical highly unstable air mass extends from Baltic countries, trough E Poland, E Hungary up to Croatia. A main polar jet stream is located between N Atlantic and Benelux. A sub-tropical jet streak stretches longitudinally from S Italy up to Belarus on the north-eastern flank of the fading Italian trough. In its northern section, a low-level jet develops over Belarus within a passage of the shortwave trough. SW Europe is under influence of a broad ridge while another high is located over W Russia. The main thunderstorm area runs along thermal boundary between tropical and polar air mass. A few more or less pronounced short-waves induce temporarily enhanced synoptic-scale lift. Severe and extremely severe thunderstorms are expected in the corridor from Serbia up to Belarus, where a a highly unstable warm sector is overlapped by a jet streak and thus strong vertical wind shear.
...area extending from W Russia up to W Balkan Peninsula...
Rich boundary layer's moisture on the eastern side of the quasi-stationary frontal boundary combined with ongoing evapotranspiration and regional confluent flow results in mixing ratios up to 13-14 g/kg. Given an overlap with vertical lapse rates exceeding 7 K/km , ML CAPE develops mostly up to 1500-2000 J/kg and locally even > 3000 J/kg. A jet streak covering warm sector on the eastern side of the frontal boundary results in a high DLS up to 25-30 m/s and locally provide a rare and an extreme overlap with high thermodynamic instability (DLS*WMAX values ~ 2000 m2/s2) in the corridor from W Ukraine and Serbia. Any thunderstorm developing in this environment may very quickly become an isolated supercell (SRH values from 250-400 m2/s2) with a potential of producing giant hail, damaging wind gusts and significant tornadoes given increasing LLS up to 10 m/s in the late afternoon hours. In addition, a strong airflow at 700 hPa and resulting 15-20 m/s MLS may potentially organise convection into bowing features where hurricane-force wind gusts are possible. Although there is not a source of significant large-scale lift, a long-lived squall line cannot be ruled out. In this scenario, thunderstorms would produce a widespread damage due to severe wind. In the northern area of lvl 2, although a thermodynamic instability is lower, a similar scenario with an extremely severe supercells is possible. Tornado threat seems to be high in this area due to a more favourable wind profile with extreme SRH values (400-600 m2/s2) and stronger LLS during the day (> 15 m/s). In addition, the area is under influence of the passing shortwave. One or two MCS in the late evening hours are possible. In addition to afromentioned phenomena, a moist vertical profile with PW exceeding 30-35mm may result in a torrential rain produced by supercell, multicell clusters and MCS in the evening hours. A highest threat is confined to a meso-low located over E Poland where a motion of the thunderstorms will be slower.
The main limiting factor for this forecast is whether a CI will take place. Most of the NWP model scenarios agree on the CI due to local convergence zones and orographic lift in the corridor from Serbia to W Ukraine. However, remaining cloud-cover from the nighttime thunderstorms may inhibit diurnal heating and thus do not allow thermals to pass CIN zone. Although we are aware of this risk, a level 3 is issued due to possibility of extremely severe thunderstorms in an extreme overlap of high DLS and very high CAPE. The more uncertain areas with environment favourable for severe storms include E Poland and E Belarus where dew point are lower and NWP models are more conservative in terms of CI over this areas. Therefore, we include these areas in the lvl 2 areas, but they cover 15% probability for lightning.
Valid: Tue 21 Jun 2016 06:00 to Wed 22 Jun 2016 06:00 UTC
Issued: Mon 20 Jun 2016 21:05
A level 3 was issued for Ukraine mainly for severe wind gusts, large to very large hail and tornadoes.
A level 3 was issued for parts of Belarus, Ukraine and W Russia mainly for damaging wind gusts, large hail, excessive rainfall and tornadoes.
A level 2 surrounds levels 3 mainly for large hail, excessive rainfall, severe wind gusts and torndoes.
A level 1 was issued for parts of Russia, Belarus, Ukraine, Moldova, E Slovakia, E Hungary, Romania,Serbia, Bosnia and Herzegovina, Montenegro and NW Bulgaria, mainly for excessive rainfall and large hail. Also landspouts/tornadoes cannot be ruled out.
5 dagen achter elkaar een level 3
Valid: Mon 18 Jul 2016 06:00 to Tue 19 Jul 2016 06:00 UTC
Issued: Mon 18 Jul 2016 03:20
Forecaster: VAN DER VELDE
Levels 2 and 3 were issued for N Ukraine, E Belarus and W Russia mainly for severe convective wind gusts and large hail, and to a lesser extent tornadoes.
A level 1 was issued for E Belarus mainly for excessive convective rain chances.
A level 1 was issued for NE France, S Germany and Slovenia/Austria border mainly for slight chances of large hail.
A mid-level ridge / anticyclone over France is flanked by a broad upper trough from Scandinavia to the Black Sea. Warm, humid air converges into an almost stationary frontal zone especially between central Ukraine and the Belarus/Russia border with MLCAPE values of 1500-2500 J/kg.
