Joe’s Weather Blog: Widespread severe threat decreasing

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9PM Update: This is turning more into a heavy rain threat for the KC area than anything else. The severe weather just can’t get it’s act together locally because the atmosphere was worked over so much this morning. We’re seeing storms now in the area but at this point they are not severe. There are still some feisty storms between Emporia and Wichita. A severe thunderstorm watch has been issued from the I-70 corridor southwards until 2AM

The most unstable air is still down in south central and SE KS…odds favor IF there are any severe storms, for them to be south of KC proper…perhaps from a Clinton>Butler>Ottawa and south line.

The main concern tonight locally appears to be the potential for localized flooding as a mass of rain moves into the region. This will continue for several hours before slowly tapering off in the morning hours Wednesday. There is the potential of 1-4″ of rainfall overnight…our latest short term model (HRRR) indicates lighter totals east of the metro with higher totals west of the metro…keep an eye on the regional radar below to see what’s coming up from the Wichita area. There have been some reports of hail with the cells on the north side of KC at 8:48 PM

hrrr_t_precip_kc_16

HRRR total rainfall forecast. Note the lighter totals towards central MO

As I’ve mentioned time after time…these scenarios that were laid out for you always throw something weird at us it seems. So far (through 9PM) there have been 2 reports of tornadoes. In Oklahoma a PDS tornado Watch was issued. That is a “rare” thing. Only 3% of all tornado watches are PDS watches. They’re issued when the expectations are for more tornadoes (quantity) and a ratchet up in intensity potential. As of 9PM…NO reports of any tornadoes have been indicated down there although there are a couple of tornado warnings still in effect down there.

 

We’ve already had quite a few severe weather reports in NE KS and parts of western MO this morning with wind gusts to 60 MPH or so and hail upwards of golf ball sized in some areas. More on that in the discussion. For the next few hours the storms will be moving out of the viewing area (see radar) and some leftover showers will persist till noon or so around the KC area before winding down in the early afternoon. The complex of storms has left behind a cool and stable air mass at the surface. I will be watching to see how far south this stable air mass goes as the push to that cool air mass will slow later this morning. It’s important because it may play a role in severe storm chances tonight locally. Also it may play a role in the types of severe storms tonight we see too.

Forecast:

Tonight (9PM update): Scattered showers early this evening coming up from the south will be weakening as they move our way through 7PM. Activity out towards Wichita will be moving towards the region later this evening…probably after 9PM. Be alert for the potential of flash flooding as well tonight…especially towards and after 10PM in the area. Lows in the 60s. Another note…the air above the immediate KC area is still stabilized somewhat from the morning complex of storms. The rain/storms to the south and west of KC prompting several severe thunderstorm warnings are weakening as of this typing as it moves closer to the KC area. Areas south towards the better instability though need to pay attention to whatever forms…this would be from roughly Butler>Ottawa>Topeka and southwards. More in the discussion.

Wednesday (4PM Update): Variable clouds with another chance of thunderstorms in the afternoon. Highs 70-75°. The storms in the afternoon may be severe with hail the main threat. There may be some ability for the PM storms to show low level rotation as well, especially in N MO…this will need to be watched too. This is what we call a low topped supercell set-up and yes you can get tornadoes with these types of set-ups…again the better chances may be up towards N MO and NE MO of something like that.

Thursday: Calmer with highs in the 60s.

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Discussion:

OK for those who don’t want to read this part of the blog I understand…here is radar to watch and you can call it a day ;).

For the other 95% of you who want to get into the weeds with me and read my ramblings…here we go. You may want to clear your schedule for the next hour or so…just kidding…I think.

5PM Update: Storms have been firing up towards the SW of KS and some pretty big storms are going right now from Topeka westwards. These storms are producing torrential rainfall (localized flooding out there). They may also be producing some hail as well. Just got a report of near to larger than golf ball sized hail in the Manhattan area.

The interesting aspect to this situation near and west of Topeka is that the more storms there are the higher the flooding risk…and the lower the tornadic risk due to all these various storm interactions.

For KC I’m watching a boundary to the south of the area. This is the outflow from the morning storms that essentially pushed to the southern and SW fringe of our viewing area. It has stopped and may be retreating northwards just a bit. Remember we have rain cooled air on top of the KC area…as a result the activity to the south of here is falling apart as it approaches KC…this is what I’ve expected.

