Area Forecast Discussion
Issued by NWS Topeka, KS
Issued by NWS Topeka, KS
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484 FXUS63 KTOP 221047 AFDTOP Area Forecast Discussion National Weather Service Topeka KS 547 AM CDT Sat Jun 22 2024 .KEY MESSAGES... - Isolated to scattered storms are forecast today. The stronger storms may have damaging winds. - Excessive heat is becoming more likely for Monday and Tuesday with heat indices up to 110 degrees F. && .DISCUSSION... Issued at 234 AM CDT Sat Jun 22 2024 07Z water vapor imagery showed upper ridging centered over the southeast ridging into the southern plains while the mean westerlies remained over the northern tier states. A shortwave was noted moving east over the Canadian plains with a more subtle wave lifting through the northern high plains. Surface obs indicated a low pressure centered just north and east of GLD while much of the central and southern plains maintained a warm and moist boundary layer. For today and tonight, the subtle wave to the north of the forecast area should continue east and help bring a weak boundary into northern parts of KS this afternoon. Low level flow is expected to be veered to the southwest so convergence may not be the greatest along the boundary. But CIN is also forecast to be weak with MUCAPE values over 3000 J/kg along and just ahead of the boundary. Deep layer shear is expected to only be around 30KT, so the main concern is for collapsing updrafts with the potential for damaging winds. RAP and NAM forecast soundings show over 1000 J/kg of downdraft CAPE ahead of the boundary. And with the warm airmass and limited shear, it could be hard for storms to sustain a hail stone long enough to reach severe magnitudes. The uncertainty in the forecast is around convective initiation. As mentioned there is not a lot of convergence along the boundary and little if any dynamics to force vertical motion in this conditionally unstable environment. Think this is the reason why CAMs struggle to generate much convection over eastern KS and the 00Z HREF keeps the higher probabilities just east of the forecast area. Given the limited coverage depicted by the CAMs have left POPs in the 30 to 50 percent range expecting isolated to scattered storms. Today`s highs are forecast to be a couple degrees warmer than yesterday with most places in the middle 90s. And dewpoints should still be around 70 degrees F especially as the boundary slides south. Forecast heat indices are in the 100 to 105 degree range. Considered the need for a heat advisory today, but the higher readings are only above 103 briefly. So the limited scope of advisory level heat indices of around 105 will preclude an advisory at this time. Surface ridging briefly moves in for Sunday bringing slightly cooler temperatures to the region. By Monday and into Tuesday, models show hot and humid temperatures back over the area with highs in the upper 90s to around 100. With some consistency in the temp and dewpoint forecast from the blend and operational solutions, confidence that we may be dealing with excessive heat is improving. The pattern for next week generally keeps an elongated upper ridge along the gulf coast while the westerlies remain over the northern states. This means the forecast is more likely to be dependent on subtle perturbations within the flow leading to a forecast with lower predictability. There are signs from the operational solution for frontal boundaries to move south Tuesday night and again Thursday night or Friday. This would bring higher chances for precip, but confidence in the solutions is only good for chance POPs of 50 percent or less. Also the boundary Tuesday night should bring slightly cooler temperatures and more manageable heat to the area for Wednesday and Thursday. && .AVIATION /12Z TAFS THROUGH 12Z SUNDAY/... Issued at 547 AM CDT Sat Jun 22 2024 Still have low confidence in whether TS will impact the terminals with the CAMs continuing to show scattered coverage. But the setup is there for TS so will include a VCTS for TOP and FOE during the most likely window for TS. Think probabilities at MHK are still on the low side to mention VCTS at this time. VFR conditions should prevail outside of any TS activity. && .TOP WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION...Wolters AVIATION...Wolters