FXUS63 KIND 091048 AFDIND Area Forecast Discussion National Weather Service Indianapolis IN 648 AM EDT Fri May 9 2025 .KEY MESSAGES... - Briefly cooler today, then warmer temperatures this weekend into next week - Mainly isolated/scattered showers/t-storms Monday-Wednesday - Expect very warm conditions w/moderate humidity late next week && .SHORT TERM (Today and tonight)... Issued at 300 AM EDT Fri May 9 2025 Northeasterly winds between 10 to 15 mph remain ahead of an approaching surface high from the north. Winds gradually die down through the afternoon today as the surface high center arrives this evening. Light and variable to calm winds then persist through the remainder of the short term period. The air mass arriving with the high is fairly dry, especially between 925mb and 500mb. Little in the way of cloud cover is anticipated given the dry and subsident column. There is a bit of moisture at 250mb along with a northeast to southwest oriented jet streak, which could lead to some thin cirrus at times. Back towards the surface, model soundings show fairly deep mixing which will promote temperatures rebounding into the high 60s to near 70. Our primary forecast challenge may be dew points, given the very dry air located between 925mb and 850mb. Guidance can struggle with deep boundary layer mixing and fail to capture how much dry air mixes to the surface. We will add more weight to the HRRR (which may be too dry) in order to bring Tds down a bit. Relative humidity values may drop as low as 20-25 percent, especially across our northern counties. Light and variable winds along with mainly clear skies will promote ideal radiational cooling conditions tonight. Temperatures should drop quickly after sunset and fall into the 40s for most locations. A few isolated locations may dip into the upper 30s. Not expecting much in the way of fog, given the dry atmosphere in place...but some patchy ground fog cannot be ruled out over southern Indiana in typically fog-prone locations. && .LONG TERM (Saturday through Thursday)... Issued at 312 AM EDT Fri May 9 2025 A broad and overall retracted upper-level pattern in a sort of weak Rex-Block formation will promote a slow transition...from pleasant late-spring conditions this weekend...to occasional showers, amid increasing humidity, and eventually warmth, by the middle of next week. Broad yet rather weak surface high pressure extending from eastern Ontario to the Ohio Valley this weekend will provide light breezes under mostly clear skies, while above normal heights bring readings indicative of late May, ranging from the 50s to mid/upper 70s. Dry conditions through Sunday night will be replaced by chances for isolated to scattered showers/t-storms that should exhibit diurnal enhancement, across the Monday to Wednesday timeframe. Stacked yet weak low pressure over the Lower Mississippi Valley will slowly lift towards the Midwest as the blocked slowly breaks down. Ample precipitable water values in the 1.25-1.50 inch range and surface dewpoints climbing through the 50s to at least the low 60s will pose the potential for precipitation, although disorganized lift from the broad trough's remnant fragments should limit heavier rainfall to isolated locations. Towards the end of the long term, the left-over southern circulation should interact with a more northern-stream trough near the High Plains to act as a sort of warm-frontal zone...ahead of an upper subtropical ridge building northward from the southern Plains. This may well allow the local region's first very warm to perhaps marginally hot days of the year, with widespread mid to upper 80s on the table for the late workweek should the pattern trend as currently expected. The normal max/min at Indianapolis through the long term is 72/52. && .AVIATION (12Z TAF Issuance)... Issued at 647 AM EDT Fri May 9 2025 Impacts: - None. Discussion: VFR conditions expected through the TAF period. Northeasterly winds around 10 knots should persist this morning hours before tapering off during the afternoon. Winds die down even further becoming light and variable tonight into Saturday. Winds turn northwesterly Saturday afternoon but remain light. Cloud cover should be limited to occasional thin cirrus. && .IND WATCHES/WARNINGS/ADVISORIES... None. && $$ SHORT TERM...Eckhoff LONG TERM...AGM AVIATION...Eckhoff