Best posts made by Jack92jk

850 hPa temperature anomaly

As already mentioned in the previous article, here we are dealing with another heat wave that will push the accelerator from tomorrow. Warm air will reach Portugal, Spain, France and Italy with peaks up to +27 degrees at an altitude of 850hpa (1500m) on the Iberian peninsula.

In France, Spain and inland areas of Portugal the temperature will exceed + 40 ° on the ground, while in Italy it will stop around + 35 °.

In the following days (Tuesday / Wednesday) the hot air will tend to invade even central Europe and Scandinavia, on the latter, peaks are expected around + 20 ° at 850hpa.

In short, hot that will reach almost all of central-western Europe, resulting particularly intense in Spain and France, where people's health will be at risk.

The anticyclone responsible for all this will initially have a double supply. Let me explain better, the hot air will flow both from Africa and from the tropical Atlantic (anticyclone of the Azores) thus forming a very strong hybrid structure.

Dual power anticyclone (Azores and Africa)

Subsequently with the further sinking towards the south of the low-pressure structure in the open Atlantic, the high pressure will lose the Atlantic feeding, but further increasing the push by the African hot air.

Between Thursday and Friday, the freshest oceanic winds will begin to blow on Portugal and northern Spain and on western France with thunderstorms also of strong intensity.

Italy will have to wait for Saturday / Sunday.

This medium-long term option appears more likely for areas facing the Atlantic Ocean while for other areas confirmation will be needed in the coming days.

The Scandinavia will live a very long period of thermal supremacy due to the isolation of an anticyclonic structure on the peninsula (scand +).

Jacopo Zannoni

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

Here we are, after this period dominated by the fresh Atlantic currents coming from the north-western quadrants, another heat wave is ready for Europe, especially the central western one.

Mathematical models in fact begin to frame a clear and decisive rise in the tropical bands starting from 140 hours, with a leveling of the tropical strips over most of Europe and a polar jet that tends to flow very north of latitude.

Unlike the last heat wave, which was very strong but of ephemeral duration, which occurred during the month of June, we are faced with a real anticyclonic wall that will rise to protect Europe without the help of a dynamic forcing (see the intense depression that was present on the Portuguese Atlantic in June).

This leveling of the tropical bands between the ocean and the continent represents the topical moment of summer, the most lasting and intense stable phase that could be for at least 15 days.

To support the thesis of this new heat wave are:

1. a very intense African monsoon and 2) a consequent Itcz (intertropical convergence line) placed at more northern latitudes than the average.

An itcz in a higher position provides a greater thrust to the hadley cell making it easier to extract the tropical anticyclonic belt to the north.

Summer will therefore return to raising its voice, bringing a long period of stability and a clear increase in temperatures.

Jacopo Zannoni

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

A strong heat wave is about to invest much of central western Europe and will bring with it truly remarkable temperature values.

In fact, the + 28 / + 30 ° will be touched at 850hpa (1500m) on part of France and Spain with consequent record values on the ground.

Also the west part of the Italy could be reached and and exceed 40 degrees on the ground stripping every previous record
.

The cut off present on the Portuguese Atlantic is responsible for this hot African ascent and, in the coming days, the further sinking of the depression towards the south will increase the African warm air thrust towards the north.

In some areas the mix between humidity and heat could create serious health problems for people with high risk of illness or even death.

France, Switzerland, Spain, italy, Germany and Austria

These regions will be the the most affected by this fierce heat wave. The temperature will reach values between +24 and + 28° at 850hpa for several days, especially in France, Italy and Spain, where even during the night it will be very difficult to find refreshment.

Belgium, Holland, Czechia, Poland, Hungary and Slovenia and south England

Even these areas will reach remarkable values and in some cases some records will be exceeded but the heat wave will be transitory with strong thunderstorm breaks.

During the transition phase between the very hot air and the colder air from the north it will be essential to follow the forecast updates because these areas could risk strong thunderstorm events due to the accumulated energy.

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)

Here we are, the African breath has reached much of central northern Italy but it is only the appetizer.

In fact, tomorrow the temperature at 850hpa (1500m in normal conditions), which is now around 1620m due to the crazy geopotentials we have on our heads, will increase even reaching the incredible value of + 28 °.

The GEOPOTENTIAL represents the necessary energy needed to move a unitary air mass upwards.

