An Active Seven Day: Fog, 70s, Rain, and… Snow Potential?

In Evening Brief by Henry LukerLeave a Comment

Happy Thursday. We’re one day closer to the weekend, and we’ve got some marvelous weather on the way for you on Friday and Saturday.

1. Dreary Thursday

Satellite from Thursday Afternoon (4/4/2019)

Regardless of whether you saw rain today, the best word any single person in the state could use to describe the weather today would be “dreary,” with overcast conditions still the predominant story from border-to-border. Ceilings sit under 500′ feet in northwest Iowa and under 1000′ southeast, while those in the middle still are overcast, but at a few thousand feet.

High-resolution models last evening did a terrific job with the main band of rainfall sitting from Decorah through Denison. Amounts generally a few tenths along that area, with Fort Dodge clocking almost a half inch at .46″ Southeasterly winds have tamed west of Interstate 35, while easterly winds east of there still range at 10-15 MPH. Winds gusted to 20-30 MPH today keeping wind chill indices to the north relatively cool (around the freezing point at noon in Mason City), with Cedar Rapids topping that leaderboard at 1:15 p.m. with a 38 MPH gust.

2. Foggy Night

Visibility at 10:30 pm

The calm winds combined with today’s rainfall and some boundary layer advection has already put some fog over northwest Iowa. Visibility at 10:00 p.m. is at a quarter mile for Council Bluffs, Denison, Harlan, and Storm Lake, a half mile in Le Mars, and at three-quarters of a mile in Cherokee and Sheldon. Expect further reductions as we head toward this evening.

Temperatures sticking to the upper-ranges of model guidance overnight tonight with cloud cover sticking around statewide. Lows will bottom out in the upper 30s northwest to the mid-40s southeast.

(Note: a dense fog advisory was issued for portions of northwest Iowa just prior to posting this; runs through 10:00 a.m.)

3. A Well-Earned Dry and Warm Friday

Finally a forecast that we can say is relatively quiet. Expect some patchy fog continuing through the mid-morning hours with mostly cloudy-to-overcast skies for most of the morning. Clouds should clear out for most of the afternoon and early evening. The best part: high temperatures will hit the 60s almost everywhere, nearing 70 in southwest Iowa.

Lows on Friday night will be in the mid-40s to low 50s with cloud cover lingering. Rain chances exist for areas west of Interstate 35, but the bulk of this will be in northwest Iowa where thunderstorms are possible. I don’t believe that area has seen a storm yet this season, so you may be in for a treat if you’re a fan. The WPC currently has about half an inch of rain for that area, so in case you were ever worrying about drought anytime soon…

4. Rain Sunday Night

Seven Day Forecast
00z NAM12 Output from Saturday Evening to Monday Morning

Rain chances are still in the picture for Sunday, but not as much as we initially thought. The entire state should still receive about a tenth of an inch with some areas receiving up to a half inch, but precipitation will be scattered in nature for the most part, at least until evening over eastern Iowa (though in the form of lighter rain). Temperatures will still sit in the 60s statewide.

5. Potential Storm Next Week?

There’s been a lot of “talk” already regarding a storm expected to impact the region towards next week. Let’s take a step back and be realistic about what we can speak confidently about for now.

What we know: Models have come into a surprising model-to-model consensus for most of the major runs recently (00z, 06z, 12z, 18z) tracking a trough (currently just a wave of energy in the western Pacific) towards northern California, undergoing cyclogenesis as it approaches the Upper Midwest. This is meteorology-talk for a deepening upper-level low pressure system, usually with large amounts of precipitation and strong winds.

The 500mb charts from the 12z GFS and Euro, respectively, in the bottom of the images above show the aforementioned closed low over western Iowa Iowa on Thursday morning. On the top are the surface pressure and precipitation, also showing a surface low nearby driving that part of the environment. The one location difference is that the Euro is much more aggressive on centering the low over Des Moines, while the GFS pushes things farther northwest. Again, these are just a pair of models on a single run, but general consistency on the idea of this solution has remained for much of the day.

All of this activity is pinned to begin Wednesday night and continue into much of the day on Thursday. The one thing you notice on the GFS surface image is the prevalence of snow on the north part of the system. This is what most people have been “freaking out” about today. But yes, models have been painting snow, potentially significant, on the northern side of this system. With windy conditions, anything that falls will easily be blown around.

However, it is way-too-early to even speculate on totals, where the heaviest snow will fall, etc. There has not been a lot of consistency on that note, and with temperatures being around freezing for a time, a rain-snow line at play, and other meteorological variables, this will end up being a tricky forecast. So much can and will change, especially as the wave moves over land and radiosonde sites that provide valuable information on these disturbances.

Be smart: As of this forecast, this is at the very end of our operational forecasting period (seven days). Models just began to come together on this today, and future runs (especially tonight at 00z) will continue to put the pieces together on this storm. There’s been a lot of hyperbole out there about a “major blizzard” or a “winter storm,” which isn’t out of the question, but at this point is simply way-too-early to call. But keep an eye on it.

The bottom line: At the very least, precipitation can be expected on Wednesday (mostly rain during the daytime) into Thursday. The best chance for any wintry precipitation will be Wednesday night into Thursday morning over northern Iowa. We’ll continue to monitor this very fluid situation closely; make sure to check in for updates.

6. And Beyond

The Climate Prediction Center’s forecasts are right. Our April is going to be a wet one.

If the Thursday system holds out, the end of next week and the weekend could shape up to be a cold one with snow pack and high pressure keeping the 30s and 40s around. It also shows another low sweeping some additional precipitation nto the region on Sunday and Wednesday. 40s and 50s return by mid-week with 60s by the weekend. Mindfully, this is very much conditional on the Sunday storm with a complete lopsided change possible. But active weather seems to be the trend as we look out towards next week.

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