Area Forecast Discussion
Issued by NWS Topeka, KS
Issued by NWS Topeka, KS
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946 FXUS63 KTOP 191706 AFDTOP Area Forecast Discussion National Weather Service Topeka KS 1206 PM CDT Thu Sep 19 2024 .KEY MESSAGES... - Severe storms may form over portions of far northeastern into far east central Kansas areas this afternoon before moving ESE of the area by mid evening. Large hail and damaging winds appear to be the primary hazards with a very low tornado threat possible. - Hot afternoon temperatures hang around possibly through Saturday. Today (Thursday) may bring heat index values close to 105 degrees mainly over east central into portions of northeastern Kansas along and ahead of the frontal boundary. - Good rain chances still in the forecast mainly Saturday night through Sunday with 2-3 inches possible mainly north of I-70 and 1-2 inches elsewhere. Some area may see locally higher amounts. - Cooler and mostly dry weather looks like the pattern heading into next week with temperatures near seasonal normals. && .DISCUSSION... Issued at 335 AM CDT Thu Sep 19 2024 The overall upper air pattern across the CONUS shows an open trough over the Mid-Atlantic region with an upper low spinning over the Dakotas and another within an elongated trough over central California. A semi-permanent anticyclone is in place over Texas with a ridge axis extending into the Mid-MS Valley region. Near the surface, a weak area of low pressure is situated over western Kansas with a weak frontal boundary poised to work east today into the area. Early this morning, mainly isolated showers and a few embedded thunderstorms have formed within an area of warm advection isentropic upglide working across the area along the 310K surface. Expect these showers and storms to last through mid morning before exiting the area to the east and then clearing into the late morning and afternoon. The aforementioned surface boundary will likely be a focus into the afternoon for storms to develop once the cap is eroded sufficiently. Hot temperatures will be common ahead of this boundary into this afternoon mainly across east central and into portions of northeastern Kansas combining with dewpoints around 70 degrees to bring heat indices close to 105 degrees over some areas. Have opted to not go with a headline for heat due to the relatively isolated area along the boundary and this being a very late season event after several previously hot episodes. Storms for this afternoon into the evening are expected to be isolated to scattered in coverage with forcing being focused well north of the area. The low level lift will be provided by a weak frontal boundary and area of low pressure advancing east into the area. As the EML mixes out, expect more opportunity for storms to fire with updrafts along or in the vicinity of the boundary. Mid level lapse rates from H7-H5 levels isn`t forecast to be as steep and one would like to see for some of the most robust updraft motion with most progs around 6C/km. Nonetheless, with good low level moisture in place and the low level lift mechanism in place, could see updrafts organize in areas as a deeper layer of effective shear comes into play with 0-6km values around 30-40kts. Surface winds appear to remain mostly southerly to slightly southwesterly. Thus, for this afternoon areas generally along and southeast of the Kansas Turnpike appear to have the best ingredients in place with a deep inverted-V sounding in place. Expect hazards to include damaging winds possibly up to 70, large hail over quarter size with a very low tornado threat which can`t be totally ruled out mainly along the weak frontal boundary. Widespread rain chances still look possible into late Saturday and Sunday periods as the upper low over central California lifts into the central Rockies and ejects into the central Plains. Strong mid- level flow around the mid to upper low should provide ample DCVA to set up across the forecast area. Strong low to mid-level theta-e advection brings back PWATs to above the 90th percentiles. Depending on how much convection develops within this this system, some rainfall totals could exceed 3 inches, especially north of I-70 within the region where the best convergence and resulting precipitation shield looks to establish itself. Any severe weather with this system is too uncertain to ascertain where it would setup at this point due to the nature of the forcing that is expected to be in place both from a temporal and spacial sense. Into next week, a northwest flow pattern sets up with drier and cooler air entering the region helping to bring temperatures back to around normal for this time of year with highs in the 70s and lows in the 50s. && .AVIATION /18Z TAFS THROUGH 18Z FRIDAY/... Issued at 1205 PM CDT Thu Sep 19 2024 Main uncertainty is the redevelopment of thunderstorms this evening across eastern Kansas ahead of a southeastward moving cold front. As of now, the best chance for storms will remain south and east of KTOP and KFOE, though can`t completely rule out a storm near these terminals. Gusty south winds this afternoon veer to the northwest once the cold front moves through, becoming lighter behind the front and after sunset. VFR conditions will prevail outside of any thunderstorms. && .CLIMATE... Issued at 235 PM CDT Wed Sep 18 2024 Record high temperature data for September 19: Record maximum temperature Forecast maximum temperature Topeka 99, set in 2022 96 Concordia 101, set in 2022 92 && .TOP WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION...Drake AVIATION...Reese CLIMATE...Poage