Marine Weather and Tide Forecast for Aurelia, IA

DISCUSSION
Issued at 231 PM CDT Mon Apr 21 2025

THIS AFTERNOON: Temperatures warming nicely through the 60s and towards the 70s this afternoon. With dry low-lvl airmass and deep mixing we're seeing dew points and resultant RH values into the 20s and 30 percent range. Further west, satellite imagery showing a compact shortwave crossing the Rockies and moving into the western Dakotas. A linear area of showers and embedded thunderstorms has develops over western South Dakota and northwestern Nebraska. This activity is expected to continue to move eastward through the afternoon reaching south central South Dakota around or after 5pm.

THIS EVENING: Aforementioned upper wave continue to move east this morning bringing showers and a few rumbles of thunder through the Tri-State area. Greatest concern this evening will be with the potential of gusty winds accompanying any high based shower/storm that moves through. Deep mixing results in favorable environments for downward momentum transfer and with DCAPE values approaching 700 J/KG gust potential increases further. High-res CAMs suggest potential for a few downdrafts upwards of 50 knots moving towards south central South Dakota early this evening.
This risk may continue eastward towards the I-29 corridor between 7-9pm though gust potential may subside slightly. This linear band of showers moves east of the CWA by midnight, though we'll have to watch trailing corridor of instability moving into the Highway 20 corridor which could lead to a very remote risk of an isolated stronger storm into the early morning hours of Tuesday.

TUESDAY: The passage of a surface frontal boundary pulls westerly winds into the CWA through the day on Tuesday. Another day that will promote deeper mixing and downward transfer of drier air to the surface. Winds aloft however are not overly strong, so while RH values may fall as low as 20%, winds are likely to stay below critical fire weather thresholds.

WEDNESDAY-THURSDAY: Troughing digging into the western CONUS will induce a period of westerly to slightly southwesterly mid-lvl flow by the middle of the week. Broad and rather weak isentropic ascent will develop by Wednesday, bringing a low-end risk for showers to the region. However, most models are now hinting at a stronger surface warm front staying planted well south of the CWA into and through Thursday which would both limit overall moisture transport northward but also limit overall PoPs/QPF. The end result may be a period of low to moderate PoPs through Thursday (centered mostly Wednesday night), but inconsistent QPF totals. The areal probabilities of QPF through Thursday sit around 70% for more than 0.25", 40% for around 0.50", and around 20% for 1.0" only near Highway 20.

FRIDAY-SUNDAY: Medium range solutions begin to diverge slightly towards the end of the week, but all indicate a period of more unsettled weather into early next week. After brief mid-lvl ridging slides through the region Friday. we'll see that previously mentioned upper trough over the western CONUS begin to slowly eject eastward. Warm advection and a lead shortwave ejecting northeast into the Plains on Saturday may initiate our next round of rain by mid-day Saturday which continues into Sunday. Temperatures overall are expected to rise back into the 70s due to warmer southerly surface flow. The eventual evolution of this trough as it moves further east remains slightly in doubt, with some medium range models suggesting a greater severe weather risk into the Plains by late Sunday into Monday/Tuesday.

AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/
Issued at 1030 PM CDT Mon Apr 21 2025

Scattered showers and isolated thunderstorms east of Interstate 29 will exit the area shortly after 06Z. Winds will transition to west/northwesterly overnight behind a frontal boundary, then increase on Tuesday afternoon - gusting near 20 kts into the early evening. Winds become light on Tuesday night.

FSD WATCHES/WARNINGS/ADVISORIES
SD...None.
MN...None.
IA...None.
NE...None.