Mogelijke (sub)tropische storm in ontwikkeling op de Middellandse Zee

[EAJ]

NOAA15 foto van 15.28UTC

[aloa]

Kaartje van de neerslagsom. Dit ziet er al uit als een tropische storm. (Hirlam).

[aloa]

Animatie van het wolkendek komende 2 dagen.

[Dennis]

WRF Italia 12km

[Johann]

WRF heeft de neerslaghoeveelheden nog een "weinig" opgehoogd. Lokaal gaat er de komende 5 dagen 400-500mm regen vallen. Vooral Corsica krijgt het zwaar voor de kiezen. Op dit moment komt de regen er overigens al met bakken uit de lucht vallen.

[ChrisMir]

Webcams Corsica:

- http://barcaggio2.axiscam.net:8083/view/index.shtml
- http://www.bastia.fr/webcam.html

[Jur]

Getsie, mijn schoonouders trekken deze weken met de caravan over heel Corsica. Vandaag rijden ze richting het noord-westen.
En nee, ik heb geen hekel aan mijn schoonouders, integendeel. Hoop dus dat ze er niet al teveel hinder van ondervinden

[Dennis]

... Sardinia and Corsica ...

Placed beneath the broad/well structured cyclonic vortex, DMC evolves all day long. A lot depends on smaller scale vortices and their development/placement, which could very well increase the risk of training storms and excessive rain. No surprise to see a tremendous spread in the QPF fields of available model data although most favor NE Corsica with high rainfall amounts. I do not want to be smarter than the models and hence a broad level 2 was issued. Next to the rain risk, waterspouts are possible due to good LL CAPE and forecast numerous convergence zones.

... Italy ...

East of the main vortex, a well structured WCB still affects areas like Sicily, the S-Tyrrhenian Sea and S-C Italy. Storms likely evolve along the wavy and leisurely eastward moving cold front with impressive BL moisture ahead (surface dewpoints in the mid twenties). Yesterday's soundings in this WCB featured PWATs in excess of 30 mm and this probably won't change during my forecact period. DLS of 15-20 m/s overspreads 1-2 kJ/kg MLCAPE which assists in well organized multicells and isolated supercells. History showed that similar "moisture streamers/WCBs" sometimes managed to support stationary V-shaped convection along convergence zones (on the meso-beta scale) with locally torrential rainfall amounts. We can't exclude this scenario and a level 2 covers that risk.

Any long-lived storms (especially those, which move along the wavy frontal boundary from Sicily to S-Italy) may temporarily acquire some better organization, posing an isolated tornado risk. Beside that, large hail accompanies thunderstorm activity.

Two level 2 areas were also added for W-Italy and N-Italy, as most models agree in the placement of active shower/thunderstorm activity with excessive rain. The one over W-Italy was merged with the one over Corsica.

The other one was issued as persistent onshore flow and long lasting and quasi-stationary convergence zone sets-up. I would not be surprised to receive an isolated tornado/waterspout report, as LL shear and LL CAPE create a favorable corridor with somewhat augmented tornado probabilities along the N-Adriatic coast. Isolated models also show another QPF maximum along the E-C coast of the Adriatic Sea, but confidence in this scenario remains too low right now to upgrade.

[Jan van Ooijen]

Foto's afkomstig van Times of Malta

[Jan van Ooijen]

[Jan van Ooijen]

Mogelijk oogvorming bij Sardinië, enigste probleem is nog  de landmassa

[corro]

dit brengt flink wat overlast zo te zien ben benieuwd hoe dit afloopt

[Dennis]

Italie komt ook aan de beurt

[Dennis]

[Dennis]

[Dennis]

Extreem regenrecord op Malta

Een ongebruikelijk heftige storm heeft maandag op Malta voor een regenrecord gezorgd. Binnen enkele uren viel 42,4 millimeter regen, terwijl het gemiddelde voor de hele maand september rond veertig millimeter ligt. Dat heeft de Maltese weerdienst gemeld.

