Severe Weather Threat for April 14, 2012

SPC's Day 2 outlook for Saturday, April 14, 2012. Descriptions of SLGT, MOD, and HIGH are below.
Courtesy: NOAA, NWS, DoC

Tornado Risk: Very High (Tornado outbreak possible)
Severe Hail Risk: Very High (Hail stones of 2″+ in diameter likely)
Severe Wind Risk: High (Wind gusts up to 70+ mph in some storms)

Descriptions of what the colors above mean:

A SLGT risk (yellow) implies that well-organized severe thunderstorms are expected but in relatively small numbers/coverage, or a small chance of a more significant severe event. Not all severe storm events will be covered with a SLGT risk, especially during the summer when short-lived, “pulse-type” severe storms are relatively common during the afternoon.

A MDT risk (red) implies a greater concentration of severe thunderstorms, and in most situations, greater magnitude of severe weather and greater forecaster confidence compared to a SLGT risk. A MDT risk is usually reserved for days with substantial severe storm coverage, or an enhanced chance for a significant severe storm outbreak. Typical MDT risk days include multiple tornadic supercells with very large hail, or intense squall lines with widespread damaging winds.

The HIGH risk (pink) implies that a major severe weather outbreak is expected, with large coverage of severe weather and the likelihood of extreme severe (i.e., violent tornadoes or very damaging convective wind events). The HIGH risk category is reserved for the most extreme events with the least forecast uncertainty, and is only used a few times each year.

Overview:

Large mid-level trough will be digging and shifting eastward Saturday, while lee cyclogenesis forms at the surface in eastern Colorado.  A dryline will extend from southern NE through west TX by 00Z Sunday. Surface dewpoints will be relatively moderate ranging form 60-65F, just east of the dryline.  With a strong upper-level jet over the central/southern Plains and rich moisture from a southerly flow in the lower levels,  long-lived tornadoes are very possible, especially late afternoon and early evening.  Low and mid-level lapse rates will also signify very large hail.  It is still difficult to pinpoint the exact timing of when storms will initiate.  Low level clouds, showers and thunderstorm will be in place during the morning hours in Kansas and Oklahoma, but things should clear by afternoon.  With diabatic heating, lapse rates should steepen by afternoon. The best chance for severe storms will be along the dryline, during the afternoon hours.  Discrete cells will need to monitored very closely, as they have the potential to go tornadic very fast.  The “high risk” area above will be the most likely areas for the POTENTIAL for long-track, deadly tornadoes.  However, EVERYONE inside the areas shaded in yellow, red and pink should keep a close eye on the weather.  Tornadoes can spawn will little to no advanced warning.  Models are in agreement with a squall line developing during the overnight hours Saturday (around midnight Sunday CDT).  This line will extend from MO through southwest TX and push southeast through Sunday morning

Impressive forecast sounding and hodograph for 00Z 4/15/2012 for the city of Wichita, KS

About Brian

University of Oklahoma graduate with a degree in Meteorology. Follow me on Twitter: @WeatherInformer
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