Nella giornata odierna si sono registrate precipitazioni di intensità fino forte localmente nel Ponente regionale e relativo entroterra appenninico con quantitativi elevati di accumulate.Da questa notte si attendono nuove piogge e temporali diffusi, anche associati a fenomeni temporaleschi di forte intensità e con possibili nubifragi.

Visto le accumulate registrate con le ultime precipitazioni, le nuove intense piogge previste per l'entroterra savonese e genovese eleverebbero sensibilmente il rischio locali frane e smottamenti in un territorio saturo portando possibili ripercussioni anche a fondo valle/costa.

Fortunatemente come già anticipato nel pomeriggio, i modelli meteo hanno ridotto fortemente la previsione del totale delle precipitazioni ma questo non può farci pensare che l'allerta sia terminata e/o ridimensionata.

In un territorio come quello ligure fatto da mille microclimi basta una convergenza tra vento di scirocco e tramontana che impedisce la traslazione del sistema temporalesco verso est per localizzare le precipitazioni per molto tempo in una porzione ben definita di territorio e mettere in crisi idrogeologicamente il territorio interessato(specie se già interessato da precipitazioni intense precedenti come quelle della Valle Stura o Bormida).

La configurazione meteorologica che ci sta interessando è infatti quella più pericolosa per il centro nord Italia: una saccatura di origine atlantica affonda verso il Mediterraneo occidentale richiamando aria calda dalle latitudine africane e nel suo cammino si carica di umidità fino a raggiungere le nostre coste, dove,scontrandosi con correnti fresche richiamate dalla stessa depressione, danno vita a queste formazioni temporalesche.

Per prealpi e pedemontana piemonte-lombarda si ci attende una intensificazione dalla nottata delle precipitazioni con accumulate molto elevate che potrebbero causare esondazioni locali specie su basso alessandrino, biellese, Verbania; temporali localmente forti su versante padano appenninico Ligure.

Alcune modellistiche anticipano possibili passaggi temporaleschi nella nottata tra le 2 e le 6.
Un miglioramenteo è previsto da martedì.
Vento di scirocco forte

Leonardo

Da Genova, Italy. Seguitemi su Facebook

Synoptic

A frontal system, inserted in an intense western flow present in free atmosphere, will pass during the day tomorrow on the north of Italy determining a full-bodied worsening of the weather, with hail, flooding and gusts of wind.

The deterioration will be divided substantially into two phases.
The first, from night until early afternoon, with prefrontal thunderstorms that will ride the ascending branch of the jet streak (movement from west / south west to east / north east).

The second, from early afternoon until the evening, with frontal thunderstorms that will affect larger areas but which will be less organized.

The most stringent parameters will be localized in the first phase, in fact we estimate, despite the night / morning hours, peaks on the 2100J / kg of Cape (energy available at the convection), shear (variation of direction and intensity of the wind with the altitude) on 20-25m / s and good values ​​of energy helicity that will favor the formation of organized systems and supercells

The frontal phase will instead see a greater entry of cold air at altitude but a simultaneous collapse of parameters such as shear and a drop in the jet.
Multi-cell or Mcs thunderstorms will be favored.

Lombardy, Veneto, Friuli Venezia Giulia, Emilia Romagna and Trentino

Very active prefrontal phase between middle high plains and Alpine area (level 2-3). The thunderstorms will develop over Lombardy in the very early hours of the night, evolving towards Veneto, Trentino and Friuli, resulting organized and with the possibility of long-lasting supercells, especially between Veronese, Vicentino, Padovano, Veneziano, Rodigino and Trevigiano, where, in the morning, it will be established a convergence between Bora and Scirocco.

In fact, despite the night / morning hours, Cape values ​​are estimated at around 2100J / kg, with the possibility of medium to large hailstorms (> 3cm), flooding, with discomfort and gusts of wind.

The frontal phase will instead be more active in the middle low plains (Emilia Romagna and Veneto border).

The entry of cold air at altitude will allow the development of many thunderstorm cells, but the simultaneous collapse of the shear will determine the evolution of multicellular-cluster or Mcs (mesoscale convective system) thunderstorms.

