July 7th Severe Weather Outlook
First we are going to start this off with saying that the majority of the day we expect to be under a CAPPED environment. .However..we anticipate this to break and for storms to effect the eastern PA region after 8 PM ..between 8 PM and up till 8 AM..
Also we are looking at a very HOT DAY! The temperatures and the humidity are going to be no joke. Do not go outside unless you have to go outside and make sure you drinking plenty of water (preferably FIJI water) ..
Temperatures today are going to be between the 80s and 100's.
http://www.twisterdata.com/data/models/nam/221/maps/2012/07/07/00/NAM_221_2012070700_F18_TMPF_2_M_ABOVE_GROUND.png
Dew points are going to be in the 60s and 70s
http://www.twisterdata.com/data/models/nam/221/maps/2012/07/07/00/NAM_221_2012070700_F18_DPTF_2_M_ABOVE_GROUND.png
With the heat index near 110 degrees! Again this heat alone can be very dangerous without adding in the severe weather aspect. We have been talking about how this has the potential to be a decent event if we can become unCAPPED. Looking at the surface expected by Saturday evening at 8 PM
http://www.hpc.ncep.noaa.gov/basicwx/94fwbgus.gif
You have a very HOT and humid air mass coming into play and you have a very strong cold front coming thru the region. Whenever you have the clashing of two air masses with strong heating in place and strong cooling coming in you are setting the stage for what could be a decent severe weather potential.
Lets look at the parameters in place across the region..
CAPE is going to be 500 to about 4000 across the zone. Remember CAPE is convective available potential energy. You can view this like fuel being added to a fire depending on the rest of the parameters.
LIFT INDEX from 0 to about -6..
http://www.twisterdata.com/data/models/nam/221/maps/2012/07/07/00/NAM_221_2012070700_F24_PLI_30_0_MB_ABOVE_GROUND.png
SHEAR is going to be supportive of severe weather with 30-40 knots across the region , where the main focus will be today (further south tomorrow)
http://www.twisterdata.com/data/models/nam/221/maps/2012/07/07/00/NAM_221_2012070700_F24_SHRM_500_MB.png
Now this is going to be where we are going to disagree with the Storm Prediction center when we look at the ENERGY HELICITY INDEX we see this:
http://www.twisterdata.com/data/models/nam/221/maps/2012/07/07/00/NAM_221_2012070700_F24_EHI_3000_M.png
This shows EHI as high as 3-5 in Eastern and Central PA
HELICITY however is lower but still around 300 and actually increases in the overnight period.
http://www.twisterdata.com/data/models/nam/221/maps/2012/07/07/00/NAM_221_2012070700_F24_HLCY_3000_M_ABOVE_GROUND_0_M_ABOVE_GROUND.png
http://www.twisterdata.com/data/models/nam/221/maps/2012/07/07/00/NAM_221_2012070700_F30_HLCY_3000_M_ABOVE_GROUND_0_M_ABOVE_GROUND.png
So in addition to the winds and hail potential across the PA into NJ region we are going to go with a 2 % tornado chance..
If you are out and about keep an eye to the sky ..especially once we head towards evening time...
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