532 FXUS63 KIND 080251 AFDIND Area Forecast Discussion National Weather Service Indianapolis IN 950 PM EST Mon Dec 7 2020 .UPDATE... The Near Term and AVIATION Sections have been updated below. && .SYNOPSIS... Issued at 407 PM EST Mon Dec 7 2020 Surface high pressure will provide dry weather through Thursday. Temperatures will warm up to above normal for the latter half of the week, then a low pressure system will bring rain showers this weekend followed by a return to colder temps early next week. && .NEAR TERM /Rest of Tonight/... Issued at 949 PM EST Mon Dec 7 2020 Increased cloud cover in the forecast based on satellite loop and trends. With the increase in cloud cover and all but the easternmost counties expected to remain overcast through the overnight hours, also increased low temperatures a bit to the middle 20s to lower 30s. Previous discussion follows... A weak upper trough will move through the area tonight. Only expecting continued cloud coverage as forcing will be weak and moisture will be limited. Satellite imagery from this afternoon shows clouds extending up to Wisconsin and Minnesota from which the airflow is coming from, bringing those clouds to the area. The northeast may see more clouds tonight as well as some lake enhanced clouds could extend into that area. Overnight lows in the mid 20s will occur again tonight. && .SHORT TERM /Tomorrow through Thursday/... Issued at 407 PM EST Mon Dec 7 2020 Ridging will move into the area throughout the short term prompting subsidence and dry weather. Model soundings show that the low to mid levels will remain dry through the period, limiting any precip from the upper moisture. Clouds will start to thin out tomorrow morning as a weak upper trough exits the region and continuing to clear through Wednesday. Winds will be shifting throughout the period with the the eastward moving ridge, starting off with colder NW flow becoming more southwesterly by mid week. This will allow warmer air to advect in and high temperatures will get to the mid to low 50s for Wednesday and Thursday. A low pressure system will start to advance into the area at the end of the period, ahead of which cloud coverage will start to increase from the NW late in the day Thursday. && .LONG TERM...(Thursday Through Monday) Issued at 232 AM EST Mon Dec 7 2020 The long term will start off Thursday night with an upper ridge of high pressure over the Great Lakes and Ohio Valley, separate troughs over the Southwest and and another over the northern Plains and another over the Pacific Northwest. At the surface, a broad ridge of high pressure will be moving the eastern states, a warm front will lift to the southern Great Lakes and cold front will be over the central and southern Plains. South and then southwest winds in between the departed high and cold front to the southwest will allow temperatures to be well above normal with highs in the middle and upper 50s in the offing Friday. Normal afternoon highs for this time of year are in the lower to middle 40s. Things will start off dry, but increasing moisture and isentropic lift on the 300K level will result in widespread rain showers by Friday night. The coupling of Great Lakes and southern states 100 plus knot upper level jets will result in increased divergence. This will result in increased vertical motion and a strengthening 40 plus knot low level jet across central Indiana Friday night into Saturday. This suggest rainfall amounts could be higher than models currently are pumping out. Could see an inch or more over all or parts of central Indiana by late Saturday. The frontal system will be moving through on Saturday, but exact timing is problematic, so confidence in temperatures is not high, but in general, model blend lower and middle 50s look reasonable. May actually see a much tighter temperature gradient, however with indirect and direct circulations of the jet streaks. Precipitation should be winding down Saturday night as the system pushes northeast. Could see a brief mix of snow with rain with any lingering shower across northeastern sections. Much colder but seasonable temperatures will be felt Sunday, in the wake of the cold front and under high pressure. Would not rule out a snow shower Sunday night though as an upper trough will be dropping down southeast and nearby. && .AVIATION /Discussion for 080300z TAF issuance/... Issued at 949 PM EST Mon Dec 7 2020 IMPACTS: -Ceilings should drop over the next few hours back to MVFR. -Winds will be light and variable overnight and into the morning, but become southwesterly around 7 to 12 kts Tuesday afternoon. DISCUSSION: An upper wave moving SSE through WI will reinforce the cloud cover over the TAF sites through the night and into Tuesday. Ceilings should drop from around 3500 ft now to 2500 to 3000 ft over the next few hours and stay there at least into Tuesday morning. Light and variable winds overnight will become stronger and southwesterly by Tuesday afternoon. CONFIDENCE: Medium confidence in MVFR ceilings returning to all the sites over the next few hours. && .IND WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...KH NEAR TERM...KH/CP SHORT TERM...KH LONG TERM....MK AVIATION...CP