314 FXUS63 KLSX 021857 AFDLSX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ST LOUIS MO 157 PM CDT Mon Jun 2 2014 .SHORT TERM: (Through Tonight) Issued at 130 PM CDT Mon Jun 2 2014 As upper level s/w continues to move sewd, believe ongoing TSRA will continue to push ewd out of the region thru the afternoon hours. However, mdls suggest area of cu across ern KS and w central MO may continue to develop into the evening, eventually producing TSRA. If these storms do develop, areas most likely to be impacted are wrn and nrn portions of the CWA. Due to uncertainty in development and track if these storms do develop, have kept POPs in the slight chance range for now. Will continue to monitor development and adjust POPs if/when necessary. Mdls also suggest FG may develop tonight, especially across the nrn third of the CWA. Will also continue to monitor as conditions continue to develop. Tilly .LONG TERM: (Tonight through Sunday) Issued at 404 AM CDT Mon Jun 2 2014 (Tonight-Wednesday) Thunderstorm chances will continue to be the primary forecast concern heading into midweek, and there are lots of different yet plausible scenarios regarding the convective trends over the CWA. While the NAM keeps the entire area dry tonight, GFS and GEM suggest nocturnal convection developing over parts of the FA. With fairly weak but persistent WAA of unstable airmass across the region ahead of frontal boundary, some small chance of showers and thunderstorms seems appropriate. Still feel that the NAM is a bit too far north with the surface boundary on Tuesday, with all of the other synoptic scale models suggesting the front will reach the I-70 corridor. The location of this feature is important, as a low chance of storms should continue continue to co-exist with its location. Any storms that develop Monday night should continue near the boundary on Tuesday morning, with additional, hit and miss development near the boundary in the afternoon as the airmass in the warm sector becomes very unstable with all of the models forecasting MUCAPES aoa 4000 j/kg. PoPs and severe weather potential will be increasing dramatically in northern sections of the CWA on Tuesday night as the very unstable air begins to interact with a substantial increase of shear over the region. Shortwave embedded in strengthening mid level flow will cause surface low to form along stalled front over the plains near the KS/NE border, with the low then moving east overnight and causing remnants of front in our area to begin moving north as a warm front. 00z runs are still in excellent agreement that intense convection that forms over the mid-Missouri valley Tuesday evening will grow upscale into an MCS that should propagate ESE and clip northern sections of the CWA Tuesday night, but don't think we can totally rule out some severe potential before the arrival of the MCS...as storms may try to develop along the Mississippi River as low level jet intensifies and veers during the predawn hours producing isentropic ascent along and north of warm front. Moderate risk outlooked by SPC in SWODY2 looks good, and was shifted south a bit to account for some uncertainly to the exact track of the MCS. Given expected evolution of this system would think that damaging winds and some hail will be the primary threats in our CWA, but some tornado potential will also exist near the warm front due to strong low level shear/helicity. Tuesday night's MCS should push out of the region fairly early Wednesday morning, with additional thunderstorm development expected during the day as cold front in the wake of the surface low sweeps south and interacts with the unstable airmass in the warm sector. (Thursday-Sunday) Medium range models indicate that baroclinic zone will linger over the region during the last part of the week before lifting north during the weekend in response to falling heights over the Plains. Ripples in the westerlies will interact with the baroclinicity to continue the seemingly non-stop forecast of showers and thunderstorms over most of the CWA. In this unsettled pattern don't see any prolonged period where rain will not be a threat. Truett && .AVIATION: (For the 18z TAFs through 18z Tuesday Afternoon) Issued at 1244 PM CDT Mon Jun 2 2014 TSRA will remain possible for the next few hours at KSTL/KSUS/KCPS, but shud gradually push SE during the afternoon hours. With clouds decreasing by sunset, radiational cooling may allow for FG development at all terminals overnight. Terminals may also see a brief period of MVFR cigs Tues around sunrise as CU develops. However, confidence is too low attm. TSRA is expected to develop Tues along the sfc boundary. However, these TSRA are currently expected to develop beyond the valid TAF period. && .PRELIMINARY POINT TEMPS/POPS: Saint Louis 84 71 89 73 / 30 20 30 40 Quincy 84 66 87 68 / 10 20 20 80 Columbia 84 67 88 72 / 20 20 40 40 Jefferson City 85 68 89 73 / 20 20 40 30 Salem 83 70 88 71 / 50 10 30 40 Farmington 82 68 88 71 / 30 20 30 20 && .LSX WATCHES/WARNINGS/ADVISORIES: MO...NONE. IL...NONE. && $$ WFO LSX