Joe’s Weather Blog: The subtleties of forecasting heat (FRI-6/29)
Good afternoon…and happy TGIF. This has been another hot week (mostly in KC) and next week, while not to the extreme I don’t think…will still be hot and above average. As a matter of fact the only day that looks to be close to seasonable is Sunday. That will be dependent on the extent of clouds though. There are other subtleties about next week that I want to write about as well.
Tonight: No real changes…lows in the 75-80° range
Saturday: About the same with highs 95-100°.
Saturday night: Tracking storms across NW MO and NE KS sagging southwards. How long they hold together when they approach KC late at night into Sunday early AM will determine how much rain we get. For now amounts may range from nothing to about 1″. Areas farther north should do better though.
Sunday: We should see quick AM drying then variable clouds. More sunshine and we’re closer to 90°…more clouds and we’re about 5° cooler or so.
Another roasty…toasty day out there…the temperatures are in the mid 90s for many and some are closing in on 100°. The title of today’s blog refers back to this tweet I sent out this morning…
Meteorologists wrangle over the subtleties of forecasting temperatures. Some days more than others. Today was one of those days (at least for me). There are subtle differences today compared to yesterday. Here is a look at the last 36 hours of temperatures…I’ve highlighted the items to write about.
The data is for KCI…the “official” KC weather station of record
Look to the far right…see the 99? that’s yesterday’s high.
Look at the bottom number highlighted in blue…that is the 2PM temperature at KCI…now look to the top highlight…that is the 2PM temperature as I start this blog. We’re one degree hotter at 2PM today compared to yesterday.
Now look a the dew points yesterday (75°)…now at 2PM today…69°…that is actually a pretty significant drop (7°) and as a result the heat index today is not as “hot” as yesterday. At 2PM it “feels like” 102° while yesterday with the higher dew points and the “less one degree” temperature the heat index was 107°. So there is a 5° change just basically because of the lower dew points.
Notice as well the increase in the winds today…yesterday SW at 9…today SSW/S gusting to 25-30°. That signifies more stirred up air and what we refer to as “mixing” and that means temperature could be hotter today…it also allows the air to dry out a pinch…hence the lower dew points.
So I was all ready to jump on the 100° bandwagon for the noon show…then I checked the temperature of the air just above the surface this morning…and it was running more than a few degrees “cooler” than yesterday…that gave me pause for pulling the trigger.
So in the end I’m agonizing over whether or not today will be 98°…99° or 100°. The subtleties of forecasting intense heat in KC.
I stuck with the 99° forecast. Let’s see where we stop. I’ll be irritated IF we hit 100°. 1) because I didn’t pull the trigger and 2) because it hasn’t happened since 9/2013!
Next week will be interesting. I sent this tweet out yesterday afternoon in light of the dust I was observing moving through the Atlantic Ocean. This is pretty common as dust streams off the continent of Africa and follows the winds aloft.
Notice the murky “brownish” shading…that is African dust…most prevalent near the coast of Africa…it disburses as it travels eastwards. I brought this up because, despite all the heat and humidity today, we actually have some decent blue skies out there…I wonder though IF next week that may change a bit.
Notice that dust has already moved into eastern TX…
Some of that dust is already in the western Gulf Of Mexico and will be streaming up towards us over the weekend…then perhaps get shoved back south…then come back north. We have models that can forecast the extent of this type of “aerosol”.
This model forecast is for next Tuesday at 7PM…the greenish areas are the thicker “haze/dust” but notice there is some “thinnish” dust moving through our area. The reason why I bring this up is I’ll be curious IF the skies aren’t quite as vibrant blue next week as they are today. IF not, assuming there is no cloud cover…it might be because we have some African dust moving through the Plains!
Onwards to the rain situation.
I’ve written about this since before the models were really indicating anything…and that would be the storm/fading rains heading our way during the middle of the weekend.
Nothing has really changed with regards to this…we still have decent+ chances of rain BUT the issue is how much we get before things sort of peter out in the cooling atmosphere. The front now is across the northern Plains…
Ahead of the front 90s/100s are prevalent. That front will slowly move towards us over the weekend. Storms will ignite tomorrow towards the NW of KC…and some may be severe too!
The issue for the Metro is that the storms will be on a declining trend (I think) when they move towards us…probably near or after 9PM-12AM. IF they can organize better and IF then can create some sort of cold pool and IF they can then surge more southwards…we might have something more to talk about…but that is a lot of IFs.
It’s not out of the question for this to happen.
Again the issue is the later this occurs the less instability will be left for the storms to feed off of. The atmosphere will be pretty swollen with moisture though…so IF we can get some slow movers there may be some locally heavy rains…
A lot of caveats for sure…but DON’T be surprised IF parts of the region are under a Severe Thunderstorm Watch later Saturday.
The blog will be updated during the afternoon.
Our feature photo comes from Mary Jo Seever…out in Cummings, KS in Atchison Co