Seguimento Europa 2009

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Chasing Thunder

Cumulonimbus
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13 Mai 2008
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Previsão do Estofex para hoje dia 17 de Abril:




SYNOPSIS

An east-west aligned trough over west/central Europe stays put despite some eastward progression along its eastern edges. Another outbreak of very cold air over NE-Europe is underway and a dry/cold continental airmass suppresses deep convection over those areas. Warm and stable conditions are present as weak ridging builds eastwards over the central Mediterranean.

DISCUSSION

... Extreme N-Adriatic Sea, NE-Italy, parts of Slovenia and Croatia between 06Z - 12Z ...

ECMWF, WRF, GFS and AFWA-WRF all agree in the eastward progress of an upper trough, having an impact on that region during the time-frame, which is denoted in the header. Some differences arise in the quality of the boundary layer, which is reflected in the instability release with GFS showing the most agressive solution, whereas ECMWF remains more reluctant. However, dewpoints along the Adriatic Sea are between 10-15°C and as CAA aloft keeps lapse rates steep enough during the morning, MLCAPE of 300-600 J/kg seem reasonable. Some backing with height and 6km bulk shear of 30m/s assist in storm organisation. Isolated large hail and mainly sub-severe wind gusts are possible. As plume of coldest mid-level air departs eastwards, thunderstorm coverage and intensity decreases gradually during the late morning hours.

... E-Slovenia, E-Austria, Czech-Republic, W-Hungary and W-Slovakia between 9Z - 21Z ...

Aforementioned impulse at higher levels seems to get better organized while crossing the eastern Alps with a strong vorticity couplet present in the past few GFS runs. Again, WRF, ECMWF and GFS agree well in strength, orientation and movement of the upper trough and the same picture at the surface, as all models have the surface cold front over extreme E-Austria at 12Z. ECMWF again is the more reluctant one regarding instability release whereas GFS/WRF agree in the build-up of roughly 500J/kg MLCAPE along this front during noon/afternoon (with peak values over E-Czech Republic and W-Slovakia ). The main question is where the surface front will be situated during peak heating and models differ somewhat in their solutions. At the surface, weak pressure fall over E-Austria keeps the wind field backed during the morning hours, resulting in a slow-down of the boundary, before increasing its forward motion around noon. GFS came up with stronger pressure fall in past few runs, so we would not be surprised to see the front lagging behind the solution of the models. Hence E-Austria was included into the level-1.
Thunderstorms over E-Slovenia move in from the SW during the late morning hours/noon and also increase in coverage over central Austria. Not much insolation needed with ongoing CAA atop of the moist BL, so instability in the level-1 area will increase to roughly 500J/kg MLCAPE. Speed shear is present with 15-20m/s DLS along the surface boundary, decreasing westwards. Directional shear is more complex with strong veering up to 600hPa, backing to 400hPa and then again veering above. We concentrate on the mid-levels, where some instability and strong speed/directional shear overlap in the hail growth zone, so large hail will be the main hazard with those thunderstorms beside strong gusts. After sunset, instability vanishes and thunderstorms decrease both in coverage and intensity.

... Corsica and NW/N-Italy ...

Numerous short-waves cross the area from the west during the forecast, keeping the period active regaring thunderstorms all day long. Moderate shear/instability overlap most of the times, pointing to an isolated large hail/strong wind gust threat. Somewhat drier air filters in from France during the night hours and mitigates thunderstorm activity.

... France ...

A diurnal driven thunderstorm day is in store for France as boundary layer features dewpoints of 8-11°C below a plume of cold mid-levels. Steep lapse rates foster SBCAPE release of 500-1000 J/kg in a weakly sheared environment. Single cells are the primary storm mode with an isolated large hail risk during their mature phase, but very weak shear precludes a level-1 as hail reports ought to be too isolated in coverage. In addition, strong wind gusts accompany those storms. Thunderstorms decrease after sunset as a more stable stratified boundary layer evolves.

... The rest of the thunderstorm regions ...

Either shear or instability are too weak for organized convection. Isolated to scattered thunderstorms are possible in those areas but no severe thunderstorm event is expected.
 

Vince

Furacão
Registo
23 Jan 2007
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10,624
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Braga
Mais algumas fotos de França, estas de ontem


l'Hérault

pano1eth.jpg

(c) Alex R.

pano2c.jpg

(c) Alex R.

atomiccb2.jpg

(c) Alex R.

cellulesuspect.jpg

(c) Alex R.