De storm veroorzaakte forse schade op Malta en de zustereilanden Gozo en Comino. Auto's werden omvergeworpen, bomen werden ontworteld en huizen liepen onder. Een man die maandagochtend door het wassende water werd meegesleept en als vermist was opgegeven is inmiddels terecht. Hij wist zichzelf in veiligheid te brengen en was zich niet bewust dat mensen naar hem op zoek waren.

_{Bron: nieuws.nl}

[EAJ]

NOAA15 van 15.04 UTC

[Fren]

[Dennis]

NO italie (200-250mm)

[Dennis]

Side note:

Since yesterday, a well structured cold-core low looped cyclonically atop Corsica and is currently situated roughly at 40°30' N and 8-9° E, featuring an E-W elongated center. Also, mid-tropospheric vortex built downwards and 19Z ASCAT scan featured a 15-20 kt surface depression just to the NW of Sardinia which moved east/southeastwards since then. A 30-35 kt surface wind maximum along its northern/western fringe is not correlated with the organizing surface circulation but exists rather due to a channeled gradient flow. Just before landfall over N-Sardinia, DMC increased in strength and organization next to the center but decreased markedly after landfall. An increase in DMC was noted along the northern/northeastern fringe due to increasing LL convergence.

During the start of the forecast period, the depression's center should emerge off of Sardinia into the N-Tyrrhenian Sea and therefore further to the north than most models indicated 24 h ago. However, due to the asymmetric and elongated circulation center and movement atop the rough orography of Sardinia, uncertainties still exist if the center may reform a bit more to the south. Anyhow, this motion brings the depression's center atop an anticyclonic eddy with SSTs of 27-28 °C / positive SST anomalies of 2-3 K and good heat content. As the cyclonic vortex is not yet vertically stacked, some slow eastward motion is still expected with a more or less quasi-stationary motion over the far NE Tyrrhenian Sea during the end of the forecast. At that time, SSTs decrease by roughly 3K. Despite a gradual warming trend of the mid-/upper level vortex and an increase of the geopotential heights as a response of the more zonal flow pattern over N-Europe, background environment remains supportive of a temporarily confined core modification. DLS is already weak and continues to weaken with some weak upper divergence forecast.

A lot depends on the final track of the depression, but confidence increases that a subtropical cyclone may evolve between Sardinia and C-Italy during the forecast. Still a few high resolution models indicate moderate to rapid intensification and is was noted that overall model tendency approached the shallow warm core phase in FSU phase diagrams. Surrounding sounding data also confirm a decrease of the dry slot strength and ongoing moistening, so overall environmental conditions seem supportive for strengthening/organization. An intensity forecast is hard to create due to

a) proximity to the islands/Italy
b) potential infiltration of more stable stratified, rain cooled air from N-C Italy during the forecast
c) uncertainty how strong/persisting convergence and DMC east of Corsica may affect the development of the depression's center and attendant banding structure

Especially in case of the depression's motion atop the warm eddy, we would not rule out a ST 2.5 classification, which would equal 35-40 kt . In any case, the feature will be closely monitored during the following 24 hours.

... Corsica, Sardinia and W-coast of C-Italy ...

A lot depends on where the depression wil be placed and how strong it will be. The main interest will be a persistent convergence zone to the north of the center, which points towards Corsica. A prolonged period of onshore moving showers and thunderstorms are forecast, producing excessive rainfall amounts. A similar risk exists over W-Italy. Beside local rainfall amounts in excess of 100 mm/24 h, a few waterspouts are well possible along any stronger convergence zone.

... Adriatic Sea and rest of Italy ...

Numerous showers and thunderstorms evolve in the area of influence of the main mid/upper vortex, despite its overall weakening trend. Compared to yesterday's deep layer flow strength, a considerably weakening trend is forecast, which may limit overall probabilities for V-shaped and training DMC activity (as observed yesterday). Nevertheless, especially N Italy may again see heavy rain due to repeatedly onshore moving showers/thunderstorms. Despite the decreasing probabilities, we can't rule out isolated V-shaped convection and hence a broad level 1 was issued mainly for heavy rain. An isolated waterspout event is possible along the coasts and along any convergence zone.