Area Forecast Discussion
Issued by NWS Topeka, KS
Issued by NWS Topeka, KS
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059 FXUS63 KTOP 080530 AFDTOP Area Forecast Discussion National Weather Service Topeka KS 1230 AM CDT Sat Jun 8 2024 .KEY MESSAGES... - Severe storms with damaging winds around 70 mph and very heavy rainfall are expected mainly across northern KS tonight. - Another round of storms with heavy rain are likely (60 to 70 percent) across east central Kansas Saturday night. && .DISCUSSION... Issued at 240 PM CDT Fri Jun 7 2024 19Z water vapor imagery showed a weak disturbance moving through central KS with a line of elevated convection. A shortwave was moving out into the northern plains as well. Surface obs have shown a strengthening trough of low pressure in the lee of the central rockies. This has allowed good moisture advection through western KS with dewpoints increasing into the middle and upper 60s. Don`t see what would cause the band of elevated showers to fall apart at this point, except that they may lose some of the better moisture advection as they continue east. Additionally there is higher levels of surface based CIN over eastern KS which may cause the line to weaken as they move east. So have bumped up POPs with coverage wording for the rest of this afternoon. Still looks like the main threat for thunderstorms will impact the forecast area overnight. The shortwave moving into the northern plains is sparking convection across northern NEB. This is expected to be the beginnings of an MCS later tonight and most guidance shows the nose of the low level jet and strongest theta-e advection focused over far northeast KS. There may still be some storms develop within the warm air advection pattern ahead of the MCS, so have POPs ranging from chance across the southern counties to categorical over northeast KS. Forecast soundings show elevated CAPE values increasing up to around 2000 J/kg thanks to the strong moisture advection and there 18Z HRRR is projecting to potential for wind gusts over 70 MPH with the MCS as it moves into northern KS. And deep layer shear will be strong enough that some supercell structure could allow for some large hail for a discrete storm or end of a line segment. PWs increase to over 2 inches so the storms will likely have heavy rain. The MCS is expected to remain progressive enough that rain totals should still be manageable with respect to flash flooding. This activity should exit east of the forecast area by daybreak Saturday with some residual cloud cover hanging around. Outflow from the MCS is progged to stall out across southern KS with an 850MB boundary setting up across east central KS. It still appears this will be a focus for renewed thunderstorms development Saturday evening. However the low level jet is not nearly as strong and veered more to the southwest. Still there is very high moisture pooling along the boundary and convection that does form will be capable of heavy rainfall. Fortunately this looks to mainly fall south of tonight`s heavy rain. Models show strong instability along this boundary and 0-6km shear is forecast to be 40KT to 50KT. So there will be a risk for severe storms. If the low level jet was stronger, there would be better confidence in severe storms. This activity could linger into Sunday morning. For Monday weak surface ridging and some dryer air look to give a break from the convection with afternoon temps in the middle 70s to around 80. Another shortwave within the northwest flow may spark some showers and storms on Tuesday, but the weak surface ridge is progged to still be over the area so moisture quality is instability are questionable at this point. Models show mid level ridging amplifying over the southern Rockies through the second half of next week. This would favor hotter temperatures with POPs generally less than 30 percent. && .AVIATION /06Z TAFS THROUGH 06Z SUNDAY/... Issued at 1230 AM CDT Sat Jun 8 2024 Main concern will be TSRA at TOP and FOE with storms moving through the local area for the first hour or two of the forecast. Expect TSRA reducing vsbys to IFR briefly as they move through. At MHK expect mainly VFR conditions as TSRA has moved to the east. Winds will be variable with the convection then settle on a southeast direction at 10 kts or less. A boundary moves south after 12Z shifting the winds to the northeast by 15Z at the terminals. Some threat for additional TSRA after 03Z at MHK so included VCTS for now. Confidence is low for placement of convection at the end of the period. && .TOP WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION...Wolters AVIATION...53