Rain Prospects Increasing (Finally)

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It’s no secret that the rainfall yesterday wasn’t exactly the most generous for the region, but things are finally looking up as we finish off the month of April. There are several things that will make the forecast rather tricky for the next couple of days including 1) the progress of a stalled front across the Ozarks area and 2) little disturbances that will create overrunning over that front and enhance the lift (rising motion) of the atmosphere allowing for the potential of some decent to significant rain to come in waves into MON AM, if not longer than that. There is also the matter of an 3) expanding area of heat that will encompass the middle part of the country and how much of that heat makes it to KC. In addition to that, 4) as the landscape gets greener and greener and the trees now have leafed out in full, will that help to knock a couple of degrees off the potential highs because our surface now is green instead of the brownish landscape we’ve had through the winter months. So much to ponder.

Let’s deal with the 1) the front first. here is the latest surface map. I’ve drawn in the front as stationary as depicted by the alternating blue/red lines on the map. In reality the front may still be moving southwards a bit (really a cold front) but that will stop sometime this evening and the front will become stationary.

South of the front the moisture from the Gulf Of Mexico is slowly increasing at the surface, although aloft there is still a lot of dry air down there. Later tonight as a weak disturbance moves through the Plains states, it will help to generate a weak low level wind flow at around 5K feet or so, from the south to the north. These winds aloft will “overrun” the stalled boundary down towards the Ozarks and allow the air to start to rise the farther north you get. Think of walking up a mountain. The air particles are going uphill and rising. As they do so they cool and the moisture condenses out. That process produces clouds and potentially rain and t/storms IF the air is rising fast enough.

So let’s talk about 2) little waves that will help to create the “overrunning” conditions. As these waves move through the flow, and as long as that boundary hangs around, the conditions will be ripe for rain/storms to form north of the frontal boundary. Here is a look at the water vapor shot of the Midwest. There are waves already showing up and while the timing of the waves will be tough to figure the conditions warrant the chance of storms/rain for Sunday.

As long as the boundary is where it is and as long as there are these little disturbances moving through…the rain chances are there somewhere. Here’s the thing though, these intervals of rain and their geographic coverage will help to move the boundary in various areas and ways influencing what happens the next time a disturbance comes across. This will then focus the rainfall in a different area or depending on the intensity of the wave and corresponding intensity of the low level wind flow over the boundary, the coverage of the rainfall north of the front. So many things to consider and the models will have a difficult time figuring things out. The bottom line will be a chance of rain for a couple of days, but typically when these things happen the rain doesn’t last all day long so there will be dry hours in there, perhaps many dry hours.

Today, there is no doubt that the GFS is going crazy depicting the amount of rainfall in the region with a bulls-eye of close to 5″ over the next 5 days.

The EURO model seems a bit more realistic through Thursday AM…but still shows some generous rainfall amounts.

The latest NAM model, which will have varying totals over the next 24 hours shows a healthy 1-2″ rainfall amount through the region through Tuesday evening.

This to me looks pretty reasonable.

There are also strong signs that we’re going to heat up quite a bit after the rain shuts off towards the middle of the week. Here are the 5K temperatures forecasts for later TUE into WED.

Those are maps every 12 hours starting late MON in the UL and late TUE in the LL. The REDS are signs of the heat that will be expanding across the Plains states.

How hot it gets may in part depend on A) the moisture in the ground and B) the green of the land, the latter is assured the former is still a bit of a question, but one thing for sure, it will be getting more and more humid I think as dewpoints get into the 60s. That means the overnight lows are going to stay pretty mild as well. It may stay pretty toasty around these parts into next weekend!

Enjoy the rain, we do deserve it, although you might want to have a plan B ready for tomorrow (Sunday)

Joe

Kansas City Weather News

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