FXUS63 KEAX 271959 AFDEAX Area Forecast Discussion National Weather Service Kansas City/Pleasant Hill MO 259 PM CDT Tue Aug 27 2024 .KEY MESSAGES... - Hazardous heat continues across areas east of US-65. Heat index values around 105F are expected. - Pop-up showers and thunderstorms possible later this afternoon through the evening. Sporadic storms are expected with higher likelihoods across far NW MO/NE KS/SE NE. - Warm conditions continue through Thursday. Storms anticipated Thursday night into Friday. - At or below normals temperatures expected for the weekend. && .DISCUSSION... Issued at 258 PM CDT Tue Aug 27 2024 A kinematically confusing setup leads to a challenging forecast for the remainder of today. A stout high pressure continues to reside over the area keeping skies relatively calm. Generally southerly flow aloft across SW to NE MO keeps the conveyor of warm moist air flowing into areas east of US-65 keeping hazardous heat around. Heat index values looking to crest 105F along and east of the corridor. Where things get more complicated is to the west of US-65. Cooler/drier outflow from overnight storms complexes to the north descends through far eastern KS and western MO. While this curtails heat indexes from reaching hazardous levels, it does not mean that conditions will be cool. Highs remain in the mid 90s with heat index values near 100F. This further complicates things because it presents a muddled meteorological picture. As this "cooler" air progresses north to south, it conflicts with the prevailing southerly flow. The NBM shows the clearest projection of this as it shows direct convergence between the N to S and S to N flow; however, the likelihood that it will be this delineated is small. This is due to the generally light nature of both air masses, winds are likely to be quite directionally variable throughout the day. CAMs have been doing a better job prototypically representing the likely kinematic setup via several washed boundaries. There are two overarching features consistent amongst guidance; the first is a slight moisture boundary between western and NE MO. Models gravitate toward developing scattered convection around this boundary during the late afternoon and evening as diurnal effects destabilize the region. The variance comes from each model handling the subtle effects of this moisture differential interacting with the overall mesoscale environment yielding several varying solutions. The second is a boundary between the high and the synoptic trough across northern Plains. The ARW model shows a decent picture of potential storm development across the NW quadrant of the high. This solution is supported by current satellite imagery showing building CU and towers across central KS extending into western WI. Given the hot and saturated environment, a combined result of these solutions seems most likely with storms already developing across central KS into northern IA with more uncertainty in the development of scattered convection across far eastern KS and western MO later this afternoon and evening. It is not unreasonable to have chances for severe storms with damaging winds and hail; however, coverage of strong storms should be quite sparse. Heavy rainfall and localized flooding is more likely as PWAT values reside between 1.5 to 2.5 inches in places indicating the potential for efficient near tropical downpours severe limiting visibilities and could cause pooling on roads and fields. Again, geographical coverage is expected to be sporadic sans NW MO where more widespread rain is expected. The probabilities for heavy rainfall are greater than for severe storms. This starts the trend of decreasing temperatures which continues through the end of the week. Highs Wednesday remain in the mid 90s, but lowered dew points keep heat index values at or below 100F. Hot conditions continue Thursday; however, a strong cold front moves through the region Thursday night into Friday really hastens the cooldown into the weekend. As this front pushes through the region during the evening, widespread showers and thunderstorms are anticipated. Most guidance points toward convection remaining elevated and post frontal with the environment ahead of the bounday losing convective favorability as sunset approaches. However, uncertainties remain in the chances for discrete development ahead of the front. Where there is high confidence is that seasonal to even below normal temperatures return for the end of the week. Upper level flow turns more northwesterly allowing cooler drier Canadian air to move into the region. High temperatures lower to the low to mid 80s with only slight precipitation chances south of I-70 leading to a picturesque holiday weekend across the area. The cool dry pattern looks to continue through mid next week. && .AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/... Issued at 1229 PM CDT Tue Aug 27 2024 VFR conditions with light and variable winds prevail through much of the period. Chances for RA/TSRA develop during the late afternoon and through the evening. Uncertainties remain with placement, but coverage is expected to be relatively scattered. Guidance points towards a little further north and west focusing impacts across MCI to STJ. Pockets of +RA are possible. Conditions return to light and variable once storms pass lasting through the rest of the period. && .EAX WATCHES/WARNINGS/ADVISORIES... MO...Heat Advisory until 8 PM CDT this evening for MOZ006>008- 015>017-023>025-031>033-039-040-046. KS...None. && $$ DISCUSSION...Pesel AVIATION...Pesel