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    Much Needed Break in the Weather Pattern

    5/05/2011, 6:32:08 AM

    Thursday, 11:25 a.m.

    Flooding persists in portions of the Ohio Valley into the Mississippi Valley, and portions of I-40 from western Tennessee to Little Rock are closed as a result. In some communities, the flooding is as bad as it has ever been, and it's not close to getting under control. The latest flooding from a geographical standpoint:

    It is a welcome pattern 'interruption' then, that we're now in the midst of. The cold front well off the East Coast has made it well down into Florida, and the humidity has been swept clean from the South. As a result, there's just not much moisture available to the feature rolling out of the Midwest this afternoon. Oh, there will be some thunderstorms this afternoon and early tonight, and there may be some locally severe weather in portions of Illinois and Missouri for a time, but that window will be pretty small. The thunderstorms should weaken late tonight, and most anything from the Ohio and Tennessee valleys to the East Coast tomorrow and tomorrow night will almost certainly not be severe. Here's the latest model projections of precipitation through Saturday evening:

    That may be enough to cause localized flooding in those two states, but most of the heavy rain will avoid the areas with the worst flooding right now. Certainly, areas from Georgia westward to Texas and Oklahoma will be rain-free going into and through the weekend.

    System number two will behave in a fairly similar fashion to the first one. It will come into the northern Plains tomorrow afternoon with little more than spotty showers and a thunderstorm. As it moves across the Midwest into the Ohio Valley late Friday night into Saturday again, there will be SOME rain and a few thunderstorms, but little in the way of organized severe weather and only pockets of heavier rain.

    Once again, the Gulf of Mexico just won't be open for business, with high pressure sitting over the Florida panhandle and the northeast Gulf on Saturday. The clouds and showers will keep temperatures in check from the northern Plains to the mid-Atlantic, and a few places will remain several degrees below normal, but that will be the exception.

    As we move into next week, a deeper trough will dig into the West. Look at the jet stream forecast for Sunday evening:

    The effect of this significant buckling of the jet stream is to force the heights to rise downstream across the Plains and Mississippi Valley, promoting warming. There will be a pretty large area of 90s showing up Sunday and Monday in the central and southern Plains before this western trough migrates eastward and pushes a front out of the Rockies.

    Then, with high pressure off to the east, persistent low-level southerly winds will finally start bringing more copious moisture to the table. Throw that in with the forecast heat, the approaching front and a deepening of low pressure in Kansas and Nebraska, and it will only be a matter of time before strong thunderstorms begin to bubble up. Initially, they may be more on the periphery of the heat, but as a cold front comes out of the Rockies, thunderstorms should find their way to that front. It may take a while to get to the southern Plains and the lower Mississippi Valley, and the more time there is before the front reaches these areas, the more time for the existing flood waters to recede. Eventually, though, this much needed break in the stormy weather pattern will give way to a stronger system next week.

    The views expressed are those of the author and not necessarily those of AccuWeather, Inc. or AccuWeather.com


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