The areas affected by heavy rain, hail and downburst with gusts above 100km / h will be considerable, with probable inconvenience.
PAY ATTENTION

Piedmont, Valle d'Aosta and Liguria

Prefrontal phase that will determine some thunderstorms between Alto Piemonte and Valle D'Aosta but rapidly evolving towards the east.

Afternoon frontal phase that will be more active on the mid-low plains, especially between Langhe and Monferrato, where the formation of multicell clusters will be possible.

Despite the level 1 emitted, the very high Cape values ​​(peaks up to 2500J / Kg) make medium-sized hailstorms and wind blows possible.
Possible thundering storms also attenuated along the Ligurian coast, especially in the stretch between Andora and Genoa.

Marche

Although not shown on the map, an obligatory citation for the northern area of ​​the Marche bordering Romagna.
Between afternoon and evening he will find himself on the southern edge of the disturbance, thus keeping shear on high values ​​and at the same time a good convergence of winds to the ground.
In this area it will be possible to form one or two supercells, with the possibility of hailstorms.

Jacopo Zannoni

The member of the storm chasers group ZenaStormChaser from Genoa, Italy. Follow ZenaStormChaser on Facebook, Instagram or Twitter

The hegemony of the North African high pressure ends under the blows of an imposing Atlantic perturbation that will literally break through, with its load of cold air, from the western quadrants, determining a perturbed weekend on most of Italy.

At the end of this summer break we will certainly count the damage for very violent phenomena.

Tomorrow will see a first baric collapse with thunderstorms mostly for relief purposes.

The jet stream (current of air present in free atmosphere that "transports" thunderstorms) will tend to dispose from west / south west with sharp and sudden destabilization of the air column

The abnormal energy in play will facilitate the formation of violent thunderstorms with the possibility of medium-large hailstorms.

Veneto, Friuli Venezia Giulia e Emilia Romagna

Thunderstorms that will develop during the early afternoon on the alpine reliefs. South-eastern ventilation on the lower Veneto will drag energy values ​​(Cape) between 2500 and 2800 J / kg up to the Alps, with a serious risk of high intensity phenomena (Level 2-3 Alpine area). Indeed, storms, floods, landslides and medium-large hailstones are likely to occur. We strongly advise against outings especially on the exposed ridges.

The storms will move from west to east, affecting the entire Alpine and pre-Alpine area of ​​Friuli by late evening.
Trespassing on the high plains is not excluded.

Between late afternoon and evening, some parameters pushed to the limit suggest a sudden trigger in the middle of the plain on the border between Emilia and Veneto.

On these areas a convergence will take place between the humid south-east rising from the Adriatic and the drier sw from the Apennines, towards evening the outflow of the alpine storms could even create a triple point of convergence.

The trigger at high altitude to trigger this bomb ready to jump appears really bland but if it were to trigger, the storm would find an abnormal energy to be exploited with peaks above 3000J / kg and the possibility of large hailstones (> 5 cm), flooding and Tornado

P.Š. Only level 2 was issued due to doubts about the trigger, possible raising to 3 in case of further confirmation by the models.

Alps (Level 1) And appennines

Afternoon phenomena with hail and in some cases local flooding, local and temporary trespassing on the neighboring plains are not excluded.

Jacopo Zannoni

The member of the storm chasers group ZenaStormChaser from Genoa, Italy. Follow ZenaStormChaser on Facebook, Instagram or Twitter

• Levels 1 and 2 were issued for parts of France and the UK for large hail, severe wind gusts, and excessive precipitation.
• A level 1 was issued for parts of Ukraine, Russia, and Belarus mainly for excessive precipitation and large hail.

Synopsis

An intensifying ridge in W Europe brings exceptionally warm air masses up to the UK and the North Sea, and a jet stream builds on its forward flank, curving east towards South Scandinavia and Poland. At the same time, two troughs are forming on the west and east side of the ridge, leading to an Omega Blocking. Downstream from these two troughs, we expect DMC events mostly covering a large part of E Europe on Tuesday 23/07. Moreover, storms are also expected in Spain and NE Portugal, which may produce locally severe wind gusts.

Discussion

France and UK

The advection of very warm air masses over France with up to 25oC at 850 hPa will create a strong cap extending north up to the UK, so we do not expect surface-based convection to use the fat CAPE profiles aloft, where very steep lapse rates create about 2.500 J/kg CAPE.