Clermont-l'Hérault

090417050233114383494553.jpg

(c) Michel Sulik

090417045038114383494548.jpg

(c) Michel Sulik



Avignon

17_04_15.jpg

(c) fredou



Périgueux

49578e33f6d4a60cade2e3d0b71bbd75.jpg

(c) Baptiste Deidda

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(c) Baptiste Deidda



Loire


rad08135.jpg
 

Chasing Thunder

Cumulonimbus
Registo
13 Mai 2008
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Previsão do Estofex para Hoje dia 18 de Abril:



SYNOPSIS

A high over low blocking pattern over western Europe will continue throughout the forecast period, leading to rather weak temperature and pressure gradients over central Europe. In the vicinity of the associated upper trough over France and northern Iberia, showers and thunderstorms will develop in an environment with little CAPE, most of them should be diurnally driven. Another upper trough over western Russia moves eastward, but there is almost no CAPE near the cold front which reduces the chances for electrified convection. Stable and quiescent conditions are expected for the eastern Mediterranean and also for northwestern Europe on the eastern flank of an upper ridge.

DISCUSSION

...N Italy...

In the morning / early afternoon, diurnal heating will create a few hundred J/kg of CAPE over N-central Italy. Even though QG forcing is rather weak, some organized multicells may develop in this weakly capped environment with 15 to 20 m/s deep layer shear. Steep LL lapse rates, weak BL winds and LCL heights only around 500m may allow an isolated funnel / brief tornado. Some marginally severe hail is also not ruled out as the freezing level is relatively low. As there is almost no elevated CAPE, thunderstorm activity will rapidly decrease after sunset.

...NW Iberia...

In the vicinity of a northwesterly 35 m/s jet streak over Portugal, about 300 J/kg CAPE are forecast to be created during the afternoon. An upper shortwave trough which moves from NW to SE will provide strong QG forcing and about 15 m/s deep layer shear may allow some briefly organized multicells that may produce small to marginally severe hail and gusty winds. Limited instability will preclude any threat level for that region.

...Balearic Islands, SW Mediterranean...

The aforementioned shortwave trough will cross the SW Mediterranean in the late evening / night hours and may initiate some organized storms over SE Spain and the SW Mediterranean. Ahead of a small surface low near the Strait of Gibraltar, LL winds may back to the east which increases directional shear and allows some short-lived mesocyclones with the stronger updrafts. The severe threat should be low but a marginally severe hail event as well as a waterspout are not ruled out.

...Other thunderstorm regions...

Severe thunderstorms are not expected in the other areas as there is a lack of instability or shear to support organized convection. Eastern Germany was excluded from the thunderstorm area as there is some weak instability but also strong subsidence at upper levels.
 

Chasing Thunder

Cumulonimbus
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Previsão do Estofex para Hoje dia 24 de Abril:




SYNOPSIS

Omega pattern over Europe persists during the forecast. A compact cold-core low over the western Alps moves west/northwestwards while weakening. A more dynamic upper trough approaches western Europe during the night hours with a nice surge of warm/humid air well to the north ahead of this feature. Cool and stable conditions prevail over NE-Europe.

DISCUSSION

... Italy,Ionian Sea and Switzerland ...

Temperatures at 500hPa just shy below -20°C and surface dewpoints in the lower to mid tens result in abundant instability (e.g. 500-800 J/kg MLCAPE). The best environment will be roughly from Rome to the southeast. Shear throughout the troposphere is weak, inhibiting widespread storm organisation. Locally robust instability release and a low WBZ however hint on a possible large hail event. Deep layer shear over Sicily increases to 20m/s with similar CAPE values, so large hail ought to be higher in coverage and therefore a level-1 was issued. The level-was was epanded well to the north (e.g. S-Italy), where GFS has more than 100J/kg LL CAPE. A short tornado event along intersecting outflow boundaries is possible in such an environment, so the combination of an isolated large hail/tornado event made a marginal level-1 necessary.
Thunderstorms also increase in coverage west of Greece during the morning hours, but shear at all levels remains too weak for storm organisation. Meanwhile, thunderstorms over Italy decrease in intensity/coverage after sunset.

A retrograd moving cold core low over the western Alps is the focus for isolated thunderstorms mainly over W-Trention, the Lombardy, Piedmont and the Valle d'Aosta, as boundary layer moisture remains high enough for some instability release. A combination of utterly low dewpoints over Switzerland and the weakening trend of the upper low ( e.g. constant warming especially below 500hPa) bring thunderstorm chances down to near zero. However, global models still have a very bad handling in complex terrain and dewpoints don't have to climb a lot for initiation as lapse rates at mid-level remain steep. We therefore accentuated parts of Switzerland, where at least a very isolated thunderstorm event seems possible. The main hazard will be hail due to strong DLS, steep lapse rates and a low WBZ. Thunderstorms weaken during the evening hours and around sunset at the latest.


... N-Spain, W-France and SW-UK...

