Wednesday, 11:30 a.m.

What do you ask is being locked out? For one, the arctic by and large. Just look at the source regions of air masses across the country now and through the weekend, and there's far more Pacific air flooding the country, as expected, than anything else. And the Gulf is locked out. For now, anyway. Just look at all of the sunshine being seen from Texas to northern Florida, and how little moisture is being drawn northward toward systems that are moving from the northern Plains and Midwest to the East Coast.

The East has turned colder in the past 24 hours as a cold front has charged offshore. And the upper-level trough that is digging into the East will have enough cold air with it for it to snow in the next 48 hours, but it will be limited in scope and should be gone Friday. That's how fast this upper-level trough will move in and out. A quick glance at the North Atlantic Oscillation shows it to be in the positive mode right now, which means no downstream blocking. For now.

But when I look at the projected surface weather maps Friday through the weekend, I see an awful lot of LOW pressure across Canada, not high pressure. When I see that, there's no good reason to predict cold air, and if you do, you'd better not forecast it to say for any length of time. And if it is cold, it's almost assuredly a result of some sort of anomalous upper-level low or deep upper-level trough that's generating clouds and precipitation.

Therefore, when the next storm sends moisture to the Northwest beginning tomorrow, and especially tomorrow night into Friday, the snow levels will be pretty high in the Cascades, and the interior areas will turn warmer. In turn, that warmer air will then get even warmer flowing over the Rockies and onto the central and northern Plains, where the landscape is devoid of snow, so no refrigeration of the air mass from below.

Meanwhile, the winds in the low levels of the atmosphere are generally from the north and northeast along the Gulf Coast region. That's thanks to a series of high pressure systems that continue to parade from the Plains to the Southeast. The next one in line will move from Kansas and Nebraska this evening to Tennessee tomorrow evening, then to the Carolinas and Virginia by Friday evening and finally to the Southeast coast Saturday evening. Only after that will there be some changes in the latter half of the lockout party.

Three things will then be watched carefully. The first is a tropical depression over the southern Caribbean, that could become a tropical storm off the coast of Honduras, if it isn't already. This will be a slow-moving system but could contribute moisture to the end game next week across the eastern half of the country.

The second feature is still brewing slowly over the southwest Gulf. We've seen high clouds moving off of this to the north into the central and northern Gulf before they thin out, so there's no immediate concern of any kind of rain on land. However, over the next four days, it will probably slowly develop and drift northward and could well become dry areas wet from Texas the central Gulf Coast region later in the weekend and early next week.

The final system to watch will be one coming from the Pacific that will help summon more of this Gulf (and perhaps Caribbean) moisture northward late in the weekend into next week. Where specifically all of the moisture will be targeted is still open for debate, but at the very least we'll see the vast sea of dry air now across the country replaced with a much stormier pattern. The Rockies will probably get some snow out of the deal early next, and the entire West will turn cooler. This will once again be more a product of the cold aloft with the upper level trough rather than any true cold (arctic) air. I would anticipate a good bit of next week from the Plains eastward to be above normal.

If you're like, you will do everything you can to take advantage of it! It's now just a matter of time.

Posted by Joe Lundberg on Wednesday, November 04, 2009 11:28 AM
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