Nevertheless, late in the afternoon and early night of Tuesday a short-wave trough is forecast to reach the west coasts of France and the UK, with strong PVA. Current thinking is that the unstable air masses in extreme NW France and SW UK will penetrate the cap, given the strong synoptic lift, and will lead to severe weather events.

The exact time of convective initiation is questionable, but any storm that will form inside the level-1 and 2 areas will be able to produce severe wind gusts, large hail and locally excessive precipitation.

A jet-streak of 20-30 m/s that will cross SW UK increase the threat level for severe convective wind gusts and large hail. In France, NWP models (for e.g. GFS, AROME, ICON) show CAPE values exceeding 2.000 J/kg with strong low/mid-level helicity, suggesting that storms may quickly become supercells and very large hail is possible near the coasts of Normandy and Brittany, but according to IFS storms will stay offshore.

After midnight the storms will continue propagating N-NE over the UK, mostly elevated. In the early morning of Wednesday 24/07 the main threat will be excessive precipitation in central parts of the UK.

Ukraine, Russia, and Belarus

In the SE side of a low/mid-level vortex embedded in a wider long-wave trough over Ukraine, a slow-moving cold front will build several storms while propagating east to Russia.

The slow storm motion and high PWAT suggest that storms will be able to produce excessive rainfall. DLS in the range of 10-20 m/s overlapping with some hundreds of CAPE, may enhance the possibility of local large hail events. On the eastern side of the level-1 area, high-delta-theta-e values increase the probability of downbursts during slow-moving storms.

Unstable air masses over the Black Sea and decreasing low-level winds behind the cold front in the afternoon increase the possibility of waterspouts near the coasts.

The ESTOFEX forecasts are published under a Creative Commons Attribution-Noncommercial-Share Alike 3.0 license

Synoptic

The cold drop, which during the day has affected and is still affecting the Italian central north, moves quickly towards the south, causing a worsening of the weather even in the south Italy.

The cyclonic vortex will find areas along its path with still a discrete "fuel" convertible into thunderstorms and heavy rains. In fact, peaks of 1600J / kg are expected, especially between Calabria, eastern Sicily and the Ionian Sea.

Molise and Puglia

The thunderstorms will move from north-east (Adriatic sea) towards south-west, in fact these regions will be located on the north-eastern edge of the low-pressure structure, and will be more intense between Molise, Foggiano and the province of Barletta Andria Trani, with local accumulations significant and flooding ( level 2).

Elsewhere more isolated thunderstorms. Waterspouts will be possible both on the Adriatic and Ionian sides of Puglia thanks to the presence of a strong helicity in the first km of atmosphere.

Calabria and Campania

On Campania, thunderstorms will tend to develop in the next few hours, resulting very intense in the central-southern part of the region.

During the night and during most of the day tomorrow a stormy corridor will be created from the Tyrrhenian towards the Ionian Sea that will cross practically all of Calabria (levels 2-3).

The most intense thunderstorms will hit the open sea but flooding along the coasts caused by the huge rainfall accumulations cannot be excluded.

The high helicity values ​​in the first km of atmosphere will favor the formation of waterspouts especially on the Tyrrhenian side.

Sicily and Basilicata

These two regions will be found respectively in the south-west and north-east of the storm channel that will hit Calabria.

Phenomena of moderate intensity will be possible but no inconvenience is expected.

A little more detail for Sicily, where, once again under a strong jet stream, thunderstorms will be more organized but also more mobile.

Jacopo Zannoni

The member of the storm chasers group ZenaStormChaser from Genoa, Italy. Follow ZenaStormChaser on Facebook, Instagram or Twitter

Fortunatamente i rimorchiatori e il comandante della nave sono riusciti a prendere il controllo della situazione e a completare la manovra senza incidenti.

DA COSA E' STATO CAUSATO?

Questo scenario è stato causato da un sistema temporalesco formatosi per via di una zona di instabilità che va da Nord-Ovest a Nord-Est, infatti, i cumuli dopo che si sviluppano scaricano tutta la loro potenza riversando grandine e forti raffiche di vento, che hanno, appunto, causato lo sbandamento della nave da Crociera Costa Deliziosa.

Giuly Merlo
from Palermo, Italy.
Follow me on Instagram and Twitter

Busy days await Northern Italy, with two different disturbed structures that will meet right next to the Italian north.

