Synoptic assessment of weather models

Every day, KNMI meteorologists analyze and interpret the results of the Hirlam, ECMWF and Harmonie weather models. Below you can read their findings, particularly educational material for those who want to understand more about the weather on the maps and in the graphs.
 
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Short-term to + 48 hours | Guidance multi-day model review
 



Models overall rating up to +48 hours

Published: 23/06/2025 23.45 uur LT
 
Guidance model assessment for the Netherlands, the Dutch coastal waters and the North Sea, based on the HIRLAM run of 12 UTC and the other mentioned models and guides with associated run time.

Synopsis
The current is west, on the ground southwest. This morning, a frontal system reaches the west of the FIR, to travel east in the afternoon and evening, especially the northern half of the country. Then the cold front is stationary above the north. On Wednesday, a south-east-north-west-oriented back is drawn across the North Sea region north-east. In the back the front dissolves. After passage of the back, the current is brought east, south at altitude, and tropical air.

Model assessment
Actually there are more cloud fields than in the models, although it seems to clear up from the west. In the frontal system there are the usual differences in the cloud image where there is too little cloud in the EC output and the base is too high. Harmony output is more or less usable in clouds. On Wednesday morning, in Harmony exports, an area with stratus expands and is missing from the Channel across the southern North Sea and the south of the Netherlands. In HarmonEps exports, the probability of <1000 vt above the far southwest of the FIR is about 80%, but to the north the probability is decreasing rapidly. In EC exports at most some turbulence stratus occurs in the early morning. We do not expect the stratus and misses itself from Expand the Channel to our FIR. Turbulence-stratus above the southwest is realistic, it dissolves during the day.Attention

Wind
Today signal 6 Bft, initially only in the north of the FIR, later elsewhere. The outliers are clearly too high in EC exports, the Harmony exports are realistic.

View
All right, falling down. Wednesday night and morning early above land local nebula, possibly also on the southern North Sea. We do not (yet) start from fog.

Temperature
In EC exports, Wednesday in the south is getting much warmer than in Harmony exports. This is because in EC there is less and thinner clouds than in the Harmony model. EC exports are preferred. The Tx for Wednesday thus ranges from approximately 20 C on the Wadden to room 29 C in the southeast.

Cloud
Above the North Sea, according to the models north of 53°N, chance of stratus in the warm sector. Further south, higher cloud base. The clouds are mainly layered, on the coast is possible sowing. Wednesday morning in the southwest chance of turbulence stratus, above the sea possibly also stratus advtive from the Channel.

Precipitation
Precipitation at the frontal system is mainly stratiform. In the north there is a local drop of about 3 mm, while elsewhere there is no significant fallout.

valid until Tuesday 24 June 2025 24.00 local time



 

Guidance multi-day

Published: 23/06/2025 04.53 uur LT
 
Long term assessment by meteorologist

Synopsis
During the whole period we probably have to deal with a sunny but somewhat meandering flow pattern, where the W-O orientation gradually tilts towards a WZW-ONO direction. The beam current will be a little more north. So we will regularly find ourselves in a rather warm air species, mostly under the influence of high pressure areas that will nest slightly south of our environment. Before this tilting takes place on Thursday 26 June, a meander passes first, in which the warm air in which we end up on Wednesday is driven away by an active disturbance.

Model assessment and uncertainties
Removing the heat later on Wednesday and Thursday can be accompanied by heavy thunderstorms, with the center of gravity above the southeast. A code yellow seems plausible but the probability of a higher warning seems small given the 'unfavorable' timing. Thursday (and Friday) there is also quite a lot of wind, although the chances of strong winds are small. Afterwards the precipitation opportunities decrease to about 15% and we see a lot of sun in the expectation. The temperature flow becomes the uncertain factor, where the proximity and orientation of the high becomes the determining factor whether or not to reach tropical air from the south. Around Sunday and Monday summer temperatures are high inland and the chances of tropical temperatures are low. Although the odds are small, thunderstorms are possible again. In the course of next week, the chances of higher temperatures decline and precipitation rates increase to about 30-40%.

Multi-day Summary
Wednesday inland summers hot, on Thursday followed by (thunderstorm) showers, lower temperatures and also quite a lot of wind. On Friday the calm, sunny and dry weather returns, with a bit higher temperatures during the weekend.

EPS Period Summary
Most dry and sunny periods, with temperatures initially above the long-term average. Later the chance of a cooler and more variable weather type increases.

Valid from Wednesday 25 June to Monday 07 July

 

 

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