Area Forecast Discussion
Issued by NWS Topeka, KS
Issued by NWS Topeka, KS
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088 FXUS63 KTOP 190528 AFDTOP Area Forecast Discussion National Weather Service Topeka KS 1228 AM CDT Thu Sep 19 2024 .KEY MESSAGES... - Isolated showers/storms possible across the area today, mainly north of I-70. (10-20%) - Isolated to scattered storms will be possible again Thursday afternoon and evening across northeast and east-central KS. A few could become strong/severe with damaging winds to 70 mph and hail up to 1.5 inches possible. - Warm temperatures persist today and into Friday before cool air filters in this weekend and next week. - Widespread chances for rain come Friday PM through Sunday with areas seeing a widespread 1 inch of rainfall. Some areas could receive totals up to 2-3 inches, mainly north of I-70. && .DISCUSSION... Issued at 235 PM CDT Wed Sep 18 2024 This afternoon, the main synoptic features across the CONUS include an occluded upper low across the northern Plains, a longer-wave trough over the northern CA coast and weak ridging over the central Plains into the Ohio River valley. A warm and pleasant day is underway today as temperatures have climbed into the low to mid 80s area-wide with some mid and high cloud cover pushing east across the area. Expect temperatures to warm a few degrees further this afternoon, topping out in the upper 80s, low 90s. An isolated shower and possibly a storm could develop this afternoon if surface convergence can help parcels overcome residual SBCIN, but overall forcing and upper-level support does not seem conducive to much development. If one can develop, some gusty winds and small hail could be realized in the strongest of storms. This evening, isentropic ascent ramps up as a nocturnal 30-40kt LLJ develops across the area. Isolated showers within this regime will be possible through the early morning hours of Thursday. By Thursday afternoon, a low-level trough axis and frontal boundary will begin to slide east into the area in unison with the main upper- level wave over the northern Plains. Skies will begin to clear from morning`s showers with mostly clear skies helping to destabilize the environment during the day. Deep mixing paired with good solar insolation should push temperatures into the mid 90s by the afternoon with dewpoints creeping into the mid to upper 60s. CAMs depict afternoon MLCAPE values ahead of the surface trough/frontal boundary ranging from 1500-2500 J/kg with 7-8C degree ML lapse rates. Increasing deep shear and inverted-V soundings should also point to a severe threat as 30-35 knots of 0-6 km shear should be realized in combination to the afternoon instability. Given these parameters and the low-level convergence along the surface boundary and trough axis, scattered convection should develop in the peak heating hours across far northeastern and east-central KS as any SBCIN erodes. Hazards within the strongest storms will be winds to 70 mph, and hail up to 1.5 inches. The tornado threat is very low, but not zero given LCLs around 1-1.5 km, slight curvature in the low- level hodographs and storm motions moving off of the surface boundary into the warm sector. Some uncertainty may come with how long cloud cover from morning showers impacts heating across eastern Kansas. If cloud cover can hold on for a bit longer, some capping may remain in place into the afternoon hours making storm coverage in the late afternoon and evening even more isolated. Storm chances will quickly move into western MO by the late evening hours tomorrow with drier air filtering in overnight into Friday. By Friday and Saturday, the weak frontal boundary stalls across southeastern Kansas before lifting north as a warm front during the day Friday in response to our next upper wave approaching from the southwest. PoPs should begin to increase along this boundary as it approaches the KS/NE border by Friday evening. PVA will increase Saturday and through the weekend as the main long wave trough ejects into Kansas and Nebraska, providing the area with much needed rainfall. Saturday afternoon through Sunday morning appears to be the timeframe when the area should see the highest rainfall totals given ample low and mid level convergence, persistent theta-e advection and PWATs hovering around 2 inches; around the 90th percentile for this time of year! Majority of the aforementioned forcing should occur north of I-70 and is where the highest rainfall totals are expected to reside, some seeing 2-3 inches. Areas south of I-70 will see a bit less, possibly between 0.5-1.5 inches. Temperatures Saturday should vary from north to south, topping out in the low to mid 80s and upper 80s respectively with temps Sunday mostly staying in the 70s. PoPs will push east by Monday as northwesterly flow builds into the region and reinforces cool, Fall-like temperatures behind the weekend`s rainy system. Expect temperatures in the 70s each afternoon with lows dipping into the 50s next week with low chances for precipitation. && .AVIATION /06Z TAFS THROUGH 06Z FRIDAY/... Issued at 1222 AM CDT Thu Sep 19 2024 VFR conditions expected to remain in place for most of the period as chances for showers and thunderstorms appear to be low at all terminals. LLWS conditons continue to look marginal at this hour with partially mixed surface winds likely to remain in place overnight. Best chance for afternoon showers and storms appear to be around or just ESE of KTOP/KFOE terminals. Chances remain too low to include in the forecast but expect best time to form around 21Z or after and lasting through around 03Z before moving SE of the area. A weak front enters the area after the 00Z time frame but winds look to be lest than 10kts at this time. && .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 95 Concordia 101, set in 2022 92 && .TOP WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION...Griesemer AVIATION...Drake CLIMATE...Poage