746 FXUS63 KIND 240711 AFDIND Area Forecast Discussion National Weather Service Indianapolis IN 311 AM EDT Mon Aug 24 2020 .UPDATE... The LONG TERM section has been updated below. && .SYNOPSIS... Issued at 242 PM EDT Sun Aug 23 2020 High pressure is expected across the area into the middle parts of this week. A frontal system, and possibly the remnants of a tropical system, may affect the area towards the end of the week. && .NEAR TERM /This Afternoon and Tonight/... Issued at 242 PM EDT Sun Aug 23 2020 Isolated convection remains possible into the early evening hours over the eastern/southeastern zones, due to the presence of a weak upper trough and little to no cap. Any activity expected to dissipate with sunset. Otherwise, short term model data suggest a mid level area of vorticity will drift into northwest Indiana from northern Illinois later tonight. An area of enhanced flow at 850mb near 20 kts associated with this feature may provide enough warm advection and lift to spark off some convection late tonight. Will bring in some small chance PoPs from the northwest after about 240600Z. Low level thicknesses generally support the GFS MOS lows. && .SHORT TERM /Monday through Wednesday/... Issued at 242 PM EDT Sun Aug 23 2020 Model data suggest tonight's upper air feature will continue to drift across the area on Monday. Moderate amounts of instability are progged for Monday, with Lifted Index values to -6 and CAPE's in excess of 2500 possible. Will hold onto chance PoPs over most of the area for Monday, as a result. Otherwise, upper ridging expected to expand into the Midwest by the middle of the week, although some weakness in the upper ridge locally may remain. Potential exists for periodic convective clusters to form over the Great Lakes from Monday night through Tuesday night, as significant short wave energy digs into New England. Air mass locally should become gradually more capped off with time, although lapse rates are expected to steepen as well. The best forcing looks to remain off to the north and east later in the period, where the stronger warm advection will be. However, convective parameters become somewhat favorable for any Great Lakes convective cluster to possibly affect the northeast zones on Tuesday or Tuesday night. Some of the ensembles have been hinting at this potential for a couple of days now. Will continue to keep the later periods dry for now, given the expanding ridge and cap, however with high amounts of instability progged, will continue to keep an eye on this. Progged low level thicknesses suggest the GFS MOS highs for Monday and Tuesday look too cool. Will raise the guidance highs a category or so both periods. The guidance lows look OK for now. && .LONG TERM (Thursday Through Sunday)... Issued at 311 AM EDT Mon Aug 24 2020 Models are close enough that the National Blend of Models initialization was accepted for most items. The remnants of a tropical system will interact with an upper trough and surface cold front to bring rain chances to central Indiana early in the long term period. At the moment, it still appears that Friday will have the highest chances for rain. However, given lingering uncertainties on the interactions of the system, will keep PoPs no higher than the chance category. Present indications are that the main heavy rain threat will be south of central Indiana. The surface front will linger to the southwest of the area, then begin a slow trek back northeast late in the period as upper flow becomes closer to zonal. This will keep rain chances around. NBM looks a little aggressive with PoPs around Saturday given that the front should be southwest of the area. Cut back PoPs some then. Temperatures will cool to below normal readings by late in the weekend. && .AVIATION /Discussion for the 24/06Z TAF Issuance/... Issued at 1153 PM EDT Sun Aug 23 2020 Conditions will generally be at VFR levels outside of any convection and fog formation. Isolated convection will be possible Monday morning and afternoon, included mention of VCTS at KIND and KBMG where confidence is a bit higher. Also, will continue with mention of MVFR fog at KHUF and KLAF in the Mon 09-12Z time frame. Meanwhile, winds will generally be southwesterly at 5 to 10 kts. && .IND WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...JAS NEAR TERM...JAS SHORT TERM...JAS LONG TERM....50 AVIATION...TDUD