Friday, April 1, 2011

April 1, 2011: 5-Day Forecast

Tomorrow, an area of precipitation will move out of the Ohio Valley and off the coast of the East.
High pressure down South will keep the South, Plains and Midwest dry.
That will be following a cold front.
There will be a low pressure system up in the Northwest creating some snow and rain in the general region.
It will be a quiet day tomorrow. The Midwest will be warming up. Quite literally, tomorrow will be the calm before the storm.

The severe weather situation will begin with storms developing in the South Plains. Those storms will expand northwards to later impact the Midwest. These storms could eventually create a widespread severe weather outbreak, with potentially a tornado outbreak in the Plains.

The severe storms will continue into the Southeast and intensify, creating some problems for the region. It is too early to tell exact threats.

Overall Severe Weather Risk April 3-5

This map is subject to potentially major changes.
The Weather Centre does believe the tornado threat will be in the Plains where the original squall line develops, with a fairly uncertain significant tornado risk in North Illinois.
The overall risk area for the first day expands across most of the Midwest and East Plains down south to the Gulf Coast.
The Risk Area for the day following will be the Southeast into the Eastern Seaboard.
This is definitely something to watch.

April 3-5 Tornado Threat Appears to be centered up North

The overall tornado threat will keep in the Plains, but the latest run of the Storm Prediction Center's SREF indicates the ingredients will come together to make up to a 20% chance of significant tornadoes in Illinois. North and Central Illinois, specifically.
Significant tornadoes are different from regular tornadoes. Significant tornadoes are strictly F2 or higher on the Fujita scale.
That said, with extreme caution, The Weather Centre is prepared to issue a dangerous situation bulletin going into the event.

Significant Severe Weather Outbreak Possible April 3-5

There is definitely potential for a significant severe weather outbreak for the Plains and South Plains into next week. We at The Weather Centre have obtained new images from an excellent source on this next outbreak.
First, let's outline where thunderstorms in general may occur.
The NAM is predicting that these storms will begin due to a low pressure system in the Oklahoma area. When these storms develop, it is crucial to know where the moisture output will be. With such a defined low pressure on this map, it can be expected a good moisture output will be present in the area.
These storms will develop into a squall line as another low pressure, with warm front and subsequent squall line. This squall line could be strong and very severe, with strong tornadoes possible. This is when we turn to another map, named the STP, or Significant Tornado Parameter. Below is that map with the same time period as the image directly above.
When such a parameter is as high as it is above, there is an extreme danger in that area.
Now, we will continue to the period where this risk moves north and east.

We definitely see a resurgence in this tornado risk as the cold front takes total control. A warm front will be dragging the moisture north.
A determining factor in tornadoes is also helicity, which is when there is updraft ROTATION in supercells. Values of 250 or higher indicate the greater potential for tornadoes.
Here, we see very high values of helicity on the brunt of the storm, suggesting tornadic supercells may occur at the beginning of the squall line.
This has been an in-depth forecast. This topic will be presented again in tonight's forecast discussion.

Northeast to get pounded with snow

In what may be a last-ditch effort for Old Man Winter, a Nor'Easter will ride along the coast and put out 12 inches or more of snow.
This late season snow certainly looks like the last one in the days to come, but will be possible, considering it is still spring.
Below is a link to all snow information on the storm.
Click Here