Marine Weather and Tide Forecast for Newton, IA

DISCUSSION
Issued at 259 AM CDT Wed Apr 30 2025

The southern stream trough has pushed into the central US with cloud cover spreading into Iowa through the early morning hours.
Conditions ahead of the precipitation are pretty dry with dewpoint depressions of 10-15 deg F. Model soundings across the area are slow to saturate into the low levels through midday and early precipitation across southern to central Iowa is expected to be fairly spotty. By this afternoon profiles saturate and CAMs develop more widespread shower and thunderstorm activity across the area. This will last through the overnight before lifting off to the east on Thursday morning. The northern stream shortwave doesn't quite phase and ends up passing across the area later Thursday afternoon, providing another window for showers and thunderstorms. A final lobe of vorticity rotates across the area on Friday with another window for showers and thunderstorms across the area. This final embedded shortwave is finally enough to shift the parent trough east of the area in time for the weekend. The entire period has meager instability with under 500 J/kg MLCAPE and little in the way of a well defined forcing mechanism to focus convection. As such, severe chances are quite low though rumbles of thunder are certainly anticipated. A widespread 0.25" of QPF is forecast with HRRR LPMM painting much of the area as such with pockets of locally higher amounts.

The western US thermal ridge will build across the area for the weekend, keeping the area dry and sending temperatures back into the 70s across Iowa. A rather robust system will develop over the western US during this time and should move into the central US sometime early next week. There is significant spread in model guidance at this range, especially in regard to timing and this will need to be fine tuned later. As is often the case with upper level cut off lows, a delay in arrival next week is possible.

AVIATION /18Z TAFS THROUGH 18Z THURSDAY/
Issued at 1222 PM CDT Wed Apr 30 2025

VFR conditions will prevail this afternoon with a few brief light showers expected to have little to no impact. By tonight lower ceilings will work in, first MVFR and then lowering to IFR at most terminals especially after midnight. More showers and isolated thunderstorms are also forecast and have included PROB30 groups around the relatively likelier time frames, however, confidence in timing and coverage is low and updates and amendments are likely overnight.

DMX WATCHES/WARNINGS/ADVISORIES
None.