Marine Weather and Tide Forecast for Newton, IA

SHORT TERM /THROUGH FRIDAY/
Issued at 359 AM CDT Thu Jun 18 2026

Temps across the state are currently in the upper 50s/low 60s with dewpoints in the mid 50s. Winds remain breezy this overnight in the wake of the cold frontal passage, with wind still between 10-15 mph and a few locations gusting over 20 mph. A mix of stratus and mid- levels cloud cover is scattered across the state currently, though this will likely transition to cumulus during the morning. High pressure will continue building in today, and the weather should be much milder than yesterday.

NW jet stream flow will continue to dominate as the trough in Canada continues to enhance flow. As has been the case all week, shortwaves will continue to orbit around the longwave and pass over Iowa. One such shortwave crosses Minnesota this afternoon, bringing in a few PoPs in northern Iowa for this afternoon. Any sort of surface convergence is quite weak, but some weak synoptic scale lift and surface CAPE may be enough to initiate a few showers and thunderstorms. The remarkably well cooled midlevels are responsible for this instability, reaching 500-800 J/kg through much of the guidance despite quite dry low levels in the wake of the front.
Given timing with peak diurnal heating and CAPE presence, these showers may produce some lightning. Straight line hodographs may be enough to support a few discrete updrafts, but the low 6km equilibrium levels for June will mean these updrafts remain low- topped, which tend not to favor any severe hazards or longevity.
There is some uncertainty as to how far south these showers/storms can make it before instability ultimately wanes enough to kill them off, with some guidance suggesting they make it as far south as I-80 by 00z.

Friday will likely be slightly warmer across at least the southern half of the state as the surface high settles in near and just to the south of Iowa. That said, more precip chances fill in during the afternoon and evening, which will bring in cloud cover to keep it cooler. Another shortwave moves across Minnesota Friday afternoon and evening, perhaps providing enough lift for precip in Iowa too.
With this system, a better defined surface low and cold front may be present and moving across southern Minnesota. PoPs added are minimal for the time being, but the potential for scattered showers and storms in northern Iowa will continue to be monitored. Moisture will be quite limited and Tds are unlikely to surpass the lower 60s. But again, several hundred J/kg of SBCAPE may develop owing to the very cool mid levels and diurnal heating. Any showers/storms that do develop will have precip falling through a relatively dry layer which could 1. Enhance downdraft winds via evaporative cooling and 2. Efficiently mix down the strong winds in the low to mid levels that develop around the base of the trough. While winds may be gusty at times, sub-severe is expected at this time, though the marginal wind risk is not far removed from the NE part of the CWA

LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/
Issued at 359 AM CDT Thu Jun 18 2026

A deeper 500 mb trough will cross the region from late Saturday into Sunday, bringing renewed rain chances to at least parts of Iowa.
However, longer-range models remain divided on the track and evolution of this system, with the GFS initiating convection farther south in Nebraska and more rigorously than the ECMWF, resulting in an apparent MCS affecting parts of Kansas, Missouri, and perhaps southern Iowa. Meanwhile the ECMWF has a broader and more northward solution depicting widespread rain across Iowa. For now will maintain the areawide 60-80% PoPs initiated by the NBM and monitor model trends in the coming days. Early next week there are indications that another trough may cross the region, but at this range details are even less clear.

AVIATION /12Z TAFS THROUGH 12Z FRIDAY/
Issued at 646 AM CDT Thu Jun 18 2026

Stratus over northeast Iowa does have some embedded MVFR cigs that may impact KMCW/KALO this morning. Some potential for cumulus develop this afternoon and a few isolated thunderstorms, mainly over northern Iowa. Did not include at this time with PoPs <30 percent at all sites. The wind may become breezy from the northwest at times today then light and variable overnight.

DMX WATCHES/WARNINGS/ADVISORIES
None.