During the day tomorrow a cut off on the Iberian peninsula will determine the establishment of an intense flow from west to north-west in free atmosphere.

Northern Italy will find itself in the limbo between very hot North African air and fresher puffs that will tend to cross the Alps, thus favoring the formation of very intense thunderstorms.

The energy available for convection will be really high with peaks of over 3,000J / kg that will go as far as the Alpine areas transported by an important low-jet jet from the south-east. The shear will also be very high, favoring the formation of highly organized thunderstorm structures and therefore supercells.

Friuli Venezia Giulia and Veneto

Thunderstorms forming during the afternoon hours on the alpine mountains with the risk of large hailstorms and flooding, we strongly advise against mountain excursions (Level 2 and 3).

The phenomena will tend to evolve towards the Friulian and eastern Veneto plains, with the possibility of supercells.
Due to the intense south-east ventilation present on the ground, combined with a Cape (energy available for thunderstorms) expected beyond 3000J / kg, vortex phenomena cannot be excluded.

In late evening / night on Sunday, possible intense thunderstorm passage with Verona / Vicenza axis towards Venetian Padua and Rovigo, but given the time it will fall in the outlook for Sunday, also for this reason only one level 1 has been issued.
We invite you to pay attention.

Lombardy, Piedmont and Trentino Alto Adige

Mostly late afternoon and evening phenomena relegated to the Alpine belt with the risk of medium-sized hailstones and local discomforts due to flooding, especially between Como and Lecco (LEVEL 2).

Towards midnight possible extension of the phenomena towards the plains, with cape (energy available for thunderstorms) that will remain really high despite the night hours, with peaks up to 2500J / Kg.

Also in this case, being beyond midnight, it will fall within Sunday's outlook, for this reason only one level 1 has been issued.

Jacopo Zannoni

The member of the storm chasers group ZenaStormChaser from Genoa, Italy. Follow ZenaStormChaser on Facebook, Instagram or Twitter

A level 2 was issued across E-Spain mainly for large to very large hail and severe wind gusts.

A level 1 surrounds the level 2 for similar hazards with lower probabilities.

A level 2 was issued for parts of France, Switzerland and N-Italy mainly for large to very large hail, severe to damaging wind gusts, excessive rain and over NE-Italy and W-Slovenia also for an augmented tornado threat.

A level 1 surrounds the level 2 for similar hazards with lower probabilities.

A level 1 was issued for S-Sweden mainly for isolated large hail.

A level 1 was issued for parts of the E-Ukraine mainly for large hail.

A level 1 was issued for the E-Turkey mainly for large hail and severe wind gusts.

A level 1 was issued for N-Spain mainly for large hail and severe wind gusts.

SYNOPSIS

An extensive zonally aligned channel with low geopotential heights covers Scandinavia. Embedded cold-core vortices plow east and maintain unsettled/cool conditions over N-Europe.

A quasi-stationary upper trough just west of the Iberian Peninsula backs a healthy subtropical ridge over the CNTRL Mediterranean, where hot and dry conditions prevail.

Attached to the frontal zone, numerous synoptic-scale fronts cross CNTRL-/E-CNTRL Europe with repeated surges of modified polar air moving south. A very moist and warm/hot air mass resides over the Mediterranean and surroundings. In-between an extensive thermal/moisture gradient evolves from France to the Alps to Hungary, where organized convection is forecast.

DISCUSSION

Please note that only level areas were issued. Attendant lightning areas will be added in the Day-1 outlook.

France, Switzerland, S-Germany, Austria, N-Italy to Slovenia, Croatia and Hungary

Certainly, the main focus for severe convections resides in this extensive swath over CNTRL-Europe.

Most robust low tropospheric moisture is forecast over N-Italy with days without any frontal passage and just temporal/regional convective overturning. Moisture over SW France improves substantially in response to a weakening cyclonic vortex just W of Portugal and resulting veering winds over the S-Bay of Biscay, which push a marine air mass onshore. Mixed signals about timing/strength of moisture recovery with an adequate moisture depth against diurnal mixing exist from S/SE France to Switzerland, S-Germany and parts of Austria. Most of the guidance, however, brings the 10 g/kg isohome into these areas.
A pronounced EML over the W-Mediterranean turns NE towards the Alps with gradually lowering values and atop the moist air mass.
Hence widespread 2000 J/kg MLCAPE evolve over W/SW and S-France with up to 3000 J/kg over N-Italy. Otherwise, MLCAPE resides in the 800-1500 J/kg range.

