Plaincast
What the forecast actually says — NWS Area Forecast Discussions, decoded into plain English.
Plaincast decodes the National Weather Service's Area Forecast Discussion — the real forecast, written 3 to 4 times a day by the meteorologist on shift — into plain English. The discussion is where a forecaster explains their reasoning: which models disagree, what they are watching, and how confident they are. Below is the current edition for Des Moines, with its shorthand expanded. The full experience — an AI plain-English summary beside the annotated original — loads with JavaScript, and every one of the 68 forecast offices has its own edition.
Breezy this afternoon with chances for showers and thunderstorms /20-40%/ returning overnight tonight.
An active weather pattern expected this weekend into the middle of next week with periods of thunderstorms, some strong to severe, along with the risk of heavy rainfall.
The latest surface analysis shows a 1017 mb surface high pressure center parked over the Great Lakes, with its influence extending across the region. Clear skies associated with the surface high are prevalent across the area, allowing temperatures to drop into the lower 60s, with a few upper 50s reported. To the northwest, a 992 mb surface low is tracking across central Canada with a trailing cold front oriented southwestward across Montana and North Dakota.
Today will feature the continued influence of the surface high pressure system; however, an upper-level trough and associated surface low will dive southeastward toward the area. Nonetheless, conditions today will remain dry, with temperatures climbing into the low to mid-80s by this afternoon. Along with rising temperatures, increasing southwesterly winds are expected as a LLJ develops ahead of the cold front advancing into the Northern Plains and Upper Mississippi Valley. The strongest winds will align with the LLJ core primarily over South Dakota and Minnesota, but the northwesternmost locations in the DMX forecast area could see gusts up to 30 mph this afternoon. The area will remain dry through much of the day courtesy of a deep layer of dry air. However, subtle moisture advection driven by the LLJ will support the potential for elevated convection later tonight as the front finally moves into the DMX area. Due to persistent low-level dry air into the overnight hours, chance of rain are capped at 30 percent along the boundary. While the strongest forcing is forecast over the Dakotas and Minnesota, the SPC has placed the far northwestern counties in a Day 1 Slight Risk, with the adjacent tier of counties to the southeast in a Day 1 Marginal Risk for localized severe winds or severe hail.
The front will progress through the region overnight Friday into Saturday morning, bringing isolated to scattered convective activity. The boundary is progged to move mostly through the area by Saturday morning before decelerating significantly. This slow movement will foster a differential heating boundary where showers and thunderstorms could redevelop Saturday afternoon. The precise placement of this differential heating boundary will dictate where CI occurs Saturday afternoon. Overnight CAM guidance places the boundary and subsequent CI primarily along and south of the I-80 corridor, rapidly translating southeastward into Missouri.
A dome of high pressure sitting over the Great Lakes is currently providing clear and mild conditions, but an approaching surface low and upper trough will push a cold front toward the area. Highs will reach the 80s today with gusty southwesterly winds ahead of the front, followed by a slight chance of elevated thunderstorms overnights. As the front slows on Saturday, daytime differential heating could initiate scattered severe-capable storms, primarily along and south of Interstate 80 into Missouri.
This is the plain-text edition, decoded without AI so it loads anywhere. Read the whole Des Moines discussion at /o/DMX/, see what changed since the last one, or open The National Desk for where the weather is today.
Data from the National Weather Service. Translated by Claude. About · For developers & agents · Subscribe: RSS feed for this office · Source on GitHub