When the geopotential is high it indicates the transit of a hot air mass, and said in a very simplistic way it is as if the troposphere were dilated.

The altitude of 1500m, in case of high geopotentials, is found higher and on the contrary with low geopotentials lower.

Thursday

Liguria, Piedmont, Lombardy

The awakening will already be dramatic with temperatures close to + 30 ° in different areas of western Liguria, foothills of Lombardy and Piedmont.

Slightly lower values ​​elsewhere but with higher humidity.
During the day, almost certain records will be torn up, in fact, subsidence (descending motions induced by very high geopotentials) and adiabatic compression will act simultaneously.

The already boiling air will undergo alpine compression with values ​​that between Piedmont, Lombardy and central-western Liguria will reach values ​​above + 42 °.

Veneto, Emilia Romagna, Trentino Alto Adige, Friuli

Even in these areas it will be tragic from the morning, with higher values ​​on the Veneto foothills and a few degrees less towards the coasts but with the high humidity price to pay.

During the day, values ​​up to +41 on the Emilian plain and between +37 and +40 degrees are expected on the rest of the flat areas.

The Val d'Agide will reach very high values ​​with temperatures close to +40, especially in the plain of Bolzano.

Tuscany

Despite some less value at 850hpa, even in this region it will be a really hot day. In the internal basins it will be possible to reach + 40 °, while along the coasts will be a Turkish bath with very high humidity values ​​and temperatures close to +30 degrees

Friday

Po valley

A return of air from the east will intervene on the Po valley, leading to a drop in temperatures that in the day will hardly exceed + 35 ° but with a general increase in humidity and a feeling of oppressive sultriness.

If the compression does not let go until morning, record values ​​will be recorded in the minimum, especially between Varese, Lecco, and Como.

Liguria

It will be the worst day on Liguria, with adiabatic compression from the north east.

Yes, just that wind that will bring about a drop in temperatures on the other regions, on Liguria it will determine a further soaring with possible boiling awakening and temperatures already above +35 in the early morning.

Compression will bring values ​​on the + 37 / + 38 degrees in the day despite a drop in temperatures to 850hpa.

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/5d1495a8cfce9e00195071e9

Si avvicina da ovest la perturbazione che in questi giorni ha insistito su Francia e penisola iberica determinando un'intensa avvezione di aria calda africana verso la penisola italiana.

Il richiamo di forti venti meridionali farà impennare i parametri convettivi su gran parte del nord Italia. I modelli a scala locale mostrano infatti picchi di 3000 J/Kg pronti ad essere utilizzati dai sistemi temporaleschi, shear compreso tra i 25 e i 30m/s , e forte elicità stimata sui 380-400 m2/s2.

Saranno possibili forti temporali supercellulari di lunga durata capaci di produrre grandine di grosse dimensioni e colpi di vento davvero intensi, attenzione anche alle cumulate, in certi casi molto elevate.

Piemonte, Valle d'Aosta e Lombardia

Situazione poco chiara dai principali modelli a scala locale che si trovano in disaccordo sull'orario di inizio dei fenomeni e del loro interessamento dei settori pianeggianti. Sarà una situazione molto delicata, dove a lavorare saranno le convergenze al suolo che potranno vincere il cap (strato di inversione che inibisce la convezione) presente sulle pianure, nonostante ciò è doveroso segnalare la possibilità di temporali molto forti. Dal pomeriggio e per tutta la serata rischio di fenomeni molto forti a partire dal Piemonte occidentale in estensione verso est.

Nelle aree contraddistinte dal livello (2 e 3) saranno possibili sistemi autorigeneranti con cumulate molto elevate e rischio di disagi, probabili supercelle in coda ai sistemi (tail end charlie supercell) a causa del forte flusso sud orientale che scorrerà dall'adriatico sino al Piemonte e che darà lo spin per la rotazione, con grandinate di grosse dimensioni e colpi di vento. Prestare attenzione

Jacopo Zannoni #Zenastormchaser #Windy

https://www.windy.com/annotation/5cfe0cf07cfb4000196744ca

Storm forecast valid Thu 20 Jun 2019 00:00- Fri 21 Jun 2019 06:00 UTC

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

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

Forecast valid for Tuesday 16 July from 00:00 until 23:59 utc

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

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

Credit: tropicaltidibits

We are experiencing a long and intense hot phase in Central Western Europe caused by the infamous atmospheric figure called omega blocking.