The proximity to the deep frontal zone pushes the 6km bulk shear in the 15-20 m/s range and hence a mixed mode of organized multicells and supercells is forecast. Most forecast hodographs offer rather straight signatures with somewhat better mid-level turning/veering over SW-France and augmented 0-3 km SRH from NE Italy to Slovenia.

A smooth mid-level flow regime turns a bit more wavy/disturbed at lower levels with numerous eastward moving small-scale waves. The strongest disturbance seems to approach CNTRL-Europe during the evening and overnight hours from the W and is accompanied by a S-ward sagging cold front.

CI can be split into the following scenarios:

a) Earliest CI seems to be a mixed mode of ongoing/developing elevated convection over CNTRL-/E-France, which moves into Switzerland. There, gradual rooting into the moist/unstable air mass is forecast with severe convection affecting Switzerland from noon onwards. Splitting cells and multicells occur with large hail and severe wind gust. A mixed/dry subcloud layer points to strong cold pools with potential line ups and concentrated swaths of severe. Constant recharging of the air mass points to repeated thunderstorm development during the day with ongoing severe. An upgrade to a level 2 was performed but may need to be broadened more in later outlooks.

b) Active mountain convection over W-Austria and Switzerland is forecast also around noon onwards which is driven by diabatic heating and potential favourable timing of a passing short-wave. It remains unclear that far out how strong convection from a) affects CI of b) and in the end, we could see a mixture of both regimes, which build into growing and E-ward moving clusters. The main hazard will be heavy rain, large hail and a few severe wind gust events.

c) Outflow boundaries from a)/b) finally serve as foci for CI over N-Italy or developing thunderstorms along the orography become mobile with maturing downdrafts and enter the lowlands from the N. Initiating storms are placed in an environment, which is favourable for long tracked supercells with large to very large hail, severe wind gusts and excessive rain. As convection approaches NE Italy/far W-Slovenia during the evening onwards, a tornado risk evolves due to backed LL winds. The level 2 was expanded far S to account for a growing and maturing MCS, which also affects parts of Croatia during the night.

d) A bit of stronger capping and later timing of the short-wave may delay CI over SE Austria into N/E Slovenia a bit into the afternoon hours, but then multicells/transient supercells evolve with large hail, severe to damaging wind gusts and heavy rain. The level 2 was already expanded into those regions and may see further modifications in later outlooks.

e)Beyond noon, a mixture of mountain convection (S-CNTRL France) and a prefrontal wind shift line over N-CNTRL France cause scattered to widespread CI. The latter activity probably starts more elevated but builds S into the unstable and weakly capped air mass while transforming into (nearly) surface based convection. CAPE/shear space supports organized multi cells/isolated supercells with all kind of severe. Growing and maturing clusters probably add concerns of swaths of concentrated severe/isolated extremely severe events. Hence an upgrade to a level 2.

f) S-Germany remains more unclear with CAPE in the 500-1000 J/kg range but favourable DLS and a deeply mixed subcloud layer. Would expect mountain convection over SW Germany to move E in the form of organized multi cells/isolated supercells. Large hail and severe wind gusts will be the main hazard. During the night, weakening clusters from France/Switzerland may affect far S-Germany but with a lower severe risk due to diminishing CAPE. Hence only a level 1 for now.

Far SW-France needs to be monitored closely for CI. Despite weak capping and mid-level ridging, not much modification is needed for a few severe thunderstorms with all kind of severe. That far out no level area was yet added but a level area may be considered in later outlooks.

Both level 2 may merge in later outlooks. Confidence due to early CI and lots of clouds is too low for already merging both level areas.

N/E-Spain

A marine BL airmass beneath very steep mid-level lapse rates causes MLCAPE in excess of 2000 J/kg. DLS remains around 20 m/s. Despite a warm 850-700 hPa layer, anticipated diabatic heating and orographic support should help for isolated CI. Large to very large hail and severe wind gusts are forecast. The activity should weaken when moving offshore (E/NE) into a strongly capped air mass. Despite missing synoptic-scale forcing and isolated CI, favourable CAPE/shear space supports an upgrade to a level 2.

