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Tópico em 'Europa' iniciado por Mário Barros 5 Jan 2008 às 14:46.
Obviamente, que me referia a furacões.
Aviso do Estofex para amanhã dia 25 de Outobro na Europa
An intense and large, deep-layer low-pressure complex is covering much of N Atlantic, resulting in a vigorous W/SWly mid-/upper-level flow over the British Isles, the northern Norh Sea, and Scandinavia. A strong jet streak imbedded in this flow regime will cross the British Isels on Saturday, and attendant to its left-exit region, an intense peripheral SFC low will travel across the N British Isles and the northern North Sea into the central Norwegian Sea by Sunday 06Z. Elsewhere, weak upper lows persists over the southern Balkan States as well as over the N Maghreb States.
... DISCUSSION ...
... N British Isles ... S Norwegian Sea ...
GFS predicts appreciable ICAPE in the plume of warm/moist air mass underneath the left-exit region of the jet streak where strong mesoscale ascent is anticipated. EL temperatures of about -30°C reflect the simulated shallow nature of the convection, which may be sufficiently deep however, to augment the strong/severe large-scale gradient flow. Convection should be of linear nature, but isolated tornadoes do seem to be possible, especially where breaks in the line occur. Lightning activity may be somewhat scarce with this system, but a thunderstorm area seems to be marginally warranted.
In the wake of the frontal system, weakly electrified cellular polar-air convection should advect into the Norwegian Sea late on Saturday. Main threat should again be a local enhancement of the wind gusts.
... W Mediterranean ...
Weak thermodynamic fields as well as weak shear profiles should limit the severe threat over the W Mediterranean, though some 15 m/s of 0-6 km bulk shear are simulated south of Sicily. An isolated marginally severe wind/hail event cannot be discounted over this region, but the overall severe potential is too low for a threat area.
Grande célula que está neste momento a sul de Sicilia( Itália)
E segundo o meteoalarm o sul e a ilha de Sardegna estão sob alerta laranja devido á percipitão e ás trovoadas
Aviso de Estofex para amanhã dia 27 de Outubro na Europa
A glance on latest nordhemispheric analysis and forecast maps reveals the development of five dominant longwave troughs with the three strongest ones over the NE-Pacific, NE-USA and NE-Atlantic, so both parts of North-America and parts of Europe face the first outbreak of markedly cooler air.
A strong and constantly amplifying upper trough shifts rapidly to the south over NW and W-Europe for the next 24 hours. Surface depressions should start to evolve along the tip/SE - quadrant of the main upper trough, but they stay in their organisation stage at least until 06Z. Warm and stable conditions persist over far east/southeast Europe with more unsettled conditions over Turkey.
... N of Scotland, 00Z onwards ...
Impressive outbreak of polar air is underway from Greenland to the S/SE. Modification of the lower column will be slow east of Greenland due to already extensive ice coverage all the way down to the Jamson Land / extreme northwestern tip of the Street of Denmark. Temperatures at 850hPa stay around or below -20°C quite far to the south (affecting Iceland during the midday hours onwards), and hence a large NNW-SSE aligned baroclinic zone becomes established. A short-wave, rounding the main cyclonic vortex west of Norway, crosses this zone during the morning hours, while racing southwards. The model pool has a bad handling on the track and strength of this feature although GFS and GEM constantly had a rapidly developing surface depression in the past runs, placed just north/northeast of Scotland during the end of the forecast. Due to the very cold mid-levels, a plume of low-end instability should accompany this feature and as the surface pressure gradient tightens, severe wind gusts should be a high risk ( e.g. keeping severe freezing spray conditions for boats in mind ). The evolution of this depression will be monitored and an update may be issued, if the depression moves faster than currently outlined and exhibits signs for enhanced deep convection.
... Highlighted areas over W/NW-Europe...
Broad-scale CAA will be underway and the main regions to look for thunderstorm development will be offshore, e.g. Bay of Biscay. Beside the fact that there will be an extensive area with low-end to moderate SBCAPE release under the base of the upper trough, it is more tricky to determine the spots, where electrified convection will indeed occur. It makes no sense to get into too many details as uncertainties of smaller-scale features in such a CAA-regime are high, which could locally enhance convective activity and hence the chance for thunderstorms. The North Sea does not look too promising for much activity until about 21Z, but then GFS continues to show a short-wave, dropping south over the SW North Sea, enhancing the thunderstorm chances along the coastal areas of the Netherlands and N-Germany. The English Channel was excluded due to persistent offshore flow of dry air, but otherwise, large thunderstorm areas were drawn. Small hail and strong wind gusts will be the main risk.
