Severe Weather Discussion for April 13-14, 2012

Severe Weather Discussion for April 13-14, 2012.
Issued:  04/10/2012.
Highlights:
–  A few severe thunderstorms are possible today and Wednesday in the TX/OK panhandles.  Primary threat is large hail.
–  Severe thunderstorms are possible on Thursday in the TX/OK panhandle and potentially far western Oklahoma.  Primary threat is damaging hail.
–  Severe thunderstorms remain possible Friday – Sunday across parts of Oklahoma, but the overall forecast is very difficult.
Discussion:
Models continue prior trends of slowing the upper system.  This slow down does several things but the least of which, pushes higher end severe threats beyond Thursday.  As such, today-Thursday aren’t a big focus of this discussion, although I’ll touch on Thursday a little.
SPC has today and Wednesday well handled with going products and see no reason to add to what they have issued.  A watch is possible in the TX/OK panhandle if convection forms.  Similar setup for Wednesday as the ridge will be overhead.  18z NAM indicates the dryline will be in the western Texas panhandle on Thursday with convection near Amarillo late Thursday.  This seems plausible given model slowing trend of the upper system.  Primary threat appears to be damaging hail but given deep layer speed/direction shear, a tornado or two certainly seems possible.  SPC has a slight risk posted and I think they’ll keep that for now, but we’ll see.
Leading edge of the upper system moves into the central U.S. as the center approaches the coast.  Friday continues to look interesting as wind speeds aloft will be good and strong directional shear will be in-place across the region.  12z/18z NAM continues to develop convection along I-35 and I-44 during the day and still not sure why as this is well removed from the dryline, which should be over the eastern Texas panhandle.  Despite the convection over central OK, decent CAPE does develop with 2000-2500 J/Kg in a small zone near the dryline.  The limited areal coverage may be due to prior convection near CDS-LTS in the morning.  There aren’t obvious forcing mechanisms, so who knows as to what is really happening.  The 12z GFS is similar with rainfall in the previously mentioned area but is also farther east with the dryline.  Models did over-convect last night and much of the convection appears to occur in areas that the models remove CIN.  This far out, really tough to call, so will monitor model trends.
Saturday and Sunday still have severe weather potential but luckily are outside the scope of this forecast.
Probabilities:
Risk area for any part of OK/TX (valid:  04/11 Day 3):
–  Slight:  100%
–  Moderate:  25%
–  High:  N/A
Chase Status:
Level 4 – watching Friday
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