N-Spain was added to a level 1 for organized mountain convection with large hail/severe wind gusts in a 15-20m/s DLS and 1000 J/kg setup.

S-Sweden

A small warm sector crosses the highlighted area during the daytime hours. Up to 500 J/kg SBCAPE and 20 m/s DLS overlap, so a few thunderstorms could turn severe on an isolated/temporal scale. Hail could become the main hazard with multicells and curved 3-6 km hodograph structures forecast.

E-Ukraine

SE-ward surging cold front/prefrontal wind shift interact with a NE-ward fanning plume of moist/unstable air (500-1000 J/kg MLCAPE). Strongest shear seems to be a bit displaced from the highest CAPE plume but still enough overlap exists for a few multicells with large hail.

Far E-Turkey

A few multicells bring large hail and severe wind gusts with locally heavy rain.

Forecast valid for Wednesday 3 July 2019 from 06:00 to 23:59 utc

One more unpredictable day but with high potential, with the possibility of forming strong thunderstorms, gusts of wind and hailstorms.
A very mild wave cable will in fact pass through northern Italy during the afternoon / evening.

The slightest drop in geopotentials combined with vorticity injection will result in the formation of multicellular storms and given the energy involved (peaks of 3000J / kg) also MCS (Mesoscale convective system).

The MCS are a mass of multicells with a duration of at least 3 hours, an extension of more than 150km and with top of the cloud that must reach certain temperature values.

Initially a very strong cap will be present on the plain but analyzing the theta e at 850hpa (about 1500m) and the curvature at 700hpa (about 3000m) it seems very probable the explosion of the convection that will literally blow up this cap.

Valle d'Aosta and Piedmont

Phenomena in formation during the afternoon hours on Alpine and Apennine reliefs. The most intense thunderstorms could hit the lower Piedmont on the border with Liguria with hailstorms and gusts of wind. Elsewhere more sporadic phenomena. Possible trespassing between Genovesato and Savonese but with phenomena of the most weak intensity

Veneto, Lombardy and Emilia Romagna

Some phenomena will be present on the upper Veneto already in the morning but the highlight of the phenomena will be between afternoon and evening.

The areas within level 2 will be those that will risk the most, with the possibility of Mcs (mesoscale convective system) and annexed hail of medium large dimensions and gusts of wind (downburst), with an intensity even higher than 100km / h.

The motion of thunderstorms will be random and guided by the winds of outflow (cold wind coming out of thunderstorms) but tend to tend to move from west to east.
Beware of hail which in some cases may exceed 4 cm in diameter.

Friuli and Trentino Alto Adige

Still under observation the alpine area with some phenomenon already in the morning and subsequently also during the afternoon, hail and very high rain rates with local inconveniences are not excluded.

Attention for those who practice mountain tours.

Jacopo Zannoni

The member of the storm chasers group ZenaStormChaser from Genoa, Italy. Follow ZenaStormChaser on Facebook, Instagram or Twitter

A slight drop in geopotentials on northern Italy, caused by an intense disturbance in southern Scandinavia, predisposes the atmosphere to the development of cumulus clouds above the Alpine hills but with trespassing towards the neighboring plains.

Piedmont, Lombardy and Valle d'Aosta

Thunderstorms in development in the coming hours on the reliefs, the amount of energy available will be enormous even in the Alpine areas, up to 2800J / Kg (cape) are expected with the possibility of hail and really high rain rates.

Possibility of extension of the phenomena to the nearby plains thanks to the outflow (fresh wind coming out of thunderstorms that undermining the warm air present in the surroundings determines the formation of thunderstorms). (Level 1)

Veneto, Friuli and Trentino Alto Adige

Another stormy day for the alpine areas of these regions. The thunderstorms will develop in the next few hours, resulting very intense in the Dolomite area.

Hailstorm with accumulations on the ground are possible, high rain rates with local flooding and gusts of wind.
The extension to the flat areas is unlikely.

Being thunderstorms inserted in a context without a jet (bearing current in free atmosphere) their motion will be random and messy.

https://www.windy.com/annotation/5d1a0101cb9d30001912361a

Jacopo Zannoni

The member of the storm chasers group ZenaStormChaser from Genoa, Italy. Follow ZenaStormChaser on Facebook, Instagram or Twitter

An important low pressure centered in the North of the British Isles determines the establishment of currents from the south/ south west, in the medium atmosphere, over most of central and eastern Europe.

