As the last of a couple of weak weather systems exits the Mid-Atlantic region later this Sat., Apr. 26, 2014, a much stronger storm will organize over the Rockies (Fig. 1). This system will begin to affect the Central Plains today (Fig. 2). As it moves out into the Plains by tomorrow, it will lead to the development of a busy severe weather week.
Today’s East Coast system will bring a few thunderstorms to parts of the Delmarva region. These storms should not be severe.
The follow-on system will not be as gentle. NOAA’s Storm Prediction Center (SPC) is indicating that a multiday severe weather outbreak can be anticipated. Starting across the Plains on later today (Fig. 3) and tonight, the system will plod eastward and affect much of the lower Mississippi River Valley and parts of the southeast during the first half of next week (Fig. 4, Fig. 5 and Fig. 6).
This system promises to bring a spate of stormy weather including tornadoes (some large and damaging), high winds, large hail and local to widespread heavy rainfall from Arkansas eastward to Alabama. The outbreak, classified as a moderate risk at the writing of this article, could easily be upgraded to the high risk category according to the SPC.
Much of Mississippi should see rainfall floodgates open with three to five inches of rainfall by next Wednesday (Fig. 7 and Fig. 8). Parts of southern Alabama and northwest Florida may see rainfall amounts approaching half a foot. Note that some waterways across central and southern Mississippi and northwest Florida remain at or above flood stage currently.
North of the low-pressure system, a chilly northeast breeze will keep daytime readings some 10 to 15 degrees below seasonal averages. Several inches of rain may fall across the western Great Lakes westward to Minnesota and Iowa during the Sunday to Thursday period.
By the middle to latter part of next week, as the system reaches the East Coast, the combined effects of slow system movement and the Appalachian Mountains can foster a large area of four to six inch rainfall from the eastern Great Lakes, through the Mid-Atlantic southward into Georgia.
Looking ahead to the first ten days of May, well below average temperatures are on tap for the two-thirds of the U.S., while temperatures are expected to continue to be warmer than average out west. It will be wet across the northeast and eastern Great Lakes, but dry to abnormally dry weather will spread eastward from the Rockies into the Plains states.
© 2014 H. Michael Mogil