Area Forecast Discussion
Issued by NWS Kansas City/Pleasant Hill, MO
Issued by NWS Kansas City/Pleasant Hill, MO
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956 FXUS63 KEAX 111804 AFDEAX Area Forecast Discussion National Weather Service Kansas City/Pleasant Hill MO 104 PM CDT Thu Jul 11 2024 .KEY MESSAGES... - Multiple chances for showers and storms through end of the week with both diurnal and nocturnal convection possible. - Trending hot and humid this weekend into early next week. Heat indices likely (>75%) above 100 and possibly (~20%) above 105. - Active pattern returns mid to late next week with multiple chances for showers and storms. && .DISCUSSION... Issued at 316 AM CDT Thu Jul 11 2024 Ongoing convection, as of 08Z, looks like it is being caused by isentropic ascent in the 305K to 310K levels with relatively strong low-level winds and moisture transport intersecting a tight pressure gradient over eastern KS and western MO. There also appears to be a weak low-level boundary draped generally along I-70. This boundary looks like it will linger in the area today and may provide enough of a focus that isolated to scattered convection develops in the afternoon heat. Which is somewhat concerning as models show afternoon MLCAPE values again climbing into the 1500 to 2000 J/kg range within a marginally strong enough shear environment of 20-30 kts. Forcing along this boundary, combined with the strong instability and modest shear, may support another round of strong to potentially severe storms this afternoon and this evening. A nearly 5000 foot deep inverted V suggest good potential for microbursts/ strong winds. Tonight, isentropic ascent will develop again on the 305K and 310K levels. Like what has been happening early this morning, this may lead to isolated to scattered convection lingering into the overnight hours. The threat of strong to severe weather looks lower overnight due to CAPE decreasing with loss of daytime heating and shear diminishing as well. For Friday, again it looks like a weak boundary will be draped from northwestern MO to the southeast. Strong diurnal heating of a very moist boundary layer will result in afternoon MLCAPE values potentially in excess of 2000 J/kg. While shear looks weaker, forecast soundings show an inverted V look and if convection can develop, looks like a classic summertime microburst setup. Coverage of precipitation looks more isolated but HREF probabilities of QPF >0.01 show 25-50% probabilities. With another two forecast cycles to fine tune things, have just increased PoPs into the slight chance range for now. Heat and humidity will noticeably increase this weekend into early next week. The upper ridge shifts eastward with its axis generally along the High Plains. Strong southwesterly low-level flow will help to push temperatures near 100 degrees Sunday and potentially in excess of 100 degrees on Monday. In fact, the NBM shows a 30-40% chance of high temperatures in excess of 100 degrees across eastern KS and western MO on Monday. This would include the KC area. Additionally, overnight low temperatures, particularly for the urban core of KC, look exceptionally warm. The NBM shows a 30-50% chance for lows to be warmer than 80 degrees Monday morning. When combined with daytime heat, there will be little to no relief from the heat. This round of excessive heat looks short-lived, fortunately, as that upper ridge is forecast to weaken and retrograde back to the western US. The tradeoff to that is that the pattern looks more active with multiple rounds of storms possible in a broadly northwesterly flow regime. That suppression of the ridge and retrograde to the west allows for relatively stronger upper-level flow to move over the area and models show a series of shortwaves moving through the northwesterly flow. All this points to an active pattern for the middle to later part of next weak. && .AVIATION /18Z TAFS THROUGH 18Z FRIDAY/... Issued at 1259 PM CDT Thu Jul 11 2024 VFR conditions are expected to last for the duration of the TAF period. A chance for showers and thunderstorms exists later this evening, however at this time they are expected to stay to south of I-70 so they were left out of the more northern terminal TAFs. Winds are expected to shift to the south tomorrow morning. A gust to 15 mph will be possible through the day. && .EAX WATCHES/WARNINGS/ADVISORIES... MO...None. KS...None. && $$ DISCUSSION...CDB AVIATION...Collier