Got to enjoy some pretty nice weather this weekend in the KC area…lots of sunshine and pleasant (near average temperatures). The story for this week will be the up and down temperatures…we should be in pretty good shape (still cool) through Wednesday but then colder weather is on tap for 48 hours before we rebound again over the weekend.
There is actually a chance of seeing some flakes of snow on Thursday associated with the next shot of colder weather…and the models are sniffing something towards Veterans Day that I’ll pay attention too. No signs of any big storms though…perhaps just more casual flakes.
Today: Cloudy skies with perhaps a few sprinkles. Highs in the 50-55° range
Tonight: Clearing out and chilly with lows in the 30-35° area.
Tomorrow: Mostly sunny and cool with highs in the 50s
Wednesday: Could be a bit warmer with highs near 60° ahead of our next front with more sunshine
We’re starting the day with a lot of clouds in the Plains region…these clouds will be gliding through the skies during the day today. The models have been trying to generate some rain from this mostly mid-level moisture for the last 18 hours or so but I”m pretty skeptical of anything but perhaps some sprinkles. This is one of the days where radar will be detecting falling raindrops aloft…farther from the radar site but in reality little to nothing is actually reaching the ground.
This occurs because the radar beam, as it goes farther from the radar site…goes in a straight line…but since the earth is curved…the beam starts to hit the clouds higher in the sky.
This gives you a rough idea how far away the beam gets..then how high up the beam is shooting in the atmosphere.
25 miles = 1800 ft up
50 miles = 4500 ft up
75 miles = 8100 ft up
100 mlies = 12,600 ft up
125 miles = 18,000 ft up
150 miles = 24,300 ft up
175 miles = 31,500 ft up
200 miles = 39,700 ft up
This is one of the reasons folks up in northern MO and NE MO are sort of in this weird black hole when it comes to radar coverage. By the time the beam gets towards the IA border from Pleasant Hill, MO…it’s up there at close to 9,000 feet! We don’t see what’s happening below that altitude.
So here is radar from Peasant Hill…
Now when you see precip detected…you have to confirm this through the radar in Topeka…
For the situation today…what you see on one radar MAY not be confirmed on the other radar…
The reason is that most of the drops falling are evaporating before they make it to the ground…we call this VIRGA.
Simple explanation why…and to explain that we need to look at the balloon sounding data from the morning taken at Topeka.
As the balloon goes up through the atmosphere it’s taking a variety of weather observations…and relaying that data back to the ground.
In the snapshot of the atmosphere below…the red line is the temperature trace and the green line is the dew point trace. For the purpose of this discussion…the closer the lines are together….the more saturated the air is…the father apart…the drier it is.
The blue numbers on the left are the pressure of the atmosphere expressed in millibars…somewhat more complicated. For the purpose of this though…850 mb is about 5,000 feet…700 mbs is about 10,000 feet and 500 mbs is about 18,000 feet.
So the air above us dries out considerably at around the 700 mb level…around 10,000 feet…and lo and behold when I looked at the KCI cloud observation just now…the base of the clouds is around 11,000 feet up.
What all this means is that the rain drops…but really snow flakes above us that are there…indicated by the saturation to the left of the freezing line are evaporating as they fall through the dry air (for the most part) below 10,000 feet. So as long as that dry later below 10,000 feet holds…it will be tough to get a lot to actually make it to the ground itself.
So now you know…
It will be a subject of conversation through the winter season…especially with weak storms and weaker winter scenarios.
The snow scenarios that I mentioned to start the blog are weak set-ups. Thursday colder air will seep into the area early in the day…IF there is some remnant moisture hanging around there could be some snow flakes…not overly concerning.
Then we’ll watch Sunday into early Monday early time frame as another strong cold front may come into the area…we’ll see if there is any moisture for it to work with with the cold air coming in.
VERY iffy for both scenarios and really just something that I’m watching right now.
Our feature photo comes from Bill Patterson out in Lyndon, KS