...Tyrrhenian Sea and parts of the western Mediterranean ...
As upper trough approaches from the NW during the evening hours, conditions over the highlighted area become fine for scattered to widespread thunderstorm development. At the surface, large-scale pressure fall goes hand in hand with the evolution of a still weak and ill defined surface pressure channel, centered somewhere over the Balearic Islands. A plume of EML overspreads a region mainly between Sicily and Sardinia and in accord with rapidly steepening mid-level lapse rates, instability release will increase markedly during the night hours with MLCAPE of well above 1000 J/kg and probably capped SBCAPE values in excess of 2kJ/kg ( ICAPE values of locally up to 3kJ/m^2). DLS is on the increase as mid-level speed max approaches from Algeria during the night hours and readings of 15-20m/s should be available. Directional shear is not yet very strong but combined with such robust instability release, organized multicell storms / supercells are likely with a large hail and strong wind gust threat. Regarding the tornado risk, warm LL should keep the tornado risk quite low although SSTs of 22°C and anticipated temperatures at 850hPa are a borderline case for more surface based storms, so we want to include at least an isolated tornado risk. No level-2 was yet issued as strongest wind field should remain in the capped airmass until 06Z.
The risk for thunderstorms also increases over the Balearic Islands and eastwards, as the surface cold front approaches from the NW. Thunderstorms will take profit of strengthening shear mainly along the frontal boundary and a few organized thunderstorm clusters are anticipated to develop during the evening and night hours.Isolated large hail/ severe wind gusts are possible and hence a level area was drawn. LL CAPE is on a rapid increase during the night hours mainly over the Balearic Islands and to the south/east, so the risk for isolated tornados should increase beside very limited LL directional shear.
Ainda não há neve, mas dá para ver duas camurças no meio do nevoeiro
Ainda no sábado
Aviso do Estofex para hoje dia 28 de Outubro
An elongated upper trough following a cold front becomes quasi stationary and stretches from Scandinavia to the Iberian Peninsula. Behind the cold front is a vast area of maritime showers, and thunder can occur particularly in regions of coastal convergence or small troughs. Late in the period a cut-off low of Arctic origin, with weak thermal gradients but significant pressure gradients, enters the northern North Sea, with associated showers and thunder.
On the warm side of the upper trough, as it enters the Mediterranean, a large area destabilizes and cyclogenesis occurs along the cold front east of Spain, in the jet entrance region.
...southern Italy, eastern Adriatic Se a...
More than 250 m2/s2 of SREH in an area with a large 1-3 MJ/m2 of vertically integrated CAPE (ICAPE) could yield multi- and supercellular storms, though deep layer shear vectors are not forecast to be as strong, 15 m/s. Large hail is likely, and 0-1 km shear >10 m/s suggests also tornados and waterspouts are possible. 00Z sounding of Cagliari shows good instability with low LFC in support of this. LAMMA NMM 12/8 km models show a concentration within the level 2 area.
Sicily may be partly capped according to GFS.
Additionally, flash floods may occur.
...Balearic Islands area...
A narrow and steep thermal gradient at the cold front is marked by CAPE and strong low level buoyancy on the warm side and 500 m2/s2 storm-relative helicity (0-3 km) and highly superadiabatic low level lapse rates on the cold side. With some slope of the frontal surface, storms may profit of the shear environment, enabling a threat of large hail and tornadoes/waterspouts when updraft rotation occurs. GFS 18Z is in favor of development of a frontal wave and this increases also the threats associated with high precipitation.
An earlier (afternoon) storm NE of the area will likely become an MCS and may have some wind and hail threat as well.
...English Channel region, southern North Sea...
A number of waterspouts are likely to occur, as strong 0-3 km buoyancy and boundary layer superadiabatic lapse rates allow for rapid upward acceleration, and weakening pressure gradients are in favor. Current 00Z soundings suggest air is relatively dry, though.