In this unstable flow, during the day tomorrow, a cold front will move really slowly favoring the formation of strong thunderstorms with very low translation speeds.

The cold front will reamain almost stationary between east Germany, Poland, Austria and Czechia.

France, Spain, Italy and Swiss

In the morning some storms will form in the south east part of France towards south west Germany. The thunderstorms will be organised along a line and they will produce heavy rain and locally strong winds.
Also in the afternoon the storms will move from France towards Swiss and south west Germany, the low directional shear will not support a supercell formation and the storms will be weak.

In the other countries the storm will develop in the afternoon, especially over the moutain regions.

Germany, Czechia, Poland and Austria

The most intense thunderstorms will develop in these regions where the thermal contrast between the Atlantic and African air will be greater.

ml-cape is estimated around 1600-2000 J/Kg, the absence of a high directional shear will favor the development of multicells or squall lines with very big hail and strong winds, but supercells are locally possible, especially between south east Germany and Austria.

The thunderstorms will form between afternoon and late evening.

Balkan

These regions will have disorganized convection but placed in a context with a lot of Cape. The thunderstorms will form during the afternoon hours and they will be able to produce hailstone.

Jacopo Zannoni

The member of the storm chasers group ZenaStormChaser from Genoa, Italy. Follow ZenaStormChaser on Facebook, Instagram or Twitter

https://www.windy.com/annotation/5d0ac80032594c0019b80a01

Previsione valida dalle 12 utc di mercoledì 19 giugno 2019 fino alle 06 utc di Giovedì 20 giugno 2019

Sinnotica

L'alta pressione protegge il Mediterraneo centro orientale mentre una perturbazione cerca di farsi largo ad ovest determinando infiltrazioni di aria più fresca sul Nord Italia. La corrente portante in libera atmosfera risulterà blanda e con direttrice da ovest/sud ovest favorendo la formazione di sistemi multicellulari semi-stazionari.

Shear attorno ai 10m/s che non sarà in grado di supportare fenomeni supercellulari.

Alpi

Fenomeni termo-convettivi che nelle prossime ore si svilupperanno lungo l'arco alpino. Saranno fenomeni di breve durata ma localmente intensi con grandinate di medio piccole dimensioni. I fenomeni più intensi si svilupperanno tra Trentino orientale, Veneto e Friuli Venezia Giulia (Livello 2) dove potranno risultare stazionari con cumulate rilevanti.

Veneto e Friuli Venezia Giulia

Fenomeni in estensione dalle aree alpine verso le pianure tra tardo pomeriggio e serata, con grandinate e colpi di vento .A causa della scarsa ventilazione a media quota i temporali saranno poco mobili e alcune aree rischieranno cumulate davvero elevate con disagi (Livello 2).

Attenzione alle grandinate visto il potenziale in gioco, si stimano infatti picchi di 2500 J/Kg.

Jacopo Zannoni

The member of the storm chasers group ZenaStormChaser from Genoa, Italy. Follow ZenaStormChaser on Facebook, Instagram or Twitter

During a chase day, a strong shelf cloud approaches the norther Piedmont plains (15 June 2019)

Synoptic

A persistent cut off interested the West Europe determinating strong storms on his ascending ramus, where the Atlantic air mass meets the Africa air mass. During next day the storms will develope under this important flow from Sud West, and they become intense where the energy available to the convection (CAPE) will be hight.

France, Switzerland and Italy

Strong storms will develope in France in the afternon, which they will move fast towards Italy and Switzerland. It will be possible the creation of squall line that will evolve in MCS ( Mesoscale Convection Sistem) with hailstorm and strong winds, in the areas signed as two and three. The high values of shear are able to support a supercell in particular in the north of Italy and in the eastern part of France.

There is a possibility percentage of flash flood in Switzerland cause by MCS storm.

Germany and Republic

The thunderstoms in this area they will form in the late afternoon/evening and they will evolve rapidly in MCS (Mesoscale convective system) with possible giant hail and strong winds. The upper flow will come from south/southwest and move the storm towards the north.

The cape is estimated around 3500J/Kg or little bit more.