NWS Paducah Area Forecast Discussion on May 8, 2024

264 FXUS63 KPAH 080741 AFDPAH Area Forecast Discussion National Weather Service Paducah KY 241 AM CDT Wed May 8 2024 .KEY MESSAGES... - Ongoing active storms with severe potential will persist until about or just shy of daybreak, with all severe hazards in  play. - A warm front's return by mid to late morning carries the next risk of severe storms, also an all hazards in play threat as   storm chances heighten again. - Once warm sectored, an approaching cold front late this afternoon will fire a widespread and significant risk of a  severe weather outbreak this afternoon and evening. Large hail, violent tornadoes, and damaging winds are all expected with this outbreak. In particular, Southeast Missouri, Southwest Illinois, and Western Kentucky have been upgraded to a Moderate Risk for severe storms. - A Flood Watch is in effect for portions of the area as the steering flow suggests training of locally heavy rainfall could produce upwards to 3" or more in some locations. - After this powerful storm system's passage is fully completed,  then cooler and drier air moves in for the end of the week and   weekend with highs in the 70s and refreshingly lower    humidity. && .DISCUSSION... Issued at 230 AM CDT Wed May 8 2024 Ongoing active strong-severe storms required a Watch extension for western Ky til daybreak. Overall, trends are weakening, however, given its over-achieving persistence, SPC determined a headline extension was warranted as RAP models peak MLCAPEs of  2-3K Joules across its approaching corridor, with bulk shear  upwards of 50 kts...meaning there is still atmospheric support  for the line to punch with supercell potential as helicities run to about 200 m2/s2 in the lower 3KM. That said, if current  trendings hold, the headline could be cancelled in about half  its time. After, all eyes turn to the much advertised daytime threat for a widespread and significant severe outbreak as the 90 kt upper jet core is incoming with the mean long wave's dynamical energy input. Bulk shear exceeds 50 kts, and mean lapse rates increase to 8C, promoting large scale ascent of the warm/juicy unstable air mass with highs in the low-mid 80s and dew points into the lower 70s. Helicity values are progged to be up into the 200-300 m2/s2 range both along the warm front and more or less hold as the cold front approaches. Speaking of, the CAMs all suggest a return/lift of the warm front outputs mid-late morning convection overspread, and then within the warm sector as the cold front approaches late this afternoon...the big show is still an all go for the afternoon/evening time frame. In particular, SEMO/SWIL/WKY has been upgraded to a MDT risk for all hazards severe, including large-giant hail and significant tornadoes. Lastly, the hyper-souping PW's and steering winds that will promote training cells overtop already wetted grounds has prompted us to issue a Flood Watch for western Ky, where WPC has bumped us into a MDT risk of excessive/FFG rainfall. Collaborative efforts are still ongoing as to if/how far west we may need to extend that, but generally, upwards to 3" areal average totals potential in western Ky trails to 2" along the MS river and lessens west of there. The cold front's passage is made tonight, and the severe threat ends as it does so. Severe storms may be self sustaining into the night until then, and convective pops linger within the broader trof even into Thursday morning, in our far east. Afterward, the air mass modification to a cooler/drier more spring-like feel, with Thursday's transition onset completing by Friday, when upper 60s-lower 70s highs and dew points in the 40s are established. Generally speaking, highs in the 70s and dew points in the 40s hold thru the weekend before returning closer to seasonal norms early next week. && .AVIATION /06Z TAFS THROUGH 06Z THURSDAY/... Issued at 230 AM CDT Wed May 8 2024 A line of storms offers restricted CIGS/VSBYS as it rolls across the terminals during the pre dawn hours. KMVN has some patchy dense fog on the cold side of the boundary. After a daybreak lull, a warm front returns and heightens storm chances again, which will offer additional deterioration to restricted categories. Increasing lapse rates suggest these hold into/thru the afternoon, when storm chances again heighten as the most violent of the storm evolutions comes to fruition with the cold front's approach. Increasingly gusty non thunderstorm winds will peak upwards to 25-30 kts this afternoon. && .PAH WATCHES/WARNINGS/ADVISORIES... IL...None. MO...None. IN...None. KY...Flood Watch through Thursday morning for KYZ001>022. && $$