Weather Alerts For Ottawa, IA

# SUMMARY -------------------- - Tornado Watch for portions of Central and Eastern Iowa Northern and West-Central Illinois Southeast Minnesota Far Northeast Missouri Central and Southern Wisconsin - Effective this Friday afternoon and evening from 1240 PM until 800 PM CDT. - Primary threats include... A few tornadoes likely with a couple intense tornadoes possible Widespread large hail and isolated very large hail events to 3.5 inches in diameter likely Scattered damaging wind gusts to 70 mph likely # DETAILS -------------------- SUMMARY - A very moist and unstable airmass exists ahead of a cold front progressing eastward/southeastward across the region. Thunderstorm development is anticipated within the warm sector ahead of the front, where discrete supercells capable of all severe hazards, including very large hail and strong to intense tornadoes, are possible. Thunderstorm development is possible along the front as well, with large hail and strong gusts the primary risk with these storms. - The tornado watch area is approximately along and 110 statute miles north and south of a line from 55 miles north northwest of Des Moines IA to 55 miles east of Madison WI. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU9). AVIATION Tornadoes and a few severe thunderstorms with hail surface and aloft to 3.5 inches. Extreme turbulence and surface wind gusts to 60 knots. A few cumulonimbi with maximum tops to 500. Mean storm motion vector 26035. ISSUED AT The NWS Storm Prediction Center has issued a ISSUED BY 1241 PM CDT Fri Apr 17 2026 HEADER Watch county notification for watch 129 | National Weather Service Des Moines IA # PRECAUTIONARY/PREPAREDNESS ACTIONS -------------------- REMEMBER...A Tornado Watch means conditions are favorable for tornadoes and severe thunderstorms in and close to the watch area. Persons in these areas should be on the lookout for threatening weather conditions and listen for later statements and possible warnings.

There is a Slight Severe Storm Risk for your location. Continue reading for today's outlook from the National Weather Service's Storm Prediction Center. -------------------- National Severe Storm Outlook THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS FROM FAR NORTHWEST OKLAHOMA THROUGH CENTRAL AND EASTERN KANSAS INTO WEST-CENTRAL MISSOURI SUMMARY Numerous severe thunderstorms are likely this afternoon into tonight across parts of the Upper Midwest southward across the lower Missouri Valley and central/southern Great Plains. Initially this may be accompanied by a risk for large to giant hail and a few strong tornadoes, before severe wind gusts of 60 to 90 mph become the most prominent hazard by this evening. Synopsis Recent surface analysis places a low over south-central MN, with a cold front extending southwestward to another low over central KS. A warm front also extends southwestward from the MN low through far southwest MN and far northern IL into central IN. This warm front is demarcated well by the 56 deg F isodrosotherm. Farther south, a dryline extends from the triple point KS low back southwestward through the TX Panhandle and into far southeast NM. A broad, moist warm sector exists to the east of the cold front and dryline, characterized largely by dewpoints in the low to mid 60s. A well-defined shortwave trough is apparent on satellite imagery, extending from southern Saskatchewan back southwestward into the eastern Great Basin. This wave is forecast to continue eastward, with a attendant increase in the mid-level flow across much of the Plains and Upper/Mid MS Valley. The cold front will surge eastward/southeastward in response to this wave as well, interacting with the warm sector to support numerous strong to severe thunderstorms from parts of the Upper Midwest southward across the lower Missouri Valley into southern Plains. Upper/Mid MS Valley Moderate to strong low-level moisture advection is expected across the Upper MS Valley today as the surface low mentioned in the synopsis progresses northeastward, with an attendant northward shift of the warm front as well. The risk across this region may evolve in several phases, beginning with the elevated thunderstorms currently ongoing across northwest WI. This storms will likely continue northeastward, posing a risk for severe hail and isolated damaging gusts. Additional development is possible northwest of this activity along the occluded front, with some hail possible here as well. Farther south, the northeastward advecting low-level moisture coupled with strong heating and steep lapse rates will result in a strongly unstable airmass along and just south of the warm front by the early afternoon. Storm initiation is anticipated within this open warm sector by early afternoon, forced by a mix of warm-air advection, low-level confluence, and subtly increasing large-scale ascent. This activity should be ahead of the front and initially discrete. The overall parameter space will be characterized by strong to very strong buoyancy, moderate deep-layer vertical shear, and strong low-level helicity. Supercells capable of all hazards are expected, including large to very large (i.e. 3"+ hail), strong to intense tornadoes, and severe wind gusts. Storm interactions are expected to strongly influence the tornado risk, with the initially discrete mode likely becoming messy quickly. Farther west, other storms are likely to evolve quickly along the front, developing into a band of severe thunderstorms that will push east coincident with the front. Damaging wind gusts will tend to become more prevalent during the evening with linear storm modes. Some tornado risk may continue into the evening as maturing bands of storms yield a threat for bowing segments and embedded mesovortices, before this activity gradually diminishes late as it moves east into IN/Lower MI late. KS/OK/MO A very unstable airmass is expected to develop along and ahead of the triple point over south-central KS an associated cold front and dryline. Strong low-level convergence will likely lead to initial storm development near the triple point. This initial activity will be supercellular and capable of very large to giant hail (over 3-3.5" in diameter). Highest coverage of very large hail is expected over from far northwest OK into south-central KS. Strong downdrafts (60 to 80 mph) are possible as well. With a largely boundary-parallel orientation to the deep-layer shear, the tornado risk appears relatively lower. However, given the supercell mode and potential interactions with outflow, a low-probability tornado risk remains. A more north-south configuration to the dryline supports a conditional tornado risk into far northwest TX. With time, upscale growth and the development of a forward-propagating MCS is anticipated across central and eastern KS. Very strong gusts (80+ mph) are possible with this MCS. Additionally, some QLCS tornado risk will exist within this line as long as it stays ahead of the surging cold front. The front will continue sweeping southeastward, with storms along this boundary yielding a risk for wind/hail.

Pollen Index: 11.7 Pollen Level: high Predominant Pollen: Elm, Poplar/Aspen/Cottonwood and Maple. The pollen levels for Saturday will be falling but stay in the extremely high range. Since the weather has a major influence on pollen dispersal, this decrease is due in part to falling temperatures and expected precipitation in the morning and evening which tends to wash pollen out of the air.