Sunday, March 17, 2013

Long Range Forecast: Late March-Early April 2013

This is The Weather Centre's Long Range Forecast for Late March into Early April.

I am anticipating a highly meridional flow to establish itself in this timeframe, in the face of a very volatile pattern across the northern Hemisphere. Excessive high pressure over the Arctic will allow for cold air masses to be forced down into lower latitudes. High pressure centered to the south of the Bering Sea and low pressure centered directly in the Bering Sea will allow for high pressure to take over the Western US. This comes as the Bering Sea low pressure extends itself down into the waters offshore the west coast of North America. The formation of the Rocky Mountain high pressure system will be helped by cycling bouts of low pressure in the Midwest, Great Lakes, Mid-Atlantic and Northeast. When these large spots of low pressure pop up in the aforementioned regions, it can be expected that a fresh dose of cooler-than-normal air will be given to many east of the Mississippi River. Based on how strong the high pressure system in the Arctic will be, I can see it possible that some isolated wintry precipitation may make its way into Florida over the next couple of weeks. That's how strong this cold air will be.

The meridional flow of the jet stream (meridional means not straight; wavy, disturbed) will allow for the jet stream to be stronger than normal at some points in the US. If a storm system manages to get into the right place at the right time, I could see a solid potential for a severe weather event in the southern Plains and Gulf Coast.

I expect dry conditions to prevail over the Rocky Mountains. This is very bad news, but the wildfire season will be influenced by this high pressure formation. If current projections hold, we could see a long-term high pressure formation over the Rockies, and this would not be good in the slightest for those in or near wildfire-prone areas.

Honestly would not be surprised to see late March allow one or two more winter weather events, possibly an accumulating snow event. Based on several other atmospheric indices I am monitoring, this snow threat would likely be confined to the Northeast and general Eastern Seaboard. The risk for Nor'easters lives on.



Anonymous said...

Actually in my opinion a high pressure system over a wildfire area is actually very good. This is because the winds would remain stagnant, and strong winds are a requirement for wildfires to grow and spread.

Eric said...

It's actually quite the contrary as areas of high pressure are indicative of sinking motion in the atmosphere, thus compression takes place near the surface, and with compression under the summer wavlengths comes heating, which also dries out the air over the given region, and when you have a strong region of high pressure in place, even with a low pressure area hundreds of miles away, the pressure gradient between the two systems would actually enhance the winds, thus along with compressional heating and dry air, conditions are very favorable for wildfires.