Tuesday, May 28, 2013

Charles Roberts


Dip in the Jet:  More Severe Storms

In a typical May, warm and humid air near the surface is easily found in the Plains.  All you need is a southward dip in the jet stream over the Rockies to send jet stream disturbances aloft over this warm, humid air.
Such will be the case this week.
Pockets of severe thunderstorms are expected onTuesday from the Plains into the southern Great Lakes, as weak disturbances aloft ripple overhead across these regions. Large hail, damaging wind gusts and some tornadoes are possible.
Background

Forecast Wednesday

Forecast Wednesday
Background

Forecast Thursday

Forecast Thursday
By Wednesday and Thursday, a moresignificant and widespread severe threat is looming.
The difference lies in the potential for a much stronger upper disturbance, or entire jet-stream level trough itself, swinging out into the Plains, where, as we mentioned earlier, warm and humid air will be in place.
While the specifics may change a bit, due to limits in predictability of severe weather, and forecast differences among weather guidance, here is our current forecast thinking:
  • More widespread severe thunderstorms, including a possible tornado outbreak, will explode across the Plains Wednesday.
  • This more widespread severe episode will likely continue in parts of the Plains and Midwest Thursday, and perhaps Friday.
In addition, this slow-moving weather pattern will continue to lead to heavy rainfall totals from the Missouri Valley east to the shores of Lake Michigan.
A stout zone of high pressure along the East Coast, severe thunderstorms are not expected to make much eastward progress this week. A warm front may bring some storms to the Northeast Wednesday. But otherwise, the East will remain largely untouched by the turbulent weather over the central states, at least through Friday.
Check back with us at weather.com, The Weather Channel TV and Weather Underground for the latest on this potential severe weather outbreak.
MORE ON WEATHER.COM:  Aerial photos of Moore, Okla. damage
For an interactive map of the Moore, Okla. damage, click here.

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