E Neste momento estão grandes células em Itália
A quantidade de precipitação prevista para os próximos dias na Europa Centro e Sul, e Marrocos é brutal!
Ao nível da temperatura, o ocidente espera uma anomalia negativa a contrastar com o oriente.
Ao nível de neve, e para os próximos 3 dias, os Alpes esperam um grande carregamento!
Bonito nevão que vai caindo em Funte De.
Que célula que está neste momento na Sicilia ( sul de itália)
Aviso do Estofex para hoje dia 29 de Outubro.
A very deep trough has settled over W Europe, stretching from Scandinavia to Iberian penninsula. Its core is filled with cold airmass, especially in the north characterized by steep mid-level lapse rates. Several short waves will rotate around it during the period, promoting deepening of surface lows. Very strong flow will surround the trough, having more than 40 m/s at 500 hPa level. Underneath the trough, broad surface low pressure system exists. Three distinct centers can be identified - one on the SW coast of Norway, which should fill during the day. Another one will travel from Ireland southwards, deepening as short wave provides strong lift over its center. The last one has formed on the significant fronal system, which has now become quasi-stationary over the Middle Europe. Further deepening of the low is expected and its center will shift NNE wards with time. Strong WAA regime will develop ahead of the front. Eastern Europe will encounter stable conditions as ridge has settled over the region.
...Bay of Biscay...
As mentioned above, surface low will move southwards from Ireland. CAA behind the front which overlays relatively warm SST leads to the development of steep lapse rates. Moreover, significant lift is expected both from surface low and short wave above, so further destabilization might occur thanks to this factor. MLCAPEs above 500 J/kg should materialize and combined with favourable lift will result in TSTM development. Strong LL buoyancy will exist over the bay and with nice convergence signals shown by several consequent GFS runs, waterspout threat seems to be quite high. Therefore, marginal Lvl 1 is introduced.
...Sardinia, Corsica to Italy coast...
Several rounds of thunderstorms are possible. Nevertheless, severe threat should arrive with the approaching cold front, which shall affect the region from 15 to 21Z. Troposphere should be conditionally unstable during the whole day, but further destabilization will occur ahead of the front with MLCAPEs above 800 J/kg. Furthermore, strong mid and low level flow will establish over the area with DLS values around 20 m/s and shear in the lowest 3 km around 15 m/s should suffice for good storm organisation. From storm spectrum, multicells should prevail but supercell is not ruled out either. Large hail will be possible with stronger cells, especially by the Italian coast. Strong low level wind field, with windspeeds up to 25 m/s at 850hPa suggest that severe wind gusts may accompany the storms. On the coasts, friction will reduce the surface winds and increase LLS, reaching 10 -15 m/s, so one or two tornadoes might occur too.
...Gargano penninsula to Adriatic sea...
A tongue of steep mid-level lapse rates will point to the area with MLCAPE values above 1000 J/kg. DLS will be between 20 - 25 m/s and MLS above 15 m/s. What is more, favourable veering of the wind with height will raise the SREH, which should reach more than 250 J/kg in the 0-3 km layer. This suggests that rotating updrafts will become a distinct possibility. Although storms should stay mostly multicellular as GFS suggests storm clustering, few isolated supercells might occur. In such case, chances for large hail would increase significantly. Steep lapse rates and also quite strong flow at 700 hPa level will combine to promote a downburst risk. Few tornado / waterspout reports are expected as SREH 0-1 km should increase to 150 J/kg and coexist with high low level buoyancy. As very good storm organisation is anticipated, along with high storm coverage, LVL 2 is issued in the belt, where the highest threat will be present. Most of the severe weather should occur between 06 and 15Z, shifting eastwards. After this period, severe weather risk will gradually dimnish.
.... N Adriatics, N Italy...
Although instability should be relatively meager in this area, passage of the cold front and presence of upper level disturbance aloft should aid in TSTM development. Impressive wind profile will dominate the region, especially by evening hours, with 30 m/s of DLS and over 15 m/s of LLS. SREH in the 0-1 km might exceed 150 J/kg with veering wind profiles. As storms should be rooted in the boundary layer, such strong low level wind profiles will result in tornado / severe wind gust threat. After the cold front passage, threat will disappear.
.... E Germany, W Czech republic...
