Ha! Some of you may be wondering about today’s title. I am going to try to keep it short and simple without going into (much) calculus and skew charts. dBZ stands for decibel relative to Z. It is a logarithmic dimensionless technical unit used in radar, mostly in weather radar, to compare the equivalent reflectivity factor of a radar signal reflected off a remote object to the return of a droplet of rain with a diameter of 1 mm . It is proportional to the number of drops per unit volume and the sixth power of drops’ diameter and is thus used to estimate the rain or snow intensity. With other variables analyzed from the radar returns it helps to determine the type of precipitation. Both the radar reflectivity factor and its logarithmic version are commonly referred to as reflectivity when the context is clear.
When it is raining, snowing or storming I can look at my Radar scope apps and move my mouse around the storm echoes to determine the storms intensity. I don’t get concerned unless the values start to exceed 55. Below is an example of some storms moving through Gladwin this morning.
The color reflected from the radar denotes the intensity of the precipitation. The cross-hairs show 47 dBZ which is moderate to heavy rain. Below are the charts which shows Doppler radar intensity conversions.
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| dBZ | R (mm/h) | Rate (in/h) | Intensity |
|---|---|---|---|
| 5 | 0.07 | < 0.01 | Hardly noticeable |
| 10 | 0.15 | < 0.01 | Light mist |
| 15 | 0.3 | 0.01 | Mist |
| 20 | 0.6 | 0.02 | Very light |
| 25 | 1.3 | 0.05 | Light |
| 30 | 2.7 | 0.10 | Light to moderate |
| 35 | 5.6 | 0.22 | Moderate rain |
| 40 | 11.53 | 0.45 | Moderate rain |
| 45 | 23.7 | 0.92 | Moderate to heavy |
| 50 | 48.6 | 1.90 | Heavy |
| 55 | 100 | 4 | Very heavy/small hail |
| 60 | 205 | 8 | Extreme/moderate hail |
| 65 | 421 | 16.6 | Extreme/large hail |
[/span6][/columns]
When you see the white reflections on the radar there is some serious weather coming.
Steadier rain will come to an end this morning from west to east. A few isolated showers and storms may redevelop this afternoon across Central Lower Michigan drifting south into the I-96 corridor with time. Mostly cloudy skies this morning, trending partly sunny later today. Highs will top out a bit above normal in the lower 70s.
Back to radar: I took a Skywarn Class while in Florida – and the teacher was a real radar-nut (Cool!) He explained that the way a radar system works is that the beam shoots out at horizon level, and makes a full circle; then raises up (5 degrees I think?) and makes another circle; and so on until it has done 13 revolutions; then starts back down in 5 degree increments. It takes 4-1/2 minutes for a full “sweep” of the sky (and explains how “quickie” Michigan and Florida Tornadoes can escape being detected). Of course, the farther you live from the actual radar, the higher in altitude the radar return becomes, which explains how it can be raining at MY house 20 miles away, and not show up on the GRR radar like this morning 🙂 And radar shows EVERYTHING: swarms of bugs or birds or bats – once in a while on a slow day, the GRR folks will show un-edited radar that shows flocks of ducks rising off a lake, for example…..LOL!
My weather station shows 5.58 inches for the month so far – most of that in the last few days of yuck. Everything is soaked: fields, lawns, roads. It was nice to get a brief peek at the sun this afternoon 🙂
Way too much rain. The good news is very little rain the rest of the week!!!!!!!!!!!!
The updated Europeans monthlies would indicate a warm June and July and a cool August with near to slightly above average for the season as a whole. As for precipitation we look to be in-between wet to our SE and dry to our west for our area it looks to be near average. So bottom line is a near average summer season. At this time the confidence level is just moderate
Slim
Not sure when the trees will leaf out along the shore of Lake Superior. I know it is one of the latest locations in the United States. Also for anyone who sill misses seeing snow here is todays picture from Houghton and Mt Ripley. In the past few summers there were snow patches well into June lets see how long they last this year. I will update from time to time.
https://www.mtu.edu/webcams/ski-hill/motion.html
and
https://www.mtu.edu/webcams/ripley/motion.html
here are more web cams from Michigan Tech
https://www.mtu.edu/webcams/
Slim
Thanks for the links.
I love it! I could play in the snow 12 months a year! Only a few more months and the snow predictions will start rolling in! Who would have thought?
Current temp is only 63 degrees! It was a very cool weekend – Friday, Saturday and Sunday all below normal! Quite a stretch especially after the brutally COLD April!
The only three below average days we see for the entire month?
Cool post, Mr. V. I leave the higher math to our daughter. I do my best to help her with her homework, but it is amazing what is available on the internet. You can literally plug in an equation and there are websites that provide step by step solutions.
Getting some light rain here again. Overnight I had 0.43″ of rain with several light thundershowers Current temperature here at my house is 62°
Slim
Great post MV. Looks like we have a nice stretch of great weather. It was foggy here early this morning but it has cleared up. I am hoping the sun comes out & dries things a little bit We have some weeding to do today. Does anybody think it is warm enough to plant flowers in the ground yet?
Yes it looks to be OK to plant. I planted my tomato plants yesterday.
Slim
Thanks. Sounds like it is time to get those too.
GFS starting May 25th has lower Michigan back in the mid 80’s, if not warmer.
The CFS weeklies give us above average temps through the end of June.
If that plays out it will be a great start to the summer season. Lets hope it plays out and stays warm all summer long. Nothing better than a long warm summer. Side note there are several posters on another blog who keep tabs on the current pattern time line and they claim we are on a 30 to 45 days pattern change time frame that could mean a pattern change sometime in June.
Slim
It’s remarkable that both WOOD and The Weather Channel had articles out in April calling for a cold May. In reality, this could be one of the warmer Mays on record.