Our next concern though is for the activity out towards central KS. I’m now comfortable with the timing of our short term HRRR model that will update for you automatically showing the next round of storms moving in towards 9PM-12AM or so

The main threats appear to be gusty winds/some hail/and torrential rainfall…a Flash Flood Watch is in effect for the area overnight.

Remain weather aware…but at least some early evening plans will be OK in the KC metro and especially up towards the north and northeast of KC

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The storms this morning played out somewhat as expected. It took a couple of extra hours for them to form but they did and they packed a pretty good punch. There have been some scattered power outages and quite a few reports of 1″+ hail. Parts of NE KS as well as the Liberty/Blue Springs area seemed to get in on the larger hailstones…golf ball sized hail has been the largest report on the MO side..while a 2.25″ hailstone(s) fell in Lancaster, KS in Atchison Co.

This was a fascinating morning to watch the 1 minute satellite images come in. I want you to look closely and see IF you can make out the outflow boundary that was pushed out from the storms…can you see it moving south?

As of 11AM the boundary appears to be slowing down and setting up near the Emporia and Salina area. That’s important because that boundary will probably be a focus for where the air is more stable initially later today and this evening (to the north of the boundary) and where it’s MUCH more unstable (to the south of the boundary). One way we’ll be measuring this is by looking at the CAPEs. CAPE stands for Convective Available Potential Energy. BIG numbers means the atmosphere has more instability that can be tapped as thunderstorms form and potentially explode into severe storms.

Here is the CAPE situation…from around 10AM this morning…I wanted to show you this because thanks to the thunderstorm complex that moved through the KC region…the atmosphere as been exhausted of instability in our area…for now. Notice already in OK the CAPE values (red contours) are VERY high…that is a powder keg of instability sitting there…waiting. Blue shaded areas show where the atmosphere still is capped to a degree. Notice as well the push of the red contours up through central KS towards the Salina area…

Capture

CAPE values at 10AM

Now I want to show you the latest CAPE map…

 

What should happen as the afternoon and early evening plays out is that new convection should fire out towards the west of the KC area towards central KS and southwards. This convection could have some REALLY big hailstones with it as it progresses ENEwards and interacts with all the big CAPE values (instability being released). Initially there may be some tornadoes especially near the I-70 corridor where that outflow boundary resides west of Topeka. The threat of tornadoes will extend southwards as well. There may not be a ton of them…but there are some indications there could be a couple of larger than average ones.

This area of storms should evolve over 3 hours into a larger area of storms that will move towards the state line later this evening. Typically when this happens the tornadic threat drops but the wind and hail threat continues and at least from a wind standpoint even can increase as gust fronts are generated.

Here is a look at the region radar…

So at this point I’m timing out the next risk of severe storms to be later tonight here in KC…probably after 9PM or so. Maybe later. With that said…should anything fire up earlier and closer to the KC area (and some of our short term model data shows this potential) we potentially could see severe weather earlier in the evening. IF that occurs there are some indications that the potential of rotating storms (and maybe an isolated tornado) might exist closer to the KC area…perhaps towards NE KS. This will be watched closely by me and the team. One key to that will be how the outflow boundary to the south of us tries to retreat northwards this afternoon. IF that boundary comes up to the I-70 corridor closer to KC…then that would be concerning! It should be noted that this particular model is already having troubles with the placement of this boundary. It’s already 4 counties off with the placement of the boundary (the model thinks it’s north of KC when in reality it’s towards Butler at 11AM). I bring this up because when the model data isn’t verifying a couple of hours after issuance..then the run to me is suspect. Let’s see if the model can catch the reality of things later this morning.

There are many other things I can write about including the dry line set-up in central KS through OK. Storms may fire with that feature as well. The wave that’s going to help this whole process along is moving through the SW part of the country now…and will be coming out into the SW Plains later today.

You can have all the instability in the atmosphere you want…but you still need some sort of trigger to get the atmosphere “fired up”…and that is what this wave should do as it comes out into the Plains.

There are many complications and twists that will happen…they always do with these situations. There are almost always things that happen that leave us to scratch our heads a bit. So I leave you with this…the latest SPC forecast for today and the current watches…

 

 

Additional blog updates will be coming out later this afternoon and probably tonight as well.

Have a great day and continue to monitor the weather and be weather aware. If I was storm chasing today I’d be on the road towards Salina,KS right now.

Joe

 

 

 

 

 

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