Joe’s Weather Blog: Upper level storm=bad weekend (FRI-4/28)

A rather dreary Friday but “most” of the rain is done for now as clouds are going to be an issue from now into Monday, if nothing else. Meanwhile flooding rains are all but guaranteed for the southern reaches of MO into N AR and perhaps even into parts of OK as well. Be aware of that threat over the weekend down to the south. I still expect the heaviest amounts of rain to be well south of KC.


Forecast:

Tonight: Misty drizzle at times but the steadier rain won’t come back into the region again till Saturday morning…so the Royals game will be “OK” but cool. Temperatures tonight will drop to near 50°

Saturday: Off and on rain (with some heavier downpours). Not a nice day with highs struggling to warm up much at all. With north winds blowing…odds favor highs only between 50-55°

Saturday Night: Interesting. Depending on where the surface low tracks (it will be coming north out of southern MO) we may see rising temperatures overnight>lunch Sunday briefly before the temperatures start falling again later in the day. See the discussion part for a path for us to get into the 60s (very iffy).

Sunday: Off and on rain (overall lighter). Again temperatures won’t go far with highs in the 50s but potentially seeing a drop in the temperatures as the winds switch back towards the NW


Discussion:

A big thank you to the folks out in Richmond, MO. Talked to a group of folks last night about my pet project concerning the overuse of severe thunderstorm warnings.

Our weather is going to be rather interesting over the next several days. A rather potent upper level storm is going to move through the Plains states into the upper Midwest early next week. This will create LOTS of rain…some rain…and even accumulating snows for the Plains and the Rockies. The snow aspect will be interesting to track through W KS into central and W NE. The dynamics of the system will be able to chill the air down in that area enough to convert the rain to heavy wet snow on the last day of April.

For this region…the main concern in the flood potential down across southern MO. All of southern MO is under a Flash Flood Watch for the weekend…you can see the scope of the watch but the areas highlighted in green in the map below. You can see the winter advisories/watches/warnings out west

Locally here are the latest watches/warnings from the NWS in Pleasant Hill.

The darker green counties are under a watch…while the lighter green areas represent the flood warnings…as of this writing all for some of the rivers/creeks that will flood over the weekend. Notice as of this afternoon…no watches/warnings are in effect for the immediate KC metro area.

In terms of how much rain is expected in the KC area I still expect 1-2″ overall for most of the region. Rainfall amounts down towards the Lake Of The Ozarks will be in the 2-5″ range with some locally higher amounts possible in southern MO. I should mention the the NAM model has the heaviest rains in the KC region as opposed to southern MO…I’m discounting this model.

Here are the differences between the GFS and the NAM model in terms of the forecast rainfall.

Again I’m NOT expecting the heaviest of the rain to be in the KC area…

I’m also NOT expecting severe weather in our area through the weekend. With that said there is a weird way though that something could happen on the MO side east of the KC Metro…and that would depend on the timing off the surface low drifting northwards towards western MO. Assuming it passes well NE of here Sunday AM…we’ll be fine…but IF it lollygags around and is in the immediate area Sunday afternoon and IF we can get some weird breaks in the clouds and IF we can warm up a bit more than expected…there could be a path where a storm could form closer to KC than what would be suggested. With a warm front dangling from the surface low…something “strange” could evolve. There are a ton of IFs in this paragraph and IF the surface low is in N MO…than this won’t be an issue at all (which is most likely).

On Sunday the upper level low will be wallowing around. I should take a step back and mention what we’re talking about. Basically an upper level low is a pocket of colder temperatures aloft. For the purpose of this…let’s show you the GFS model as we step through a few periods.

See that pocket of -25° air (we’re looking at roughly 18,000 feet up in the atmosphere) along the AZ/NM border…that’s our upper level storm

Now let’s step forward…

This map is for 7AM Sunday…now it’s in the TX Panhandle

Finally 7AM Monday…

Now it’s towards the I-80 corridor near Des Moines

So that cold pocket of air aloft…combined with “warmer” near ground temperatures creates “lift”. This lift turns into clouds and showers which will be an issue here, at times, Sunday and Monday.

So that’s the upper levels…at the surface things react differently. There will be a surface low in southern MO that will move northwards later Saturday night into Sunday. What’s interesting is that there are some suggestions that some of the warmer air down to the south MAY come to KC briefly Sunday AM>Lunch or so before it’s swept away from the area in the afternoon as the winds switch towards the W or NW. As a matter of fact the EURO model has the surface low near St Joe by 1PM Sunday…which would allow a brief surge of 60s to come UP the state line in the morning Sunday lingering into the early afternoon.

Look at the EURO forecast for 1PM Sunday…

See how the warm air pinches into the KC area…then by 7PM we’re tanking again down towards 50° or so.

That’s the rub…and why I wrote that paragraph of IF’s earlier. IF that surface low is in N MO later in the day…with a warm front up there too…I just wonder.

OK so that’s a lot of writing about this storm…the bottom line is Saturday looks worse than Sunday. The Royals should be OK tonight…very iffy Saturday night…and somewhat iffy but perhaps doable on Sunday. Make you’re plans accordingly.

Our feature photo comes from Joan Buie Thornbrugh up in Lawson, MO.

Joe

 

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