Synopsis
A large low pressure area southwest of Iceland maintains a southwest current. This provides soft and fairly moist air. An NNO-ZZW oriented frontal system reaches the west of the FIR tonight and draws in activity declining east. The (weak) heat front runs north of the FIR east, quickly followed by the cold front. Due to wave formation south of the British islands, the frontal zone continues to drag NO-ZW towards the northwest of the country in the morning. In the afternoon, this front moves north as a heat front. The frontal wave will then move north tonight just northwest of the FIR. The associated cold front reaches the west of the country in the night to Friday, and then slowly moves east. An NNO-ZZW-oriented cold air development (CAD) runs into this and reaches the west of the country at the end of the night to Friday. The cold front leaves the east of the country on Friday morning, followed by the CAD in the afternoon.

Model assessment
Between the models near the frontal systems regarding the cloud base the usual differences between Ha43 and EC, with Ha43 (given the current and past results) best followed. The deactivation of precipitation above land is clearly reflected in the models, with Ha43 being a bit more dashing with a few showers on the CAD Friday morning (the profiles are a bit damper than EC). Furthermore, Ha43 exaggerates the winds at sea (the 10-min wind is easy to follow). Due to the winds that land, there is no yellow at all. With regard to the formation of fog Friday evening this is especially seen in Ha43, at EC we see more high and high clouds that prevent/remove the formation.Attention

Wind
South, 6-7 Bft approaching the frontal system. Over the sea, heavy winds (>75 km/h) are calculated, but due to the landing wind (and the relatively stable build-up above the sea) they do not reach the country. During the day, especially north of the front, wind decreases to 4-5 Bft, south of which wind force 6 (sometimes) remains possible in the coastal area. In the frontal zone other than the northeast of the FIR above sea 7-8 Bft. Har43 calculates outliers >90 km/h in many places above sea, but given the stable structure this is probably exaggerated (also seen in the calibrated Har43 wind forecasts (HARPOON)). Along the coast in the far northwest, outliers >75 km/h are possible, but these do not enter the country due to the south wind direction. Friday, the wind gradually subsides and disappears from the south from the signals during the evening.

View
Initially tonight in the northeast still moderate views. Due to the increase in wind, the views rise in the course of the night. In precipitation at the frontal zone, and above land in the night to Friday at the cold front moderate to bad views (rain and drizzle). The course of Friday evening formation of some (ground) fog banks, the night to Saturday possibly on a large scale (close) fog (except the southeast).

Temperature
EC is in the warm sector this afternoon and tonight several degrees warmer, and drier than Ha43. For the temperature we follow EC, this is usually more realistic with this. Particularly soft, the maximum (around 13°C in Zeeland) is only reached during the evening. The night to Friday with minimums of 9-10°C again very soft, Friday during the day changes little in temperature.

Cloud
At the frontal zone this morning on extensive scale St, this one may just reach the northwest coast. In the afternoon in the north of the FIR deteriorating conditions on the ground front with chance of St on deck. At the cold front tonight and at night to Friday especially in the coastal area and above land increasingly St. At the CAD a single TCU/CB with peaks between FL100-FL150.

Precipitation
At the weak cold front local still drizzle. At the frontal zone of rain, but the intensity is declining inland. In the (outer) southeast it probably stays dry. At the cold front on tonight and the night to Friday occasionally (light) rain and drizzle. At the CAD a single shower.

Synopsis
Until next Saturday we are north of a back of high pressure between high pressure areas over the Azores and near the Black Sea. In combination with some low pressure areas that move from Newfoundland to Scandinavia, we have to deal with a southwest flow and supply of soft air. This Sunday, a low pressure area near Iceland will dive southwards and via England to the Bay of Biscay, after which high pressure builds between Iceland and Scandinavia and the current is blocked. The current in our environment is then gradually (north) east with supply of drier continental air. Eventually, a high pressure belt extends from the northwest of Russia to the Azores. In the post-Christmas period, the center of the high pressure probably moves westwards between Iceland and the British Isles, making the current north and making it more variable.

Model assessment and uncertainties
The transition to a gradually colder and mainly dry weather from the weekend onwards is already clear in EPS. The transition to this dry continental flow is temporarily accompanied by a transition in which the flow largely disappears and the air is still relatively humid. Coming weekend and the beginning of next week we see some chances of fog in the night and morning, especially next Saturday. From the beginning of next week, the air supplied gradually gets colder, but since the source areas (yet) are not really cold and the supply is about a largely snowless route it will remain with some winter quail weather. After Christmas it seems that colder air can reach us (about 40% chance of moderate frost in the night and morning, but the probability of ice days remains very low by about 10%), but possibly frost can still be tempered by the production of Sc clouds over the Baltic Sea, which happens more often during the first more serious cold of the season. By the way, 20-30% of members still position the axis of high pressure south of our country and with a western supply it can simply become rather soft. The EC 1612 operating/control run also indicates what can be achieved in winter weather and is among the coldest members of EPS. In addition to the fact that it is likely to remain almost dry from the weekend ahead (precipitation rates of about 20%), the chance of winter rainfall remains virtually negligible (the upper air remains relatively warm at first). A white Christmas is therefore not in this year, the maximum possible seems to be a single flake from the Sc fields. When, somewhere in the period after Christmas, the current may become more northern, the chance of a few winter showers really increases, but that is still very far away.

Multi-day Summary
First soft and occasionally rain. From the weekend mainly dry, gradually less soft and in the night and morning chance of fog.

EPS Period Summary
High risk (70%) on dry and (free) cold winter weather and a small chance (30%) on slightly variable and rather soft conditions.

Valid from Friday 19 December to Wednesday 31 December