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NICE WHILE IT LASTED...

After a long winter, spring officially arrived Sunday and it lived up to its billing with two absolutely beautiful days of weather. Monday was the warmest with my entire area in the 70s. Iowa City peaked at 77 and at the NWS Quad Cities site the mercury reached 76. That is the warmest day there going back to October 10th when the high reached 80 (a total of 172 days). Readings like that are a good 20-25 degrees above normal. It was splendid!

As the saying goes, all good things must come to an and so it is for this batch of fine weather. You can already see a large moisture laden spring storm advancing on the central U.S. thanks to the GOES infra-red satellite image Monday night.

This storm has the characteristics of what's known as a cut-off low. In the animation below you can see the "bowling ball" like feature in Texas that gradually rolls northeast through the Midwest where it merges with another piece of energy dropping into the mean trough from the north. The slow moving system will take 3-4 days to clear the region meaning we've definitely seen the best of this weeks weather.

With a system like this, the vorticity (energy) comes in waves or spokes around the storm center. These enhance rainfall as they rotate in a counter clockwise direction around the slow moving parent low. One of these has entered the area overnight and will weaken and lift out of the region during the morning, allowing the rain to diminish and perhaps end in the afternoon, especially from the Quad Cities southeast. That little punch of dry air will likely allow readings to warm into the mid 50s north to the low 60s south Wednesday. The HRRR show this.

The center of the storm will drift towards SE Iowa Tuesday night and be centered near Keokuk Wednesday morning. Additional spokes of energy will reinvigorate the rains at times Tuesday night and Wednesday. At this point winds are now turning in from the east/northeast starting to pull in colder air, especially Wednesday when readings will hold steady or fall into the 40s in all areas Wednesday afternoon.


By Thursday morning the storm has only progressed to southern Lake Michigan and cold unstable air is continuing to lower temperatures and generate periods of light rain. It's even possible that some wet snow gets mixed in as the cold core of the upper low sets overhead. If any snow can works its way to the surface amounts would be minimal (if at all). The GFS and EURO show this for snow amounts.


The EURO

The GFS

The long duration of precipitation should mean the area sees another beneficial rain which helps alleviate the dry conditions that have developed since last fall. There are differences in the placement of the heavier rains which is tied to how models track the storm and estimate its intensity. No matter what model you look at, most of my area is in line for another 3/4 to 1 inch of rain. The EURO indicates these amounts.

The GFS shows these totals.

12K NAM

One thing is for sure, temperatures behind the system will be nowhere near what we enjoyed Wednesday. Highs Thursday will be stuck deep in the 40s and unless it's in the south, may not reach 50 Friday. Saturday and Sunday also look chilly with highs in the 40s north to low 50s south.


The next significant wave of rain is not likely until next Tuesday or Wednesday (days 7 and 8). Overall, we are in what's considered an" active wave train" and that means above normal precipitation is expected over the next 2 weeks. The GFS shows this for rain through April 6th.

The EURO indicates this for rain totals through April 5th.

The 8-14 day outlook from the Climate Prediction Center also shows above normal precipitation and temperatures that are close to normal for the period ending April 4th. Pretty high confidence in this verifying.

I guess the big take away from this post is the party is over for the exceptional weather of the past two days. Damp weather is on the table with steadily cooling temperatures the next 72 hours. Into everyone's lives a little rain must fall, and it will in our world the next couple of days. Roll weather...TS

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