Mostly elevated instability is predicted over the region. Strong isentropic lift across the front will provide the initiation for thunderstorms. Despite the fact that favourable wind profiles for organised storms will be available, no threat is expected, as storms should stay elevated in nature and instability will be only marginal.
Ontem à noite praticamente não havia neve ainda em lado nenhum.
Hoje de manhã, alguns habitantes dos Alpes Suíços, acordaram com imagens assim:
Temperatura à instantes:
Precipitação acumuladas das 6h UTC de ontem às 6h UTC de hoje em algumas estações da Europa:
Aviso do Estofex para Hoje dia 30 de Outubro.
Intense am amplified trough over western Europe extends into Iberian Peninsula. Strong upper jet streaks are located along the periphery of the trough. On Thursday, a 60 m/s 300 hPa jet streak spreads northward from central Italy to western Poland and into the Baltic Sea later in the period. Another jet streak curves around the troughs base and enters north-western Mediterranean. At lower levels, two lows are located over Bay of Biscay region and eastern Germany. A cold front will extend from southern Italy to central Balkans, Czech, and western Poland, and warm and moist air mass is advected northward in the range of a strong low-level jet pointing into southern Baltic Sea. Cold polar air masses over western Europe will be pushed to the north as warm maritime air mass spreads into Bay of Biscay.
Sicily to southern Adriatic, southern Balkan region
Ahead of the surface cold front, rich low-level moisture is indicated by latest observations. Soundings also show steep mid-level lapse rates extending over a broad area, where CAPE values up to 1000 J/kg are indicated. A rather weak inversion is present at low levels. On Thursday, strong QG forcing is forecast as axis of upper short-wave trough will move north-eastwards, and latest model out indicates increasing instability due to ageostrophic flow and upper height falls reaching 1500 to 2000 J/kg. Thunderstorms seem to be quite likely along and east of the cold front given low-level forcing and upslope flow near the coasts. Impressive vertical wind shear in the right entry region of the mid-level jet streak is expected to favor supercells and especially well-developed bow-echoes. Severe wind gusts seem to be quite likely along the cold front. Isolated tornadoes are also forecast given strong low-level vertical wind shear of 10 m/s in the lowest kilometer. Severe hail is not ruled out. Convection will likely spread north-eastwards into Balkans and Greece late in the period, where severe threat is forecast to decrease given weaker instability and forcing. However, isolated severe weather is not excluded along the cold front throughout the night over the Balkans and Greece.
Poland and southern Baltic States
Strong mid-level jet streak moves northward over Poland, associated with strong QG forcing. Along the well-developed frontal boundary extending over western Poland, models indicate that moist air mass will spread north-westward at the 850 hPa level, where strong low-level jet is forecast to reach 25 m/s. Ageostrophic flow and upper height falls are likely and models indicate increasing instability from Czech to western Poland ahead of the cold front. Given strong forcing, deep convection is expected to develop, and showers and thunderstorms will likely move northwards over eastern Germany and western Poland. Main question is where this convection will root to the relatively cool but moist boundary-layer. This seems to be most likely over central Poland, where temperatures will likely reach about 16 to 18°C with dewpoints around 12°C. Storms that root to the boundary-layer will have a potential of producing tornadoes given up to 20 m/s 0-1km vertical wind shear and strong low-level veering profiles in the warm sector, and a few events are forecast. Even strong tornadoes are not ruled out. Severe wind gusts are also possible. During the day, stable low-level air mass over western Poland is expected to spread eastward, limiting severe potential. However, isolated tornadoes are not ruled out in the warm sector over southern Baltic Sea, southern Finland, and Baltic States in the evening and night hours given rich low-level moisture and strong low-level vertical wind shear.
Southern Bay of Biscay region
South of low pressure system over Bay of Biscay, maritime air mass spreads into Iberian Peninsula and southern Bay of Biscay region. Strong QG forcing at the cyclonic flank of the mid-level jet streak will likely be associated with widespread rain and embedded showers given moist low-level air mass and rather cool mid-levels. Strong vertical wind shear just along the coasts may be favorable for a few tornadoes affecting northern Spain and south-western France during the period. Overall threat seems to be quite weak given rather poor low-level buoyancy and limited low-level forcing.
Neve em Mayenne, no noroeste de França, em Outubro já não se via há 28 anos.
E em Londres também