Sunrise 6:18 AM   Sunset 8:20 PM Moonrise 3:25 AM   Moonset 3:29 PM

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FXUS63 KTOP 040528 AFDTOP

Area Forecast Discussion National Weather Service Topeka KS 1228 AM CDT Sat May 4 2024

KEY MESSAGES

-A line of thunderstorms is expected to move from west to east across the area tonight into early Saturday morning. There is a low chance for a few damaging wind gusts.

-A better chance for severe weather arrives Monday afternoon as a stronger system impacts the central US. All modes of severe weather will be possible.

DISCUSSION
Issued at 240 PM CDT Fri May 3 2024

This afternoon, a shortwave trough is evident on water vapor imagery over Wyoming with southwest flow over KS. Surface obs show high pressure centered in eastern Iowa. South-southeast winds are beginning to transport higher dew points back into the area, which will continue as high pressure slides further northeast and low level flow increases this evening. The shortwave over WY will move eastward across the Dakotas this evening and tonight, bringing a cold front across KS. A linear complex of thunderstorms is expected to develop in western Nebraska/Kansas near the boundary this evening, marching eastward into tonight. Instability will initially increase in eastern KS with the theta-e advection this evening, but CIN is also expected to increase as the night progresses and the storms approach. HRRR MUCAPE values range from about 1000-1500 J/kg ahead of the front, with storms likely along or just behind the instability gradient. Shear still looks to range from about 30-35 kts, helping to maintain storm structure aloft. Given these parameters, strong winds and small hail will be the main concerns with storms as they move through tonight.

Lingering post-frontal showers, and gusty northwest winds will be possible through Saturday morning before high pressure brings in a cooler and drier air mass. High temperatures Saturday afternoon look to run about ten degrees cooler than today. Another shortwave trough could then bring precipitation back to the forecast area, but this time from the south. That trough will move across TX and the Red River Valley, then into the Ozarks on Sunday.
Instability and moisture will be more limited, so severe weather is not expected. Have also decreased POPs slightly with some deterministic models now keeping most of the area dry. Still think there is at least a slight chance for light QPF mainly south of I-70.

A much stronger and more impactful system is still on track for the Monday afternoon/evening timeframe. A deep H5 trough looks to move across the Rockies and take on a negative tilt as it progresses over the High Plains Monday afternoon. Strong southerly flow will quickly transport moisture into the region ahead of a deepening surface low.
Instability will build in the warm sector across central and eastern KS in response, with models showing anywhere between 2000-3500 J/kg of SBCAPE. With effective bulk shear possibly exceeding 40 kts and 0-3 km SRH above 200 m2/s2, another round of severe weather is anticipated. All modes will be possible, including damaging winds, large hail and tornadoes.

Severe weather is not currently expected for the rest of next week, but a series of shortwave troughs embedded the the flow aloft could at least keep some POPs around through midweek.

AVIATION /06Z TAFS THROUGH 06Z SUNDAY/
Issued at 1227 AM CDT Sat May 4 2024

Line of showers and thunderstorms ahead of a cold front will move through KMHK around 0830z and KTOP/KFOE around KFOE, give or take an hour. Precipitation only looks to last for a couple hours at any one spot. Winds veer to the northwest behind this line as the cold front moves through, with ceilings falling to MVFR and possibly IFR at times. These lower ceilings gradually clear through the afternoon, with 10-13 kt northwest winds weakening after sunset.

TOP WATCHES/WARNINGS/ADVISORIES
None.

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