Area Forecast Discussion
Issued by NWS Kansas City/Pleasant Hill, MO
Issued by NWS Kansas City/Pleasant Hill, MO
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661 FXUS63 KEAX 070049 AFDEAX Area Forecast Discussion National Weather Service Kansas City/Pleasant Hill MO 749 PM CDT Thu Jun 6 2024 .KEY MESSAGES... - Showers and thunderstorms are likely (50 to 70 percent) Friday night into Sat. morning. Locally heavy rain and perhaps some large hail could be a problem. - A second round of heavy rain is possible (40 to 70 percent) Saturday night. This rain should be shifted south but may still lead to flooding issues. - Mild temperatures with mainly dry conditions are forecast to begin next week. && .DISCUSSION... Issued at 234 PM CDT Thu Jun 6 2024 19Z water vapor imagery showed an upper trough axis from the great lakes into northern Alberta with a modest upper ridge over the southwestern U.S. This has lead to northwest flow through the middle and lower MO river valley. The weak isentropic upglide had shifted south of the forecast area with sunny skies across northern and central MO. At the surface weak high pressure was nosing into southwest MO with some dry air advecting into northern MO. This high pressure is forecast to remain over the MO and KS state line into Friday morning leading to clear skies and light winds helping lows to fall back into the middle and upper 50s. The main focus of the forecast is the developing return flow Friday night night. 12Z models continue to show strong theta-e and moisture advection with the latest runs shifting the nose of the low level jet into northwest MO. This in turn has caused the track of the possible MCS to shift north from previous solutions. The NBM still shows pretty high probabilities for precip, but given the variability in the placement of the MCS, have opted to keep POPs in the 60 to 70 percent range for now. With models showing PWs increasing to around 2 inches, areas within the path of the MCS could pick up an inch or two of rain. But again the predictability of where the rainfall may occur is to low to say with much confidence where the heavy rain will set up. Forecast soundings also show elevated instability with CAPE values between 1000 and 2000 J/kg depending on which model you look at. 0-6km shear is progged to be plenty strong enough for organized updrafts so in addition to the heavy rain risk, there could be some risk for large hail and strong wind gusts with the storms. A frontal boundary/outflow from the MCS Saturday morning is progged to set up over southwestern MO and southeastern KS Saturday afternoon. This could act as a focus for redevelopment of showers and thunderstorms into Saturday evening and POPs have been increased because of this. Models continue to show a fair amount of moisture along this boundary and the mean flow looks to be a little more parallel to the boundary that could aid in training storms. So a second round of heavy rain is possible Saturday night into Sunday morning. Fortunately this second round of rain should be displaced further south from the Friday night rain. Still there could be some local flooding issue develop by Sunday morning. The forecast for next week looks to be a little more nuanced depending on where and when shortwaves may move through within an overall northwest flow pattern. With the operational runs of the GFS and ECMWF showing low continuity with these smaller scale features, the spread in possible outcomes in higher than normal and predictability is lower. So have kept the blend forecast from the NBM as it is a good first iteration to the forecast. && .AVIATION /00Z TAFS THROUGH 00Z SATURDAY/... Issued at 745 PM CDT Thu Jun 6 2024 VFR conditions are expected to continue for the next 24 hours. North to northwest winds will diminish this evening, becoming light and variable overnight. A light south or southwest wind will develop by daybreak, with speeds increasing to around 10 kt (and occasional gusts to 15 to 20 kt) Friday afternoon. Thunderstorms are expected Friday night, but should occur after 00z Saturday. && .EAX WATCHES/WARNINGS/ADVISORIES... MO...None. KS...None. && $$ DISCUSSION...Wolters AVIATION...CMS