Area forecast discussion National Weather Service Topeka Kansas 622 am CDT Wednesday Jun 19 2013 Short term...(today and tonight) issued at 345 am CDT Wednesday Jun 19 2013 Regional mosaic radar shows a large complex of thunderstorms activity across southwest Kansas and northwest Oklahoma. While this activity will likely remain South/West of the forecast area they could play a role in how the rest of the day plays out regarding potential thunderstorm activity. Several outflow boundaries can be seen on radar criss- crossing through the area. Another interesting feature that shows up on regional mosaic as well as the kgld radar is a subtle mesoscale convective vortex...which is moving eastward along Interstate 70 through central Kansas. Given that soundings across the forecast area are largely uncapped later this afternoon points where these boundaries interact and create some low level convergence and/or where this mesoscale convective vortex moves through the subsequent low level lift could be points where convection forms. Should some isolated convection occur it could trigger other storms as more outflow boundaries are created. Expect around 2000 to 2500 j/kg of MUCAPE at peak heating this afternoon...with very little cinh to overcome. Surprisingly despite the lack of fast moving flow in the middle levels good turning and an increasing low level jet through the afternoon/evening will bring a decent amount of deep layer shear...on the order of 30 to 40 kts. So should a storm be able to form this afternoon it will have good enough ingredients to become quasi-organized...perhaps bringing another hail and wind threat...again...assuming a storm can get going. The better chances for showers on Wednesday/Wednesday night will come later in the evening to over night hours as High Plains convection will push eastward through western and central Kansas. Early discreet cells in the High Plains should eventually congeal into a multicell mesoscale convective system which will be fed by an increasing low level jet and a weak disturbance embedded within the zonal flow north of the middle level ridge. Should a complex be able to form in west Kansas we can expect it to roll through the forecast area during the overnight hours Wednesday night. Jl Long term...(thursday through tuesday) issued at 345 am CDT Wednesday Jun 19 2013 A broad upper level ridge across the Desert Southwest and southern High Plains will amplify across the southern and Central Plains Thursday into Saturday...ahead of a longer wave-length trough over the west central Continental U.S.. as the loner wave length trough retrogrades westward over the Pacific northwest early next week...the upper ridge axis will expand across much of the Continental U.S. Into next week. Thursday...a shorter wave-length upper trough will ride around the ridge axis and move southeast across southeast NE...eastern Kansas and MO during the morning hours. A combination of ascent ahead of the 500 mb trough combined with warm air advection/isentropic lift will provide at least chance probability of precipitation for showers and thunderstorms for much of the County Warning Area during the morning hours. If a complex of storms develops across the High Plains Wednesday evening and maintains itself east-southeast across eastern Kansas through the morning hours of Thursday...then probability of precipitation may have to be increased. For now I will just carry chance probability of precipitation. Most of the showers and thunderstorms should shift east of the County Warning Area as the upper trough digs east-southeast across northern and central MO...and the stronger warm air advection shifts east of the County Warning Area. Skies will clear Thursday afternoon across the County Warning Area and temperatures should warm into the lower to middle 90s. Thursday night through Saturday night...the upper level ridge axis will slowly shift eastward into the the middle MS River Valley and extend southwest into North Texas. Expect hot and humid conditions across the County Warning Area with day time highs in the middle to upper 90s and overnight lows in the middle 70s. Saturday night an 500 mb trough will move east across the northern plains and cause a cold front to push southward across the Central Plains. Heat indices could reach around 100 degrees both Friday and Saturday afternoon. Sunday and Sunday night...the 500 mb trough over the northern plains will lift northeast across the northern Great Lakes. A weak cold front will drift southeast across the County Warning Area and may provide enough surface convergence during the afternoon for a slight chance for showers and thunderstorms and the thunderstorms may last into Sunday evening. The best chance for thunderstorms will be north of I-70 late Sunday afternoon and Sunday night. Increased cloud cover and the weak front may keep highs a few degrees cooler on Sunday with only lower to middle 90s expected. Though increased surface dewpoints may make it feel warmer with heat indices in the upper 90s to around 100. Monday and Tuesday...the upper ridge axis will build northwest over the southern and Central Plains. Expect highs to warm back into the middle to upper 90s with heat indices in the 100 to 104 degree range during the afternoon hours. Gargan && Aviation...(for the 12z tafs through 12z Thursday morning) issued at 619 am CDT Wednesday Jun 19 2013 Expect VFR conditions to persist through aviation forecast period. Similarly to yesterday there will be a possibility for thunderstorms to form near the terminals this afternoon through this evening. Exact location of any thunderstorm activity is uncertain at this point...so will handle the threat with thunderstorms in the vicinity. Another round of thunderstorms may form in the High Plains and roll eastward overnight...but uncertainty in development and the fact that if they form they'll likely affect the aviation sites near 12z have left that mention for convection off of this forecast. Jl && Top watches/warnings/advisories... none. && $$ Short term...jl long term...gargan aviation...Leighton