Area Forecast Discussion
Issued by NWS Wichita, KS
Issued by NWS Wichita, KS
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253 FXUS63 KICT 301812 AFDICT Area Forecast Discussion National Weather Service Wichita KS 112 PM CDT Tue Apr 30 2024 .KEY MESSAGES... - A few severe thunderstorms expected this afternoon/evening east of Intestate-135 - A period of heavy rain tonight across southern/southeast KS may lead to additional flooding/river flooding - Another round of severe storms possible Wednesday afternoon/evening - The active weather pattern continues into the weekend && .DISCUSSION... Issued at 303 AM CDT Tue Apr 30 2024 As of 3 AM this morning, an area of midlevel WAA was generating very isolated showers/storms across the Flint Hills. These should come to an end by sunrise. Further west, a midlevel low was coming ashore across the Pacific northwest with an attendant 120 kt speed max. Further deepening of a surface low across the high Plains will surge low-level moisture northward with dew points returning to the 60s for most locations. By mid to late afternoon, the surface low will remain across southeast CO with the inverted trough extending into north central KS. Latest deterministic and ensemble guidance place the dryline around 4 PM from near Omaha, NE to Manhattan, KS to Wichita. As a lead, midlevel shortwave trough ejects across NE this afternoon, widespread thunderstorm development is expected along the dryline/trough axis across NE. Large scale forcing for ascent decreases with southern extent into portions of KS. That being said, modest surface convergence along the dryline from Newton to Manhattan may yield convective initiation in the 4-6 PM timeframe. Long, veering hodographs combined with MLCAPE between 3000-4000 J/kg will support supercells capable of baseball sized hail and damaging winds up to 70 mph. Furthermore, effective storm relative helicity will increase to near 200 M2/S2 by 6 PM, which suggests a tornado is possible as well. After 6 PM, the main trough axis is forecast to begin overtaking the dryline from north to south. Increased convergence along the boundary should support more-widespread thunderstorm development from roughly Hillsboro to Wichita. While the overall hodograph structures remain favorable for discrete supercells, the linear forcing along the boundary should grow convection upscale into more of a linear fashion with embedded supercells possible. As such, the hail and tornado threat will gradually decrease after 7 PM, while the damaging wind and flooding threat are likely to increase. The line segments/MCS will gradually dive south and southeast into the highest zone of low-level theta-e across southern KS. As the convection becomes displaced from the midlevel shortwave trough after 10 PM, the southward push will likely come to an end. The cold pool orientation will remain largely east to west. As the evening progresses a 50-60 kt LLJ will overspread the western flank of the cold pool. This seems to point towards a setup for training storms across southern/southeast KS for a good chunk of the night. Rainfall rates are likely to be quite efficient with PW values forecast to range from 1.25-1.50", which would approach May 1st daily maximums. All of that to say, have hoisted a Flood Watch across southeast KS due to the ongoing flooding issues and the likelihood for more heavy rain. Transitioning from Tuesday night into Wednesday, a complex and potentially significant severe weather setup will emerge. WAA driven showers and storms across southern KS are likely to continue through much of the morning hours. On the western flank of the convection, low-level moisture should being to surge northward as a warm front retreats north. The main uncertainty with Wednesday is the eastern bound of the warm sector. Forecast soundings suggest this WAA pattern atop of thick low-level stratus deck may shunt the buoyant sector west of I-135. Should the stratus scatter by early to mid- afternoon, the background environment will become increasingly favorable for supercells with all hazards probable. These threats would include very large hail up to baseball size, damaging winds up to 70 mph, and tornadoes. Impressive low-level veering with upwards of 200- 300 M2/S2 of effective SRH would support a significant tornado threat with the most intense supercells. These mesoscale details will have to monitored through the morning/afternoon hours Wednesday to truly delineate the greatest severe weather threat area. Similar to Tuesday night, as the trough axis overtakes the dryline, more-widespread thunderstorm development overnight across eastern KS. The chief concern overnight will be heavy rain and flooding. The main midlevel trough will eject across the central Plains Thursday afternoon/evening. The aforementioned surface trough will reside across eastern KS by afternoon. Additional storm development is expected Thursday afternoon/evening along the front. The active weather pattern looks to continue into the weekend with a series of shortwave trough axis` ejecting into the Plains. && .AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/... Issued at 1249 PM CDT Tue Apr 30 2024 A number of aviation concerns are expected over the next 24 hours. SCT to BKN MVFR cigs are slowly moving eastward across south- central Kansas early this afternoon, but shouldn`t affect TAF sites from here on out. VFR conditions should prevail at most TAF sites until about 22Z. A weak frontal boundary/dry line sliding across the area, and a pronounced wind shift from southerly to northwest/westerly. Sustained winds are generally around 15 to 20 knots with gusts up to 30 to 35 knots on both sides of the boundary. By 22Z, thunderstorm development is anticipated along the boundary, and a line of broken strong to severe storms will gradually slide eastward through the late afternoon and evening hours along and east of the Kansas Turnpike. The main concerns will be very large hail, damaging wind gusts, and perhaps a tornado or two. These storms may impact KICT, but it`s difficult to go with more than a PROB30 at this time given coverage may be isolated. Storms are expected to continue moving eastward tonight, and KCNU may also be impacted later tonight. Additional thunderstorm development is expected during the nighttime hours into Wednesday morning, but this activity is not expected to be severe. However, frequent lightning and heavy rainfall may accompany these storms Wednesday morning. && .ICT WATCHES/WARNINGS/ADVISORIES... Flood Watch from 8 PM CDT this evening through Wednesday morning for KSZ069>072-093>096-098>100. && $$ DISCUSSION...BMB AVIATION...JC