...Ukraine, E. Belarus, W Russia...
At 00Z, surface mixing ratios of 13-15 g/kg (Td 17-20°C) are observed over N Ukraine, SE Belarus and adjacent W Russia. The 00Z Gomel sounding indicates very steep lapse rates from low levels to 550 hPa and 1000 J/kg CAPE, which will increase during the day with diurnal heating. GFS MLCAPE using a 1000 m deep layer exceeds 2000 J/kg with ICAPE over 4 MJ/m² thanks to the deep moist boundary layer. The LCL is at 2000 m over Russia decreased to below 1000 m over Belarus southward into Ukraine in the cold air advection region. Storms on the western boundary will be slow-moving storms with chances of excessive convective precipitation and flash floods. Storms in the warm air advection regime marked by the level 2 and 3 area will develop in about 15 m/s 0-6 km shear vector magnitude and over 250 m²/s² of 0-3 km storm-relative helicity, which will turn a number of storms into supercells which can produce very large hail and severe wind gusts, and clustering of storms will generate squall lines with significant severe wind gust potential. The environment contains Delta-Theta-E values of 20-30 Kelvin thanks to the warm and humid low levels (high theta-e) but cold and dry mid levels (low theta-e). The evaporational cooling of large precipitation masses can accelerate downdrafts and cause microburst wind phenomena.
Low level shear is adequate to moderate (7-15 m/s 0-1 km shear) and will favor bow echo formation. It also allows for local tornadogenesis. Weak capping over a deep layer for much of the day suggests early storm development. This may diminish available CAPE, but the strong moist/warm air advection from the southeast may compensate sufficiently.
...S Germany, NE France, Austria-Slovenia border...
With roughly 10 m/s deep layer shear and 500-1000 J/kg MLCAPE (250 J/kg Slovenia), some large hail may be produced by some storms. The lift conditions for initiation are very limited by the high pressure nearby, so will likely depend on orographic enhancement.
...C and W France...
Dry air with steep lapse rates from the south meet with moist air in this area, where 1000 J/kg MLCAPE can result. There is also more than 10 m/s DLS. However, storm initiation will be very difficult by the lack of low level lift close to the N France anticyclonic center, with divergent winds, and mid level subsidence just east of the ridge axis.
Valid: Tue 01 Aug 2017 06:00 to Wed 02 Aug 2017 06:00 UTC
Issued: Mon 31 Jul 2017 22:12
A level 3 was issued for Germany and NW Poland for severe to damaging wind gusts, large or very large hail, excessive precipitation and strong tornadoes.
A level 3 was issued for NE Poland, Kaliningrad Oblast and Lithuania for severe to damaging wind gusts, large or very large hail, excessive precipitation and strong tornadoes.
A level 2 was issued across parts of France, Switzerland, S Belgium, Luxembourg, Germany, Czech Republic, Poland, Kaliningrad Oblast, Lithuania and Latvia mainly for severe winds and large or very large hail, excessive precipitation and tornadoes.
A level 1 was issued across a larger part of Spain, France, Switzerland, S Belgium, Luxembourg, Germany, Czech Republic, Poland, S Sweden, S Denmark, Kaliningrad Oblast, Lithuania, Latvia and Estonia for the same risks.
A quasi-stationary frontal boundary is found ahead and around the extensive ridge, stretching from N Spain towards the Baltic States. A vigorous mid-level jet is forecast to cross Germany, Poland and the Baltic States during the passage of fast-moving short-wave trough. The air masses converging on the aforementioned boundary along with the upper-air dynamics should create a potentially dangerous environment during Tuesday and the early morning of Wednesday. For this reason, two level 3 areas were issued to address the anticipated severe weather risks. For the rest parts of the continent, some convective phenomena are expected in the British Isles and in Scandinavia, but risk threat for severe weather events is limited.
.... Germany and NW Poland .....
Ongoing convective activity from the previous night will create a shield of clouds over northern Germany in the morning that is expected to become less thick until 12z. The highly unstable tropical air mass at the leading edge of the ridge, with elevated mixed layer, will create large amounts of MLCAPE up to 2000 3000 J/kg. A sharp gradient of mid-level geopotential will lead to enhanced DLS between 20-35 m/s, overlapping with high CAPE values. Widespread CI is expected in Germany along the main convergence zone where significant SREH0-3km indicate that most of the storms will become supercells able to produce very large hail and tornadoes. Diurnal heating and local convergence zones will first provide enough lift for discrete cells to form and then organize into clusters (MCS). Several scenarios from high-resolution models suggest the development of a QLCS, with NE-ward bowing structures that will be capable of producing severe to damaging wind gusts. Inside level 3 area, veering wind profiles with strong LLS configuration and very low LCLs increase the potential of tornadogenesis, with some strong tornadoes (F2 or stronger). During the night, a short-wave trough will provide additional lift and a new round of multicellular systems is expected to cross N Germany, entering NW Poland. Excessive precipitation, severe wind gusts and tornadoes will be the main threats. In northern parts of Poland, diurnal heating seems that will not be able to provide enough lift, due to note-worthy CIN values, this is why a level 3 was excluded.
