Area Forecast Discussion
Issued by NWS Kansas City/Pleasant Hill, MO
Issued by NWS Kansas City/Pleasant Hill, MO
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671 FXUS63 KEAX 302014 AFDEAX Area Forecast Discussion National Weather Service Kansas City/Pleasant Hill MO 314 PM CDT Thu May 30 2024 .KEY MESSAGES... - Rain Showers Tonight; Isolated Thunderstorms Possible - Rain Continues Friday and Saturday; Minor Flooding Possible - Above Normal Temperatures By End of Next Week && .DISCUSSION... Issued at 313 PM CDT Thu May 30 2024 H5 ridge axis has been moving across the forecast area this afternoon which provided a warm and dry start to the day. However the first short-wave in a series of multiple waves over the next couple of days has been producing shower and isolated thunderstorm activity throughout Kansas and Oklahoma this morning and afternoon. H5 height falls should start in our western counties in the next few hours, developing new showers in eastern Kansas. An MCV over central Oklahoma has stalled moisture transport into the lower Missouri River Valley, which has slowed the eastward progress of the rainfall this afternoon and has also slightly lowered QPF totals. However, a longer period of insolation allowed for slightly better destabilization of the boundary layer. Therefore, probabilities for a few isolated thunderstorms are greater within widespread shower activity later this evening. Our western forecast area is touched the by the SWODY1 Marginal Risk given that a few CAM solutions eventually erode most of the CINH after 00z this evening. However, upper-level flow even with the passing vort max is not overly strong, thus limiting deep layer shear and the ability for convection to organize if it develops. Most favorable timing for heaviest precipitation will between 01-03z west of Interstate 35 then expanding eastward into Central Missouri overnight. Thunderstorm chances should drop off overnight as most of the instability should diminish by then. However continued weak H5 height falls with increasing moisture transport should help to promote more rain activity across the area. Friday, first short-wave stalls near the Mississippi River Valley while another vort max breaks away from the main PV anomaly over the Pacific Northwest. This second short-wave is currently progged to be deeper and by Friday afternoon becomes a mid-level closed-low system. Prior to becoming a closed low, stronger dCVA should promote surface pressure falls across the Plains facilitating cyclogenesis across the region. This will enhance lower-level meridional flow across the lower Missouri River Valley and provide isentropic ascent that will continue to support rain shower potential through most of the afternoon on Friday. With persistent cloud cover starting the day off, boundary layer destabilization will be hard to come by, and CAPE values remain rather low (HREF mean under 500 J/kg). Therefore a convective mode will not be dominant, though perhaps a few pockets of instability could promote some isolated thunderstorm activity. With weak mid-level flow and weak deep layer shear, any isolated thunderstorms are not expected to present any kind of severe threat. The main hazard concern will be attributed to flooding with persistent rainfall. Synoptic scale ensemble probabilities currently depict 40-50 percent chances for at least 1.00 inch of QPF for the western two-thirds of our forecast area. This encompasses a 24 hour accumulation total from Thursday evening (00z Friday) to Friday evening (00z Saturday). Probability matched mean values from the 12z HREF are in this same general vicinity, with a few pockets of 1.5 to 1.75 inches. Would think if an isolated thunderstorm is able to develop that these higher end values depicted in the PMM HREF output could be reached. But again, with the lack of destabilization would will be difficult to achieve. At the current moment, hourly rainfall rates from the HREF do not exceed more than 0.75 inches, which will help to mitigate much of the flash flood threat across the area as this distributes heavier rainfall over a longer period of time. Will need to watch some urban areas and spots that more prone to flooding if an isolated convective storm moves over. By the end of the day Friday, standing water in some locations may become possible, as well as rises on local creeks and streams. The WPC excessive rainfall outlooks currently highlight this potential. Rainfall activity may linger into the early morning hours of Saturday as the system is progged to become vertically stacked. Continued rising motion may promote some new development of shower activity. By Saturday afternoon, most of the forcing should move into the Ohio River Valley and give way to mid-level height rises across the region, and bring a break from the precipitation later into the day on Saturday. Another short-wave trough and vort max moves through on Sunday with ensemble probabilities in the ballpark of 50-60 percent chance for at least 0.10 inches of QPF. The wet pattern continues through Wednesday of next week, with probabilities for 0.10 inches over any 24 hour period above 60 percent for most of the forecast period with several locations above 80 percent. Inner-quartile spreads of 10-12 degrees amongst NBM members highlights the likelihood of multiple periods of precipitation and how that may affect afternoon peak heating on any given day. At this time, there is no strong signal for any severe weather, but will need to monitor as if there is any period of destabilization the flow could support more organized activity. Toward the end of the week, medium to long range deterministic model guidance depicts a strong riding pattern across the western two-thirds of the United States that will allow temperatures to steadily climb upward, leading to above normal temperatures. Most of this signal though is just outside of our 7 day forecast. && .AVIATION /18Z TAFS THROUGH 18Z FRIDAY/... Issued at 1242 PM CDT Thu May 30 2024 Watching a group of showers move across Kansas this afternoon that will eventually reach the stateline region early this evening. Showers expected at most of the terminals with isolated thunderstorms possible. At some point, conditions drop to MVFR as coverage of showers increase. More shower activity expected into Saturday. && .EAX WATCHES/WARNINGS/ADVISORIES... MO...None. KS...None. && $$ DISCUSSION...Krull AVIATION...Krull