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Thunderstorms in Ukraine - Jun.11-13

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Author Topic: Thunderstorms in Ukraine - Jun.11-13  (Read 295 times)
Roman White
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« on: June 12, 2009, 03:20:24 am »

I wasn't going to start this topic until the thunderstorm arrived here at 5AM  Grin

First look at ESTOFEX forecast for Jun.11:
Level 1 alert issued for W & E Ukraine including Poltava, T-storms in surround
Level 2 alert issued for some regions in N Ukraine and for the most part of Belarus

Quote
(...)
A level 2 was issued for western Ukraine, Belarus, and western Russia mainly for large hail and tornadoes.
A level 1 was issued for Central Balkans to western Romania, and western Ukraine mainly for large hail.

(...)

SYNOPSIS
A subtropic high ridges into the Iberian Peninsula. A mid-level jet over western Europe intensifies as a trough will move across the North Sea. The trough axis becomes negatively tilted over central Europe and provides strong QG forcing. As a consequence, a low pressure system that moves into southern Scandinavia will intensify. While rather cool air masses flood into most of western Europe, unstable air masses remain from northern Italy to eastern Europe.

DISCUSSION

Central Balkans to western Romania, western Ukraine, Belarus, and western Russia
An unstable air mass is present over a broad region of eastern Europe, characterized by an EML from Greece to western Ukraine and western Russia and rich boundary-layer moisture. High CAPE in the order of 2000 J/kg will likely build during the day. On Thursday morning, a cold front is forecast to spread into this region and will become quasi-stationary in the southern portions, while a frontal wave will lead to warm air advection from Belarus to western Russia.

Models indicate that a jet streak will evolve in the range of the frontal boundary that will be strongest from the western Ukraine and Belarus to western Russia, where strong vertical wind shear is forecast. Especially in the afternoon and evening hours, 15 to 20 m/s 0-3 km and 10 to 15 m/s 0-1 km vertical wind shear are quite likely. This will be sufficient for supercells that are forecast to produce large or very large hail. Tornadoes are forecast especially over Belarus and extremely western Russia where low-level vertical wind shear and veering profiles are strongest. Excessive rain is expected to be most likely over western and central Belarus, where low-level convergence and moisture are forecast to reach the highest values.

In the southern portions of the risk area, vertical wind shear will be weaker, but 10 to 15 m/s winds at the 700 hPa level are possible. Thunderstorms are likely along the low-level convergence, and some supercells are forecast to develop, capable of producing very large hail. Isolated severe wind gusts and local flash flooding are not ruled out with stronger cells, while the tornado threat is forecast to be rather low. Convective activity is forecast to spread further east in the night hours as the trough axis of the central European trough moves across the region. The potential of severe weather will only decrease slightly from the Ukraine to Russia as strong low-level winds will continue ahead of an old front that develops to the west.

(...)
I don't know about other regions, but about Poltava this forecast sounds ridiculous!  Undecided
In fact, it was clear until 4PM with temperatures +33...+38C, next the sky became covered with As layer, temperature falled to +30...+25C. I agree, there was some possibility of rain during late evening, but nothing as serious as forecasted.
« Last Edit: June 12, 2009, 07:58:18 pm by Roman White » Report Spam   Logged

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Roman White
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« Reply #1 on: June 12, 2009, 03:34:26 am »

June 12

ESTOFEX:
Level 1 alert issued for all Ukraine except of extreme NW.

Quote
(...)
A level 1 was issued for the areas surrounding the level-2, Ukraine, Moldova and N-Romania mainly for tornadoes, large hail and severe wind gusts.
A level 1 was issued for the areas E/NE Czech Republic, E/NE Hungary, Slovakia, S-Poland and W-Ukraine mainly for large hail.

SYNOPSIS
The progressive weather pattern continues with one trough over E-Europe moving slowly eastwards whereas another one approaches Ireland from the west. Ridging is present in-between backed by the northward advection of very hot African air over the Iberian Peninsula. Downstream of the E-Europe trough, strong WAA also results in hot and unsettled conditions well to the north.