..... NE Poland, Kaliningrad Oblast and Lithuania .....
This area of interest is another hot-spot for severe DMC during Tuesday. Between 12z and 15z, discrete storm cells can become supercells as DLS will exceed 20 m/s and forecast hodographs show LL air masses with strong helicity and shear. These storms will be able to produce large hail, severe wind gusts and tornadoes. A second round of severe storms is expected during the night, as a MCS from the Baltic Sea is forecast to cross the area, ahead of the short-wave trough axis. Very steep lapse rates can pose a threat for large hail and severe wind gusts even during the night, but the main threat will be excessive precipitation as training convection is simulated by most NWP models.
..... France, Switzerland, Luxembourg, S Belgium .....
The widespread overnight elevated convection is expected continue affecting a large part of France. Diurnal heating will provide lift for new cells in the afternoon, propagating E- NE. The highly sheared environment, the moist PBL, the steep mid-level lapse rates and the high PW values increase the probability for storms to become severe and produce all kinds of severe events. The enhanced SREH0-3km suggests that storms will acquire rotation and become supercells. Any supercell storm will be able of producing large hail and damaging wind gusts. In addition, strong LLS indicates that a risk of tornadoes will exist.
.... Spain .....
A level 1 was issued for parts of Spain where strong DLS and some 1000-2000 J/kg CAPE are expected, under a relatively strong cap. If an isolated storm develops, it may quickly turn into a supercell producing large hail and severe wind gusts.
Valid: Mon 03 Jul 2017 06:00 to Tue 04 Jul 2017 06:00 UTC
Issued: Mon 03 Jul 2017 03:54
Forecaster: VAN DER VELDE
A level 3 was issued for eastern Bulgaria mainly for very large hail and severe convective wind gusts.
A level 2 was issued for Bulgaria and southern Romania mainly for excessive convective rainfall, and for large hail and severe wind gusts in Bulgaria and NE Greece.
The southwestern half of Europe is under the influence of a stable high pressure system, while southern Scandinavia, and the eastern Balkan / Black Sea region are affected by very vigorous troughs that will activate deep convection.
The mid level trough coming from the northern Atlantic Ocean intensifies as it approaches Denmark by 18Z, then ploughs into the southern Baltic Sea region where on Tuesday 06Z it should start to move into Lithuania. CAPE is weak (50-200 J/kg)
A larger trough is moving very slowly across the Balkan, where Bulgaria and southern Romania will be under more than 24 hours of intense dynamic lifting of warm air, with MUCAPE between 1000-2000 J/kg until it is removed around 18Z. The subtropical jet stream blows from SW-NE over this zone
..eastern Balkan and Black Sea region...
A strong easterly flow over the Black Sea advects a moisture-rich air mass into Bulgaria and southern Romania (11-15 g/kg mixed over 0-1 km, GFS model), with currently Td of mostly 18-20 C, even 22 degree dewpoints in central Bulgaria. The flow should replenish the supply consumed by nocturnal thunderstorms, until it is pushed eastward by the cold front, which will come with intense thunderstorm activity. Because of opposing low and mid level flow, deep layer shear (0-6 km) will be over 30 m/s and 0-3 km storm-relative helicity ranges between 250 and 400 m2/s2 in the unstable airmass. Therefore, conditions look very favorable for a high concentration of severe storms, with supercells and squall lines bringing very large hail, severe wind gusts (Cordfidi>25 m/s, Delta Theta-e>20K S Bulgaria) and perhaps a tornado (0-1 km shear generally remains below 10 m/s, except along the BG-RO border). The combination of high PW, high column relative humidity, strong convergence and slow storm motion makes severe convective precipitation intensity and duration likely across northern Bulgaria and southern Romania with extensive flash flooding possible. As the system moves into the Black Sea during the evening, a strong cap prevents eastward propagation of the storms, but they likely will remain active along the Romanian and Moldovan coast, fed by strong low level moisture transport vectors.
...southern Scandinavia, southern Baltic Sea, northern Germany and northen Poland...
Low CAPE but strong dynamics and moderate shear in low and mid levels will be present at 18-21Z when the trough enters Denmark, southern Sweden and N Germany. A well-defined surface convergence line seems to be missing according to GFS output while the 3 km theta-e fields show an intensifying mid-level cold front. Shear is mostly friction-induced and reaches over 12 m/s 0-1 km over parts of Denmark, N Germany and N Poland, which could allow an isolated tornado, while gusts seem to remain under 20 m/s. A level 1 does not appear to be necessary.
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