Weather news: Cold season ahead: big uncertainties 02/01/2023
Several scenarios call for cooling in the second week of February, and some media are already declaring a “cold wave”. It is important to adjust forecasts for this return of cold.
Poor configuration
The creation of a possible “cold wave” for next week follows a series of events predicted by the American model. This significant cooling will be initiated in the Norwegian Sea on Sunday, February 5, 2023 by a trough moving down towards Germany, where a cold drop will form. This will then plunge towards Italy and contribute to the formation of an active depression near the Gulf of Genoa. This will then act as a ‘cold pump’ by forcing continental cold air into our regions, emphasizing the continental flow from the northeast sector over France and Central Europe.
Geopotential anomalies causing a possible cold snap according to the American model – via wxcharts.com
The fact is that cold weather is a difficult event for models. The cold infall must be dynamic enough (and therefore the thalweg at its origin must be deep) to act as a “cold pump” for the low pressures to be active towards Italy. However, other models suggest a shallower thalweg where cold intrusion will be weak and cause limited cyclogenesis only in the Mediterranean. Without an active depression, the continental flow would be weaker and more transient, draining colder France less efficiently. This will also help the anticyclone pull directly over the hexagon faster.
Status as of February 6, 2023 for American, European, and British models – via meteociel.fr
Finally, it should be remembered that France is at the end of the cold continental currents due to its position in the westernmost part of our continent. Thus, even the most wintry scenarios proposed by the American model imply a cold stop near the oceanic arc. This means that the margin is small, and a simple shift of 1000 km eastward (nothing at the one-week deadline) would be enough to save the entire country from the risk of a cold wave. Suffice it to say that the situation remains very fragile…
Air masses at 850 hPa (about 1500 m) for February 7, 2023, according to the American model – via wxcharts.com
Average scenarios are the majority
So, some mass media have already announced a “cold wave” in France for the next week, simply considering the scenario of the American model. However, the latter suggests a scenario that seems isolated compared to the others. In the comparison below, we can see that it considers a noticeable cold for Tuesday, January 7, 2023, with no thaw in the east. However, its three European counterparts, German and British, suggest a very different scenario, with a more classic chill for the season (4-6°C in the northeast, 7-10°C in the west, 11-15°C in the Mediterranean). ).
Maximum temperatures for February 7, 2023 according to American, European, German and British models – via meteorologix.com
Moreover, the deterministic scenario (unique projection) becomes invalid when the deadline increases. It is recommended to consult the panel as a whole, it allows to show which are the different simulations and therefore the different possible scenarios. The latter indicates that the final scenario of the American model is much lower than the average of the panel! Therefore, this projection appears to be isolated from the average, which tends to remain more classic cold for the season. It seems inappropriate to use this unique scenario to announce a chilling moment.
Panel of American model scenarios for air mass temperature in Paris by February 9, 2023 – via meteociel.fr
So far, no one knows how much the cooling will be next week, but most scenarios are for a moderate cooling that leads to winter values, but is far from a so-called “cold snap.” . We recommend regularly monitoring the evolution of our forecast bulletins >>>
