April 24 Severe Weather Update #1

The cold front continues to slowly sag southeast, currently located from Minneapolis southwest to Storm Lake and then south of Sioux City, near Hastings, NE and then near Goodland, KS per latest surface analysis. The frontal located around 4 PM will be the key, as anytime from that point on we may see initiation of thunderstorms. As mentioned the front is moving slowly southeast, thus still expect all but northwest and southeast corners to see good thunderstorms this evening/overnight.

Temperatures well into the 70s already, with dew points approaching 60; yielding 1000-2000 J/kg of surface based CAPE already. The depth of moisture is somewhat in question, as this mornings 12z radiosondes indicated that the good moisture had only reached as far north as Topeka, KS. Omaha sounding was very dry above 850hPa and with the low level jet already subsiding it seems questionable as to whether or not a good depth of moisture will reach well into Iowa. Nonetheless, thunderstorms are still likely to develop along the front and may be able to remain discrete for an hour or two before sunset. These initial discrete storms will be capable of large hail and damaging winds, and a minimal tornado threat. The tornado threat also appears minimized right now with little to no shear present, it does appear that at least meager values will be present this afternoon to warrant at least the mention.

Thunderstorms expected to evolve into line segments as the evening progresses, likely into one or more squall lines given strong unidirectional shear and relatively dry levels between 850-600 hPa. This will likely continue the threat for large hail and especially damaging winds across the state of Iowa as storms move northeastward.

I will not be chasing this event, nor any events this weekend as I have prior commitments. But, will be watching things closely and hopefully providing a few updates for those that wish to keep up to speed on things.