May 1 Severe Weather Outlook

Severe Weather Outlook For May 1st 2012
Taking a look at the water vapor image in motion you can virtually see that the moisture is lifting towards the NNE ..
http://www.ssd.noaa.gov/goes/comp/ceus/flash-wv.html
On the backside you can see dry air that is pushing into the TX region..to go along with this is the 700 mb which is for by 7 PM ..
http://www.twisterdata.com/data/models/nam/221/maps/2012/05/01/00/NAM_221_2012050100_F24_RH_700_MB.png
You can see the RH level at 700 mb is dry for the majority of the region..So this has factored into the equation as that area is going to be CAPPED....

Now lets get to the heart of things for today..

Temperatures are going to be in the 70s to 90s
Dew points 60s and 70s

CAPE levels are 500-4000 depending where you are
http://www.twisterdata.com/data/models/nam/221/maps/2012/05/01/00/NAM_221_2012050100_F24_CAPE_SURFACE.png
Levels of CAPE by definition:
*Interpretation of values:
*1 to 1,500 Positive CAPE
*1,500 to 2,500 Large
*2,500+ Extreme

Lift Index
http://www.twisterdata.com/data/models/nam/221/maps/2012/05/01/00/NAM_221_2012050100_F24_PLI_30_0_MB_ABOVE_GROUND.png
As low as -8-9 depending on where you are.....

EHI
http://www.twisterdata.com/data/models/nam/221/maps/2012/05/01/00/NAM_221_2012050100_F24_EHI_1000_M.png

You can see pretty much a large section has EHI that is at 1 or above ..

*Interpretation of values:
*Greater than 1:    Super cells likely
*1 to 5:     Possibility of F2, F3 tornadoes
*5+:     Possibility of F4, F5 tornadoes

Helicity 300 or less
http://www.twisterdata.com/data/models/nam/221/maps/2012/05/01/00/NAM_221_2012050100_F21_HLCY_1000_M_ABOVE_GROUND_0_M_ABOVE_GROUND.png

Interpretation of values:
*150-300 Possible Super cell
*300 to 400 Super cell Severe Favorable
*400+ Tornadic Thunderstorms Favorable

Mid Level Lapse rates 6.0 or above
http://raleighwx.americanwx.com/models/gfs/00zgfslapse024.gif
Surface Bulk shear 35 knots +
http://www.twisterdata.com/data/models/nam/221/maps/2012/05/01/00/NAM_221_2012050100_F24_SHRM_500_MB.png

At the surface a low pressure area is over western S Dakota with a dry line stretching to the south all the way into western TX.. Low pressure will be moving out of Montana to the east with a cold front attached to it. By 18 Z this low will then be located over the Dakotas border . From that low pressure area extends a stationary (quasi) front to a low pressure that will be over NYC..The western half of this front will lift into the Great Lakes region as a warm front ..
It is this low pressure area that will be moving out of Montana towards the lakes that will be responsible for the severe weather with also some severe possible along the quasi stationary front...

Due to the EHI more so then the Helicity we have added a large red zone. This red zone means that there is the potential in this highlighted area for all three aspects of severe weather from winds of 65 MPH or greater to Large hail to Tornado potential.

If you are in this area please stay tuned to your local weather radio and keep tuned into Down To Earth Forecasting as we will be providing coverage of watches and warnings from about 1 PM EST on till 6:30 AM..