After so many days in which the weather was delightful, the weather pattern is turning upside down again. What does the weekend have in store for us as we check out Iowa City?
At 1152AM, CT, Iowa City was reporting a temperature of 66 degrees with clear skies and a brisk west wind. Skies will remain clear through the afternoon, over the course of the evening, some clouds may begin to filter in, as a lee trough begins to become enhanced by a weak upper level wave translating through the northern High Plains.
Surface low pressure will organize along the Minnesota-Iowa border, with most of the precipitation confined to Minnesota initially, with little cold air cycled in by the developing low, still at this point mostly born of lee troughing. The circulation in and of itself will bring about a northwesterly flow, and the changing winds in and of themselves are expected to trigger a few thunderstorms in the increasingly favorable environment of eastern Iowa tomorrow afternoon. Meanwhile, the upper level pattern will begin to trough out over the southern Rockies. Overnight tomorrow, the trough will emerge into the southern Plains, helping to generate a much stronger and more significant surface low. This low will have the benefit of a full layer involvement, and will induce a greater clash of airmasses. Sunday morning, the remnants of Saturdays showers and storms will stall and regenerate thanks to an advancing warm front, which will stall around Iowa City. The stalled boundary, in conjunction with one of the first incursions of warm Gulf air will lead to widespread, heavy rain across the region throughout most of the day on Sunday. Because the rain fall and clouds will be so complete, severe storms aren’t expected on Sunday, but given a full day to heat up on Saturday, there could be an isolated severe storm in the evening then. Cold air will begin to press in after about 6pm on Sunday, and the Sunday low will likely be at midnight.
Tomorrow – Warm and sunny, with some strong afternoon thunderstorms, High 73, Low 48
Sunday – Rain and thunderstorms likely, getting cooler in the evening, High 62, Low 42
TWC: Tomorrow – PM T-Storms High 77, Low 46
Sunday – T-Storms High 60, Low 56
AW: Tomorrow – Partly sunny and warm; a couple of p.m. t-storms; thunderstorms can bring hail and damaging winds High 73, Low 45
Sunday – Breezy and cooler with periods of rain and a thunderstorm High 62, Low 45
NWS: Tomorrow – A 40 percent chance of showers and thunderstorms, mainly after 1pm High 76, Low 47
Sunday – Rain and possibly a thunderstorm, High 60, Low 42
WB: Tomorrow – Breezy. Partly sunny with a 50 percent chance of showers and thunderstorms. High 76, Low 46
Sunday – Cooler. Rain and isolated thunderstorms. High 60, Low 55
WN: Tomorrow – Isolated Storms High 75, Low 46
Sunday – Rain High 59, Low 54
As is often the case, people who don’t provide hourly forecasts out through 60 hours are going to be in trouble with this verification. If you want a hint as to the value numerical weather prediction models provide, take a look at the satellite and try to figure out where that next system is coming from. Not much organization anywhere!