THE ‘GLOOM’ 101 – WHY THE DRAMATIC CONTRAST IN WEATHER ACROSS THE REGION TODAY??!!
THE ‘GLOOM’ 101 – WHY THE DRAMATIC CONTRAST IN WEATHER ACROSS THE REGION TODAY??!!
Our High Pressure systems (Anticyclones) are usually associated with sunny & calm conditions, but occasionally during the cooler months May through to September we’ll see these dreary cool days, where the sun doesn’t even make an appearance. A set – up often referred to as anticyclone ‘gloom’.
Today was a prime example of a large high pressure in firm control, a lack of wind, cooler temperatures and we see low cloud (strata) & fog pushed onshore. While most of coastal Canterbury will experience gloomy weather, inland area & basins will escape with sunny & calm days. Often low cloud burns off during the morning, but as we experienced today, it can hang around all day, if there is no change in the big ‘picture’ movement of systems & fronts.
The likes of Hanmer Springs, Castle Hill, and Mackenzie basin are often the places to be, when we experience this set up. Occasionally during the winter months, this low cloud and fog may penetrate into these areas, but as a general rule it’s more a coastal event (places under 300m elevation). This was the case today, with most of Canterbury escaping the low cloud, while areas closer to the coast were dominated by low cloud, drizzle and cool temperatures.
Why is it difficult to forecast? It’s difficult to forecast because these situations aren’t associated with any moisture content and the actual cloud is formed offshore; additionally maps, models provide little idea on when these days will occur. What makes it even more difficult is on the day; the million dollar question ‘’Will we see the sun??!! Basically in this set up, we don’t know, nobody does, and it’s often a waiting game, as we head into later stages of the morning! What we do know is where to escape the cloudy & cool weather and what can possibly bring about this frequent scenario.
WHAT’S THE GO TOMORROW? Another familiar Canterbury set up, low cloud and fog, with isolated patches of drizzle across the region early, with surface winds from the NE. During the afternoon an active low pressure from the Tasman will bring milder Norwest winds, with extensive high cloud developing, this will eventually touch down across the Plains during the afternoon, pushing away this low strata cloud & replacing it with extensive high cloud; yes, we should see some sun!
Hope that helps a bit, it’s been a long day!
Weather Analyst: Russell Voice