Mar 28, 2012; 9:48 AM ET
Wednesday, 11:30 a.m.
Normals are changing at a rapid pace throughout the country these days, rising a degree every two or three days. The mid-latitudes are gaining a solid three minutes of daylight each day, more to the north and less to the south. We've already seen a massive warm spell in a large part of the country, showing the potential of the atmosphere even at this early stage of spring.
At the same time, there's still some cold air around. Just look at how cold it was across the Northeast yesterday. The West has been cooler than normal much of the month, and it has been decidedly cold in much of Alaska. Another little chunk of chilly air will slide by the Great Lakes into the Northeast tomorrow into Friday, giving quite a bit of resistance to the next surge of warm air coming out of the Plains.
Nevertheless, the pattern is still a warm one heading into April. Look at the GFS seven-day ensemble means for tomorrow through the following Wednesday:
Despite the development of an upper-level low over southeastern Canada in the next few days, the pattern will remain a progressive one as well. In other words, the features that you see on the weather maps will march steadily along from one part of the country to the next.
As an example, an upper-level disturbance crossing the Northwest late today will move into the central and northern Rockies tonight then into the northern Plains tomorrow. Eventually, a decent storm will form that will bring rain and some strong thunderstorms across the middle and upper Mississippi Valley. That rain and thunderstorm area will then cross the Great Lakes and Ohio Valley Friday then speed off the mid-Atlantic coast by Saturday morning. It should be noted that snow is a real possibility north of the track of the storm, and that includes northeastern Minnesota and northern and central Michigan, as well as portions of upstate New York.
A much stronger upper-level trough of low pressure will crash the West Coast late Friday night and Saturday, spreading heavy rain and mountain snow across Oregon and northern and central California. In response to the lowering of heights with this feature, the heights will rise downstream over the eastern Rockies and Plains, promoting still more warming and preventing any really cold air from reaching these areas.
The exceptions will be along the West Coast, and in particular the Northwest, where persistent clouds and the passage of multiple disturbances will keep it cool and moist. Another will be in the Northeast, though even there a foray of warmth probably gets in for a day or two early next week ahead of another upper-level trough later in the week.
We could use some rain over the western Plains and eastern Rockies. The wildfire in Jefferson County, Colo., is just a harbinger of what's to come if no rain gets into these areas. The relative humidity Monday afternoon when the strong winds kicked in and spread that fire was about 4 or 5 percent. Unfortunately, another strong wind/dry air mass 'event' is shaping up for late Friday or Friday night into Saturday, with hardly any showers out of the passage of a cold front, even in the mountains.
No comments:
Post a Comment