A dynamic upper trough over the Bay of Biscay swings eastward during the evening and night hours. At the same time, a north-south aligned cold front shifts eastwards,too, speeding up over SW-UK and NW-/W-Central France during the night hours, while stalling over SW-France and NW-Spain. There are still some uncertainties with exact timing of those features (GFS retarded the arrival during the past 3 runs) and the strength of the developing surface depression just west of SW-UK (ECMWF has the deepest solution, whereas GFS remains more reluctant). Boundary layer recovery in most of the models is impressive with surface dewpoints in the lower to mid tens. Latest synop reports along the W-coast of France and NW-Spain have indeed dewpoints around 10°C, so we think that 9-12°C are reasonable well inland over SW-France, which is somewhat lower what models predict.
Strong WAA during the daytime hours keep atmosphere capped until the evening hours, as cold front approaches from the west. Lapse rates at mid-levels are steep enough for some instability release although it still remains uncertain how strong this release will finally be. ECMWF and GFS agree in an rapid thunderstorm increase over the SE-Bay of Biscay and the coastal areas of NW-Spain/SW-France around 18Z-00Z. 20-30m/s DLS and strong directional shear help thunderstorms to gain organisation rapidly with an attendant large hail/severe wind gust risk (e.g. lapse rates between 800-600hPa in excess of 8K), especially over N-Spain, where stronger cap should keep thunderstorms more discrete.
Thunderstorms then start to line up along the cold front over SW-France. It depends on how much instability exists with ECMWF showing the strongest signals, whereas GFS just has rapidly diminishing MUCAPE over W-France. Strong forcing could offset decreasing instability, so for now, we went with the idea of a forward propagating MCS over W-central France after midnight. We just issued a general thunderstorm area for that region as new model runs have to be evaluated. If indeed more instability becomes available, an upgrade may become necessary. Strong to severe wind gusts and marginal hail are possible over SW/W-France.

During the night hours, some MUCAPE is also forecast over SW-UK/E-Ireland but the most likely scenario is a few embedded storms in a more stratiform rain shield. This area has to be monitored, too as shear would be supportive for storm organisation.
 

nimboestrato

Nimbostratus
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8 Jan 2008
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Pedras Rubras-Aeroporto
E eis mais uma bela imagem daquilo que a gente gosta
( entre outras coisas)

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A depressão a oeste do golfo de bristol é efectivamente muito fotogénica.
E já agora aqui vai uma previsão das temperaturas pela Europa
para a próxima segunda-feira às 12 horas

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Mais uma vez nesta Primavera, Lisboa e Madrid bem mais frescas
que Varsóvia, Berlim, paises Bálticos,Copenhaga, Estocolmo e a generalidade dos paises do centro europeu.
E a tendência será para assim se manter para mais uns 2, 3 dias.
Curiosidades, apenas isso...
 

irpsit

Cumulonimbus
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9 Jan 2009
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Inverness, Escocia
Já viram pelas imagens de satélite como as massas nublosas se inflamaram a Sul e este de Espanha! Agota surgiu um vortex a sul de Cadiz, vejam!
E toda a Itália deve estar debaixo de tempestades!
 

AnDré

Moderação
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22 Nov 2007
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Odivelas (140m) / Várzea da Serra (930m)
Há horas a fio que chove nas vertentes sul dos Alpes.

Maiores valores acumulados em 24h.


- Das 18h às 18h:
98.0 mm Robiei (Switzerland)
90.0 mm Milano / Malpensa (Italy)
78.7 mm Locarno-Monti (Switzerland)
77.3 mm Ulrichen (Switzerland)
76.0 mm Genova / Sestri (Italy)
 

Gerofil

Furacão
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21 Mar 2007
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Estremoz
Gran caldo in Russia e Ucraina

Sono Russia ed Ucraina le nazioni europee in cui ha fatto più caldo mercoledì 29 aprile. In Ucraina, 27,6°C la massima di Kharkov, 27,2°C quella della capitale Kiev (12,5°C la media delle massime di maggio). Notevolissimi anche i 26,9°C di Poltava e i 26,7°C di Chernihiv. In Russia, Saratov 27,5°C (7,4°C la media delle massime di aprile), Ersov 27,4°C, Kalac 27,2°C, Aleksandrov-Gaj 27,1°C, Bogucar e Penza 26,8°C. 25,4°C la massima a Mosca, quasi 20°C oltre la media delle massime di aprile e 12,3°C oltre quella di maggio.
L'onda di calore è salita fino alla Lituania, dove Kaunas ha registrato una massima di 25,6°C e Uthena 25,7°C (10,5° e 10,7°C le medie delle massime di aprile). 25,3°C la massima di Vilnius (media di aprile 10,7°C, di maggio 18,2°C). In Lettonia, Jelgava 26,1°C, Riga 25,9°C (media di aprile 9,8°C, di maggio 16,6°C).

il Meteo Giornale
 
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