958 FXUS63 KIND 090616 AFDIND Area Forecast Discussion National Weather Service Indianapolis IN 216 AM EDT Thu Sep 9 2021 .Short Term...(Today through Friday) Issued at 216 AM EDT Thu Sep 9 2021 Skies were mainly clear across central Indiana early this morning with a surface ridge centered to the west over the Missouri Valley. Pockets of clouds were drifting southeast off Lake Michigan in association with a weak wave traversing through the parent upper level trough centered over the Great Lakes. These clouds were grazing our northeast counties this morning. Comfortable morning in progress with 0630Z temperatures ranging from the mid 50s to lower 60s in most areas. Very quiet weather is expected to round out the work week as the aforementioned surface ridge shifts east and serves as a dominant influence for the Ohio Valley. The upper trough will also remain a factor at least for today before it begins to lift out to the northeast into New England by Friday. The weak waves tracking through the trough will remain to the northeast of the region but enough cold air aloft will remain across the Ohio Valley on the back side of the trough for a decent diurnally driven cu field to form for this afternoon over much of the forecast area. The clouds will diminish towards sunset with skies returning to mostly clear overnight. As the upper trough departs Friday and mid level heights begin to recover as a result...expect less cu coverage for the afternoon with a broad mid level cap taking over. Northwest winds today will transition to more of a southwest direction Friday as the surface high passes through and moves into the central Appalachians by late Friday. Temps...pleasant temperatures and humidity levels by early September standards are set up for today and Friday...and frankly will feel refreshing with the expected return of the heat by late weekend into next week. Low level thermals and the likelihood of greater cu coverage this afternoon warrant cooler temps than Wednesday...with much of the forecast area in the mid to upper 70s. Temperatures will recover a few degrees for Friday. Lows tonight will be cool with low to mid 50s. Would not be a shock to see a few of our normal cool spots slip into the upper 40s early Friday...especially northeast of the Indy metro. && .Long Term...(Friday Night through Wednesday) Issued at 216 AM EDT Thu Sep 9 2021 Upper level northwesterly flow will moderate and level out Friday night into the weekend as the deep trough currently moving through continues to push off to the east. Zonal flow then is expected for the weekend as a broad ridge builds across The Plains. Southerly surface flow will help bring warmer than normal temperatures into the area late this week into the weekend with highs generally in the mid to upper 80s and lows in the mid to upper 60s. Some areas look to into the low 90s Sunday and Monday when the ridge is expected to be at its strongest. A fairly strong upper level low pressure system will be moving through the Hudson Bay area early next week with a strong mid level jet streak moving through the Great Lakes Region. Upper level forcing associated with that jet streak may reach as far south as the northern counties with small chances for rain Tuesday into Tuesday night. Confidence in this remains quite low with significant model spread on both the strength of the jet streak and how far south the associated forcing reaches. Will keep small POPs across the area with gradually decreasing chances across the Indianapolis area and further south. Better chances for rain arrive Wednesday into Wednesday night as a low pressure builds in the lee of the Rockies with a diffuse surface front stretching to the aforementioned stronger low across the Hudson Bay area. Weak surface convergence associated with the front will help bring those better chances for rain mid-week with perhaps a rumble of thunder or two during peak heating with expected CAPE near 1000 J/kg. && .Aviation...(090600Z TAF Issuance) Issued at 1133 PM EDT Wed Sep 8 2021 IMPACTS: - Surface winds 310-340 degrees at 8-12 kts by late morning Thursday. DISCUSSION: No significant weather expected at the terminals through midday Thursday, as surface high pressure builds in from the northwest. Some shallow instability cloud based around 040 expected to develop towards midday Thursday, under thermal troughing aloft. && .IND WATCHES/WARNINGS/ADVISORIES...None. && $$ Short Term...Ryan Long Term...White Aviation...JAS