Rain Through Tomorrow

In Evening Brief by Henry LukerLeave a Comment

Happy (dreary) Wednesday to you. Truly a tail of two sides today — Council Bluffs struggled to hit 46, while Iowa City and Davenport hit 58. 22 degree difference over the span of around 220 miles.

1. Will it ever stop raining? (No)t tonight.

Radar around 10:00 p.m.

A look across the region shows a very active night of weather. Towards the Oklahoma and Texas panhandles, a Severe Thunderstorm Watch is in effect. Hail close to softball size was seen there just past 7:00 p.m. Closer to our area, the state has been enveloped by cloudy and rainy conditions most of the day.

Rain continues moving easterly this evening along and north of a line from Logan to Carroll to Keokuk. Total rainfall with this system may be over an inch in some areas, primarily in northwest Iowa. Most of this band should weaken or move out of the area by daybreak tomorrow.

Elsewhere, windy conditions in the northeast, red flag concerns in southeast New Mexico and western Texas, as well as in eastern Pennsylvania and New Jersey, and winter storm watches over the Sierra Cascade.

2. (No)t tomorrow.

Sporadic rain chances remain in the forecast tomorrow. While our state map above keeps some areas dry/some areas marked AM/PM only, there will be continual limited (20-30%) chances for the entire state all day. Any rain that does fall will be light in nature, perhaps up to a quarter inch at most.

Three predominant notes on the high-resolution models seen this evening:

  1. The bulk of the rain activity in northwest Iowa should hopefully move off to the east by the noon hour with only isolated chances for the remainder of the day
  2. North central and northeast Iowa, unfortunately, will see most of the day “washed out” by remaining light activity
  3. Southeast Iowa will see another round of rainfall towards the afternoon hours, but the morning should be dry.

Temperatures struggle to reach the mid-40s northeast to almost the mid-50s southeast.

3. (No)t Sunday.

500mb Currents over the Pacific and United States

Best way to at least begin to understand our situation for Sunday would be to look at the 500mb chart from this evening, showing an aggressive trough right around Hudson Bay and through portions of Quebec and Ontario; a slight trough in the Central Rockies, but otherwise zonal flow for the rest of the country.

Our focus is on the pair of upper-level lows, one just off the coast of the Pacific Northwest and one south of the Aleutians. The GFS shows a disturbance ejecting off the first low towards the southwestern US by Friday night, moving towards the Upper Mississippi Valley by Saturday night, before the pair of upper-lows amalgamates just off the coasts of Yukon and British Columbia. As this begins to occur, additional energy splits off from that system and looks to affect the area towards Sunday. Some of this will support the synoptic situation in Iowa, but most of it will split off towards the north and south.

At the surface, a low should move alongside the shortwave northward. This will begin chances of showers over southwestern Iowa beginning late Saturday night. Models are very much all over the place with the evolution of this system with limited confidence with this forecast. Currently, we’re sticking with the GFS’s solution of tracking the low from northeast Nebraska through northern Wisconsin, bringing widespread rainfall for much of the day Sunday and lingering into early Monday morning. Later runs have stalled it out a bit over the UP of Michigan, but we don’t expect rain holding out through the majority of the day Monday.

This is obviously a very fluid event and you should continue to check back to later forecasts.

4. Friday and Saturday? Yes, for the most part.

Central Iowa Seven Day Forecast

Friday will be a warm and dry with zonal flow aloft. High temperatures will hit the 50s and 60s under partly-to-mostly sunny skies.

Saturday will be warmer, hitting the 70s for much of the state. Cloudy skies expected with limited precipitation chances, primarily for northwest Iowa. Saturday will definitely be the day to get outside before rain chances arrive by late evening (see above section).

Showers linger into Monday morning with cooler temperatures during the week. Monday and Tuesday will see highs in the 50s and 60s with Wednesday dropping a bit with presumed rain chances (see below).

5. Looking toward the long term

Still ways out for these storms, but the GFS shows another couple rounds of rain toward two Wednesday night’s from now (4/10-4/11) and two Sunday night’s from now (4/14-4/15).

The ECMWF is very aggressive with the first aforementioned storm, so we’ve introduced precipitation chances for most of the area on Wednesday. GFS is a lot less aggressive so specific details will need to be worked out (this is at the end of the seven day, after all). Euro doesn’t see out to the second storm quite yet (hello, Goonie period), but something to keep an eye on regardless.

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