Joe’s Weather World: Saturday won’t be terrible…but not great either (FRI-5/17)

One of the many things I learned while doing weekend weather for almost 25 years…is to never under-promise rain. My thought process is to be prepared for rain and hope for the best in these somewhat iffy situations. We’ve talked all week about the rain chances on Saturday…so unless it doesn’t rain through the night…this won’t be a surprise when it does rain. The timing though of this mess has been the main issue…and since there are so many outdoor things happening a lot of folks are weather sensitive about tomorrow especially.

I also try and remind you from time to time…our job is to sometimes predict things that don’t exist. The rain that will in time affect the region tomorrow…doesn’t exist now…nor will it today. It won’t come from Nebraska..where strong storms are forecast later today…it will either come from OK and southern KS (it’s not there now…nor will it be tonight)…or it will materialize somewhere in the area tomorrow as the day moves along.

That’s a LOT of balls being juggled and as I’ve told you for days…the timing is the real issue along with the threats of stronger storms. What happens with one will affect the other and since none of this exists yet…there is a lot that can go wrong.



  • Forecast: 

Rest of today: Mostly sunny, windy and warm with highs into the mid 80s

Tonight: Partly cloudy but dry with lows near 70

Saturday: Increasing AM clouds with a few showers possible. I don’t think we have a lot of coverage in the AM on radar though. Then increasing PM chances of storms/rain. Highs well into the 70s

Saturday night: Storms still possible as we watch to see how strong the storms may or may not get

Sunday: Clearing morning skies then partly cloudy…not too bad of a day…cooler and blustery with highs well into the 60s



  • Discussion:

As you know the Saturday dilemma has been front and center of the blog all week long. You know that. Here it is…Friday afternoon and there are still forecast issues…mostly because of the fact that whatever is going to affect us doesn’t exist on radar and won’t for hours to come (notice how I keep bringing this up).

Typically we use computer models to sort of “guide” us through the day…and that’s what we show you nightly. Always remember that those models are flawed for various reasons and as we’ve said time and time again the timing is the main issue not whether or not it will rain at some point. We’ve had a 80-100% chance of rain now for Saturday for a couple of days…it won’t rain 80-100% of the time though as a matter of fact as I mentioned on Thursday there will be hours of dry time between rains that come through.

Here is what I’m thinking right now…the better coverage of rain should be towards the later morning hours…the early AM hours (through 9AM) may not be too terrible from a rain standpoint.

The near lunch onwards through mid afternoon rains are tied to what happens towards daybreak towards OK. Assuming some sort of wave develops there…it would tend to come NNEwards towards eastern KS and western MO. That would be rain chance #1. Some may not get much from that…before noon Saturday

Then that wave goes by at some point in the afternoon and again there may be a few hours of drier weather or at least less overall rains…and the issue then becomes whether or not storms develop or not. After the 1st wave goes by…there should be some sinking air…that would tend to stabilize the atmosphere for a few hours…then we look to see if things get more unstable or not.

Rain chance #2 is after 2-3PM in the afternoon into the evening. Storms are possible…whether or not they are severe remains very much to be seen…by no means is that set in stone though. That one will be played by ear. There may be pockets of instability worth watching toward the south of the Metro in the evening and overnight but again all this will be determined by the rain that doesn’t exist till tomorrow.

Then there may be residua storms/rain into the wee hours of Sunday before drying out towards daybreak and then everything moves away.

Some areas may see 1-2″ or rain…others may get less than 1/3″. Who gets what again is still somewhat of a question.

So let’s step back for a second and try to wrap our minds why this is so complicated. The model data tomorrow is sort of not sure where exactly the best areas of “lift” are going to set-up…and one issue is that IF they’re wrong at time A that will ripple through the rest of the forecast through tomorrow night because everything is connect with everything else.

For example…10AM Saturday…looking for “lift” at around 18,000 feet to get storms/rain to form or maintain themselves as whatever comes NNE.

Use the slider bar and go left and right…see how the main areas of “lift” are in different locations…that affects where potential rain/storms set-up and to a certain extent the coverage as well.

Now 1PM…

Notice how the NAM model starts generating a crazy amount of lift in localized areas…this is what we refer to as “convective feedback”. The model sees storms and blows things up in the atmosphere and this can contaminate the model for hours afterwards.

Now 4PM…

Oh boy…the NAM has a wave moving away…as a matter of fact it has a dry evening locally because we’re in the sinking air behind the late AM wave. The GFS isn’t as convinced on that…and it would have more rain going through the afternoon and evening.

Other models that I’ve looked at are also all over the place.

The higher res NAM model…which might fare a bit better in this convective scenario…shows this much rain by 9AM…

Then by 7PM…

finally by 1AM Sunday…

Some of those high end totals are probably overdone towards Topeka. There will be a risk though of heavy rains with any of these storms…and again 1/2″-2″ is possible for parts of the area…

The severe weather issue will be dealt with tomorrow morning in the blog…this thing has gotten too long already.

I wish we could have 100% confidence in every hour of the day tomorrow…but right now we can’t. Again that whole predicting things that don’t exist issue.

Our feature photo comes from ‎Taylor Petzoldt‎

Joe

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