The above outlook is once again based on a blend of the NAM/SREF and also the GFS. As you can see this map is a little different from what we normally would issue. We have what would be the severe zone. To the north of the red line indicates where we think is the best chance for any tornado’s. The purple circle is the area we think has the greatest chance or highest risk (not the same as issuing a high risk outlook) of those tornado’s due to the parameters that will be in place. So with that said lets look at the latest parameters..
CAPE is 500-5000 depending on where you are located
Lift Index is 0 to –12 depending on where you are located
SWEAT index is highest 350-400 from Majority of PA to the Southern New England into Maine region and then from where the zone is in Tx back into OK and Missouri and then into KS, Nebraska and Iowa.
EHI is highest in the areas of SNE where it is about 1.5 .
With the SWEAT coinciding with the highest EHI it is this region , we feel that this will be the region with the greatest potential for tornado’s.
Current thinking is that storms will form ahead of and along the cold front which should be approaching the northern regions from 12 Z to 18 Z and then other regions between 18 Z and 00z or 2 PM and 8 PM. These storms will be along and ahead of the cold front and the actual cold front should not cross the southern areas till between 8 PM and 8 AM. So this means that locations in PA to SNE may very well continue to see rain and thunderstorms embedded even after 8 PM.
There is a distinct possibility with the air mass that is presently in place..that the models could be underdoing some of these parameters. If this is the case a moderate risk may be needed for the area to the North of the red line. By evening a low pressure area should develop over Eastern VA and this may enhance some rainfall across the region.
Dewpoints are currently in the high 60s to near 70 so there is no need in pointing out the intensity heat wise of this air mass and the potential that a strong cold front can bring to the region.
Stay tuned for the latest information on what could be a potentially nasty day across parts of the region!
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