Area Forecast Discussion
Issued by NWS Topeka, KS
Issued by NWS Topeka, KS
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518 FXUS63 KTOP 301955 AFDTOP Area Forecast Discussion National Weather Service Topeka KS 255 PM CDT Sun Jun 30 2024 .KEY MESSAGES... - Showers and thunderstorms move across the area overnight into Monday morning with best chances (50-70%) north of I-70. - Heat Advisory has been issued for parts of north central KS Monday. Heat becomes more widespread on Tuesday. - Periodic chances for storms for much of the week, though greatest risk for organized severe weather appears to be Tuesday afternoon/evening. && .DISCUSSION... Issued at 254 PM CDT Sun Jun 30 2024 Upper ridge remains dominant over the southern CONUS with two troughs noted over the northern half, one heading towards New England and the other moving through the Pacific Northwest. Sfc high pressure in the Upper Midwest has kept cool easterly winds with drier air filtering into the area throughout the day. As such, the better moisture has remained west of the area, preventing showers from materializing in north central KS where dew point depressions remain rather large. Will maintain slight chances this afternoon in case these manage to make it farther east, though confidence is pretty low at this point. Better rain chances come overnight into Monday morning, with isentropic lift increasing across the area after midnight. CAMs aren`t exactly in agreement on how widespread any thunderstorms will be, as some depict the entire area seeing rain while others suggest this activity looks confined to the I-70 corridor northward. In any case, not expecting severe weather with MUCAPE of less than 1000 J/kg and weak vertical shear. That said, the moisture axis with Pwat between 2-2.25" could result in some heavy downpours. The good news is this system should be fairly progressive, so there doesn`t appear to be a widespread flooding concern, but the increasing moisture in the column could bring a quick inch or more of rainfall to isolated locations. Isentropic lift weakens by midday, which should bring an end to the rain from west to east through the morning, exiting the area around 18Z. North central KS areas will have more time to clear out and see greater insolation with increasing humidity area-wide. More cloud cover in far eastern locations should keep highs in the 80s, but north central KS is still forecast to reach the mid 90s to near 100. This should bring heat indices between 105-109, so have gone ahead with a Heat Advisory for Cloud, Ottawa, Dickinson, and Clay Counties. If it looks like these conditions could spread to surrounding counties, more could be added to the advisory but think this highlights the area of greatest confidence for now. Heading into the evening hours, the main upper trough looks to be far enough northwest of the area with the associated sfc front and trough progged to develop thunderstorms in central NE. The LLJ strengthens and is stronger to the north, which should keep the majority if not all of the storm activity north of the area. Have kept low PoPs along the KS/NE border Monday evening/night, but confidence in these areas being impacted by severe weather is low. By Tuesday, the upper ridge holds strong near the Gulf states with the aforementioned northwestern trough slowly moving closer to the area. The cold front should be the focal point for thunderstorms to develop in the afternoon/evening as it crosses the area. There looks to be sufficient shear and instability to support organized severe weather, with all hazards possible, although wherever any tornado risk exists would depend on where exactly the sfc low and triple point set up. The frontal boundary should push south of the area to bring some relief to the heat by Wednesday with highs back into the 80s. The baroclinic zone looks to hang around the area through Thursday with embedded vort maxima keeping storm chances around through at least the 4th of July holiday with mainly evening/nighttime periods highlighted at this time. The end of the week looks quieter before another system perhaps at the beginning of next week. && .AVIATION /18Z TAFS THROUGH 18Z MONDAY/... Issued at 1248 PM CDT Sun Jun 30 2024 VFR conditions continue until the morning hours. Main concern is whether or not convection becomes widespread enough overnight into early Monday morning to impact terminals. Some CAMs bring thunderstorms across the entire area, while others have this activity mostly confined to I-70 northward. With this in mind, there is still a chance storms could miss terminals to the north, but felt there was enough of a signal to mention VCTS for a short time window, which may need to be adjusted. Any storms that do move through should do so quickly, but could bring some heavy downpours so wouldn`t rule out brief vis reductions with those. In any case, the better chance for flight restrictions comes with MVFR cigs during the morning, which should lift toward the very end of this period. && .TOP WATCHES/WARNINGS/ADVISORIES... Heat Advisory from 1 PM to 8 PM CDT Monday for KSZ020-KSZ021- KSZ034-KSZ035. && $$ DISCUSSION...Picha AVIATION...Picha