Area forecast discussion National Weather Service quadrant cities Iowa Illinois 604 am CDT sun may 19 2013 Update... issued at 554 am CDT sun may 19 2013 An elevated warm air advection Wing has allowed showers and storms to develop over the western County warning forecast area over the past several hours. The elevated Wing of storms is moving further away from the better moisture and into the upper ridge so weakening is expected this morning. There may or may not be a brief lull in precipitation from middle to late morning as the atmosphere slowly warms in spite of the thick cs/cirrus shield from the plains mesoscale convective system. Differential heating and boundaries left over from the nocturnal convection will provide the focus for new storm development this afternoon. && Synopsis... issued at 249 am CDT sun may 19 2013 06z surface analysis has synoptic lows south of kabr and in southwest Kansas. Numerous mesoscale lows and highs were across Nebraska/Kansas behind the now decaying mesoscale convective system in western Iowa and Missouri. The main front ran from the kabr low into southwest Wisconsin and then into the Ohio Valley. Dew points over most of the Midwest and plains were in the 50s and 60s with 40s and 50s over the Great Lakes. && Short term...(today and tonight) issued at 249 am CDT sun may 19 2013 Nonlinear processes are driving the sensible weather. Thus one must look more carefully at the models. Mesoscale convective system and lift tools indicate the current mesoscale convective system over the western parts of Iowa/MO will continue to slowly decay as it out runs the better moisture and runs into the upper ridge. Outflow boundaries from the mesoscale convective system will help fire new convection through sunrise with isolated to possibly scattered convection entering the western County warning forecast area. This convection will slowly weaken after sunrise as the low level jet shifts back into the plains. Isolated to scattered convection should linger through the morning across the County warning forecast area as mesoscale induced shortwaves and boundaries move through the area. The mesoscale convective system and lift tools indicate new convection should fire in central Iowa around middle day and enter the western County warning forecast area by middle afternoon. Mesoscale boundaries will play heavily into the overall evolution of this convection but it should evolve into an mesoscale convective system by late afternoon. Given the moisture/instability severe storms are a threat. The more significant severe storms should be across eastern Kansas/western MO but there should be some threat of severe wind/hail during the afternoon and evening hours. Tonight...strong to possibly severe storms should be seen across the area during the evening. Mesoscale convective system/lift tools suggest an mesoscale convective system moving through during the evening. A more substantial mesoscale convective system should develop by sunset in the western parts of Iowa/MO and move through the area overnight. Strong to severe storms may be possible with this mesoscale convective system as well. 08 Long term...(monday through saturday) issued at 249 am CDT sun may 19 2013 Showers and thunderstorms into Wednesday then cooler and dry into next weekend with another rain event by Sunday. Overview...all solutions again are adequate on kinematic or flow fields but as is normal with convection are having difficulties. Verification at 06z supports a 70/30 mix of hi-res ECMWF/GFS. This suggests periods of showers and thunderstorms with poor confidence on timing except for likely decent rounds late PM today and once again late Monday. Run to run variance supports below average to poor confidence of timing and showers and storms Tuesday/Wednesday with next 36-48 hours Keys to how last upper wave passes. Most locations still on track to pick up 1 to 3 inches or rain by time event ends Wednesday. Monday...chance probability of precipitation with lingering showers and storms with enough heating and forcing for thunderstorms to fire middle to late PM. Conditions continue to support good chance of severe storms with shear profiles and moderate instability. Local tools continue to support good unidirectional shear for mixing down winds aloft for winds of 60-70 miles per hour and also enough dry air aloft with wbz of 10 to 11k above ground level for large hail up to 1.75 inches. An isolated tornado may be possible with some backing of surface winds but this does not suggest any stronger or longer track events unless winds back more allowing for more scl directional shear. Temperatures and probability of precipitation little change with highs roughly 80-85 and lows in the middle 60s. Chance probability of precipitation in the day with likely at night as storms fire well into the evening hours. Rain amounts could be locally heavy with 1-2 inch amounts in the strongest storms with precipitable water/S of 1.25 to 1.5 inches and some storm training potential. Tuesday...more energy to pass across area with lots of clouds and showers and storms. Poor confidence on maximum temperatures due to cloud coverage and how much precipitation moves into area or fires during the day. Generally highs of 75-80 are suggested based on convective temperatures. Kept mostly likely probability of precipitation in the day with chance probability of precipitation overnight but timing is poor when this next organized event occurs. Mins at night in the lower 60s. Marginal severe potential suggested due to limited instability. Wednesday...upper low rotates slowly over area with popcorn showers and isolated to scattered storms with mostly chance probability of precipitation in the north and east sections. Highs mostly in the lower 70s with mins falling into the 50s as winds shift to the north as cold front passes most areas by Thursday morning. Thursday and Friday...clearing skies and seasonably cool and comfortable with highs upper 60s to lower 70s and mins upper 40s to lower 50s. Mins Saturday morning with surface Canadian high pressure overhead may need lowering by 3+ degrees with isolated lower 40s possible in low lying locations. Saturday...warm and upper disturbance from west to interact with cool airmass to bring clouds and areas of rain and rainshowers with strong evaporative cooling by late Saturday into Sunday. Have chance probability of precipitation that should br raised in the next day or so when timing issues better clarified. Event looks like another moderate to locally heavy rain event. Nichols && Aviation...(for the 12z tafs through 12z Monday morning) issued at 554 am CDT sun may 19 2013 Storms have developed over eastern Iowa but will continue to weaken as they move northeast. This convection will likely affect kdbq/kmli/kbrl with brief MVFR conditions. Otherwise VFR conditions are expected through 18z/19. After 18z/19 new convection will develop and move through eastern Iowa and Illinois. The probability of a thunderstorms and rain affecting a taf site will increase. After 00z/20 several rounds of convection will affect Iowa/Illinois with the potential for MVFR conditions. && Dvn watches/warnings/advisories... Iowa...none. Illinois...none. MO...none. && $$ Update...08 synopsis...08 short term...08 long term...Nichols aviation...08