A powerful African high pressure, fed to the sides respectively by an intense Atlantic depression and a cut off present on the Balkan peninsula, has led to the overcoming of several heat records.

In these days the contextual expansion of a promontory of high pressure of Azorean matrix and the formation of an intense low pressure vortex, filled with cold air,

on the Scandinavia will determine a general filing of heat peaks with the first strong thunderstorms which, already during today, they will affect several states of central and eastern Europe, with large hailstorms and gusts of wind.

While on the one hand most of the Central European states will experience a large thermal drop on the other, the states facing the Mediterranean will have to wait at least one more week.

The main global models are beginning to give great indications on a possible reversal pattern by the end of the first decade of July on Europe.

An important help will be given by Mjo (madden julian oscillation) which represents the displacement of tropical convection maxima and is therefore able to modify the undulatory trend of the circulation of mid-latitudes.

The diagram is made up of 8 phases that represent the displacement of the convection maxima between the continents. To be forced, the line must exit the circle, in fact the further away from the circle the greater the magnitude. Each phase strengthens differently depending on the area and the Enso signal (nino, nina and nada).

Thanks to an important work done by the scientific committee of meteonetwork that has correlated the phases of the Mjo with the signal Enso (nino, nina, nada), we can understand what will be the trend for the next days with the shift of the convection maxima in phase 1 .

The resulting pattern would represent an inverted omega with tendency to heat waves on the eastern countries facing the Mediterranean and high blocking pressures in the Atlantic.

Wr1 pattern

In short, a summer that started very strongly but could suffer a violent stop, with temperatures below average and massive thunderstorms

Jacopo Zannoni

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

forecast valid from 06.00 to 23.59 UTC on Friday 26 July

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

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.

Storm forecast valid until 23:59 p.m. local time on monday 1 july 2019

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

Forecast valid from Sunday 14 July to 21:00 until 23:59 of Monday 15 July 2019

Synoptic

A small cold drop in the next few hours will approach the western Alps determining, from today's late evening, rains and thunderstorms over most of northern Italy.

Subsequently, the translation towards the south-east of the same, will determine strong thunderstorms on the Tyrrhenian, Corsica and Tuscany with flash flood risk for different areas.

Thunderstorms will often be stationary causing hydrogeological stress conditions, due to the low jet present at high altitude and the little mobile convergences that will be established here and there on the Italian western basins.

Even Sicily will see relevant phenomena, in fact it will be dominated by a branch of the jet streak with intense thunderstorms moving from west to east ..

Piedmont, Lombardy and Emilia Romagna

Rains and thunderstorms that already from the late evening of today will affect the high plains but that during the night and morning will tend to conquer the lowlands.

The greatest risks will derive from the accumulations, locally very high, with the risk of flooding and inconvenience. Western and southern Piedmont and Emilia Romagna are under observation.

The continuous rains with the passing of the hours will replace the thunderstorms due to the lack of energy available to the convection

Liguria, Tuscany, Corsica and Sardinia

An intense south-east flow will blow from the Tyrrhenian Sea up to the Ligurian gulf carrying with it a fair amount of energy (up to 1500J / kg).

Just on the gulf a clear convergence will be established, already in the early hours of the day, between the north wind that will devalue from the Ligurian Apennine passes and the sirocco rising from the south east, with very violent thunderstorms that will mainly affect the open sea and the finger of Corsica (level 3).

There should be no major risks to the Ligurian coast with phenomena "filed" by the presence of the north wind in the lower layers.

Also in the morning strong storms will affect the island of Elba and southern Tuscany, with risk of flash floods and severe traffic disruptions.

In this area, thunderstorms will persist in alternate phases until the late afternoon hours, with the possibility of waterspout also trespassing along the coasts, be careful.
Some phenomena will also affect the North of Sardinia but no criticalities are expected.

Sicily

This region will be crossed by a branch of the jet streak with clear and sudden destabilization of the air column. The first thunderstorms will be formed on the north of the island during the early afternoon resulting immediately intense (level 2-3).

The phenomena will ride the jet stream, moving rapidly to the east and also affecting the eastern areas of the island by evening.

Also in this case the greatest risks will derive from the huge accumulations. The hailstorms will be at most medium-small size.

Jacopo Zannoni

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

forecast valid from 00:00 until 23:00 on Friday 2 August

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