Next Weeks Polar Blast - What We Know
On Tuesday, reports surfaced on several weather pages on Facebook about the possibility of snow falling close to sea level. One specific publication even went as far as forecasting 5cm of snow for Christchurch a week ahead of the expected event. Such premature predictions can be risky and misleading due to the fluctuating nature of extreme changes in model data over such a long period.
Severe Weather NZ's forecasters approach snowstorm forecasts cautiously, providing ample time for those potentially affected to make necessary preparations. The upcoming weather system is complex, with multiple factors requiring careful observation and analysis for accurate forecasts. We have recently begun to see some model consistency regarding event set up, but there are still discrepancies between models. Variations in forecasted scenarios, such as Warm Advection snow versus an active front from the south, are commonplace during significant cold spells. Over the next few days, we anticipate the convergence of data sets towards a more cohesive forecast.
With the beginnings of model agreement, we have been able to identify some areas that may be affected by snow in the upcoming days but please take caution that things are likely to change. Currently, high country regions have been issued a SLIGHT risk for Otago and Canterbury in our 'Significant Weather Outlook' on our home page for Monday and Tuesday - an update to this Significant Weather Outlook will be made during Thursday afternoon. However before we can make a firm forecast or increase risk areas we need more time to observe any significant trends that could assist us in predicting the amount of snow expected in these at-risk areas accurately. It is crucial to note that there are various variables that we must consider to ensure an accurate forecast.
One critical variable is warm advection snow, a phenomenon common in New Zealand where moisture travels from the Tasman Sea or even the sub-tropics, while cold air from Antarctica moves upwards, creating ideal conditions for snow formation and precipitation. Keep an eye on updates as we monitor the situation closely, especially for our farmers who are directly impacted by such weather events. Stay informed with Severe Weather NZ for the latest developments.
For this advection setup to work effectively, it is crucial for the moist air and the cold airmass to coincide at the same time. If the moisture arrives and departs before the cold airmass, the conditions are not favorable for snowfall. In the upcoming weather event next week, it is anticipated that the moisture will linger for several days. However, there remains a significant uncertainty regarding the exact amount of moisture present and the potential for snowfall, including the altitude at which it might occur.
We hope this article creates a better understanding of this complicated weather system and a small insight into whats involved with forecasting snow.
Please keep up to date by checking our website regularly and our Facebook page.
