Synopsis
A western current leads polar air. From the west a weak back today slowly moves across our country. The current gradually becomes weak southwest. A weak occlusion over the west of the North Sea moves east and reaches the west coast at the end of the morning and slowly continues east over our country this afternoon and tonight. Then the current increases in strength. Thursday during the day, an active low pressure area southeast of Iceland travels along the Norwegian Sea. The corresponding active occlusion range in the second half of Thursday morning the west coast and leaves mid-afternoon the east, but in the lower 6000 vt we remain in the damp air. Furthermore, we see an active peripheral disturbance in the Thursday afternoon and evening passing through Scotland towards the middle of the North Sea, after which it already moves further east in the night to Friday through the German Bend. The associated heat front travels northeast over our country in the evening, the occlusion point draws north of our country east. The cold front reaches the northwest at the end of the evening and leaves the southeast in the second half of the night. With a strong western current, maritime polar air is brought in.

Model assessment
The precipitation activity in today's weak occlusion is consistent in the various outputs. It's about mild precipitation from the high clouds causing sowing in TCu. The fog signal next night is still present, although it seems to be more about low stratus, because the geowind is rapidly increasing. On the west side of the occlusion St-clouding, where the base in the Harmony output is lowest. This looks realistic, the basis is too high in EC exports. On Thursday the wind and active frontal systems will play a major role. The synoptic differences between HA43 and EC are small but then we see that HA43 always shows a more realistic lower cloud base. Another point of interest is the wind field on the south slope of the low for Thursday on Friday with the possibility of heavy wind gusts for the west. There are still differences in detail between EC and Harmony. For the moment, the southwest seems to have a reasonable chance of strong winds of about 90 km/h.Issues

Wind
Thursday morning before the occlusion above the North Sea ZZW 7-8 Bft. Landing winds ensure that wind warning criteria are not met above land. In the afternoon temporary decrease to 6 Bft but in the warm sector of the next edge failure again 7-8 Bft. After passage of the cold front later Thursday evening and in the night to Friday persistent 7-8 Bft, because the wind has turned west then possibly heavy winds that can rise a little further up the country. The heavy winds are limited to coastal provinces, at sea winds up to about 90 km/h, see also model assessment.

Visibility
Local shallow fog banks this morning. Coming night in the northeast nebulous, chances of real fog seem small. In intensified frontal precipitation moderate to poor visual conditions, especially in the drizzle after passage of the first occlusion.

Temperature
Road deck temperatures remain above zero by night. Depending a little bit on the degree of decoupling, but chances of slippery on a bridge or viaduct in the northeast seem to me to be low.

Cloud
In the polar air today, Cu/TCu. We also see some Sc fields. In the weak occlusion some more stratiform clouds with Cu underneath. During the night to Thursday especially in HA43 formation of quite a lot of St-clouding, St locally below 500 vt. Due to the attracting wind later in the night, the St-cloud disappears temporarily. At the active occlusion on Thursday during the day a massive package of layered clouds with ever lower St clouds in the afternoon, in HA43 almost to the ground. In the hot sector of the subsequent edge failure is somewhat higher, but still around 500 ft. With the passage of the cold front, the St Cloud also disappears. In the polar air then follows convective clouds with also Cb's with tops up to ca. FL180.

Precipitation
The light showers we are dealing with today often go on a little longer than the models show. The light showers will disappear tonight. At the active occlusion a zone with moderate rainfall, behind it to the heat front also drizzle. At passage of the fronts of the active edge interference again periods with moderate rainfall, most rain than in the north, which is closest to the occlusion point. Thursday is 10-20 mm, mostly in the north, in the north local to more than 30 mm in Harmony exports. After passage of the cold front some showers. Cumulative until Friday morning there is 15-30 mm, most precipitation in the north.

Synoptic development
On the southern flank of a layer above the Norwegian Sea, an active edge disturbance over the middle of the North Sea east moves to Friday and Friday morning. A second active peripheral disturbance is moving east on Saturday, but the precise course of this system is still somewhat uncertain. Eventually, during the weekend, a large (height) layer forms above Central Europe and at the same time a firm back above the Atlantic Ocean with an elongator towards Scandinavia. In our environment a few days later there will be a northeastern current in which polar air is originally brought in and from time to time some fronts (along with the layer above Central Europe) move retrograde westward over our environment. Later next week, the (height) layer over Central Europe gradually disappears and further development becomes uncertain.

Model assessment and uncertainties
The main focus for the short term is the sequence of active frontal systems and peripheral failures. Besides the precipitation, the wind is also a focus. The course of the low on Saturdays is uncertain. A northerly course across our country causes a lot of wind and precipitation. On the north slope of the layer the air is cold and the precipitation may fall locally as (wet) snow. It also brings with it a lot of wind and there is a clear chance of strong wind blows, even a small chance of very heavy wind blows. However, in the ensemble there are also enough solutions with a cowl (clear) south of our country, in terms of wind there will be little going on with us. From Sunday we are in the polar air, with especially on Sunday showers from the North Sea, Monday the showers because of the somewhat clearing wind stay more on the North Sea. Temperatures go down and especially inland increases with sufficient clearances the chance of frost and in the night and morning, even during the day it gets considerably colder, but there is no real winter cold. On the north slope of the (altitude) layer, next week we see some retrograde disturbances about Poland and Germany approaching, this creates some uncertainty in the expectation of cloudiness, precipitation and temperature. From the middle of next week we see the majority of EPS coming back with a southwest wind. In an increasing number of members we see it gradually softening and precipitation opportunities are gradually increasing. However, the spread in the ensemble remains large and still cold solutions remain visible, even a few that get even colder.

Multi-day Summary
Until the weekend with occasional rain and sometimes a lot of wind. After the weekend, calm down. From Sunday it gradually gets colder.

EPS Period Summary
The expectation for this period is uncertain. It probably gets a bit more variable (60%) again with slightly rising temperatures and an increasing probability of precipitation. In addition, there is also a (smaller) chance that it stays on the cold side.

Valid from Friday 06 December to Wednesday 18 December