DISCUSSION
...E-Belarus, Ukraine and regions SW/W of Moscow ...
The focus for widespread thunderstorm activity is the eastward sliding cold front. Slow forward propagation characterizes this boundary, separating a warm/muggy airmass ahead from cooler and more stable air to its west. As prefrontal airmass destabilizes constantly with MLCAPE values between 1-1.5kJ/kg (locally higher peaks) and DLS near 20m/s, thunderstorms ought to gain organisation rapidly. It is the current thought that numerous northward traveling short waves periodically enhance thunderstorm development along this front with numerous northward moving thunderstorm clusters all day long. Severe wind gusts and large hail are all possible with discrete supercells but the prevailing hazard is flooding rain beneath those clusters, especially when numerous clusters affect the same region due to the slow forward propagation of the cold front.

During the evening hours, surface pressure drops ahead/along of the cold front as another, elongated and weakly organized surface depression evolves over N-Ukraine and E-Belarus. Despite gradually decreasing instability values, shear especially at lower levels ramps up and hence the tornado risk increases next to severe wind gusts and large hail. Latest GFS runs would bring a set-up to the Moscow are, supportive for tornadic thunderstorms, but we want to see more consistence also in the rest of the models in respect of the strength/position of the surface depression, before acting.

(...)

... E/NE Czech Republic, E/NE Hungary, Slovakia, S-Poland and W-Ukraine ...
Cold mid-levels beneath eastward building upper trough and residual moisture in the postfrontal airmass clear the way for scattered, partially diurnal driven thunderstorms in the left exit of a 40m/s mid-level jet. Low WBZ and 10-15m/s DLS point to a marginal to isolated large hail risk, likely maximized over E/NE Hungary, extreme S-Poland and W/SW-Ukraine, where instability is the best (roughly 500J/kg MLCAPE). Thunderstorms decrease after sunset.

(...)
sounds interesting, doesn't it?  Wink

Ukrainian meteocenter alert as well...
Due to the cold front passage on Jun.11 PM and next night in W Ukraine, on Jun.12 and next night in N, S and most of central regions thundery rain will occure, locally with heavy showers, hail, squalls 19-24 m/s, possibly even large hail and squalls 25-28 m/s. After the front passage the temperature will drop in 10-15 degrees (...)

Moderate rain here at 5-8AM, along with thunder. Good lightning activity between 5:25-5:55 and again near 7AM .
The thunderstorm is approaching from E, it is visible in this chart too...


Looking forward for something interesting today. Smiley
« Last Edit: June 12, 2009, 09:00:54 am by Roman White » Report Spam   Logged

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Roman White
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« Reply #2 on: June 12, 2009, 09:37:49 am »

Well... +38C @ RH 25% was much better than today's +26C @ RH 80% - it is a horror!  Lips sealed
Dewpoint was +13C on yesterday afternoon, max. +18...+20C in recent days, and today it has reached +21C...
« Last Edit: June 12, 2009, 10:53:21 am by Roman White » Report Spam   Logged

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Roman White
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« Reply #3 on: June 12, 2009, 08:04:47 pm »

Nothing severe was here today... just a weak t-storm again at 6-7PM, now, in late evening, still raining.

Storm alert for tomorrow (Jun.13) from Ukrainian meteocentre:
Jun.13: thunderstorms, locally with hail, wind gusts and squalls 15-20 m/s. Also heavy rain will occure in Crimea and during the night in Carpathians, N and central regions.
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Roman White
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« Reply #4 on: June 13, 2009, 11:41:01 am »

Also heavy rain will occure in Crimea and during the night in Carpathians, N and central regions.

The forecast was correct... Loud thunder woke me up today at 3:15 AM, there was heavy rain and a good thunderstorm during the night. The cold front has passed early in the morning.
 
I walked across the city today at noon and saw plently of broken tree branches, no serious damage.
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martinastro
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« Reply #5 on: June 13, 2009, 11:43:39 am »

Great to hear it Roman  Smiley
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Roman White
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« Reply #6 on: June 13, 2009, 02:39:40 pm »

BTW, here is an ESTOFEX forecast which has been issued for today, Jun.13:

Quote
(...)
SYNOPSIS
High-amplitude upper flow pattern is developing over Europe, with an upper ridge building over central portions of Europe and two adjacent long-wave troughs over the E Atlantic and over E Europe, respectively. The SFC pattern features two low-pressure systems attendant to the upper troughs and quiescent conditions between these features underneath ther upper ridge over the central parts of Europe. Ahead of the E Atlantic trough, warm and unsstable subtropical air is advected northwards into France.
(...)

It seems that nothing more will occure today after front passage (though there are still t-storms in Kharkiv region, 200 km E from me).
But the storm which occured during the night maybe was close to 'level 1'...
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